Implement checking observe declarations (#6709)

This adds SemIR structs and implements building `observe` lists, as well
as naming, formatting, and importing `observe` declarations.

---------

Co-authored-by: Dana Jansens <danakj@orodu.net>

toolchain/check/testdata/interop/cpp/basics/import/cpp_namespace.carbon

@@ -162,5 +162,7 @@ fn F() {
 // CHECK:STDOUT:   %system_function.ref: %system_function.cpp_overload_set.type = name_ref system_function, imports.%system_function.cpp_overload_set.value [concrete = constants.%system_function.cpp_overload_set.value]
 // CHECK:STDOUT:   %system_function.call: init %empty_tuple.type = call imports.%system_function.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/basics/import/import.carbon

@@ -140,6 +140,8 @@ fn F() {
 // CHECK:STDOUT:   %x.ref: <error> = name_ref x, %x [concrete = <error>]
 // CHECK:STDOUT:   %Foo.ref: <error> = name_ref Foo, <error> [concrete = <error>]
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_todo_import_function_api.carbon
@@ -187,5 +189,7 @@ fn F() {
 // CHECK:STDOUT:   %FooInt.ref: <error> = name_ref FooInt, imports.%Main.FooInt [concrete = <error>]
 // CHECK:STDOUT:   %int_9: Core.IntLiteral = int_value 9 [concrete = constants.%int_9]
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/basics/import/indirect.carbon

@@ -191,6 +191,8 @@ fn UseZ() -> Cpp.A.Z {
 // CHECK:STDOUT:   %X.cpp_destructor.bound: <bound method> = bound_method %.loc9_12.2, constants.%X.cpp_destructor
 // CHECK:STDOUT:   %X.cpp_destructor.call: init %empty_tuple.type = call %X.cpp_destructor.bound(%.loc9_12.2)
 // CHECK:STDOUT:   return %Int.as.Copy.impl.Op.call
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Function() -> out %return.param: %i32 {
@@ -206,6 +208,8 @@ fn UseZ() -> Cpp.A.Z {
 // CHECK:STDOUT:   %X.cpp_destructor.bound: <bound method> = bound_method %.loc15_12.2, constants.%X.cpp_destructor
 // CHECK:STDOUT:   %X.cpp_destructor.call: init %empty_tuple.type = call %X.cpp_destructor.bound(%.loc15_12.2)
 // CHECK:STDOUT:   return %X.g.call
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- indirect_import_via_alias.carbon
@@ -322,6 +326,8 @@ fn UseZ() -> Cpp.A.Z {
 // CHECK:STDOUT:   %X.cpp_destructor.bound: <bound method> = bound_method %ax.var, constants.%X.cpp_destructor
 // CHECK:STDOUT:   %X.cpp_destructor.call: init %empty_tuple.type = call %X.cpp_destructor.bound(%ax.var)
 // CHECK:STDOUT:   return %.loc10_24 to %return.param
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_template.carbon
@@ -403,6 +409,8 @@ fn UseZ() -> Cpp.A.Z {
 // CHECK:STDOUT:   %Y.cpp_destructor.bound: <bound method> = bound_method %.loc9_12.2, constants.%Y.cpp_destructor.be1864.1
 // CHECK:STDOUT:   %Y.cpp_destructor.call: init %empty_tuple.type = call %Y.cpp_destructor.bound(%.loc9_12.2)
 // CHECK:STDOUT:   return %Int.as.Copy.impl.Op.call
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @UseZ() -> out %return.param: %Z {
@@ -430,5 +438,7 @@ fn UseZ() -> Cpp.A.Z {
 // CHECK:STDOUT:   %Y.cpp_destructor.bound: <bound method> = bound_method %.loc15_12.2, constants.%Y.cpp_destructor.be1864.2
 // CHECK:STDOUT:   %Y.cpp_destructor.call: init %empty_tuple.type = call %Y.cpp_destructor.bound(%.loc15_12.2)
 // CHECK:STDOUT:   return %.loc15_13.7 to %return.param
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/basics/inline/import.carbon

@@ -79,6 +79,8 @@ fn Run() {
 // CHECK:STDOUT:   %func.ref: %func.cpp_overload_set.type = name_ref func, imports.%func.cpp_overload_set.value [concrete = constants.%func.cpp_overload_set.value]
 // CHECK:STDOUT:   %func.call: init %empty_tuple.type = call imports.%func.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- with_language_marker.carbon
@@ -112,5 +114,7 @@ fn Run() {
 // CHECK:STDOUT:   %another_func.ref: %another_func.cpp_overload_set.type = name_ref another_func, imports.%another_func.cpp_overload_set.value [concrete = constants.%another_func.cpp_overload_set.value]
 // CHECK:STDOUT:   %another_func.call: init %empty_tuple.type = call imports.%another_func.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/basics/unsupported_decl_type.carbon

@@ -54,5 +54,7 @@ fn F() -> i32 {
 // CHECK:STDOUT:   %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
 // CHECK:STDOUT:   %a.ref: <error> = name_ref a, <error> [concrete = <error>]
 // CHECK:STDOUT:   return <error>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/class/import/abstract.carbon

@@ -151,5 +151,7 @@ fn F() -> Cpp.AbstractFinal {
 // CHECK:STDOUT:   %.loc11_14.1: ref %AbstractFinal = splice_block %return.param {}
 // CHECK:STDOUT:   %F.call: init %AbstractFinal to %.loc11_14.1 = call %F.ref()
 // CHECK:STDOUT:   return %F.call to %return.param
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/class/import/access.carbon

@@ -1666,6 +1666,8 @@ fn Call(var instance: Cpp.PublicPrivate) {
 // CHECK:STDOUT:     %static_data.patt: %pattern_type.6b6 = value_binding_pattern static_data [concrete = constants.%static_data.patt.405]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_non_function_member_public_extend.carbon
@@ -1713,6 +1715,8 @@ fn Call(var instance: Cpp.PublicPrivate) {
 // CHECK:STDOUT:     %static_data.patt: %pattern_type.6b6 = value_binding_pattern static_data [concrete = constants.%static_data.patt.405]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_non_function_member_protected_extend_call_in_member.carbon
@@ -1797,6 +1801,8 @@ fn Call(var instance: Cpp.PublicPrivate) {
 // CHECK:STDOUT:     %base_static_data.patt: %pattern_type.6b6 = value_binding_pattern base_static_data [concrete = constants.%base_static_data.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_function_member_public.carbon
@@ -1843,6 +1849,8 @@ fn Call(var instance: Cpp.PublicPrivate) {
 // CHECK:STDOUT:   %static_fn.ref: %S.static_fn.cpp_overload_set.type = name_ref static_fn, imports.%S.static_fn.cpp_overload_set.value [concrete = constants.%S.static_fn.cpp_overload_set.value]
 // CHECK:STDOUT:   %S.static_fn.call: init %empty_tuple.type = call imports.%S.static_fn.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_todo_import_function_member_protected_extend_call_instance_in_member.carbon
@@ -1875,6 +1883,8 @@ fn Call(var instance: Cpp.PublicPrivate) {
 // CHECK:STDOUT:   %instance_fn.ref: %C.instance_fn.cpp_overload_set.type = name_ref instance_fn, imports.%C.instance_fn.cpp_overload_set.value [concrete = constants.%C.instance_fn.cpp_overload_set.value]
 // CHECK:STDOUT:   %bound_method: <bound method> = bound_method %self.ref, %instance_fn.ref
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_function_member_protected_extend_call_static_in_member.carbon
@@ -1924,6 +1934,8 @@ fn Call(var instance: Cpp.PublicPrivate) {
 // CHECK:STDOUT:   %static_fn.ref.loc12: %C.static_fn.cpp_overload_set.type = name_ref static_fn, imports.%C.static_fn.cpp_overload_set.value [concrete = constants.%C.static_fn.cpp_overload_set.value]
 // CHECK:STDOUT:   %C.static_fn.call.loc12: init %empty_tuple.type = call imports.%C.static_fn.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_overload_set_public.carbon
@@ -2023,6 +2035,8 @@ fn Call(var instance: Cpp.PublicPrivate) {
 // CHECK:STDOUT:   %PublicCall.cpp_destructor.bound.loc8: <bound method> = bound_method %.loc8_37.3, constants.%PublicCall.cpp_destructor
 // CHECK:STDOUT:   %PublicCall.cpp_destructor.call.loc8: init %empty_tuple.type = call %PublicCall.cpp_destructor.bound.loc8(%.loc8_37.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_overload_set_protected_base.carbon
@@ -2154,6 +2168,8 @@ fn Call(var instance: Cpp.PublicPrivate) {
 // CHECK:STDOUT:   %PublicCall.cpp_destructor.bound: <bound method> = bound_method %.loc11_49.3, constants.%PublicCall.cpp_destructor
 // CHECK:STDOUT:   %PublicCall.cpp_destructor.call: init %empty_tuple.type = call %PublicCall.cpp_destructor.bound(%.loc11_49.3)
 // CHECK:STDOUT:   return %.loc11_52 to %return.param
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @D.MakeProtected() -> out %return.param: %D {
@@ -2183,6 +2199,8 @@ fn Call(var instance: Cpp.PublicPrivate) {
 // CHECK:STDOUT:   %ProtectedCall.cpp_destructor.bound: <bound method> = bound_method %.loc17_55.3, constants.%ProtectedCall.cpp_destructor
 // CHECK:STDOUT:   %ProtectedCall.cpp_destructor.call: init %empty_tuple.type = call %ProtectedCall.cpp_destructor.bound(%.loc17_55.3)
 // CHECK:STDOUT:   return %.loc17_58 to %return.param
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @D.CallPublic() {
@@ -2203,6 +2221,8 @@ fn Call(var instance: Cpp.PublicPrivate) {
 // CHECK:STDOUT:   %PublicCall.cpp_destructor.bound: <bound method> = bound_method %.loc23_40.3, constants.%PublicCall.cpp_destructor
 // CHECK:STDOUT:   %PublicCall.cpp_destructor.call: init %empty_tuple.type = call %PublicCall.cpp_destructor.bound(%.loc23_40.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @D.CallProtected() {
@@ -2223,6 +2243,8 @@ fn Call(var instance: Cpp.PublicPrivate) {
 // CHECK:STDOUT:   %ProtectedCall.cpp_destructor.bound: <bound method> = bound_method %.loc29_46.3, constants.%ProtectedCall.cpp_destructor
 // CHECK:STDOUT:   %ProtectedCall.cpp_destructor.call: init %empty_tuple.type = call %ProtectedCall.cpp_destructor.bound(%.loc29_46.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_overload_set_public_base_class_call_public.carbon
@@ -2286,6 +2308,8 @@ fn Call(var instance: Cpp.PublicPrivate) {
 // CHECK:STDOUT:   %PublicCall.cpp_destructor.bound: <bound method> = bound_method %.loc8_49.3, constants.%PublicCall.cpp_destructor
 // CHECK:STDOUT:   %PublicCall.cpp_destructor.call: init %empty_tuple.type = call %PublicCall.cpp_destructor.bound(%.loc8_49.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_overload_set_public_base_class_derived_call_non_private.carbon
@@ -2398,6 +2422,8 @@ fn Call(var instance: Cpp.PublicPrivate) {
 // CHECK:STDOUT:   %PublicCall.cpp_destructor.bound: <bound method> = bound_method %.loc11_40.3, constants.%PublicCall.cpp_destructor
 // CHECK:STDOUT:   %PublicCall.cpp_destructor.call: init %empty_tuple.type = call %PublicCall.cpp_destructor.bound(%.loc11_40.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_overload_set_protected_base_class_derived_call_non_private.carbon
@@ -2510,6 +2536,8 @@ fn Call(var instance: Cpp.PublicPrivate) {
 // CHECK:STDOUT:   %PublicCall.cpp_destructor.bound: <bound method> = bound_method %.loc11_40.3, constants.%PublicCall.cpp_destructor
 // CHECK:STDOUT:   %PublicCall.cpp_destructor.call: init %empty_tuple.type = call %PublicCall.cpp_destructor.bound(%.loc11_40.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- base_class_public_access_allowed.carbon
@@ -2592,6 +2620,8 @@ fn Call(var instance: Cpp.PublicPrivate) {
 // CHECK:STDOUT:   %ProtectedStatic.ref.loc17: %Public.ProtectedStatic.cpp_overload_set.type = name_ref ProtectedStatic, imports.%Public.ProtectedStatic.cpp_overload_set.value [concrete = constants.%Public.ProtectedStatic.cpp_overload_set.value]
 // CHECK:STDOUT:   %Base.ProtectedStatic.call.loc17: init %empty_tuple.type = call imports.%Base.ProtectedStatic.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Derived.CallInstance(%instance.param: ref %Public) {
@@ -2611,6 +2641,8 @@ fn Call(var instance: Cpp.PublicPrivate) {
 // CHECK:STDOUT:   %.loc26_5.3: ref %Base = converted %instance.ref.loc26, %.loc26_5.2
 // CHECK:STDOUT:   %Base.ProtectedInstance.call: init %empty_tuple.type = call imports.%Base.ProtectedInstance.decl(%.loc26_5.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Call(%instance.param: ref %Public) {
@@ -2637,6 +2669,8 @@ fn Call(var instance: Cpp.PublicPrivate) {
 // CHECK:STDOUT:   %.loc37_3.3: ref %Base = converted %instance.ref.loc37, %.loc37_3.2
 // CHECK:STDOUT:   %Base.PublicInstance.call.loc37: init %empty_tuple.type = call imports.%Base.PublicInstance.decl(%.loc37_3.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_base_class_public_access_denied.carbon
@@ -2665,6 +2699,8 @@ fn Call(var instance: Cpp.PublicPrivate) {
 // CHECK:STDOUT:   %instance.ref: ref %Public = name_ref instance, %instance
 // CHECK:STDOUT:   %PrivateInstance.ref: <error> = name_ref PrivateInstance, <error> [concrete = <error>]
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- base_class_protected_access_allowed.carbon
@@ -2747,6 +2783,8 @@ fn Call(var instance: Cpp.PublicPrivate) {
 // CHECK:STDOUT:   %ProtectedStatic.ref.loc17: %Protected.ProtectedStatic.cpp_overload_set.type = name_ref ProtectedStatic, imports.%Protected.ProtectedStatic.cpp_overload_set.value [concrete = constants.%Protected.ProtectedStatic.cpp_overload_set.value]
 // CHECK:STDOUT:   %Base.ProtectedStatic.call.loc17: init %empty_tuple.type = call imports.%Base.ProtectedStatic.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Derived.CallInstance(%instance.param: ref %Protected) {
@@ -2766,6 +2804,8 @@ fn Call(var instance: Cpp.PublicPrivate) {
 // CHECK:STDOUT:   %.loc26_5.3: ref %Base = converted %instance.ref.loc26, %.loc26_5.2
 // CHECK:STDOUT:   %Base.ProtectedInstance.call: init %empty_tuple.type = call imports.%Base.ProtectedInstance.decl(%.loc26_5.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- base_class_public_protected_access_allowed.carbon
@@ -2849,6 +2889,8 @@ fn Call(var instance: Cpp.PublicPrivate) {
 // CHECK:STDOUT:   %ProtectedStatic.ref.loc17: %PublicProtected.ProtectedStatic.cpp_overload_set.type = name_ref ProtectedStatic, imports.%PublicProtected.ProtectedStatic.cpp_overload_set.value [concrete = constants.%PublicProtected.ProtectedStatic.cpp_overload_set.value]
 // CHECK:STDOUT:   %Base.ProtectedStatic.call.loc17: init %empty_tuple.type = call imports.%Base.ProtectedStatic.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Derived.CallInstance(%instance.param: ref %PublicProtected) {
@@ -2870,5 +2912,7 @@ fn Call(var instance: Cpp.PublicPrivate) {
 // CHECK:STDOUT:   %.loc26_5.4: ref %Base = converted %instance.ref.loc26, %.loc26_5.3
 // CHECK:STDOUT:   %Base.ProtectedInstance.call: init %empty_tuple.type = call imports.%Base.ProtectedInstance.decl(%.loc26_5.4)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/class/import/base.carbon

@@ -562,6 +562,8 @@ class V {
 // CHECK:STDOUT:   %bound_method.loc8_11.2: <bound method> = bound_method %.loc8_11.3, %specific_fn
 // CHECK:STDOUT:   %ptr.as.Copy.impl.Op.call: init %ptr.0e0 = call %bound_method.loc8_11.2(%.loc8_11.3)
 // CHECK:STDOUT:   return %ptr.as.Copy.impl.Op.call
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @ConvertVal(%d.param: %Derived) {
@@ -574,6 +576,8 @@ class V {
 // CHECK:STDOUT:   %.loc16_13.4: %Base = acquire_value %.loc16_13.3
 // CHECK:STDOUT:   %AcceptVal.call: init %empty_tuple.type = call %AcceptVal.ref(%.loc16_13.4)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- use_static_member.carbon
@@ -624,6 +628,8 @@ class V {
 // CHECK:STDOUT:   %derived_fn.ref: %Derived.derived_fn.cpp_overload_set.type = name_ref derived_fn, imports.%Derived.derived_fn.cpp_overload_set.value [concrete = constants.%Derived.derived_fn.cpp_overload_set.value]
 // CHECK:STDOUT:   %Derived.derived_fn.call: init %empty_tuple.type = call imports.%Derived.derived_fn.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- use_base_field.carbon
@@ -674,6 +680,8 @@ class V {
 // CHECK:STDOUT:   %bound_method.loc8_11.2: <bound method> = bound_method %.loc8_11.5, %specific_fn
 // CHECK:STDOUT:   %Int.as.Copy.impl.Op.call: init %i32 = call %bound_method.loc8_11.2(%.loc8_11.5)
 // CHECK:STDOUT:   return %Int.as.Copy.impl.Op.call
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @AccessQualified(%d.param: %Derived) -> out %return.param: %i32 {
@@ -693,6 +701,8 @@ class V {
 // CHECK:STDOUT:   %bound_method.loc14_11.2: <bound method> = bound_method %.loc14_11.5, %specific_fn
 // CHECK:STDOUT:   %Int.as.Copy.impl.Op.call: init %i32 = call %bound_method.loc14_11.2(%.loc14_11.5)
 // CHECK:STDOUT:   return %Int.as.Copy.impl.Op.call
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- use_base_method.carbon
@@ -744,6 +754,8 @@ class V {
 // CHECK:STDOUT:   %.loc8_3.4: %Base = acquire_value %.loc8_3.3
 // CHECK:STDOUT:   %f__carbon_thunk.call: init %empty_tuple.type = call imports.%f__carbon_thunk.decl(%.loc8_3.4)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @CallQualified(%d.param: %Derived) {
@@ -759,6 +771,8 @@ class V {
 // CHECK:STDOUT:   %.loc14_3.4: %Base = acquire_value %.loc14_3.3
 // CHECK:STDOUT:   %g__carbon_thunk.call: init %empty_tuple.type = call imports.%g__carbon_thunk.decl(%.loc14_3.4)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @CallBaseQualifiedByDerived(%d.param: %Derived, %b.param: %Base) {
@@ -780,5 +794,7 @@ class V {
 // CHECK:STDOUT:   %bound_method.loc24: <bound method> = bound_method %b.ref, %f.ref.loc24
 // CHECK:STDOUT:   %f__carbon_thunk.call.loc24: init %empty_tuple.type = call imports.%f__carbon_thunk.decl(%b.ref)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/class/import/class.carbon

@@ -391,6 +391,8 @@ fn GenericUse(p2: Generic(Cpp.Class1)) {
 // CHECK:STDOUT:   %foo.ref: %Bar.foo.cpp_overload_set.type = name_ref foo, imports.%Bar.foo.cpp_overload_set.value [concrete = constants.%Bar.foo.cpp_overload_set.value]
 // CHECK:STDOUT:   %Bar.foo.call: init %empty_tuple.type = call imports.%Bar.foo.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_static_data_member.carbon
@@ -431,6 +433,8 @@ fn GenericUse(p2: Generic(Cpp.Class1)) {
 // CHECK:STDOUT:     %bar.patt: %pattern_type = value_binding_pattern bar [concrete = constants.%bar.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_data_member.carbon
@@ -487,6 +491,8 @@ fn GenericUse(p2: Generic(Cpp.Class1)) {
 // CHECK:STDOUT:     %foo_bar.patt: %pattern_type = value_binding_pattern foo_bar [concrete = constants.%foo_bar.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- call_dynamic.carbon
@@ -549,6 +555,8 @@ fn GenericUse(p2: Generic(Cpp.Class1)) {
 // CHECK:STDOUT:   %bound_method: <bound method> = bound_method %.loc8, %f.ref
 // CHECK:STDOUT:   %Bar.f.call: init %empty_tuple.type = call imports.%Bar.f.decl(%.loc8)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_to_inherit_public.carbon
@@ -603,6 +611,8 @@ fn GenericUse(p2: Generic(Cpp.Class1)) {
 // CHECK:STDOUT:   %foo.ref: %Bar.foo.cpp_overload_set.type = name_ref foo, imports.%Bar.foo.cpp_overload_set.value [concrete = constants.%Bar.foo.cpp_overload_set.value]
 // CHECK:STDOUT:   %Bar.foo.call: init %empty_tuple.type = call imports.%Bar.foo.decl()
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_template.carbon

toolchain/check/testdata/interop/cpp/class/import/constructor.carbon

@@ -364,6 +364,8 @@ fn F() {
 // CHECK:STDOUT:   %C.cpp_destructor.bound: <bound method> = bound_method %.loc8_33.3, constants.%C.cpp_destructor
 // CHECK:STDOUT:   %C.cpp_destructor.call: init %empty_tuple.type = call %C.cpp_destructor.bound(%.loc8_33.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- implicit_default.carbon
@@ -422,6 +424,8 @@ fn F() {
 // CHECK:STDOUT:   %C.cpp_destructor.bound: <bound method> = bound_method %c.var, constants.%C.cpp_destructor
 // CHECK:STDOUT:   %C.cpp_destructor.call: init %empty_tuple.type = call %C.cpp_destructor.bound(%c.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_non_default.carbon
@@ -515,6 +519,8 @@ fn F() {
 // CHECK:STDOUT:   %C.cpp_destructor.bound: <bound method> = bound_method %.loc8_41.3, constants.%C.cpp_destructor
 // CHECK:STDOUT:   %C.cpp_destructor.call: init %empty_tuple.type = call %C.cpp_destructor.bound(%.loc8_41.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_multiple.carbon
@@ -635,6 +641,8 @@ fn F() {
 // CHECK:STDOUT:   %C.cpp_destructor.bound.loc8: <bound method> = bound_method %.loc8_34.3, constants.%C.cpp_destructor
 // CHECK:STDOUT:   %C.cpp_destructor.call.loc8: init %empty_tuple.type = call %C.cpp_destructor.bound.loc8(%.loc8_34.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_default_arguments.carbon
@@ -763,6 +771,8 @@ fn F() {
 // CHECK:STDOUT:   %C.cpp_destructor.bound.loc8: <bound method> = bound_method %.loc8_38.3, constants.%C.cpp_destructor
 // CHECK:STDOUT:   %C.cpp_destructor.call.loc8: init %empty_tuple.type = call %C.cpp_destructor.bound.loc8(%.loc8_38.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_template.carbon
@@ -927,6 +937,8 @@ fn F() {
 // CHECK:STDOUT:   %C.cpp_destructor.bound.loc8: <bound method> = bound_method %c1.var, constants.%C.cpp_destructor
 // CHECK:STDOUT:   %C.cpp_destructor.call.loc8: init %empty_tuple.type = call %C.cpp_destructor.bound.loc8(%c1.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op(%self.param: ref bool) = "no_op";
@@ -1051,6 +1063,8 @@ fn F() {
 // CHECK:STDOUT:   %C.cpp_destructor.bound.loc8: <bound method> = bound_method %.loc8_35.3, constants.%C.cpp_destructor
 // CHECK:STDOUT:   %C.cpp_destructor.call.loc8: init %empty_tuple.type = call %C.cpp_destructor.bound.loc8(%.loc8_35.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_implicit_multi_arguments.carbon
@@ -1220,5 +1234,7 @@ fn F() {
 // CHECK:STDOUT:   %C.cpp_destructor.bound.loc8: <bound method> = bound_method %.loc8_38.3, constants.%C.cpp_destructor
 // CHECK:STDOUT:   %C.cpp_destructor.call.loc8: init %empty_tuple.type = call %C.cpp_destructor.bound.loc8(%.loc8_38.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/class/import/field.carbon

@@ -329,6 +329,8 @@ fn Test(m: Cpp.UnsupportedMembers*) {
 // CHECK:STDOUT:   %.loc8_43.7: init %tuple.type.ccd to %return.param = tuple_init (%.loc8_43.2, %.loc8_43.3, %.loc8_43.4, %.loc8_43.5, %.loc8_43.6)
 // CHECK:STDOUT:   %.loc8_44: init %tuple.type.ccd = converted %.loc8_43.1, %.loc8_43.7
 // CHECK:STDOUT:   return %.loc8_44 to %return.param
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- use_union_fields.carbon
@@ -370,6 +372,8 @@ fn Test(m: Cpp.UnsupportedMembers*) {
 // CHECK:STDOUT:   %bound_method.loc8_11.2: <bound method> = bound_method %.loc8_11.2, %specific_fn
 // CHECK:STDOUT:   %Int.as.Copy.impl.Op.call: init %i32 = call %bound_method.loc8_11.2(%.loc8_11.2)
 // CHECK:STDOUT:   return %Int.as.Copy.impl.Op.call
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @G(%u.param: %Union) -> out %return.param: %i32 {
@@ -384,6 +388,8 @@ fn Test(m: Cpp.UnsupportedMembers*) {
 // CHECK:STDOUT:   %bound_method.loc14_11.2: <bound method> = bound_method %.loc14_11.2, %specific_fn
 // CHECK:STDOUT:   %Int.as.Copy.impl.Op.call: init %i32 = call %bound_method.loc14_11.2(%.loc14_11.2)
 // CHECK:STDOUT:   return %Int.as.Copy.impl.Op.call
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @H(%u.param: %Union) -> out %return.param: %i32 {
@@ -400,6 +406,8 @@ fn Test(m: Cpp.UnsupportedMembers*) {
 // CHECK:STDOUT:   %bound_method.loc20_10.2: <bound method> = bound_method %.loc20_10.2, %specific_fn
 // CHECK:STDOUT:   %Int.as.Copy.impl.Op.call: init %i32 = call %bound_method.loc20_10.2(%.loc20_10.2)
 // CHECK:STDOUT:   return %Int.as.Copy.impl.Op.call
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- use_non_bitfields_in_type_with_bitfields.carbon
@@ -441,6 +449,8 @@ fn Test(m: Cpp.UnsupportedMembers*) {
 // CHECK:STDOUT:   %bound_method.loc8_11.2: <bound method> = bound_method %.loc8_11.2, %specific_fn
 // CHECK:STDOUT:   %Int.as.Copy.impl.Op.call: init %i32 = call %bound_method.loc8_11.2(%.loc8_11.2)
 // CHECK:STDOUT:   return %Int.as.Copy.impl.Op.call
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @G(%s.param: %Union) -> out %return.param: %i32 {
@@ -455,6 +465,8 @@ fn Test(m: Cpp.UnsupportedMembers*) {
 // CHECK:STDOUT:   %bound_method.loc14_11.2: <bound method> = bound_method %.loc14_11.2, %specific_fn
 // CHECK:STDOUT:   %Int.as.Copy.impl.Op.call: init %i32 = call %bound_method.loc14_11.2(%.loc14_11.2)
 // CHECK:STDOUT:   return %Int.as.Copy.impl.Op.call
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_todo_use_bitfields.carbon
@@ -471,6 +483,8 @@ fn Test(m: Cpp.UnsupportedMembers*) {
 // CHECK:STDOUT:   %s.ref: %Struct = name_ref s, %s
 // CHECK:STDOUT:   %b.ref: <error> = name_ref b, <error> [concrete = <error>]
 // CHECK:STDOUT:   return <error>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @G(%s.param: %Union) -> out %return.param: %i32 {
@@ -478,5 +492,7 @@ fn Test(m: Cpp.UnsupportedMembers*) {
 // CHECK:STDOUT:   %s.ref: %Union = name_ref s, %s
 // CHECK:STDOUT:   %d.ref: <error> = name_ref d, <error> [concrete = <error>]
 // CHECK:STDOUT:   return <error>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/class/import/method.carbon

@@ -491,6 +491,8 @@ fn Call(e: Cpp.ExplicitObjectParam, n: i32, a: Cpp.Another) {
 // CHECK:STDOUT:   %HasQualifiers.cpp_destructor.bound.loc19: <bound method> = bound_method %.loc19_8.2, %Op.ref.loc19
 // CHECK:STDOUT:   %HasQualifiers.cpp_destructor.call.loc19: init %empty_tuple.type = call %HasQualifiers.cpp_destructor.bound.loc19(%.loc19_8.2)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- use_object_param_qualifiers_overloaded.carbon
@@ -593,6 +595,8 @@ fn Call(e: Cpp.ExplicitObjectParam, n: i32, a: Cpp.Another) {
 // CHECK:STDOUT:   %Destroy.Op.bound.loc8: <bound method> = bound_method %a.var, constants.%Destroy.Op.1a2547.3
 // CHECK:STDOUT:   %Destroy.Op.call.loc8: init %empty_tuple.type = call %Destroy.Op.bound.loc8(%a.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc9(%self.param: ref %ptr.d08) = "no_op";
@@ -602,6 +606,8 @@ fn Call(e: Cpp.ExplicitObjectParam, n: i32, a: Cpp.Another) {
 // CHECK:STDOUT: fn @Destroy.Op.loc8_3.2(%self.param: ref %i32) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @CallFWithRefQualifier(%v.param: %WithRefQualifier, %p.param: %ptr.90c) {
@@ -639,6 +645,8 @@ fn Call(e: Cpp.ExplicitObjectParam, n: i32, a: Cpp.Another) {
 // CHECK:STDOUT:   %Destroy.Op.bound.loc15: <bound method> = bound_method %a.var, constants.%Destroy.Op.1a2547.3
 // CHECK:STDOUT:   %Destroy.Op.call.loc15: init %empty_tuple.type = call %Destroy.Op.bound.loc15(%a.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- call_explicit_object_param.carbon
@@ -716,6 +724,8 @@ fn Call(e: Cpp.ExplicitObjectParam, n: i32, a: Cpp.Another) {
 // CHECK:STDOUT:   %addr.loc10: %ptr.bad = addr_of %.loc10
 // CHECK:STDOUT:   %H__carbon_thunk.call: init %empty_tuple.type = call imports.%H__carbon_thunk.decl(%addr.loc10)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- call_explicit_object_param_overloaded.carbon
@@ -787,5 +797,7 @@ fn Call(e: Cpp.ExplicitObjectParam, n: i32, a: Cpp.Another) {
 // CHECK:STDOUT:   %addr.loc10: %ptr.bad = addr_of %.loc10
 // CHECK:STDOUT:   %F__carbon_thunk.call.loc10: init %empty_tuple.type = call imports.%F__carbon_thunk.decl.828b0d.3(%addr.loc10)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/class/import/template.carbon

@@ -166,6 +166,8 @@ fn F() {
 // CHECK:STDOUT:   %bound_method.loc10_11.2: <bound method> = bound_method %.loc10_11.2, %specific_fn
 // CHECK:STDOUT:   %Int.as.Copy.impl.Op.call: init %i32 = call %bound_method.loc10_11.2(%.loc10_11.2)
 // CHECK:STDOUT:   return %Int.as.Copy.impl.Op.call
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @G(%p.param: %ptr.f2d) -> out %return.param: %ptr.0e0 {
@@ -181,6 +183,8 @@ fn F() {
 // CHECK:STDOUT:   %bound_method.loc17_11.2: <bound method> = bound_method %.loc17_11.3, %specific_fn
 // CHECK:STDOUT:   %ptr.as.Copy.impl.Op.call: init %ptr.0e0 = call %bound_method.loc17_11.2(%.loc17_11.3)
 // CHECK:STDOUT:   return %ptr.as.Copy.impl.Op.call
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_use_instantiation_error.carbon
@@ -270,5 +274,7 @@ fn F() {
 // CHECK:STDOUT:   %.loc21: init %i32 = converted %int_0.loc21, %Core.IntLiteral.as.ImplicitAs.impl.Convert.call.loc21 [concrete = constants.%int_0.3c0]
 // CHECK:STDOUT:   assign file.%y.var, %.loc21
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/class/import/union.carbon

@@ -312,6 +312,8 @@ fn MyF(bar: Cpp.Bar(Cpp.X)*);
 // CHECK:STDOUT:   %foo.ref: %Bar.foo.cpp_overload_set.type = name_ref foo, imports.%Bar.foo.cpp_overload_set.value [concrete = constants.%Bar.foo.cpp_overload_set.value]
 // CHECK:STDOUT:   %Bar.foo.call: init %empty_tuple.type = call imports.%Bar.foo.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_static_data_member.carbon
@@ -352,6 +354,8 @@ fn MyF(bar: Cpp.Bar(Cpp.X)*);
 // CHECK:STDOUT:     %bar.patt: %pattern_type = value_binding_pattern bar [concrete = constants.%bar.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_data_member.carbon
@@ -408,6 +412,8 @@ fn MyF(bar: Cpp.Bar(Cpp.X)*);
 // CHECK:STDOUT:     %foo_bar.patt: %pattern_type = value_binding_pattern foo_bar [concrete = constants.%foo_bar.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_template.carbon

toolchain/check/testdata/interop/cpp/enum/anonymous.carbon

@@ -124,5 +124,7 @@ fn G() {
 // CHECK:STDOUT:   %C.cpp_destructor.bound: <bound method> = bound_method %.loc10_11.3, constants.%C.cpp_destructor
 // CHECK:STDOUT:   %C.cpp_destructor.call: init %empty_tuple.type = call %C.cpp_destructor.bound(%.loc10_11.3)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/enum/convert.carbon

@@ -188,5 +188,7 @@ fn F() {
 // CHECK:STDOUT:     %c.patt: %pattern_type.d91 = value_binding_pattern c [concrete = constants.%c.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/enum/copy.carbon

@@ -97,6 +97,8 @@ fn F() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %a.var, constants.%Destroy.Op
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%a.var)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op(%self.param: ref %Enum) = "no_op";

toolchain/check/testdata/interop/cpp/enum/fixed.carbon

@@ -79,5 +79,7 @@ fn F() {
 // CHECK:STDOUT:     %b.patt: %pattern_type = value_binding_pattern b [concrete = constants.%b.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/enum/member.carbon

@@ -87,5 +87,7 @@ fn F() {
 // CHECK:STDOUT:     %b.patt: %pattern_type = value_binding_pattern b [concrete = constants.%b.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/enum/scoped.carbon

@@ -78,5 +78,7 @@ fn F() {
 // CHECK:STDOUT:     %a.patt: %pattern_type = value_binding_pattern a [concrete = constants.%a.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/enum/unscoped.carbon

@@ -121,5 +121,7 @@ fn F() {
 // CHECK:STDOUT:     %b.patt: %pattern_type = value_binding_pattern b [concrete = constants.%b.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/enum/using.carbon

@@ -138,5 +138,7 @@ fn F() {
 // CHECK:STDOUT:     %pet2.patt: %pattern_type.8cd = value_binding_pattern pet2 [concrete = constants.%pet2.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/function/export/generic.carbon

@@ -276,6 +276,8 @@ void G() {
 // CHECK:STDOUT:   witness = (@I.WithSelf.%I.WithSelf.Doit.decl)
 // CHECK:STDOUT:
 // CHECK:STDOUT: !requires:
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: impl @A.as.I.impl: %Self.ref as %I.ref {
@@ -353,11 +355,15 @@ void G() {
 // CHECK:STDOUT: fn @A.as.I.impl.Doit(%self.param: %A) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @B.as.I.impl.Doit(%self.param: %B) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: generic fn @F(%T.loc20_7.2: %I.type) {
@@ -388,6 +394,8 @@ void G() {
 // CHECK:STDOUT:     %bound_method.loc21_10: <bound method> = bound_method %t.ref, %specific_impl_fn.loc21_4.1
 // CHECK:STDOUT:     %I.WithSelf.Doit.call: init %empty_tuple.type = call %bound_method.loc21_10(%t.ref)
 // CHECK:STDOUT:     return
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !observes:
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -397,6 +405,8 @@ void G() {
 // CHECK:STDOUT:   %bound_method: <bound method> = bound_method %self.param, %impl.elem0
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %bound_method(%self.param)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc9_9.1(%self.param: ref %empty_struct_type) = "no_op";
@@ -404,6 +414,8 @@ void G() {
 // CHECK:STDOUT: fn @Destroy.Op.loc9_9.2(%self.param: ref %A) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @B.__destroy_thunk(%self.param: ref %B) {
@@ -412,11 +424,15 @@ void G() {
 // CHECK:STDOUT:   %bound_method: <bound method> = bound_method %self.param, %impl.elem0
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %bound_method(%self.param)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc14(%self.param: ref %B) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @F__carbon_thunkinst64000035(%_.param: ref %A) {
@@ -430,6 +446,8 @@ void G() {
 // CHECK:STDOUT:   %.loc20_19.3: %A = acquire_value %_.param
 // CHECK:STDOUT:   %F.call: init %empty_tuple.type = call %F.specific_fn(%.loc20_19.3)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @F__carbon_thunkinst64000050(%_.param: ref %B) {
@@ -443,6 +461,8 @@ void G() {
 // CHECK:STDOUT:   %.loc20_19.3: %B = acquire_value %_.param
 // CHECK:STDOUT:   %F.call: init %empty_tuple.type = call %F.specific_fn(%.loc20_19.3)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: specific @I.WithSelf(constants.%Self.37e) {

toolchain/check/testdata/interop/cpp/function/import/arithmetic_types_bridged.carbon

@@ -605,6 +605,8 @@ fn F() {
 // CHECK:STDOUT:   %addr: %ptr.bb2 = addr_of %.loc8_11.2 [concrete = constants.%addr]
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op(%self.param: ref bool) = "no_op";
@@ -659,6 +661,8 @@ fn F() {
 // CHECK:STDOUT:   %addr: %ptr.bb2 = addr_of %.loc8_11.2 [concrete = constants.%addr]
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op(%self.param: ref bool) = "no_op";
@@ -767,6 +771,8 @@ fn F() {
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call constants.%Destroy.Op.bound(constants.%.309)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_11.1(%self.param: ref %i8.builtin) = "no_op";
@@ -774,6 +780,8 @@ fn F() {
 // CHECK:STDOUT: fn @Destroy.Op.loc8_11.2(%self.param: ref %i8) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_unsigned_char_param.carbon
@@ -863,6 +871,8 @@ fn F() {
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call constants.%Destroy.Op.bound(constants.%.599)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_11.1(%self.param: ref %u8.builtin) = "no_op";
@@ -870,6 +880,8 @@ fn F() {
 // CHECK:STDOUT: fn @Destroy.Op.loc8_11.2(%self.param: ref %u8) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_char_param.carbon
@@ -946,6 +958,8 @@ fn F() {
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call constants.%Destroy.Op.bound(constants.%.2ff)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_11.1(%self.param: ref %u8.builtin) = "no_op";
@@ -953,11 +967,15 @@ fn F() {
 // CHECK:STDOUT: fn @Destroy.Op.loc8_11.2(%self.param: ref %u8) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_11.3(%self.param: ref %char) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_todo_import_wchar_t_param.carbon
@@ -982,6 +1000,8 @@ fn F() {
 // CHECK:STDOUT:   %foo.ref: %foo.cpp_overload_set.type = name_ref foo, imports.%foo.cpp_overload_set.value [concrete = constants.%foo.cpp_overload_set.value]
 // CHECK:STDOUT:   %.loc12: Core.CharLiteral = char_value U+0058 [concrete = constants.%.d16]
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_todo_import_char8_t_param.carbon
@@ -1040,6 +1060,8 @@ fn F() {
 // CHECK:STDOUT:   %.loc13_11.2: %i32 = converted %int_1, %.loc13_11.1 [concrete = constants.%int_1.0c6]
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl(%.loc13_11.2)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_todo_import_char16_t_param.carbon
@@ -1064,6 +1086,8 @@ fn F() {
 // CHECK:STDOUT:   %foo.ref: %foo.cpp_overload_set.type = name_ref foo, imports.%foo.cpp_overload_set.value [concrete = constants.%foo.cpp_overload_set.value]
 // CHECK:STDOUT:   %int_1: Core.IntLiteral = int_value 1 [concrete = constants.%int_1]
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_todo_import_char32_t_param.carbon
@@ -1088,6 +1112,8 @@ fn F() {
 // CHECK:STDOUT:   %foo.ref: %foo.cpp_overload_set.type = name_ref foo, imports.%foo.cpp_overload_set.value [concrete = constants.%foo.cpp_overload_set.value]
 // CHECK:STDOUT:   %int_1: Core.IntLiteral = int_value 1 [concrete = constants.%int_1]
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_short_param.carbon
@@ -1178,6 +1204,8 @@ fn F() {
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call constants.%Destroy.Op.bound(constants.%.597)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_13.1(%self.param: ref %i16.builtin) = "no_op";
@@ -1185,6 +1213,8 @@ fn F() {
 // CHECK:STDOUT: fn @Destroy.Op.loc8_13.2(%self.param: ref %i16) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_short_param_max.carbon
@@ -1274,6 +1304,8 @@ fn F() {
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call constants.%Destroy.Op.bound(constants.%.0d8)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_11.1(%self.param: ref %i16.builtin) = "no_op";
@@ -1281,6 +1313,8 @@ fn F() {
 // CHECK:STDOUT: fn @Destroy.Op.loc8_11.2(%self.param: ref %i16) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_short_param_min.carbon
@@ -1387,6 +1421,8 @@ fn F() {
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call constants.%Destroy.Op.bound(constants.%.60a)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_11.1(%self.param: ref %i16.builtin) = "no_op";
@@ -1394,6 +1430,8 @@ fn F() {
 // CHECK:STDOUT: fn @Destroy.Op.loc8_11.2(%self.param: ref %i16) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_short_int_param.carbon
@@ -1484,6 +1522,8 @@ fn F() {
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call constants.%Destroy.Op.bound(constants.%.597)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_13.1(%self.param: ref %i16.builtin) = "no_op";
@@ -1491,6 +1531,8 @@ fn F() {
 // CHECK:STDOUT: fn @Destroy.Op.loc8_13.2(%self.param: ref %i16) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_signed_short_param.carbon
@@ -1581,6 +1623,8 @@ fn F() {
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call constants.%Destroy.Op.bound(constants.%.597)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_13.1(%self.param: ref %i16.builtin) = "no_op";
@@ -1588,6 +1632,8 @@ fn F() {
 // CHECK:STDOUT: fn @Destroy.Op.loc8_13.2(%self.param: ref %i16) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_signed_short_int_param.carbon
@@ -1678,6 +1724,8 @@ fn F() {
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call constants.%Destroy.Op.bound(constants.%.597)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_13.1(%self.param: ref %i16.builtin) = "no_op";
@@ -1685,6 +1733,8 @@ fn F() {
 // CHECK:STDOUT: fn @Destroy.Op.loc8_13.2(%self.param: ref %i16) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_int16_t_param.carbon
@@ -1775,6 +1825,8 @@ fn F() {
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call constants.%Destroy.Op.bound(constants.%.597)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_13.1(%self.param: ref %i16.builtin) = "no_op";
@@ -1782,6 +1834,8 @@ fn F() {
 // CHECK:STDOUT: fn @Destroy.Op.loc8_13.2(%self.param: ref %i16) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_float16_param.carbon
@@ -1871,6 +1925,8 @@ fn F() {
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call constants.%Destroy.Op.bound(constants.%.b6a)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_15.1(%self.param: ref %f16.3ab) = "no_op";
@@ -1878,6 +1934,8 @@ fn F() {
 // CHECK:STDOUT: fn @Destroy.Op.loc8_15.2(%self.param: ref %f16.907) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_float_param.carbon
@@ -1967,6 +2025,8 @@ fn F() {
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call constants.%Destroy.Op.bound(constants.%.798)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_15.1(%self.param: ref %f32.9b3) = "no_op";
@@ -1974,6 +2034,8 @@ fn F() {
 // CHECK:STDOUT: fn @Destroy.Op.loc8_15.2(%self.param: ref %f32.c73) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_double_param.carbon
@@ -2063,6 +2125,8 @@ fn F() {
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call constants.%Destroy.Op.bound(constants.%.2a9)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_15.1(%self.param: ref %f64.794) = "no_op";
@@ -2070,6 +2134,8 @@ fn F() {
 // CHECK:STDOUT: fn @Destroy.Op.loc8_15.2(%self.param: ref %f64.dc1) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_float128_param.carbon
@@ -2159,6 +2225,8 @@ fn F() {
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call constants.%Destroy.Op.bound(constants.%.4aa)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_15.1(%self.param: ref %f128.853) = "no_op";
@@ -2166,6 +2234,8 @@ fn F() {
 // CHECK:STDOUT: fn @Destroy.Op.loc8_15.2(%self.param: ref %f128.e39) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_bool_return.carbon
@@ -2214,6 +2284,8 @@ fn F() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %.loc8_37.3, constants.%Destroy.Op
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%.loc8_37.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op(%self.param: ref bool) = "no_op";
@@ -2267,6 +2339,8 @@ fn F() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %.loc8_37.3, constants.%Destroy.Op.1a2547.2
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%.loc8_37.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_37.1(%self.param: ref %i16.builtin) = "no_op";
@@ -2274,6 +2348,8 @@ fn F() {
 // CHECK:STDOUT: fn @Destroy.Op.loc8_37.2(%self.param: ref %i16) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_todo_import_bit_int_24_param.carbon
@@ -2298,6 +2374,8 @@ fn F() {
 // CHECK:STDOUT:   %foo.ref: %foo.cpp_overload_set.type = name_ref foo, imports.%foo.cpp_overload_set.value [concrete = constants.%foo.cpp_overload_set.value]
 // CHECK:STDOUT:   %int_1: Core.IntLiteral = int_value 1 [concrete = constants.%int_1]
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_double_return.carbon
@@ -2349,6 +2427,8 @@ fn F() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %.loc8_38.3, constants.%Destroy.Op.1a2547.2
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%.loc8_38.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_38.1(%self.param: ref %f64.794) = "no_op";
@@ -2356,5 +2436,7 @@ fn F() {
 // CHECK:STDOUT: fn @Destroy.Op.loc8_38.2(%self.param: ref %f64.dc1) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/function/import/arithmetic_types_direct.carbon

@@ -372,6 +372,8 @@ fn F() {
 // CHECK:STDOUT:   %.loc8_11.2: %i32 = converted %int_1, %.loc8_11.1 [concrete = constants.%int_1.0c6]
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl(%.loc8_11.2)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_int_param_max.carbon
@@ -430,6 +432,8 @@ fn F() {
 // CHECK:STDOUT:   %.loc8_11.2: %i32 = converted %int_2147483647, %.loc8_11.1 [concrete = constants.%int_2147483647.a0e]
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl(%.loc8_11.2)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_int_param_min.carbon
@@ -505,6 +509,8 @@ fn F() {
 // CHECK:STDOUT:   %.loc8_11.4: %i32 = converted %Core.IntLiteral.as.Negate.impl.Op.call, %.loc8_11.3 [concrete = constants.%int_-2147483648.45f]
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl(%.loc8_11.4)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_signed_int_param.carbon
@@ -563,6 +569,8 @@ fn F() {
 // CHECK:STDOUT:   %.loc8_11.2: %i32 = converted %int_1, %.loc8_11.1 [concrete = constants.%int_1.0c6]
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl(%.loc8_11.2)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_signed_param.carbon
@@ -621,6 +629,8 @@ fn F() {
 // CHECK:STDOUT:   %.loc8_11.2: %i32 = converted %int_1, %.loc8_11.1 [concrete = constants.%int_1.0c6]
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl(%.loc8_11.2)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_unsigned_int_param.carbon
@@ -679,6 +689,8 @@ fn F() {
 // CHECK:STDOUT:   %.loc8_11.2: %u32 = converted %int_1, %.loc8_11.1 [concrete = constants.%int_1.92d]
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl(%.loc8_11.2)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_int32_t_param.carbon
@@ -737,6 +749,8 @@ fn F() {
 // CHECK:STDOUT:   %.loc8_11.2: %i32 = converted %int_1, %.loc8_11.1 [concrete = constants.%int_1.0c6]
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl(%.loc8_11.2)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_int_params.carbon
@@ -807,6 +821,8 @@ fn F() {
 // CHECK:STDOUT:   %.loc8_14.2: %i32 = converted %int_2, %.loc8_14.1 [concrete = constants.%int_2.295]
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl(%.loc8_11.2, %.loc8_14.2)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_multiple_int_params.carbon
@@ -915,6 +931,8 @@ fn F() {
 // CHECK:STDOUT:   %.loc9_15.2: %i32 = converted %int_4, %.loc9_15.1 [concrete = constants.%int_4.4eb]
 // CHECK:STDOUT:   %foo2.call: init %empty_tuple.type = call imports.%foo2.decl(%.loc9_12.2, %.loc9_15.2)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_unnamed_int_param.carbon
@@ -973,6 +991,8 @@ fn F() {
 // CHECK:STDOUT:   %.loc8_11.2: %i32 = converted %int_1, %.loc8_11.1 [concrete = constants.%int_1.0c6]
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl(%.loc8_11.2)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_int_return.carbon
@@ -1012,6 +1032,8 @@ fn F() {
 // CHECK:STDOUT:   %.loc10_26.2: %i32 = converted %foo_int.call, %.loc10_26.1
 // CHECK:STDOUT:   %Carbon_foo.call: init %empty_tuple.type = call %Carbon_foo.ref(%.loc10_26.2)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_long_param.carbon
@@ -1070,5 +1092,7 @@ fn F() {
 // CHECK:STDOUT:   %.loc8_11.2: %i64 = converted %int_1, %.loc8_11.1 [concrete = constants.%int_1.d98]
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl(%.loc8_11.2)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/function/import/class.carbon

@@ -632,6 +632,8 @@ fn F() {
 // CHECK:STDOUT:   %addr: %ptr.0a2 = addr_of %.loc8
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_import_non_copyable_param_type.carbon
@@ -667,6 +669,8 @@ fn F() {
 // CHECK:STDOUT:   %c.ref: %C = name_ref c, %c
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl(%c.ref)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- pass_move_only_param_temporary.carbon
@@ -719,6 +723,8 @@ fn F() {
 // CHECK:STDOUT:   %addr.loc8_21: %ptr.0a2 = addr_of %_.var
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr.loc8_21)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_definition_single_data_member_value_param_type.carbon
@@ -757,6 +763,8 @@ fn F() {
 // CHECK:STDOUT:   %addr: %ptr.0a2 = addr_of %.loc8
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_definition_multiple_data_members_value_param_type.carbon
@@ -795,6 +803,8 @@ fn F() {
 // CHECK:STDOUT:   %addr: %ptr.0a2 = addr_of %.loc8
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_definition_in_namespace_value_param_type.carbon
@@ -876,6 +886,8 @@ fn F() {
 // CHECK:STDOUT:   %C.cpp_destructor.bound: <bound method> = bound_method %x.var, constants.%C.cpp_destructor
 // CHECK:STDOUT:   %C.cpp_destructor.call: init %empty_tuple.type = call %C.cpp_destructor.bound(%x.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_definition_in_relative_namespace_value_param_type.carbon
@@ -923,6 +935,8 @@ fn F() {
 // CHECK:STDOUT:   %addr: %ptr.eda = addr_of %.loc8
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_definition_in_outer_definition.carbon
@@ -1000,6 +1014,8 @@ fn F() {
 // CHECK:STDOUT:   %O.cpp_destructor.bound: <bound method> = bound_method %x.var, constants.%O.cpp_destructor
 // CHECK:STDOUT:   %O.cpp_destructor.call: init %empty_tuple.type = call %O.cpp_destructor.bound(%x.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_definition_and_static_method_call_before.carbon
@@ -1048,6 +1064,8 @@ fn F() {
 // CHECK:STDOUT:   %addr: %ptr.0a2 = addr_of %.loc9
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_definition_and_static_method_call_after.carbon
@@ -1096,6 +1114,8 @@ fn F() {
 // CHECK:STDOUT:   %bar.ref: %C.bar.cpp_overload_set.type = name_ref bar, imports.%C.bar.cpp_overload_set.value [concrete = constants.%C.bar.cpp_overload_set.value]
 // CHECK:STDOUT:   %C.bar.call: init %empty_tuple.type = call imports.%C.bar.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_decl_pointer_param_type.carbon
@@ -1132,6 +1152,8 @@ fn F() {
 // CHECK:STDOUT:   %c.ref: %ptr = name_ref c, %c
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl(%c.ref)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_definition_pointer_param_type.carbon
@@ -1168,6 +1190,8 @@ fn F() {
 // CHECK:STDOUT:   %c.ref: %ptr = name_ref c, %c
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl(%c.ref)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_definition_value_return_type.carbon
@@ -1209,6 +1233,8 @@ fn F() {
 // CHECK:STDOUT:   %C.cpp_destructor.bound: <bound method> = bound_method %.loc8_11.3, constants.%C.cpp_destructor
 // CHECK:STDOUT:   %C.cpp_destructor.call: init %empty_tuple.type = call %C.cpp_destructor.bound(%.loc8_11.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_decl_pointer_return_type.carbon
@@ -1241,6 +1267,8 @@ fn F() {
 // CHECK:STDOUT:   %foo.ref: %foo.cpp_overload_set.type = name_ref foo, imports.%foo.cpp_overload_set.value [concrete = constants.%foo.cpp_overload_set.value]
 // CHECK:STDOUT:   %foo.call: init %ptr = call imports.%foo.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_definition_pointer_return_type.carbon
@@ -1273,5 +1301,7 @@ fn F() {
 // CHECK:STDOUT:   %foo.ref: %foo.cpp_overload_set.type = name_ref foo, imports.%foo.cpp_overload_set.value [concrete = constants.%foo.cpp_overload_set.value]
 // CHECK:STDOUT:   %foo.call: init %ptr = call imports.%foo.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/function/import/decayed_param.carbon

@@ -281,21 +281,29 @@ fn F() {
 // CHECK:STDOUT:   %Destroy.Op.bound.loc10: <bound method> = bound_method %n.var, constants.%Destroy.Op.1a2547.8
 // CHECK:STDOUT:   %Destroy.Op.call.loc10: init %empty_tuple.type = call %Destroy.Op.bound.loc10(%n.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc13_21.1(%self.param: ref %.0f8) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc13_21.2(%self.param: ref %MaybeUnformed.b84) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc13_21.3(%self.param: ref %Optional.c4d) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc10_3.1(%self.param: ref %i32.builtin) = "no_op";
@@ -303,11 +311,15 @@ fn F() {
 // CHECK:STDOUT: fn @Destroy.Op.loc10_3.2(%self.param: ref %i32) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc10_3.3(%self.param: ref %array_type.d58) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_todo_call_params_2.carbon
@@ -427,6 +439,8 @@ fn F() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %n.var, constants.%Destroy.Op.1a2547.4
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%n.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc22_3.1(%self.param: ref %i32.builtin) = "no_op";
@@ -434,10 +448,14 @@ fn F() {
 // CHECK:STDOUT: fn @Destroy.Op.loc22_3.2(%self.param: ref %i32) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc22_3.3(%self.param: ref %array_type.d58) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/function/import/default_arg.carbon

@@ -408,6 +408,8 @@ fn Call() {
 // CHECK:STDOUT:   %Op.ref.loc12: %X.cpp_destructor.type = name_ref Op, imports.%X.cpp_destructor.decl [concrete = constants.%X.cpp_destructor]
 // CHECK:STDOUT:   %Op.ref.loc10: %X.cpp_destructor.type = name_ref Op, imports.%X.cpp_destructor.decl [concrete = constants.%X.cpp_destructor]
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- call_with_default.carbon
@@ -825,6 +827,8 @@ fn Call() {
 // CHECK:STDOUT:   %Op.ref.loc13: %X.cpp_destructor.type = name_ref Op, imports.%X.cpp_destructor.decl [concrete = constants.%X.cpp_destructor]
 // CHECK:STDOUT:   %Op.ref.loc11: %X.cpp_destructor.type = name_ref Op, imports.%X.cpp_destructor.decl [concrete = constants.%X.cpp_destructor]
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @GlobalNoReturn.1(%a.param: %i32, %b.param: %i32);
@@ -859,6 +863,8 @@ fn Call() {
 // CHECK:STDOUT:   %X.cpp_destructor.bound: <bound method> = bound_method %self.param, %Op.ref
 // CHECK:STDOUT:   %X.cpp_destructor.call: init %empty_tuple.type = call %X.cpp_destructor.bound(%self.param)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_call_too_few_args.carbon
@@ -943,5 +949,7 @@ fn Call() {
 // CHECK:STDOUT:   %Op.ref.loc76: %X.cpp_destructor.type = name_ref Op, imports.%X.cpp_destructor.decl [concrete = constants.%X.cpp_destructor]
 // CHECK:STDOUT:   %Op.ref.loc56: %X.cpp_destructor.type = name_ref Op, imports.%X.cpp_destructor.decl [concrete = constants.%X.cpp_destructor]
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/function/import/extern_c.carbon

@@ -94,6 +94,8 @@ fn MyF(a: Cpp.X, b: Cpp.X) -> Cpp.X {
 // CHECK:STDOUT:   %foo.ref: %foo.cpp_overload_set.type = name_ref foo, imports.%foo.cpp_overload_set.value [concrete = constants.%foo.cpp_overload_set.value]
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- extern_c_function_with_cpp_overload_set.carbon
@@ -158,6 +160,8 @@ fn MyF(a: Cpp.X, b: Cpp.X) -> Cpp.X {
 // CHECK:STDOUT:   %.loc12_11.2: %i32 = converted %int_5, %.loc12_11.1 [concrete = constants.%int_5.eef]
 // CHECK:STDOUT:   %foo.call.loc12: init %empty_tuple.type = call imports.%foo.decl.6431a3.2(%.loc12_11.2)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- extern_c_variable.carbon
@@ -205,6 +209,8 @@ fn MyF(a: Cpp.X, b: Cpp.X) -> Cpp.X {
 // CHECK:STDOUT:   %bound_method.loc10_13.2: <bound method> = bound_method %.loc10, %specific_fn
 // CHECK:STDOUT:   %Int.as.Copy.impl.Op.call: init %i32 = call %bound_method.loc10_13.2(%.loc10)
 // CHECK:STDOUT:   return %Int.as.Copy.impl.Op.call
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- extern_c_with_special_name.carbon
@@ -238,5 +244,7 @@ fn MyF(a: Cpp.X, b: Cpp.X) -> Cpp.X {
 // CHECK:STDOUT:   %operator_Plus__carbon_thunk.call: init %empty_tuple.type = call imports.%operator_Plus__carbon_thunk.decl(%addr.loc11_12.1, %addr.loc11_12.2, %addr.loc11_12.3)
 // CHECK:STDOUT:   %.loc11_12: init %X to %.loc9_34.1 = mark_in_place_init %operator_Plus__carbon_thunk.call
 // CHECK:STDOUT:   return %.loc11_12 to %return.param
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/function/import/full_semir.carbon

@@ -195,6 +195,8 @@ fn F() {
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call constants.%Destroy.Op.bound(constants.%.597)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @foo(%a.param: %i16);
@@ -206,6 +208,8 @@ fn F() {
 // CHECK:STDOUT: fn @Destroy.Op.loc7_13.2(%self.param: ref %i16) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_int_param.carbon
@@ -301,6 +305,8 @@ fn F() {
 // CHECK:STDOUT:   %.loc7_11.2: %i32 = converted %int_1, %.loc7_11.1 [concrete = constants.%int_1.0c6]
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl(%.loc7_11.2)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @foo(%a.param: %i32);
@@ -390,6 +396,8 @@ fn F() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %.loc7_37.3, constants.%Destroy.Op.1a2547.2
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%.loc7_37.3)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @foo_short() -> out %return.param: %i16;
@@ -401,5 +409,7 @@ fn F() {
 // CHECK:STDOUT: fn @Destroy.Op.loc7_37.2(%self.param: ref %i16) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/function/import/function.carbon

@@ -207,6 +207,8 @@ fn G() -> i32 {
 // CHECK:STDOUT:   %foo.ref: %foo.cpp_overload_set.type = name_ref foo, imports.%foo.cpp_overload_set.value [concrete = constants.%foo.cpp_overload_set.value]
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_special_name_call_escaped.carbon
@@ -234,6 +236,8 @@ fn G() -> i32 {
 // CHECK:STDOUT:   %base.ref: %base.cpp_overload_set.type = name_ref r#base, imports.%base.cpp_overload_set.value [concrete = constants.%base.cpp_overload_set.value]
 // CHECK:STDOUT:   %base.call: init %empty_tuple.type = call imports.%base.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_overloaded.carbon
@@ -261,6 +265,8 @@ fn G() -> i32 {
 // CHECK:STDOUT:   %foo.ref: %foo.cpp_overload_set.type = name_ref foo, imports.%foo.cpp_overload_set.value [concrete = constants.%foo.cpp_overload_set.value]
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_todo_import_variadic.carbon
@@ -285,6 +291,8 @@ fn G() -> i32 {
 // CHECK:STDOUT:   %foo.ref: %foo.cpp_overload_set.type = name_ref foo, imports.%foo.cpp_overload_set.value [concrete = constants.%foo.cpp_overload_set.value]
 // CHECK:STDOUT:   %int_8: Core.IntLiteral = int_value 8 [concrete = constants.%int_8]
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- todo_fail_import_static.carbon
@@ -312,6 +320,8 @@ fn G() -> i32 {
 // CHECK:STDOUT:   %foo.ref: %foo.cpp_overload_set.type = name_ref foo, imports.%foo.cpp_overload_set.value [concrete = constants.%foo.cpp_overload_set.value]
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_template_function.carbon
@@ -382,6 +392,8 @@ fn G() -> i32 {
 // CHECK:STDOUT:   %.loc8_13.2: %i32 = converted %int_1, %.loc8_13.1 [concrete = constants.%int_1.0c6]
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl(%.loc8_13.2)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @G() -> out %return.param: %i32 {
@@ -399,5 +411,7 @@ fn G() -> i32 {
 // CHECK:STDOUT:   %.loc14_20.2: %i32 = converted %int_1, %.loc14_20.1 [concrete = constants.%int_1.0c6]
 // CHECK:STDOUT:   %bar.call: init %i32 = call imports.%bar.decl(%.loc14_20.2)
 // CHECK:STDOUT:   return %bar.call
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/function/import/in_template.carbon

@@ -92,5 +92,7 @@ fn F() {
 // CHECK:STDOUT:   %.loc8_11.2: %i32 = converted %int_42, %.loc8_11.1 [concrete = constants.%int_42.ac4]
 // CHECK:STDOUT:   %X.f.call: init %empty_tuple.type = call imports.%X.f.decl(%.loc8_11.2)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/function/import/inline.carbon

@@ -111,6 +111,8 @@ fn MyF() {
 // CHECK:STDOUT:   %foo.ref: %foo.cpp_overload_set.type = name_ref foo, imports.%foo.cpp_overload_set.value [concrete = constants.%foo.cpp_overload_set.value]
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- todo_fail_import_without_definition.carbon
@@ -141,6 +143,8 @@ fn MyF() {
 // CHECK:STDOUT:   %foo.ref.loc20: %foo.cpp_overload_set.type = name_ref foo, imports.%foo.cpp_overload_set.value [concrete = constants.%foo.cpp_overload_set.value]
 // CHECK:STDOUT:   %foo.call.loc20: init %empty_tuple.type = call imports.%foo.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- automatic_return_type.carbon
@@ -362,6 +366,8 @@ fn MyF() {
 // CHECK:STDOUT:   %Destroy.Op.call.loc15: init %empty_tuple.type = call %Destroy.Op.bound.loc15(%.loc15_43.3)
 // CHECK:STDOUT:   %Destroy.Op.call.loc14: init %empty_tuple.type = call constants.%Destroy.Op.bound(constants.%.597)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc16_41.1(%self.param: ref %i16.builtin) = "no_op";
@@ -369,5 +375,7 @@ fn MyF() {
 // CHECK:STDOUT: fn @Destroy.Op.loc16_41.2(%self.param: ref %i16) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/function/import/multiple_too_few_args_calls.carbon

@@ -67,5 +67,7 @@ fn Call() {
 // CHECK:STDOUT:   %Cpp.ref.loc27: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
 // CHECK:STDOUT:   %F2.ref: %F2.cpp_overload_set.type = name_ref F2, imports.%F2.cpp_overload_set.value [concrete = constants.%F2.cpp_overload_set.value]
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/function/import/overloads.carbon

@@ -920,6 +920,8 @@ fn F() {
 // CHECK:STDOUT:   %bar__carbon_thunk.call: init %empty_tuple.type = call imports.%bar__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call constants.%Destroy.Op.bound(constants.%.597)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @bar(%a.param: %i16);
@@ -931,6 +933,8 @@ fn F() {
 // CHECK:STDOUT: fn @Destroy.Op.loc7_13.2(%self.param: ref %i16) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_overloaded_functions.carbon
@@ -1027,6 +1031,8 @@ fn F() {
 // CHECK:STDOUT:   %.loc7_13.2: %i32 = converted %int_1, %.loc7_13.1 [concrete = constants.%int_1.0c6]
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl(%.loc7_13.2)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @foo(%a.param: %i32);
@@ -1203,6 +1209,8 @@ fn F() {
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call constants.%Destroy.Op.bound(constants.%.597)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @foo.1(%a.param: %i32);
@@ -1216,6 +1224,8 @@ fn F() {
 // CHECK:STDOUT: fn @Destroy.Op.loc8_13.2(%self.param: ref %i16) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_multiple_overloaded_sets.carbon
@@ -1342,6 +1352,8 @@ fn F() {
 // CHECK:STDOUT:   %.loc8_13.2: %i32 = converted %int_1.loc8, %.loc8_13.1 [concrete = constants.%int_1.0c6]
 // CHECK:STDOUT:   %bar.call: init %empty_tuple.type = call imports.%bar.decl(%.loc8_13.2)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @foo(%a.param: %i32);
@@ -1807,6 +1819,8 @@ fn F() {
 // CHECK:STDOUT:   %Destroy.Op.call.loc22_51: init %empty_tuple.type = call %Destroy.Op.bound.loc22(%.loc22_51.3)
 // CHECK:STDOUT:   %Destroy.Op.call.loc22_32: init %empty_tuple.type = call constants.%Destroy.Op.bound.eaa(constants.%.e05)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @foo.1(%a.param: %i32) -> out %return.param: %i32;
@@ -1822,6 +1836,8 @@ fn F() {
 // CHECK:STDOUT: fn @Destroy.Op.loc31_71.2(%self.param: ref %i128) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_import_large_int_literal.carbon
@@ -1878,6 +1894,8 @@ fn F() {
 // CHECK:STDOUT:     %h.patt: %pattern_type.97f = value_binding_pattern h [concrete = constants.%h.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_negative_int_literal.carbon
@@ -1992,6 +2010,8 @@ fn F() {
 // CHECK:STDOUT:   %.loc8_11.4: %i32 = converted %Core.IntLiteral.as.Negate.impl.Op.call, %.loc8_11.3 [concrete = constants.%int_-1.4ef]
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl(%.loc8_11.4)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @foo(%a.param: %i32);
@@ -2108,6 +2128,8 @@ fn F() {
 // CHECK:STDOUT:   %.loc15_11.4: %u32 = converted %Core.IntLiteral.as.Negate.impl.Op.call, %.loc15_11.3 [concrete = constants.%int_-1.002]
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl(%.loc15_11.4)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @foo(%a.param: %u32);
@@ -2266,6 +2288,8 @@ fn F() {
 // CHECK:STDOUT:   %Destroy.Op.call.loc7_34: init %empty_tuple.type = call %Destroy.Op.bound(%.loc7_34.3)
 // CHECK:STDOUT:   %Destroy.Op.call.loc7_31: init %empty_tuple.type = call constants.%Destroy.Op.bound(constants.%.011)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @foo(%a.param: %f64.dc1) -> out %return.param: %f64.dc1;
@@ -2277,6 +2301,8 @@ fn F() {
 // CHECK:STDOUT: fn @Destroy.Op.loc7_34.2(%self.param: ref %f64.dc1) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_import_large_floating_point_literal.carbon
@@ -2418,6 +2444,8 @@ fn F() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %.loc15_19.3, constants.%Destroy.Op.1a2547.2
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%.loc15_19.3)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @foo(%a.param: %f64.dc1) -> out %return.param: %f64.dc1;
@@ -2429,6 +2457,8 @@ fn F() {
 // CHECK:STDOUT: fn @Destroy.Op.loc15_19.2(%self.param: ref %f64.dc1) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- struct_init.carbon
@@ -2592,6 +2622,8 @@ fn F() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %.loc15_30.2, constants.%Destroy.Op
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%.loc15_30.2)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @PassNoFields(%s.param: %NoFields);
@@ -2781,6 +2813,8 @@ fn F() {
 // CHECK:STDOUT:   %addr.loc72: %ptr.6c3 = addr_of <error> [concrete = <error>]
 // CHECK:STDOUT:   %PassThreeFields__carbon_thunk.call.loc72: init %empty_tuple.type = call imports.%PassThreeFields__carbon_thunk.decl(%addr.loc72)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @PassThreeFields(%t.param: %ThreeFields.1b4);
@@ -2845,6 +2879,8 @@ fn F() {
 // CHECK:STDOUT:   %int_3.loc25: Core.IntLiteral = int_value 3 [concrete = constants.%int_3]
 // CHECK:STDOUT:   %.loc25: %struct_type.a.x.c = struct_literal (%int_1.loc25, %int_2.loc25, %int_3.loc25) [concrete = constants.%struct.11a]
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_struct_init_unsupported_field_name.carbon
@@ -2891,6 +2927,8 @@ fn F() {
 // CHECK:STDOUT:   %int_1: Core.IntLiteral = int_value 1 [concrete = constants.%int_1]
 // CHECK:STDOUT:   %.loc11: %struct_type.base = struct_literal (%int_1) [concrete = constants.%struct]
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_struct_init_from_tuple.carbon
@@ -3135,6 +3173,8 @@ fn F() {
 // CHECK:STDOUT:   %addr.loc62: %ptr.027 = addr_of <error> [concrete = <error>]
 // CHECK:STDOUT:   %PassNoFields__carbon_thunk.call.loc62: init %empty_tuple.type = call imports.%PassNoFields__carbon_thunk.decl(%addr.loc62)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @PassNoFields(%s.param: %NoFields);
@@ -3175,6 +3215,8 @@ fn F() {
 // CHECK:STDOUT:   %addr.loc118: %ptr.6c3 = addr_of <error> [concrete = <error>]
 // CHECK:STDOUT:   %PassThreeFields__carbon_thunk.call.loc118: init %empty_tuple.type = call imports.%PassThreeFields__carbon_thunk.decl(%addr.loc118)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @PassThreeFields(%t.param: %ThreeFields.1b4);
@@ -3259,6 +3301,8 @@ fn F() {
 // CHECK:STDOUT:   %.loc33_16.2: %i32 = converted %.loc33_16.1, <error> [concrete = <error>]
 // CHECK:STDOUT:   %PassInt.call.loc33: init %empty_tuple.type = call imports.%PassInt.decl(<error>)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @PassInt(%n.param: %i32);
@@ -3341,6 +3385,8 @@ fn F() {
 // CHECK:STDOUT:   %.loc34_23.2: %i32 = converted %.loc34_23.1, <error> [concrete = <error>]
 // CHECK:STDOUT:   %PassOverloaded.call.loc34: init %empty_tuple.type = call imports.%PassOverloaded.decl(<error>)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @PassOverloaded(%n.param: %i32);
@@ -3396,6 +3442,8 @@ fn F() {
 // CHECK:STDOUT:   %int_3: Core.IntLiteral = int_value 3 [concrete = constants.%int_3]
 // CHECK:STDOUT:   %.loc15_43: %struct_type.a.n = struct_literal (%.loc15_34, %int_3) [concrete = constants.%struct.7ea]
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_todo_pass_nested_structs.carbon
@@ -3516,6 +3564,8 @@ fn F() {
 // CHECK:STDOUT:   %addr: %ptr.dc0 = addr_of <error> [concrete = <error>]
 // CHECK:STDOUT:   %TakeB__carbon_thunk.call: init %empty_tuple.type = call imports.%TakeB__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @TakeB(%_.param: %B);
@@ -3623,6 +3673,8 @@ fn F() {
 // CHECK:STDOUT:   %.loc18_13.3: %i32 = converted %.loc18_13.2, <error> [concrete = <error>]
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl(<error>)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @foo(%a.param: %i32);
@@ -3730,6 +3782,8 @@ fn F() {
 // CHECK:STDOUT:   %addr: %ptr = addr_of <error> [concrete = <error>]
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @foo(%a.param: %i16);
@@ -3811,6 +3865,8 @@ fn F() {
 // CHECK:STDOUT:   %.loc15_13.1: %i64 = value_of_initializer %Core.IntLiteral.as.As.impl.Convert.call [concrete = constants.%int_1.d98]
 // CHECK:STDOUT:   %.loc15_13.2: %i64 = converted %int_1, %.loc15_13.1 [concrete = constants.%int_1.d98]
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_import_ambiguous_overload.carbon
@@ -3888,6 +3944,8 @@ fn F() {
 // CHECK:STDOUT:   %.loc19_13.1: %i64 = value_of_initializer %Core.IntLiteral.as.As.impl.Convert.call [concrete = constants.%int_1.d98]
 // CHECK:STDOUT:   %.loc19_13.2: %i64 = converted %int_1, %.loc19_13.1 [concrete = constants.%int_1.d98]
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_import_deleted_function.carbon
@@ -3965,6 +4023,8 @@ fn F() {
 // CHECK:STDOUT:   %.loc19_13.1: %i32 = value_of_initializer %Core.IntLiteral.as.As.impl.Convert.call [concrete = constants.%int_1.0c6]
 // CHECK:STDOUT:   %.loc19_13.2: %i32 = converted %int_1, %.loc19_13.1 [concrete = constants.%int_1.0c6]
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_missing_impl.carbon
@@ -4043,6 +4103,8 @@ fn F() {
 // CHECK:STDOUT:   witness = ()
 // CHECK:STDOUT:
 // CHECK:STDOUT: !requires:
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: generic fn @EchoValue(%ValueT.loc10_20.2: %I.type, %value.loc10_38.2: @EchoValue.%ValueT.as_type.loc10_41.1 (%ValueT.as_type)) {
@@ -4058,6 +4120,8 @@ fn F() {
 // CHECK:STDOUT:   fn() {
 // CHECK:STDOUT:   !entry:
 // CHECK:STDOUT:     return
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !observes:
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -4067,6 +4131,8 @@ fn F() {
 // CHECK:STDOUT:   %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
 // CHECK:STDOUT:   %foo.ref: %foo.cpp_overload_set.type = name_ref foo, imports.%foo.cpp_overload_set.value [concrete = constants.%foo.cpp_overload_set.value]
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: specific @I.WithSelf(constants.%Self) {

toolchain/check/testdata/interop/cpp/function/import/param_unsupported.carbon

@@ -118,6 +118,8 @@ fn F(x: i8388608) {
 // CHECK:STDOUT:   %foo.ref: %foo.cpp_overload_set.type = name_ref foo, imports.%foo.cpp_overload_set.value [concrete = constants.%foo.cpp_overload_set.value]
 // CHECK:STDOUT:   %int_11: Core.IntLiteral = int_value 11 [concrete = constants.%int_11]
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_todo_import_unsupported_primitive_type_among_params.carbon
@@ -144,5 +146,7 @@ fn F(x: i8388608) {
 // CHECK:STDOUT:   %int_1: Core.IntLiteral = int_value 1 [concrete = constants.%int_1]
 // CHECK:STDOUT:   %int_20: Core.IntLiteral = int_value 20 [concrete = constants.%int_20]
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/function/import/pointer.carbon

@@ -486,6 +486,8 @@ fn F() {
 // CHECK:STDOUT:   %S.cpp_destructor.bound: <bound method> = bound_method %s.var, constants.%S.cpp_destructor
 // CHECK:STDOUT:   %S.cpp_destructor.call: init %empty_tuple.type = call %S.cpp_destructor.bound(%s.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_non_nullable_pointer_param_using_const_pointer.carbon
@@ -550,6 +552,8 @@ fn F() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %p.var, constants.%Destroy.Op.1a2547.2
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%p.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc10_3.1(%self.param: ref %ptr) = "no_op";
@@ -557,6 +561,8 @@ fn F() {
 // CHECK:STDOUT: fn @Destroy.Op.loc10_3.2(%self.param: ref %const) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_double_non_nullable_pointer_param.carbon
@@ -658,6 +664,8 @@ fn F() {
 // CHECK:STDOUT:   %S.cpp_destructor.bound: <bound method> = bound_method %s.var, constants.%S.cpp_destructor
 // CHECK:STDOUT:   %S.cpp_destructor.call: init %empty_tuple.type = call %S.cpp_destructor.bound(%s.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op(%self.param: ref %ptr.037) = "no_op";
@@ -722,11 +730,15 @@ fn F() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %s.var, constants.%Destroy.Op
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%s.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op(%self.param: ref %const) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_non_nullable_pointer_to_const_param_using_non_const.carbon
@@ -791,6 +803,8 @@ fn F() {
 // CHECK:STDOUT:   %S.cpp_destructor.bound: <bound method> = bound_method %s.var, constants.%S.cpp_destructor
 // CHECK:STDOUT:   %S.cpp_destructor.call: init %empty_tuple.type = call %S.cpp_destructor.bound(%s.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_const_non_nullable_pointer_param_using_const.carbon
@@ -855,6 +869,8 @@ fn F() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %p.var, constants.%Destroy.Op.1a2547.2
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%p.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc10_3.1(%self.param: ref %ptr) = "no_op";
@@ -862,6 +878,8 @@ fn F() {
 // CHECK:STDOUT: fn @Destroy.Op.loc10_3.2(%self.param: ref %const) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_const_non_nullable_pointer_param_using_non_const.carbon
@@ -922,6 +940,8 @@ fn F() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %p.var, constants.%Destroy.Op
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%p.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op(%self.param: ref %ptr) = "no_op";
@@ -1060,26 +1080,36 @@ fn F() {
 // CHECK:STDOUT:   %Destroy.Op.bound.loc10: <bound method> = bound_method %p.var, constants.%Destroy.Op.1a2547.5
 // CHECK:STDOUT:   %Destroy.Op.call.loc10: init %empty_tuple.type = call %Destroy.Op.bound.loc10(%p.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc11_11.1(%self.param: ref %.08a0) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc11_11.2(%self.param: ref %MaybeUnformed.9f2) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc11_11.3(%self.param: ref %Optional.659) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc10(%self.param: ref %const.f96) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_const_nullable_pointer_param_using_non_const.carbon
@@ -1204,21 +1234,29 @@ fn F() {
 // CHECK:STDOUT:   %Destroy.Op.bound.loc10: <bound method> = bound_method %p.var, constants.%Destroy.Op.1a2547.1
 // CHECK:STDOUT:   %Destroy.Op.call.loc10: init %empty_tuple.type = call %Destroy.Op.bound.loc10(%p.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc11_11.1(%self.param: ref %.08a0) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc11_11.2(%self.param: ref %MaybeUnformed.9f2) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc11_11.3(%self.param: ref %Optional.659) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_non_nullable_pointer_return.carbon
@@ -1263,6 +1301,8 @@ fn F() {
 // CHECK:STDOUT:   %foo.ref.loc11: %foo.cpp_overload_set.type = name_ref foo, imports.%foo.cpp_overload_set.value [concrete = constants.%foo.cpp_overload_set.value]
 // CHECK:STDOUT:   %foo.call.loc11: init %ptr = call imports.%foo.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_double_pointer_return.carbon
@@ -1308,6 +1348,8 @@ fn F() {
 // CHECK:STDOUT:   %foo.ref.loc11: %foo.cpp_overload_set.type = name_ref foo, imports.%foo.cpp_overload_set.value [concrete = constants.%foo.cpp_overload_set.value]
 // CHECK:STDOUT:   %foo.call.loc11: init %ptr.65c = call imports.%foo.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_const_non_nullable_pointer_return.carbon
@@ -1353,6 +1395,8 @@ fn F() {
 // CHECK:STDOUT:   %foo.ref.loc11: %foo.cpp_overload_set.type = name_ref foo, imports.%foo.cpp_overload_set.value [concrete = constants.%foo.cpp_overload_set.value]
 // CHECK:STDOUT:   %foo.call.loc11: init %ptr = call imports.%foo.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- non_nullable_pointer_arg_to_pointer_param.carbon
@@ -1480,21 +1524,29 @@ fn F() {
 // CHECK:STDOUT:   %S.cpp_destructor.bound: <bound method> = bound_method %s.var, constants.%S.cpp_destructor
 // CHECK:STDOUT:   %S.cpp_destructor.call: init %empty_tuple.type = call %S.cpp_destructor.bound(%s.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc9_11.1(%self.param: ref %.08a0) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc9_11.2(%self.param: ref %MaybeUnformed.9f2) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc9_11.3(%self.param: ref %Optional.659) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- null_pointer_arg_to_pointer_param.carbon
@@ -1597,21 +1649,29 @@ fn F() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %.loc8_38.2, constants.%Destroy.Op.1a2547.4
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%.loc8_38.2)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_38.1(%self.param: ref %.08a) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_38.2(%self.param: ref %MaybeUnformed.9f2) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_38.3(%self.param: ref %Optional.db1) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- nonnull_pointer_arg_to_pointer_param.carbon
@@ -1744,21 +1804,29 @@ fn F() {
 // CHECK:STDOUT:   %S.cpp_destructor.bound: <bound method> = bound_method %s.var, constants.%S.cpp_destructor
 // CHECK:STDOUT:   %S.cpp_destructor.call: init %empty_tuple.type = call %S.cpp_destructor.bound(%s.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc9_40.1(%self.param: ref %.08a0) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc9_40.2(%self.param: ref %MaybeUnformed.9f2) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc9_40.3(%self.param: ref %Optional.659) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- forward_nullable_pointer.carbon
@@ -1845,21 +1913,29 @@ fn F() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %.loc8_19.2, constants.%Destroy.Op.1a2547.4
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%.loc8_19.2)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_19.1(%self.param: ref %.08a) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_19.2(%self.param: ref %MaybeUnformed.9f2) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_19.3(%self.param: ref %Optional.19d) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_deduced_any_param_as_pointer.carbon
@@ -1934,6 +2010,8 @@ fn F() {
 // CHECK:STDOUT:   %S.cpp_destructor.bound: <bound method> = bound_method %s.var, constants.%S.cpp_destructor
 // CHECK:STDOUT:   %S.cpp_destructor.call: init %empty_tuple.type = call %S.cpp_destructor.bound(%s.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_deduced_pointer_param_as_pointer.carbon
@@ -2127,20 +2205,28 @@ fn F() {
 // CHECK:STDOUT:   %S.cpp_destructor.bound: <bound method> = bound_method %s.var, constants.%S.cpp_destructor
 // CHECK:STDOUT:   %S.cpp_destructor.call: init %empty_tuple.type = call %S.cpp_destructor.bound(%s.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc13_65.1(%self.param: ref %.08a0) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc13_65.2(%self.param: ref %MaybeUnformed.9f2) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc13_65.3(%self.param: ref %Optional.659) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/function/import/qualified_param.carbon

@@ -139,5 +139,7 @@ fn F() {
 // CHECK:STDOUT:   %S.cpp_destructor.bound: <bound method> = bound_method %s.var, constants.%S.cpp_destructor
 // CHECK:STDOUT:   %S.cpp_destructor.call: init %empty_tuple.type = call %S.cpp_destructor.bound(%s.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/function/import/reference.carbon

@@ -540,6 +540,8 @@ fn PassConstRef(ref x: const X) {
 // CHECK:STDOUT:   %S.cpp_destructor.bound: <bound method> = bound_method %s.var, constants.%S.cpp_destructor
 // CHECK:STDOUT:   %S.cpp_destructor.call: init %empty_tuple.type = call %S.cpp_destructor.bound(%s.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_param_lvalue_ref.carbon
@@ -692,6 +694,8 @@ fn PassConstRef(ref x: const X) {
 // CHECK:STDOUT:   %S.cpp_destructor.bound.loc8: <bound method> = bound_method %v.var, constants.%S.cpp_destructor
 // CHECK:STDOUT:   %S.cpp_destructor.call.loc8: init %empty_tuple.type = call %S.cpp_destructor.bound.loc8(%v.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- call_param_rvalue_ref.carbon
@@ -738,6 +742,8 @@ fn PassConstRef(ref x: const X) {
 // CHECK:STDOUT:   %addr: %ptr.037 = addr_of %_.var
 // CHECK:STDOUT:   %TakesRValue__carbon_thunk.call: init %empty_tuple.type = call imports.%TakesRValue__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_param_rvalue_ref.carbon
@@ -858,6 +864,8 @@ fn PassConstRef(ref x: const X) {
 // CHECK:STDOUT:   %S.cpp_destructor.bound: <bound method> = bound_method %s.var, constants.%S.cpp_destructor
 // CHECK:STDOUT:   %S.cpp_destructor.call: init %empty_tuple.type = call %S.cpp_destructor.bound(%s.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- call_param_const_lvalue_ref_with_ref.carbon
@@ -941,6 +949,8 @@ fn PassConstRef(ref x: const X) {
 // CHECK:STDOUT:   %S.cpp_destructor.bound: <bound method> = bound_method %s.var, constants.%S.cpp_destructor
 // CHECK:STDOUT:   %S.cpp_destructor.call: init %empty_tuple.type = call %S.cpp_destructor.bound(%s.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- call_param_const_lvalue_ref_with_value.carbon
@@ -1018,6 +1028,8 @@ fn PassConstRef(ref x: const X) {
 // CHECK:STDOUT:   %.loc11_40.2: %ptr.711 = converted %addr.loc11, %.loc11_40.1
 // CHECK:STDOUT:   %TakesConstLValue__carbon_thunk.call.loc11: init %empty_tuple.type = call imports.%TakesConstLValue__carbon_thunk.decl(%.loc11_40.2)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- param_value_arg_for_const_rvalue_ref.carbon
@@ -1070,6 +1082,8 @@ fn PassConstRef(ref x: const X) {
 // CHECK:STDOUT:   %.loc9_26.2: %ptr.711 = converted %addr.loc9, %.loc9_26.1
 // CHECK:STDOUT:   %TakesConstRValue__carbon_thunk.call.loc9: init %empty_tuple.type = call imports.%TakesConstRValue__carbon_thunk.decl(%.loc9_26.2)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_param_lvalue_ref_arg_const_rvalue_ref.carbon
@@ -1172,6 +1186,8 @@ fn PassConstRef(ref x: const X) {
 // CHECK:STDOUT:   %S.cpp_destructor.bound: <bound method> = bound_method %s.var, constants.%S.cpp_destructor
 // CHECK:STDOUT:   %S.cpp_destructor.call: init %empty_tuple.type = call %S.cpp_destructor.bound(%s.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- call_return_lvalue_ref.carbon
@@ -1211,6 +1227,8 @@ fn PassConstRef(ref x: const X) {
 // CHECK:STDOUT:     %s.patt: %pattern_type = ref_binding_pattern s [concrete = constants.%s.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- call_return_rvalue_ref.carbon
@@ -1250,6 +1268,8 @@ fn PassConstRef(ref x: const X) {
 // CHECK:STDOUT:     %s.patt: %pattern_type = ref_binding_pattern s [concrete = constants.%s.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- call_return_const_lvalue_ref.carbon
@@ -1291,6 +1311,8 @@ fn PassConstRef(ref x: const X) {
 // CHECK:STDOUT:     %s.patt: %pattern_type = ref_binding_pattern s [concrete = constants.%s.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- forwarding_reference.carbon
@@ -1366,6 +1388,8 @@ fn PassConstRef(ref x: const X) {
 // CHECK:STDOUT:   %.loc28_37.2: %ptr.faf = converted %addr, %.loc28_37.1
 // CHECK:STDOUT:   %TakeAnything_ExpectConstRRef__carbon_thunk.call: init %empty_tuple.type = call imports.%TakeAnything_ExpectConstRRef__carbon_thunk.decl(%.loc28_37.2)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @PassRef(%x.param: ref %X) {
@@ -1376,6 +1400,8 @@ fn PassConstRef(ref x: const X) {
 // CHECK:STDOUT:   %.loc34: %X = ref_tag %x.ref
 // CHECK:STDOUT:   %TakeAnything_ExpectLRef.call: init %empty_tuple.type = call imports.%TakeAnything_ExpectLRef.decl(%x.ref)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @PassConstRef(%x.param: ref %const) {
@@ -1392,6 +1418,8 @@ fn PassConstRef(ref x: const X) {
 // CHECK:STDOUT:   %.loc40_37.2: %ptr.faf = converted %addr, %.loc40_37.1
 // CHECK:STDOUT:   %TakeAnything_ExpectConstLRef__carbon_thunk.call: init %empty_tuple.type = call imports.%TakeAnything_ExpectConstLRef__carbon_thunk.decl(%.loc40_37.2)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @PassInit() {
@@ -1405,5 +1433,7 @@ fn PassConstRef(ref x: const X) {
 // CHECK:STDOUT:   %addr: %ptr.db8 = addr_of %_.var
 // CHECK:STDOUT:   %TakeAnything_ExpectRRef__carbon_thunk.call: init %empty_tuple.type = call imports.%TakeAnything_ExpectRRef__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/function/import/return.carbon

@@ -172,6 +172,8 @@ fn Var() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %.loc11_22.3, constants.%Destroy.Op.1a2547.2
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%.loc11_22.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc11_22.1(%self.param: ref %i16.builtin) = "no_op";
@@ -179,6 +181,8 @@ fn Var() {
 // CHECK:STDOUT: fn @Destroy.Op.loc11_22.2(%self.param: ref %i16) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- var_from_thunk_param.carbon
@@ -243,6 +247,8 @@ fn Var() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %c.var, constants.%Destroy.Op.1a2547.5
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%c.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc11_3.1(%self.param: ref %ptr.00a) = "no_op";
@@ -250,16 +256,22 @@ fn Var() {
 // CHECK:STDOUT: fn @Destroy.Op.loc11_3.2(%self.param: ref %.a7d) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc11_3.3(%self.param: ref %MaybeUnformed.399) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc11_3.4(%self.param: ref %Cpp.nullptr_t) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- return_from_thunk_param.carbon
@@ -342,6 +354,8 @@ fn Var() {
 // CHECK:STDOUT:   %ReturnU8__carbon_thunk.call: init %empty_tuple.type = call imports.%ReturnU8__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   %.loc8_40.2: init %u8 to %.loc8_40.1 = mark_in_place_init %ReturnU8__carbon_thunk.call
 // CHECK:STDOUT:   return %.loc8_40.2
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @ReturnU8() -> out %return.param: %u8;
@@ -428,6 +442,8 @@ fn Var() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %my_u32.var, constants.%Destroy.Op.1a2547.2
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%my_u32.var)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @ReturnU32() -> out %return.param: %u32;
@@ -437,5 +453,7 @@ fn Var() {
 // CHECK:STDOUT: fn @Destroy.Op.loc9_3.2(%self.param: ref %u32) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/function/import/struct.carbon

@@ -527,6 +527,8 @@ fn F() {
 // CHECK:STDOUT:   %addr: %ptr.037 = addr_of %.loc8
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_import_non_copyable_param_type.carbon
@@ -562,6 +564,8 @@ fn F() {
 // CHECK:STDOUT:   %s.ref: %S = name_ref s, %s
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl(%s.ref)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- definition_single_data_member_value_param_type.carbon
@@ -600,6 +604,8 @@ fn F() {
 // CHECK:STDOUT:   %addr: %ptr.037 = addr_of %.loc8
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- definition_multiple_data_members_value_param_type.carbon
@@ -638,6 +644,8 @@ fn F() {
 // CHECK:STDOUT:   %addr: %ptr.037 = addr_of %.loc8
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_definition_in_namespace_value_param_type.carbon
@@ -719,6 +727,8 @@ fn F() {
 // CHECK:STDOUT:   %S.cpp_destructor.bound: <bound method> = bound_method %x.var, constants.%S.cpp_destructor
 // CHECK:STDOUT:   %S.cpp_destructor.call: init %empty_tuple.type = call %S.cpp_destructor.bound(%x.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_definition_in_relative_namespace_value_param_type.carbon
@@ -766,6 +776,8 @@ fn F() {
 // CHECK:STDOUT:   %addr: %ptr.b0f = addr_of %.loc8
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_definition_in_outer_definition.carbon
@@ -843,6 +855,8 @@ fn F() {
 // CHECK:STDOUT:   %O.cpp_destructor.bound: <bound method> = bound_method %x.var, constants.%O.cpp_destructor
 // CHECK:STDOUT:   %O.cpp_destructor.call: init %empty_tuple.type = call %O.cpp_destructor.bound(%x.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_definition_and_static_method_call_before.carbon
@@ -891,6 +905,8 @@ fn F() {
 // CHECK:STDOUT:   %addr: %ptr.037 = addr_of %.loc9
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_definition_and_static_method_call_after.carbon
@@ -939,6 +955,8 @@ fn F() {
 // CHECK:STDOUT:   %bar.ref: %S.bar.cpp_overload_set.type = name_ref bar, imports.%S.bar.cpp_overload_set.value [concrete = constants.%S.bar.cpp_overload_set.value]
 // CHECK:STDOUT:   %S.bar.call: init %empty_tuple.type = call imports.%S.bar.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_decl_pointer_param_type.carbon
@@ -975,6 +993,8 @@ fn F() {
 // CHECK:STDOUT:   %s.ref: %ptr = name_ref s, %s
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl(%s.ref)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_definition_pointer_param_type.carbon
@@ -1011,6 +1031,8 @@ fn F() {
 // CHECK:STDOUT:   %s.ref: %ptr = name_ref s, %s
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl(%s.ref)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_definition_value_return_type.carbon
@@ -1052,6 +1074,8 @@ fn F() {
 // CHECK:STDOUT:   %S.cpp_destructor.bound: <bound method> = bound_method %.loc8_11.3, constants.%S.cpp_destructor
 // CHECK:STDOUT:   %S.cpp_destructor.call: init %empty_tuple.type = call %S.cpp_destructor.bound(%.loc8_11.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_decl_pointer_return_type.carbon
@@ -1084,6 +1108,8 @@ fn F() {
 // CHECK:STDOUT:   %foo.ref: %foo.cpp_overload_set.type = name_ref foo, imports.%foo.cpp_overload_set.value [concrete = constants.%foo.cpp_overload_set.value]
 // CHECK:STDOUT:   %foo.call: init %ptr = call imports.%foo.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_definition_pointer_return_type.carbon
@@ -1116,5 +1142,7 @@ fn F() {
 // CHECK:STDOUT:   %foo.ref: %foo.cpp_overload_set.type = name_ref foo, imports.%foo.cpp_overload_set.value [concrete = constants.%foo.cpp_overload_set.value]
 // CHECK:STDOUT:   %foo.call: init %ptr = call imports.%foo.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/function/import/union.carbon

@@ -487,6 +487,8 @@ fn F() {
 // CHECK:STDOUT:   %addr: %ptr.2fe = addr_of %.loc8
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_definition_single_data_member_value_param_type.carbon
@@ -525,6 +527,8 @@ fn F() {
 // CHECK:STDOUT:   %addr: %ptr.2fe = addr_of %.loc8
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_definition_multiple_data_members_value_param_type.carbon
@@ -563,6 +567,8 @@ fn F() {
 // CHECK:STDOUT:   %addr: %ptr.2fe = addr_of %.loc8
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_definition_in_namespace_value_param_type.carbon
@@ -644,6 +650,8 @@ fn F() {
 // CHECK:STDOUT:   %U.cpp_destructor.bound: <bound method> = bound_method %x.var, constants.%U.cpp_destructor
 // CHECK:STDOUT:   %U.cpp_destructor.call: init %empty_tuple.type = call %U.cpp_destructor.bound(%x.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_definition_in_relative_namespace_value_param_type.carbon
@@ -691,6 +699,8 @@ fn F() {
 // CHECK:STDOUT:   %addr: %ptr.6d9 = addr_of %.loc8
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_definition_in_outer_definition.carbon
@@ -768,6 +778,8 @@ fn F() {
 // CHECK:STDOUT:   %O.cpp_destructor.bound: <bound method> = bound_method %x.var, constants.%O.cpp_destructor
 // CHECK:STDOUT:   %O.cpp_destructor.call: init %empty_tuple.type = call %O.cpp_destructor.bound(%x.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_definition_and_static_method_call_before.carbon
@@ -816,6 +828,8 @@ fn F() {
 // CHECK:STDOUT:   %addr: %ptr.2fe = addr_of %.loc9
 // CHECK:STDOUT:   %foo__carbon_thunk.call: init %empty_tuple.type = call imports.%foo__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_definition_and_static_method_call_after.carbon
@@ -864,6 +878,8 @@ fn F() {
 // CHECK:STDOUT:   %bar.ref: %U.bar.cpp_overload_set.type = name_ref bar, imports.%U.bar.cpp_overload_set.value [concrete = constants.%U.bar.cpp_overload_set.value]
 // CHECK:STDOUT:   %U.bar.call: init %empty_tuple.type = call imports.%U.bar.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_decl_pointer_param_type.carbon
@@ -900,6 +916,8 @@ fn F() {
 // CHECK:STDOUT:   %u.ref: %ptr = name_ref u, %u
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl(%u.ref)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_definition_pointer_param_type.carbon
@@ -936,6 +954,8 @@ fn F() {
 // CHECK:STDOUT:   %u.ref: %ptr = name_ref u, %u
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl(%u.ref)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_definition_value_return_type.carbon
@@ -977,6 +997,8 @@ fn F() {
 // CHECK:STDOUT:   %U.cpp_destructor.bound: <bound method> = bound_method %.loc8_11.3, constants.%U.cpp_destructor
 // CHECK:STDOUT:   %U.cpp_destructor.call: init %empty_tuple.type = call %U.cpp_destructor.bound(%.loc8_11.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_decl_pointer_return_type.carbon
@@ -1009,6 +1031,8 @@ fn F() {
 // CHECK:STDOUT:   %foo.ref: %foo.cpp_overload_set.type = name_ref foo, imports.%foo.cpp_overload_set.value [concrete = constants.%foo.cpp_overload_set.value]
 // CHECK:STDOUT:   %foo.call: init %ptr = call imports.%foo.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_definition_pointer_return_type.carbon
@@ -1041,5 +1065,7 @@ fn F() {
 // CHECK:STDOUT:   %foo.ref: %foo.cpp_overload_set.type = name_ref foo, imports.%foo.cpp_overload_set.value [concrete = constants.%foo.cpp_overload_set.value]
 // CHECK:STDOUT:   %foo.call: init %ptr = call imports.%foo.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/function/import/variadic.carbon

@@ -117,6 +117,8 @@ fn Call3() {
 // CHECK:STDOUT:   %.loc8_11.2: %i32 = converted %int_1, %.loc8_11.1 [concrete = constants.%int_1.0c6]
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl.6431a3.1(%.loc8_11.2)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Call2() {
@@ -141,6 +143,8 @@ fn Call3() {
 // CHECK:STDOUT:   %.loc14_14.2: %i32 = converted %int_2, %.loc14_14.1 [concrete = constants.%int_2.295]
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl.6431a3.2(%.loc14_11.2, %.loc14_14.2)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Call3() {
@@ -173,5 +177,7 @@ fn Call3() {
 // CHECK:STDOUT:   %.loc20_17.2: %i32 = converted %int_3, %.loc20_17.1 [concrete = constants.%int_3.410]
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl.6431a3.3(%.loc20_11.2, %.loc20_14.2, %.loc20_17.2)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/function/import/void_pointer.carbon

@@ -145,6 +145,8 @@ fn F() {
 // CHECK:STDOUT:   %input.ref: %ptr = name_ref input, %input
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl(%input.ref)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- non_nullable_return_value.carbon
@@ -191,6 +193,8 @@ fn F() {
 // CHECK:STDOUT:     %output.patt: %pattern_type = value_binding_pattern output [concrete = constants.%output.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- nullable_param.carbon
@@ -292,21 +296,29 @@ fn F() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %.loc10_11.3, constants.%Destroy.Op.1a2547.4
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%.loc10_11.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc10_11.1(%self.param: ref %.a7d) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc10_11.2(%self.param: ref %MaybeUnformed.399) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc10_11.3(%self.param: ref %Optional.c11) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- null_param.carbon
@@ -416,21 +428,29 @@ fn F() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %.loc10_41.2, constants.%Destroy.Op.1a2547.4
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%.loc10_41.2)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc10_41.1(%self.param: ref %.a7d) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc10_41.2(%self.param: ref %MaybeUnformed.399) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc10_41.3(%self.param: ref %Optional.d90) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- nullable_return_value.carbon
@@ -532,21 +552,29 @@ fn F() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %.loc10_57.2, constants.%Destroy.Op.1a2547.4
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%.loc10_57.2)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc10_57.1(%self.param: ref %.a7d) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc10_57.2(%self.param: ref %MaybeUnformed.399) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc10_57.3(%self.param: ref %Optional.752) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- non_nullable_pointer.carbon
@@ -618,6 +646,8 @@ fn F() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %non_nullable_pointer.var, constants.%Destroy.Op
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%non_nullable_pointer.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op(%self.param: ref %ptr.6f9) = "no_op";
@@ -691,6 +721,8 @@ fn F() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %const_void_pointer.var, constants.%Destroy.Op
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%const_void_pointer.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op(%self.param: ref %ptr) = "no_op";

toolchain/check/testdata/interop/cpp/impls/as.carbon

@@ -236,6 +236,8 @@ fn ConversionExplicit(s: Cpp.ConditionallyExplicitFalse) {
 // CHECK:STDOUT:   %Dest.cpp_destructor.bound: <bound method> = bound_method %.loc8_5.4, %Op.ref
 // CHECK:STDOUT:   %Dest.cpp_destructor.call: init %empty_tuple.type = call %Dest.cpp_destructor.bound(%.loc8_5.4)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @ConstructorConversion(%s.param: %Source2) {
@@ -257,6 +259,8 @@ fn ConversionExplicit(s: Cpp.ConditionallyExplicitFalse) {
 // CHECK:STDOUT:   %Dest2.cpp_destructor.bound: <bound method> = bound_method %.loc14_5.4, %Op.ref
 // CHECK:STDOUT:   %Dest2.cpp_destructor.call: init %empty_tuple.type = call %Dest2.cpp_destructor.bound(%.loc14_5.4)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @ExplicitConstructorTest(%s.param: %Source) {
@@ -278,6 +282,8 @@ fn ConversionExplicit(s: Cpp.ConditionallyExplicitFalse) {
 // CHECK:STDOUT:   %ExplicitConstructor.cpp_destructor.bound: <bound method> = bound_method %.loc20_5.4, %Op.ref
 // CHECK:STDOUT:   %ExplicitConstructor.cpp_destructor.call: init %empty_tuple.type = call %ExplicitConstructor.cpp_destructor.bound(%.loc20_5.4)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @ExplicitConversionTest(%s.param: %ExplicitConversion) {
@@ -296,6 +302,8 @@ fn ConversionExplicit(s: Cpp.ConditionallyExplicitFalse) {
 // CHECK:STDOUT:   %Dest.cpp_destructor.bound: <bound method> = bound_method %.loc26_5.4, %Op.ref
 // CHECK:STDOUT:   %Dest.cpp_destructor.call: init %empty_tuple.type = call %Dest.cpp_destructor.bound(%.loc26_5.4)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- conditionally_explicit.carbon
@@ -419,6 +427,8 @@ fn ConversionExplicit(s: Cpp.ConditionallyExplicitFalse) {
 // CHECK:STDOUT:   %ConditionallyExplicit.cpp_destructor.bound.loc8: <bound method> = bound_method %.loc8_43.5, %Op.ref.loc8
 // CHECK:STDOUT:   %ConditionallyExplicit.cpp_destructor.call.loc8: init %empty_tuple.type = call %ConditionallyExplicit.cpp_destructor.bound.loc8(%.loc8_43.5)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @ConstructorExplicit(%s.param: %Source) {
@@ -440,6 +450,8 @@ fn ConversionExplicit(s: Cpp.ConditionallyExplicitFalse) {
 // CHECK:STDOUT:   %ConditionallyExplicit.cpp_destructor.bound: <bound method> = bound_method %.loc15_5.4, %Op.ref
 // CHECK:STDOUT:   %ConditionallyExplicit.cpp_destructor.call: init %empty_tuple.type = call %ConditionallyExplicit.cpp_destructor.bound(%.loc15_5.4)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @ConversionNotExplicit(%s.param: %ConditionallyExplicit.3cd) {
@@ -479,6 +491,8 @@ fn ConversionExplicit(s: Cpp.ConditionallyExplicitFalse) {
 // CHECK:STDOUT:   %Dest.cpp_destructor.bound.loc21: <bound method> = bound_method %.loc21_21.4, %Op.ref.loc21
 // CHECK:STDOUT:   %Dest.cpp_destructor.call.loc21: init %empty_tuple.type = call %Dest.cpp_destructor.bound.loc21(%.loc21_21.4)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @ConversionExplicit(%s.param: %ConditionallyExplicit.3cd) {
@@ -497,6 +511,8 @@ fn ConversionExplicit(s: Cpp.ConditionallyExplicitFalse) {
 // CHECK:STDOUT:   %Dest.cpp_destructor.bound: <bound method> = bound_method %.loc28_5.4, %Op.ref
 // CHECK:STDOUT:   %Dest.cpp_destructor.call: init %empty_tuple.type = call %Dest.cpp_destructor.bound(%.loc28_5.4)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_conditionally_explicit_implicit.carbon
@@ -557,6 +573,8 @@ fn ConversionExplicit(s: Cpp.ConditionallyExplicitFalse) {
 // CHECK:STDOUT:     %_.patt: %pattern_type.04c = value_binding_pattern _ [concrete = constants.%_.patt.d67]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @ConversionExplicit(%s.param: %ConditionallyExplicit.3cd) {
@@ -583,5 +601,7 @@ fn ConversionExplicit(s: Cpp.ConditionallyExplicitFalse) {
 // CHECK:STDOUT:   %Dest.cpp_destructor.bound: <bound method> = bound_method %.loc21_21.4, %Op.ref
 // CHECK:STDOUT:   %Dest.cpp_destructor.call: init %empty_tuple.type = call %Dest.cpp_destructor.bound(%.loc21_21.4)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/impls/copy.carbon

@@ -267,6 +267,8 @@ fn EqualWitnesses(p: Wrap(Cpp.Copyable)*) -> Wrap(Cpp.Copyable)* {
 // CHECK:STDOUT:   %Copyable__carbon_thunk.call: init %empty_tuple.type = call imports.%Copyable__carbon_thunk.decl(%.loc8_10.4, %addr.loc8_10.2)
 // CHECK:STDOUT:   %.loc8_10.5: init %Copyable to %.loc6_40.1 = mark_in_place_init %Copyable__carbon_thunk.call
 // CHECK:STDOUT:   return %.loc8_10.5 to %return.param
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @CopyExplicitCopy(%c.param: %ExplicitCopy) -> out %return.param: %ExplicitCopy {
@@ -286,6 +288,8 @@ fn EqualWitnesses(p: Wrap(Cpp.Copyable)*) -> Wrap(Cpp.Copyable)* {
 // CHECK:STDOUT:   %ExplicitCopy__carbon_thunk.call: init %empty_tuple.type = call imports.%ExplicitCopy__carbon_thunk.decl(%.loc14_10.4, %addr.loc14_10.2)
 // CHECK:STDOUT:   %.loc14_10.5: init %ExplicitCopy to %.loc12_48.1 = mark_in_place_init %ExplicitCopy__carbon_thunk.call
 // CHECK:STDOUT:   return %.loc14_10.5 to %return.param
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- copy_generically.carbon
@@ -332,6 +336,8 @@ fn EqualWitnesses(p: Wrap(Cpp.Copyable)*) -> Wrap(Cpp.Copyable)* {
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT:   %Copy.call: init %Copyable to %.loc10_34.1 = call %Copy.specific_fn(%c.ref)
 // CHECK:STDOUT:   return %Copy.call to %return.param
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @EqualWitnesses(%p.param: %ptr.fa1) -> out %return.param: %ptr.fa1 {
@@ -343,5 +349,7 @@ fn EqualWitnesses(p: Wrap(Cpp.Copyable)*) -> Wrap(Cpp.Copyable)* {
 // CHECK:STDOUT:   %bound_method.loc20_10.2: <bound method> = bound_method %p.ref, %specific_fn
 // CHECK:STDOUT:   %ptr.as.Copy.impl.Op.call: init %ptr.fa1 = call %bound_method.loc20_10.2(%p.ref)
 // CHECK:STDOUT:   return %ptr.as.Copy.impl.Op.call
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/impls/destroy.carbon

@@ -337,6 +337,8 @@ fn F() {
 // CHECK:STDOUT:   %PublicDestructor.cpp_destructor.bound: <bound method> = bound_method %a.var, constants.%PublicDestructor.cpp_destructor
 // CHECK:STDOUT:   %PublicDestructor.cpp_destructor.call: init %empty_tuple.type = call %PublicDestructor.cpp_destructor.bound(%a.var)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @PublicDestructor.cpp_destructor(%self.param: ref %PublicDestructor);
@@ -369,6 +371,8 @@ fn F() {
 // CHECK:STDOUT:   %TrivialDestructor.cpp_destructor.bound: <bound method> = bound_method %a.var, %Op.ref
 // CHECK:STDOUT:   %TrivialDestructor.cpp_destructor.call: init %empty_tuple.type = call %TrivialDestructor.cpp_destructor.bound(%a.var)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @TrivialDestructor.cpp_destructor(%self.param: ref %TrivialDestructor) = "no_op";
@@ -379,6 +383,8 @@ fn F() {
 // CHECK:STDOUT:   %TrivialDestructor.cpp_destructor.bound: <bound method> = bound_method %self.param, %Op.ref
 // CHECK:STDOUT:   %TrivialDestructor.cpp_destructor.call: init %empty_tuple.type = call %TrivialDestructor.cpp_destructor.bound(%self.param)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_todo_destroy_protected_base_destructor.carbon
@@ -424,16 +430,22 @@ fn F() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %a.var, constants.%Destroy.Op.1a2547.2
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%a.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc20_3.1(%self.param: ref %struct_type.base.454) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc20_3.2(%self.param: ref %Derived) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_destroy_private_base_destructor.carbon
@@ -479,15 +491,21 @@ fn F() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %a.var, constants.%Destroy.Op.1a2547.2
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%a.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc21_3.1(%self.param: ref %struct_type.base.9aa) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc21_3.2(%self.param: ref %Derived) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/impls/implicit_as.carbon

@@ -508,6 +508,8 @@ fn InitFromStruct() {
 // CHECK:STDOUT:   %Dest.cpp_destructor.bound: <bound method> = bound_method %.loc8_21.4, %Op.ref
 // CHECK:STDOUT:   %Dest.cpp_destructor.call: init %empty_tuple.type = call %Dest.cpp_destructor.bound(%.loc8_21.4)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @NonConstConversion.loc12(%s.param: ref %NonConstConversion.689) {
@@ -533,6 +535,8 @@ fn InitFromStruct() {
 // CHECK:STDOUT:   %Dest.cpp_destructor.bound: <bound method> = bound_method %.loc14_21.4, %Op.ref
 // CHECK:STDOUT:   %Dest.cpp_destructor.call: init %empty_tuple.type = call %Dest.cpp_destructor.bound(%.loc14_21.4)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @ConstructorConversion(%s.param: %Source2) {
@@ -561,6 +565,8 @@ fn InitFromStruct() {
 // CHECK:STDOUT:   %Dest2.cpp_destructor.bound: <bound method> = bound_method %.loc20_22.5, %Op.ref
 // CHECK:STDOUT:   %Dest2.cpp_destructor.call: init %empty_tuple.type = call %Dest2.cpp_destructor.bound(%.loc20_22.5)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_expr_category.carbon
@@ -595,6 +601,8 @@ fn InitFromStruct() {
 // CHECK:STDOUT:     %_.patt: %pattern_type.b72 = value_binding_pattern _ [concrete = constants.%_.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_access.carbon
@@ -686,6 +694,8 @@ fn InitFromStruct() {
 // CHECK:STDOUT:   %InaccessibleConstructor.cpp_destructor.bound: <bound method> = bound_method %.loc16_40.5, %Op.ref
 // CHECK:STDOUT:   %InaccessibleConstructor.cpp_destructor.call: init %empty_tuple.type = call %InaccessibleConstructor.cpp_destructor.bound(%.loc16_40.5)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @InaccessibleConversionTest(%s.param: %InaccessibleConversion) {
@@ -712,6 +722,8 @@ fn InitFromStruct() {
 // CHECK:STDOUT:   %Dest.cpp_destructor.bound: <bound method> = bound_method %.loc30_21.4, %Op.ref
 // CHECK:STDOUT:   %Dest.cpp_destructor.call: init %empty_tuple.type = call %Dest.cpp_destructor.bound(%.loc30_21.4)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_deleted.carbon
@@ -754,6 +766,8 @@ fn InitFromStruct() {
 // CHECK:STDOUT:     %_.patt: %pattern_type.937 = value_binding_pattern _ [concrete = constants.%_.patt.a57]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @DeletedConversionTest(%s.param: %DeletedConversion) {
@@ -769,6 +783,8 @@ fn InitFromStruct() {
 // CHECK:STDOUT:     %_.patt: %pattern_type.b72 = value_binding_pattern _ [concrete = constants.%_.patt.664]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_explicit.carbon
@@ -811,6 +827,8 @@ fn InitFromStruct() {
 // CHECK:STDOUT:     %_.patt: %pattern_type.eae = value_binding_pattern _ [concrete = constants.%_.patt.411]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @ExplicitConversionTest(%s.param: %ExplicitConversion) {
@@ -826,6 +844,8 @@ fn InitFromStruct() {
 // CHECK:STDOUT:     %_.patt: %pattern_type.b72 = value_binding_pattern _ [concrete = constants.%_.patt.664]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- i32_to_int.carbon
@@ -888,6 +908,8 @@ fn InitFromStruct() {
 // CHECK:STDOUT:   %IntConstructor.cpp_destructor.bound: <bound method> = bound_method %.loc8_31.4, %Op.ref
 // CHECK:STDOUT:   %IntConstructor.cpp_destructor.call: init %empty_tuple.type = call %IntConstructor.cpp_destructor.bound(%.loc8_31.4)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_no_u32_to_int_conversion_in_carbon.carbon
@@ -952,6 +974,8 @@ fn InitFromStruct() {
 // CHECK:STDOUT:   %IntConstructor.cpp_destructor.bound: <bound method> = bound_method %.loc19_31.5, %Op.ref
 // CHECK:STDOUT:   %IntConstructor.cpp_destructor.call: init %empty_tuple.type = call %IntConstructor.cpp_destructor.bound(%.loc19_31.5)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- default_constructor.carbon
@@ -1013,6 +1037,8 @@ fn InitFromStruct() {
 // CHECK:STDOUT:   %DefaultConstructor.cpp_destructor.bound: <bound method> = bound_method %.loc9_36.5, %Op.ref
 // CHECK:STDOUT:   %DefaultConstructor.cpp_destructor.call: init %empty_tuple.type = call %DefaultConstructor.cpp_destructor.bound(%.loc9_36.5)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- construct_multi_argument.carbon
@@ -1230,6 +1256,8 @@ fn InitFromStruct() {
 // CHECK:STDOUT:   %Two.cpp_destructor.bound: <bound method> = bound_method %.loc8_25.5, %Op.ref.loc8
 // CHECK:STDOUT:   %Two.cpp_destructor.call: init %empty_tuple.type = call %Two.cpp_destructor.bound(%.loc8_25.5)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_todo_aggregate_from_tuple.carbon
@@ -1292,6 +1320,8 @@ fn InitFromStruct() {
 // CHECK:STDOUT:     %_.patt.loc31: %pattern_type.5dc = value_binding_pattern _ [concrete = constants.%_.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_todo_aggregate_from_struct.carbon
@@ -1354,6 +1384,8 @@ fn InitFromStruct() {
 // CHECK:STDOUT:     %_.patt.loc31: %pattern_type.5dc = value_binding_pattern _ [concrete = constants.%_.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- non_aggregate_from_tuple.carbon
@@ -1520,6 +1552,8 @@ fn InitFromStruct() {
 // CHECK:STDOUT:   %NonAggregate.cpp_destructor.bound.loc8: <bound method> = bound_method %.loc8_30.5, %Op.ref.loc8
 // CHECK:STDOUT:   %NonAggregate.cpp_destructor.call.loc8: init %empty_tuple.type = call %NonAggregate.cpp_destructor.bound.loc8(%.loc8_30.5)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_non_aggregate_from_struct.carbon
@@ -1582,5 +1616,7 @@ fn InitFromStruct() {
 // CHECK:STDOUT:     %_.patt.loc31: %pattern_type.273 = value_binding_pattern _ [concrete = constants.%_.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/macros/macros.carbon

@@ -1059,6 +1059,8 @@ fn F() {
 // CHECK:STDOUT:     %f.patt: %pattern_type.6b6 = value_binding_pattern f [concrete = constants.%f.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_macro_and_non_macro_same_name.carbon
@@ -1183,6 +1185,8 @@ fn F() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %a.var, constants.%Destroy.Op.1a2547.3
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%a.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc10_3.1(%self.param: ref %f32.9b3) = "no_op";
@@ -1190,11 +1194,15 @@ fn F() {
 // CHECK:STDOUT: fn @Destroy.Op.loc10_3.2(%self.param: ref %f32.c73) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc10_3.3(%self.param: ref %array_type) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_unary_operator.carbon
@@ -1225,6 +1233,8 @@ fn F() {
 // CHECK:STDOUT:     %a.patt: %pattern_type.6b6 = value_binding_pattern a [concrete = constants.%a.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_binary_operator.carbon
@@ -1255,6 +1265,8 @@ fn F() {
 // CHECK:STDOUT:     %a.patt: %pattern_type.6b6 = value_binding_pattern a [concrete = constants.%a.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_casting.carbon
@@ -1320,6 +1332,8 @@ fn F() {
 // CHECK:STDOUT:     %d.patt: %pattern_type.6b6 = value_binding_pattern d [concrete = constants.%d.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_nested_macros.carbon
@@ -1350,6 +1364,8 @@ fn F() {
 // CHECK:STDOUT:     %a.patt: %pattern_type.6b6 = value_binding_pattern a [concrete = constants.%a.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_string_literal_object_like_macro.carbon
@@ -1461,6 +1477,8 @@ fn F() {
 // CHECK:STDOUT:     %g.patt: %pattern_type.adf = value_binding_pattern g [concrete = constants.%g.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_floating_point_literal_macro.carbon
@@ -1516,6 +1534,8 @@ fn F() {
 // CHECK:STDOUT:     %c.patt: %pattern_type.240 = value_binding_pattern c [concrete = constants.%c.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_character_literals.carbon
@@ -1600,6 +1620,8 @@ fn F() {
 // CHECK:STDOUT:     %f.patt: %pattern_type.2ff = value_binding_pattern f [concrete = constants.%f.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_character_literals_operators.carbon
@@ -1654,6 +1676,8 @@ fn F() {
 // CHECK:STDOUT:     %c.patt: %pattern_type.831 = value_binding_pattern c [concrete = constants.%c.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_boolean_literal_macro.carbon
@@ -1779,6 +1803,8 @@ fn F() {
 // CHECK:STDOUT:     %k.patt: %pattern_type.6b6 = value_binding_pattern k [concrete = constants.%k.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- nullptr.carbon
@@ -1878,21 +1904,29 @@ fn F() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %.loc11_14.3, constants.%Destroy.Op.1a2547.5
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%.loc11_14.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc11_14.1(%self.param: ref %.0f8) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc11_14.2(%self.param: ref %MaybeUnformed.b84) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc11_14.3(%self.param: ref %Optional.a18) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- enums.carbon
@@ -1926,6 +1960,8 @@ fn F() {
 // CHECK:STDOUT:     %a.patt: %pattern_type = value_binding_pattern a [concrete = constants.%a.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- constexpr_int.carbon
@@ -1968,6 +2004,8 @@ fn F() {
 // CHECK:STDOUT:     %a.patt: %pattern_type.6b6 = value_binding_pattern a [concrete = constants.%a.patt.bb2]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- constexpr_int_addr.carbon
@@ -2014,6 +2052,8 @@ fn F() {
 // CHECK:STDOUT:   %N.ref: ref %const = name_ref N, imports.%n.var [concrete = imports.%n.var]
 // CHECK:STDOUT:   %addr: %ptr = addr_of %N.ref [concrete = constants.%addr]
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- lambda.carbon
@@ -2044,6 +2084,8 @@ fn F() {
 // CHECK:STDOUT:     %i.patt: %pattern_type.6b6 = value_binding_pattern i [concrete = constants.%i.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_macro_redefined.carbon
@@ -2074,6 +2116,8 @@ fn F() {
 // CHECK:STDOUT:     %a.patt: %pattern_type.6b6 = value_binding_pattern a [concrete = constants.%a.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_macro_defined_twice.carbon
@@ -2104,6 +2148,8 @@ fn F() {
 // CHECK:STDOUT:     %a.patt: %pattern_type.6b6 = value_binding_pattern a [concrete = constants.%a.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- assign.carbon
@@ -2157,6 +2203,8 @@ fn F() {
 // CHECK:STDOUT:   %.loc10: init %i32 = converted %int_2, %Core.IntLiteral.as.ImplicitAs.impl.Convert.call [concrete = constants.%int_2.295]
 // CHECK:STDOUT:   assign %m.ref, %.loc10
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- assign_subobject.carbon
@@ -2220,5 +2268,7 @@ fn F() {
 // CHECK:STDOUT:   %.loc17_9: init %i32 = converted %int_2, %Core.IntLiteral.as.ImplicitAs.impl.Convert.call [concrete = constants.%int_2.295]
 // CHECK:STDOUT:   assign %m.ref, %.loc17_9
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/namespace/import.carbon

@@ -395,6 +395,8 @@ fn F() {
 // CHECK:STDOUT:   %foo.ref: %foo.cpp_overload_set.type = name_ref foo, imports.%foo.cpp_overload_set.value [concrete = constants.%foo.cpp_overload_set.value]
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_multiple.carbon
@@ -460,6 +462,8 @@ fn F() {
 // CHECK:STDOUT:   %foo3.ref: %foo3.cpp_overload_set.type = name_ref foo3, imports.%foo3.cpp_overload_set.value [concrete = constants.%foo3.cpp_overload_set.value]
 // CHECK:STDOUT:   %foo3.call: init %empty_tuple.type = call imports.%foo3.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_inline.carbon
@@ -492,6 +496,8 @@ fn F() {
 // CHECK:STDOUT:   %foo.ref: %foo.cpp_overload_set.type = name_ref foo, imports.%foo.cpp_overload_set.value [concrete = constants.%foo.cpp_overload_set.value]
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_inline_ambiguity_not_triggered.carbon
@@ -533,6 +539,8 @@ fn F() {
 // CHECK:STDOUT:   %X.cpp_destructor.bound: <bound method> = bound_method %.loc8_11.3, constants.%X.cpp_destructor
 // CHECK:STDOUT:   %X.cpp_destructor.call: init %empty_tuple.type = call %X.cpp_destructor.bound(%.loc8_11.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_special_name_call_escpaed.carbon
@@ -565,5 +573,7 @@ fn F() {
 // CHECK:STDOUT:   %foo.ref: %foo.cpp_overload_set.type = name_ref foo, imports.%foo.cpp_overload_set.value [concrete = constants.%foo.cpp_overload_set.value]
 // CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call imports.%foo.decl()
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/operators/arithmetic_operators.carbon

@@ -1534,6 +1534,8 @@ fn TestUnaryOperators(a: Cpp.Int16, b: Cpp.Int32) {
 // CHECK:STDOUT:     %bound_method.loc126_5.4: <bound method> = bound_method %.loc126_5.3, %specific_impl_fn.loc126_5.2
 // CHECK:STDOUT:     %Destroy.WithSelf.Op.call: init %empty_tuple.type = call %bound_method.loc126_5.4(%.loc126_5.3)
 // CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !observes:
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -1578,6 +1580,8 @@ fn TestUnaryOperators(a: Cpp.Int16, b: Cpp.Int32) {
 // CHECK:STDOUT:     %bound_method.loc137_5.4: <bound method> = bound_method %.loc137_5.3, %specific_impl_fn.loc137_5.2
 // CHECK:STDOUT:     %Destroy.WithSelf.Op.call: init %empty_tuple.type = call %bound_method.loc137_5.4(%.loc137_5.3)
 // CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !observes:
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -1622,6 +1626,8 @@ fn TestUnaryOperators(a: Cpp.Int16, b: Cpp.Int32) {
 // CHECK:STDOUT:     %bound_method.loc148_5.4: <bound method> = bound_method %.loc148_5.3, %specific_impl_fn.loc148_5.2
 // CHECK:STDOUT:     %Destroy.WithSelf.Op.call: init %empty_tuple.type = call %bound_method.loc148_5.4(%.loc148_5.3)
 // CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !observes:
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -1666,6 +1672,8 @@ fn TestUnaryOperators(a: Cpp.Int16, b: Cpp.Int32) {
 // CHECK:STDOUT:     %bound_method.loc159_5.4: <bound method> = bound_method %.loc159_5.3, %specific_impl_fn.loc159_5.2
 // CHECK:STDOUT:     %Destroy.WithSelf.Op.call: init %empty_tuple.type = call %bound_method.loc159_5.4(%.loc159_5.3)
 // CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !observes:
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -1710,6 +1718,8 @@ fn TestUnaryOperators(a: Cpp.Int16, b: Cpp.Int32) {
 // CHECK:STDOUT:     %bound_method.loc170_5.4: <bound method> = bound_method %.loc170_5.3, %specific_impl_fn.loc170_5.2
 // CHECK:STDOUT:     %Destroy.WithSelf.Op.call: init %empty_tuple.type = call %bound_method.loc170_5.4(%.loc170_5.3)
 // CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !observes:
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -1740,6 +1750,8 @@ fn TestUnaryOperators(a: Cpp.Int16, b: Cpp.Int32) {
 // CHECK:STDOUT:     %bound_method.loc227_5.2: <bound method> = bound_method %x.ref, %specific_impl_fn.loc227_5.1
 // CHECK:STDOUT:     %AddAssignWith.WithSelf.Op.call: init %empty_tuple.type = call %bound_method.loc227_5.2(%x.ref, %y.ref)
 // CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !observes:
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -1770,6 +1782,8 @@ fn TestUnaryOperators(a: Cpp.Int16, b: Cpp.Int32) {
 // CHECK:STDOUT:     %bound_method.loc233_5.2: <bound method> = bound_method %x.ref, %specific_impl_fn.loc233_5.1
 // CHECK:STDOUT:     %SubAssignWith.WithSelf.Op.call: init %empty_tuple.type = call %bound_method.loc233_5.2(%x.ref, %y.ref)
 // CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !observes:
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -1800,6 +1814,8 @@ fn TestUnaryOperators(a: Cpp.Int16, b: Cpp.Int32) {
 // CHECK:STDOUT:     %bound_method.loc239_5.2: <bound method> = bound_method %x.ref, %specific_impl_fn.loc239_5.1
 // CHECK:STDOUT:     %MulAssignWith.WithSelf.Op.call: init %empty_tuple.type = call %bound_method.loc239_5.2(%x.ref, %y.ref)
 // CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !observes:
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -1830,6 +1846,8 @@ fn TestUnaryOperators(a: Cpp.Int16, b: Cpp.Int32) {
 // CHECK:STDOUT:     %bound_method.loc245_5.2: <bound method> = bound_method %x.ref, %specific_impl_fn.loc245_5.1
 // CHECK:STDOUT:     %DivAssignWith.WithSelf.Op.call: init %empty_tuple.type = call %bound_method.loc245_5.2(%x.ref, %y.ref)
 // CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !observes:
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -1860,6 +1878,8 @@ fn TestUnaryOperators(a: Cpp.Int16, b: Cpp.Int32) {
 // CHECK:STDOUT:     %bound_method.loc251_5.2: <bound method> = bound_method %x.ref, %specific_impl_fn.loc251_5.1
 // CHECK:STDOUT:     %ModAssignWith.WithSelf.Op.call: init %empty_tuple.type = call %bound_method.loc251_5.2(%x.ref, %y.ref)
 // CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !observes:
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -1885,6 +1905,8 @@ fn TestUnaryOperators(a: Cpp.Int16, b: Cpp.Int32) {
 // CHECK:STDOUT:     %bound_method.loc280_3.2: <bound method> = bound_method %x.ref, %specific_impl_fn.loc280_3.1
 // CHECK:STDOUT:     %Inc.WithSelf.Op.call: init %empty_tuple.type = call %bound_method.loc280_3.2(%x.ref)
 // CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !observes:
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -1910,6 +1932,8 @@ fn TestUnaryOperators(a: Cpp.Int16, b: Cpp.Int32) {
 // CHECK:STDOUT:     %bound_method.loc286_3.2: <bound method> = bound_method %x.ref, %specific_impl_fn.loc286_3.1
 // CHECK:STDOUT:     %Dec.WithSelf.Op.call: init %empty_tuple.type = call %bound_method.loc286_3.2(%x.ref)
 // CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !observes:
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -1952,6 +1976,8 @@ fn TestUnaryOperators(a: Cpp.Int16, b: Cpp.Int32) {
 // CHECK:STDOUT:     %bound_method.loc296_3.4: <bound method> = bound_method %.loc296_3.4, %specific_impl_fn.loc296_3.2
 // CHECK:STDOUT:     %Destroy.WithSelf.Op.call: init %empty_tuple.type = call %bound_method.loc296_3.4(%.loc296_3.4)
 // CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !observes:
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/operators/deref.carbon

@@ -181,6 +181,8 @@ fn TestDerefFail(not_ptr: Cpp.NotAPtr) {
 // CHECK:STDOUT:   %ConstDeref.cpp_operator.bound: <bound method> = bound_method %.loc13, %Op.ref.loc13_43
 // CHECK:STDOUT:   %operator_Star__carbon_thunk.call: ref %i32 = call imports.%operator_Star__carbon_thunk.decl(%.loc13)
 // CHECK:STDOUT:   return %operator_Star__carbon_thunk.call
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- mutable_deref.carbon
@@ -230,5 +232,7 @@ fn TestDerefFail(not_ptr: Cpp.NotAPtr) {
 // CHECK:STDOUT:   %.loc13: %MutableDeref = acquire_value %int_ptr.ref
 // CHECK:STDOUT:   %MutableDeref.cpp_operator.call: ref %i32 = call %bound_method(%.loc13)
 // CHECK:STDOUT:   return %MutableDeref.cpp_operator.call
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/operators/eq_with.carbon

@@ -475,6 +475,8 @@ fn Test(only_neq: Cpp.OnlyNeq,
 // CHECK:STDOUT:     %bound_method.loc14_5.2: <bound method> = bound_method %x.ref.loc14, %specific_impl_fn.loc14_5.1
 // CHECK:STDOUT:     %EqWith.WithSelf.NotEqual.call: init bool = call %bound_method.loc14_5.2(%x.ref.loc14, %y.ref.loc14)
 // CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !observes:
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -739,6 +741,8 @@ fn Test(only_neq: Cpp.OnlyNeq,
 // CHECK:STDOUT:     %bound_method.loc37_5.2: <bound method> = bound_method %x.ref.loc37, %specific_impl_fn.loc37_5.1
 // CHECK:STDOUT:     %EqWith.WithSelf.NotEqual.call: init bool = call %bound_method.loc37_5.2(%x.ref.loc37, %y.ref.loc37)
 // CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !observes:
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/operators/operators.carbon

@@ -1161,6 +1161,8 @@ fn F() {
 // CHECK:STDOUT:   %C.cpp_destructor.bound.loc8: <bound method> = bound_method %c.var, %Op.ref.loc8
 // CHECK:STDOUT:   %C.cpp_destructor.call.loc8: init %empty_tuple.type = call %C.cpp_destructor.bound.loc8(%c.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_binary_operators.carbon
@@ -1968,6 +1970,8 @@ fn F() {
 // CHECK:STDOUT:   %C.cpp_destructor.bound.loc8: <bound method> = bound_method %c1.var, %Op.ref.loc8
 // CHECK:STDOUT:   %C.cpp_destructor.call.loc8: init %empty_tuple.type = call %C.cpp_destructor.bound.loc8(%c1.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op(%self.param: ref bool) = "no_op";
@@ -2138,6 +2142,8 @@ fn F() {
 // CHECK:STDOUT:   %C.cpp_destructor.bound.loc8: <bound method> = bound_method %.loc8_27.3, %Op.ref.loc8
 // CHECK:STDOUT:   %C.cpp_destructor.call.loc8: init %empty_tuple.type = call %C.cpp_destructor.bound.loc8(%.loc8_27.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_todo_rewrite_spaceship.carbon
@@ -2306,6 +2312,8 @@ fn F() {
 // CHECK:STDOUT:   %C.cpp_destructor.bound.loc15: <bound method> = bound_method %c1.var, %Op.ref.loc15
 // CHECK:STDOUT:   %C.cpp_destructor.call.loc15: init %empty_tuple.type = call %C.cpp_destructor.bound.loc15(%c1.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op(%self.param: ref bool) = "no_op";
@@ -2439,6 +2447,8 @@ fn F() {
 // CHECK:STDOUT:   %C.cpp_destructor.bound.loc12: <bound method> = bound_method %c1.var, %Op.ref.loc12
 // CHECK:STDOUT:   %C.cpp_destructor.call.loc12: init %empty_tuple.type = call %C.cpp_destructor.bound.loc12(%c1.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op(%self.param: ref bool) = "no_op";
@@ -2568,6 +2578,8 @@ fn F() {
 // CHECK:STDOUT:   %C.cpp_destructor.bound.loc8: <bound method> = bound_method %.loc8_31.3, %Op.ref.loc8
 // CHECK:STDOUT:   %C.cpp_destructor.call.loc8: init %empty_tuple.type = call %C.cpp_destructor.bound.loc8(%.loc8_31.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_multiple_namespaces.carbon
@@ -2757,6 +2769,8 @@ fn F() {
 // CHECK:STDOUT:   %C1.cpp_destructor.bound: <bound method> = bound_method %.loc8_36.3, %Op.ref.loc8
 // CHECK:STDOUT:   %C1.cpp_destructor.call: init %empty_tuple.type = call %C1.cpp_destructor.bound(%.loc8_36.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_todo_import_operands_in_namespace_operator_in_global.carbon
@@ -2863,6 +2877,8 @@ fn F() {
 // CHECK:STDOUT:   %C.cpp_destructor.bound.loc8: <bound method> = bound_method %.loc8_31.3, %Op.ref.loc8
 // CHECK:STDOUT:   %C.cpp_destructor.call.loc8: init %empty_tuple.type = call %C.cpp_destructor.bound.loc8(%.loc8_31.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_inner_class.carbon
@@ -2988,6 +3004,8 @@ fn F() {
 // CHECK:STDOUT:   %C.cpp_destructor.bound.loc8: <bound method> = bound_method %.loc8_31.3, %Op.ref.loc8
 // CHECK:STDOUT:   %C.cpp_destructor.call.loc8: init %empty_tuple.type = call %C.cpp_destructor.bound.loc8(%.loc8_31.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_inner_class_in_namespace.carbon
@@ -3122,6 +3140,8 @@ fn F() {
 // CHECK:STDOUT:   %C.cpp_destructor.bound.loc8: <bound method> = bound_method %.loc8_35.3, %Op.ref.loc8
 // CHECK:STDOUT:   %C.cpp_destructor.call.loc8: init %empty_tuple.type = call %C.cpp_destructor.bound.loc8(%.loc8_35.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_member_add_with.carbon
@@ -3250,6 +3270,8 @@ fn F() {
 // CHECK:STDOUT:   %C.cpp_destructor.bound.loc8: <bound method> = bound_method %c1.var, %Op.ref.loc8
 // CHECK:STDOUT:   %C.cpp_destructor.call.loc8: init %empty_tuple.type = call %C.cpp_destructor.bound.loc8(%c1.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- indirect_template_instantiation.carbon
@@ -3281,6 +3303,8 @@ fn F() {
 // CHECK:STDOUT:   %addr.loc14_12.2: %ptr.307 = addr_of %.loc14_14
 // CHECK:STDOUT:   %operator_Plus__carbon_thunk.call: init %i32 = call imports.%operator_Plus__carbon_thunk.decl(%addr.loc14_12.1, %addr.loc14_12.2)
 // CHECK:STDOUT:   return %operator_Plus__carbon_thunk.call
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- import_overloading.carbon
@@ -3346,5 +3370,7 @@ fn F() {
 // CHECK:STDOUT:   %C.cpp_destructor.bound.loc10: <bound method> = bound_method %.loc10_29.3, %Op.ref.loc10
 // CHECK:STDOUT:   %C.cpp_destructor.call.loc10: init %empty_tuple.type = call %C.cpp_destructor.bound.loc10(%.loc10_29.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/operators/ordered_with.carbon

@@ -569,6 +569,8 @@ fn Test(missing_less: Cpp.MissingLess,
 // CHECK:STDOUT:     %bound_method.loc18_5.2: <bound method> = bound_method %x.ref.loc18, %specific_impl_fn.loc18_5.1
 // CHECK:STDOUT:     %OrderedWith.WithSelf.GreaterOrEquivalent.call: init bool = call %bound_method.loc18_5.2(%x.ref.loc18, %y.ref.loc18)
 // CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !observes:
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -945,6 +947,8 @@ fn Test(missing_less: Cpp.MissingLess,
 // CHECK:STDOUT:     %bound_method.loc59_5.2: <bound method> = bound_method %x.ref.loc59, %specific_impl_fn.loc59_5.1
 // CHECK:STDOUT:     %OrderedWith.WithSelf.GreaterOrEquivalent.call: init bool = call %bound_method.loc59_5.2(%x.ref.loc59, %y.ref.loc59)
 // CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !observes:
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/operators/spaceship.carbon

@@ -415,6 +415,8 @@ fn Test(returns_strong_ordering: Cpp.ReturnsStrongOrdering) {
 // CHECK:STDOUT:     %bound_method.loc7_5.2: <bound method> = bound_method %x.ref.loc7, %specific_impl_fn.loc7_5.1
 // CHECK:STDOUT:     %EqWith.WithSelf.NotEqual.call: init bool = call %bound_method.loc7_5.2(%x.ref.loc7, %y.ref.loc7)
 // CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !observes:
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -490,6 +492,8 @@ fn Test(returns_strong_ordering: Cpp.ReturnsStrongOrdering) {
 // CHECK:STDOUT:     %bound_method.loc16_5.2: <bound method> = bound_method %x.ref.loc16, %specific_impl_fn.loc16_5.1
 // CHECK:STDOUT:     %OrderedWith.WithSelf.GreaterOrEquivalent.call: init bool = call %bound_method.loc16_5.2(%x.ref.loc16, %y.ref.loc16)
 // CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !observes:
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/primitive_types/arithmetic.carbon

@@ -465,6 +465,8 @@ fn F() {
 // CHECK:STDOUT:     %carbon_double.patt: %pattern_type.fb7 = value_binding_pattern carbon_double [concrete = constants.%carbon_double.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_todo_unsupported_types.carbon
@@ -519,6 +521,8 @@ fn F() {
 // CHECK:STDOUT:     %carbon_long_double.patt: %pattern_type.fb7 = value_binding_pattern carbon_long_double [concrete = constants.%carbon_long_double.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- override_builtin.carbon
@@ -602,5 +606,7 @@ fn F() {
 // CHECK:STDOUT:   %unsigned_int.cpp_destructor.bound: <bound method> = bound_method %unsigned_int.var, constants.%unsigned_int.cpp_destructor
 // CHECK:STDOUT:   %unsigned_int.cpp_destructor.call: init %empty_tuple.type = call %unsigned_int.cpp_destructor.bound(%unsigned_int.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/primitive_types/long_and_long_long.llp64.carbon

@@ -847,6 +847,8 @@ fn CopyUnsignedLong() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %a.var, constants.%Destroy.Op.1a2547.3
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%a.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc11_3.1(%self.param: ref %f32.9b3) = "no_op";
@@ -854,11 +856,15 @@ fn CopyUnsignedLong() {
 // CHECK:STDOUT: fn @Destroy.Op.loc11_3.2(%self.param: ref %f32.c73) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc11_3.3(%self.param: ref %array_type) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- unsigned_long_long.carbon
@@ -1024,6 +1030,8 @@ fn CopyUnsignedLong() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %a.var, constants.%Destroy.Op.1a2547.3
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%a.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc11_3.1(%self.param: ref %f32.9b3) = "no_op";
@@ -1031,11 +1039,15 @@ fn CopyUnsignedLong() {
 // CHECK:STDOUT: fn @Destroy.Op.loc11_3.2(%self.param: ref %f32.c73) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc11_3.3(%self.param: ref %array_type) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- long.carbon
@@ -1342,6 +1354,8 @@ fn CopyUnsignedLong() {
 // CHECK:STDOUT:   %LongResult.cpp_destructor.bound.loc16: <bound method> = bound_method %.loc16_69.3, constants.%LongResult.cpp_destructor
 // CHECK:STDOUT:   %LongResult.cpp_destructor.call.loc16: init %empty_tuple.type = call %LongResult.cpp_destructor.bound.loc16(%.loc16_69.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc26_3.1(%self.param: ref %f32.9b3) = "no_op";
@@ -1349,11 +1363,15 @@ fn CopyUnsignedLong() {
 // CHECK:STDOUT: fn @Destroy.Op.loc26_3.2(%self.param: ref %f32.c73) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc26_3.3(%self.param: ref %array_type) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- copy_long.carbon
@@ -1440,6 +1458,8 @@ fn CopyUnsignedLong() {
 // CHECK:STDOUT:   %Destroy.Op.bound.loc8: <bound method> = bound_method %a.var, constants.%Destroy.Op.1a2547.3
 // CHECK:STDOUT:   %Destroy.Op.call.loc8: init %empty_tuple.type = call %Destroy.Op.bound.loc8(%a.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc9_3.1(%self.param: ref %i32.builtin) = "no_op";
@@ -1447,11 +1467,15 @@ fn CopyUnsignedLong() {
 // CHECK:STDOUT: fn @Destroy.Op.loc9_3.2(%self.param: ref %i32) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc9_3.3(%self.param: ref %Cpp.long) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- comparisons_homogeneous_long.carbon
@@ -1581,6 +1605,8 @@ fn CopyUnsignedLong() {
 // CHECK:STDOUT:   %bound_method.loc15: <bound method> = bound_method %a.ref.loc15, %impl.elem1.loc15
 // CHECK:STDOUT:   %Cpp.long.as.OrderedWith.impl.LessOrEquivalent.call: init bool = call %bound_method.loc15(%a.ref.loc15, %b.ref.loc15)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- comparisons_heterogeneous_long_left_side.carbon
@@ -2037,6 +2063,8 @@ fn CopyUnsignedLong() {
 // CHECK:STDOUT:   %.loc22_8.2: %Cpp.long = converted %int_1.loc22, %.loc22_8.1 [concrete = constants.%int_1.9ce]
 // CHECK:STDOUT:   %Cpp.long.as.OrderedWith.impl.LessOrEquivalent.call.loc22: init bool = call %bound_method.loc22_5.3(%a.ref.loc22, %.loc22_8.2)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- comparisons_heterogeneous_long_right_side.carbon
@@ -2515,6 +2543,8 @@ fn CopyUnsignedLong() {
 // CHECK:STDOUT:   %.loc22_3.2: %Cpp.long = converted %int_1.loc22, %.loc22_3.1 [concrete = constants.%int_1.9ce]
 // CHECK:STDOUT:   %T.as_type.as.OrderedWith.impl.LessOrEquivalent.call.loc22: init bool = call %bound_method.loc22_5.3(%.loc22_3.2, %a.ref.loc22)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- arithmetic_homogeneous_long.carbon
@@ -2731,6 +2761,8 @@ fn CopyUnsignedLong() {
 // CHECK:STDOUT:     %f.patt: %pattern_type.25e = value_binding_pattern f [concrete = constants.%f.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- compound_assignment_homogeneous_long.carbon
@@ -3173,6 +3205,8 @@ fn CopyUnsignedLong() {
 // CHECK:STDOUT:   %Destroy.Op.bound.loc8: <bound method> = bound_method %a.var, constants.%Destroy.Op.1a2547.3
 // CHECK:STDOUT:   %Destroy.Op.call.loc8: init %empty_tuple.type = call %Destroy.Op.bound.loc8(%a.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc9_3.1(%self.param: ref %i32.builtin) = "no_op";
@@ -3180,11 +3214,15 @@ fn CopyUnsignedLong() {
 // CHECK:STDOUT: fn @Destroy.Op.loc9_3.2(%self.param: ref %i32) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc9_3.3(%self.param: ref %Cpp.long) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- compound_assignment_hereogeneous_long_and_i32.carbon
@@ -3642,6 +3680,8 @@ fn CopyUnsignedLong() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %a.var, constants.%Destroy.Op.1a2547.3
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%a.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc9_3.1(%self.param: ref %i32.builtin) = "no_op";
@@ -3649,11 +3689,15 @@ fn CopyUnsignedLong() {
 // CHECK:STDOUT: fn @Destroy.Op.loc9_3.2(%self.param: ref %i32) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc9_3.3(%self.param: ref %Cpp.long) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- compound_assignment_heterogeneous_long_and_int_literal.carbon
@@ -3751,6 +3795,8 @@ fn CopyUnsignedLong() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %a.var, constants.%Destroy.Op.1a2547.3
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%a.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_3.1(%self.param: ref %i32.builtin) = "no_op";
@@ -3758,11 +3804,15 @@ fn CopyUnsignedLong() {
 // CHECK:STDOUT: fn @Destroy.Op.loc8_3.2(%self.param: ref %i32) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_3.3(%self.param: ref %Cpp.long) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- compound_assignment_heterogeneous_long_and_runtime_i32.carbon
@@ -3899,6 +3949,8 @@ fn CopyUnsignedLong() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %a.var, constants.%Destroy.Op.1a2547.3
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%a.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_3.1(%self.param: ref %i32.builtin) = "no_op";
@@ -3906,11 +3958,15 @@ fn CopyUnsignedLong() {
 // CHECK:STDOUT: fn @Destroy.Op.loc8_3.2(%self.param: ref %i32) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_3.3(%self.param: ref %Cpp.long) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- increment_decrement_long.carbon
@@ -3994,6 +4050,8 @@ fn CopyUnsignedLong() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %a.var, constants.%Destroy.Op.1a2547.3
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%a.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_3.1(%self.param: ref %i32.builtin) = "no_op";
@@ -4001,11 +4059,15 @@ fn CopyUnsignedLong() {
 // CHECK:STDOUT: fn @Destroy.Op.loc8_3.2(%self.param: ref %i32) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_3.3(%self.param: ref %Cpp.long) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- unsigned_long.carbon
@@ -4308,6 +4370,8 @@ fn CopyUnsignedLong() {
 // CHECK:STDOUT:   %ULongResult.cpp_destructor.bound.loc16: <bound method> = bound_method %.loc16_89.3, constants.%ULongResult.cpp_destructor
 // CHECK:STDOUT:   %ULongResult.cpp_destructor.call.loc16: init %empty_tuple.type = call %ULongResult.cpp_destructor.bound.loc16(%.loc16_89.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc24_3.1(%self.param: ref %f32.9b3) = "no_op";
@@ -4315,11 +4379,15 @@ fn CopyUnsignedLong() {
 // CHECK:STDOUT: fn @Destroy.Op.loc24_3.2(%self.param: ref %f32.c73) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc24_3.3(%self.param: ref %array_type) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- copy_unsigned_long.carbon
@@ -4406,6 +4474,8 @@ fn CopyUnsignedLong() {
 // CHECK:STDOUT:   %Destroy.Op.bound.loc8: <bound method> = bound_method %a.var, constants.%Destroy.Op.1a2547.3
 // CHECK:STDOUT:   %Destroy.Op.call.loc8: init %empty_tuple.type = call %Destroy.Op.bound.loc8(%a.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc9_3.1(%self.param: ref %u32.builtin) = "no_op";
@@ -4413,10 +4483,14 @@ fn CopyUnsignedLong() {
 // CHECK:STDOUT: fn @Destroy.Op.loc9_3.2(%self.param: ref %u32) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc9_3.3(%self.param: ref %Cpp.unsigned_long) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/primitive_types/long_and_long_long.lp64.carbon

@@ -795,6 +795,8 @@ fn CopyUnsignedLongLong() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %a.var, constants.%Destroy.Op.1a2547.3
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%a.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc11_3.1(%self.param: ref %f32.9b3) = "no_op";
@@ -802,11 +804,15 @@ fn CopyUnsignedLongLong() {
 // CHECK:STDOUT: fn @Destroy.Op.loc11_3.2(%self.param: ref %f32.c73) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc11_3.3(%self.param: ref %array_type) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- unsigned_long.carbon
@@ -972,6 +978,8 @@ fn CopyUnsignedLongLong() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %a.var, constants.%Destroy.Op.1a2547.3
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%a.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc11_3.1(%self.param: ref %f32.9b3) = "no_op";
@@ -979,11 +987,15 @@ fn CopyUnsignedLongLong() {
 // CHECK:STDOUT: fn @Destroy.Op.loc11_3.2(%self.param: ref %f32.c73) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc11_3.3(%self.param: ref %array_type) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- long_long.carbon
@@ -1267,6 +1279,8 @@ fn CopyUnsignedLongLong() {
 // CHECK:STDOUT:   %LongLongResult.cpp_destructor.bound.loc16: <bound method> = bound_method %.loc16_87.3, constants.%LongLongResult.cpp_destructor
 // CHECK:STDOUT:   %LongLongResult.cpp_destructor.call.loc16: init %empty_tuple.type = call %LongLongResult.cpp_destructor.bound.loc16(%.loc16_87.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc24_3.1(%self.param: ref %f32.9b3) = "no_op";
@@ -1274,11 +1288,15 @@ fn CopyUnsignedLongLong() {
 // CHECK:STDOUT: fn @Destroy.Op.loc24_3.2(%self.param: ref %f32.c73) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc24_3.3(%self.param: ref %array_type) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- copy_long_long.carbon
@@ -1365,6 +1383,8 @@ fn CopyUnsignedLongLong() {
 // CHECK:STDOUT:   %Destroy.Op.bound.loc8: <bound method> = bound_method %a.var, constants.%Destroy.Op.1a2547.3
 // CHECK:STDOUT:   %Destroy.Op.call.loc8: init %empty_tuple.type = call %Destroy.Op.bound.loc8(%a.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc9_3.1(%self.param: ref %i64.builtin) = "no_op";
@@ -1372,11 +1392,15 @@ fn CopyUnsignedLongLong() {
 // CHECK:STDOUT: fn @Destroy.Op.loc9_3.2(%self.param: ref %i64) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc9_3.3(%self.param: ref %Cpp.long_long) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- comparisons_homogeneous_long_long.carbon
@@ -1506,6 +1530,8 @@ fn CopyUnsignedLongLong() {
 // CHECK:STDOUT:   %bound_method.loc15: <bound method> = bound_method %a.ref.loc15, %impl.elem1.loc15
 // CHECK:STDOUT:   %Cpp.long_long.as.OrderedWith.impl.LessOrEquivalent.call: init bool = call %bound_method.loc15(%a.ref.loc15, %b.ref.loc15)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- comparisons_heterogeneous_long_long_left_side.carbon
@@ -1962,6 +1988,8 @@ fn CopyUnsignedLongLong() {
 // CHECK:STDOUT:   %.loc22_8.2: %Cpp.long_long = converted %int_1.loc22, %.loc22_8.1 [concrete = constants.%int_1.b19]
 // CHECK:STDOUT:   %Cpp.long_long.as.OrderedWith.impl.LessOrEquivalent.call.loc22: init bool = call %bound_method.loc22_5.3(%a.ref.loc22, %.loc22_8.2)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- comparisons_heterogeneous_long_long_right_side.carbon
@@ -2440,6 +2468,8 @@ fn CopyUnsignedLongLong() {
 // CHECK:STDOUT:   %.loc22_3.2: %Cpp.long_long = converted %int_1.loc22, %.loc22_3.1 [concrete = constants.%int_1.b19]
 // CHECK:STDOUT:   %T.as_type.as.OrderedWith.impl.LessOrEquivalent.call.loc22: init bool = call %bound_method.loc22_5.3(%.loc22_3.2, %a.ref.loc22)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- compound_assignment_homogeneous_long_long.carbon
@@ -2882,6 +2912,8 @@ fn CopyUnsignedLongLong() {
 // CHECK:STDOUT:   %Destroy.Op.bound.loc8: <bound method> = bound_method %a.var, constants.%Destroy.Op.1a2547.3
 // CHECK:STDOUT:   %Destroy.Op.call.loc8: init %empty_tuple.type = call %Destroy.Op.bound.loc8(%a.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc9_3.1(%self.param: ref %i64.builtin) = "no_op";
@@ -2889,11 +2921,15 @@ fn CopyUnsignedLongLong() {
 // CHECK:STDOUT: fn @Destroy.Op.loc9_3.2(%self.param: ref %i64) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc9_3.3(%self.param: ref %Cpp.long_long) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- compound_assignment_hereogeneous_long_long_and_i64.carbon
@@ -3351,6 +3387,8 @@ fn CopyUnsignedLongLong() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %a.var, constants.%Destroy.Op.1a2547.3
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%a.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc9_3.1(%self.param: ref %i64.builtin) = "no_op";
@@ -3358,11 +3396,15 @@ fn CopyUnsignedLongLong() {
 // CHECK:STDOUT: fn @Destroy.Op.loc9_3.2(%self.param: ref %i64) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc9_3.3(%self.param: ref %Cpp.long_long) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- compound_assignment_heterogeneous_long_long_and_int_literal.carbon
@@ -3460,6 +3502,8 @@ fn CopyUnsignedLongLong() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %a.var, constants.%Destroy.Op.1a2547.3
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%a.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_3.1(%self.param: ref %i64.builtin) = "no_op";
@@ -3467,11 +3511,15 @@ fn CopyUnsignedLongLong() {
 // CHECK:STDOUT: fn @Destroy.Op.loc8_3.2(%self.param: ref %i64) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_3.3(%self.param: ref %Cpp.long_long) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- compound_assignment_heterogeneous_long_long_and_runtime_i64.carbon
@@ -3608,6 +3656,8 @@ fn CopyUnsignedLongLong() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %a.var, constants.%Destroy.Op.1a2547.3
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%a.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_3.1(%self.param: ref %i64.builtin) = "no_op";
@@ -3615,11 +3665,15 @@ fn CopyUnsignedLongLong() {
 // CHECK:STDOUT: fn @Destroy.Op.loc8_3.2(%self.param: ref %i64) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_3.3(%self.param: ref %Cpp.long_long) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- increment_decrement_long_long.carbon
@@ -3703,6 +3757,8 @@ fn CopyUnsignedLongLong() {
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %a.var, constants.%Destroy.Op.1a2547.3
 // CHECK:STDOUT:   %Destroy.Op.call: init %empty_tuple.type = call %Destroy.Op.bound(%a.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_3.1(%self.param: ref %i64.builtin) = "no_op";
@@ -3710,11 +3766,15 @@ fn CopyUnsignedLongLong() {
 // CHECK:STDOUT: fn @Destroy.Op.loc8_3.2(%self.param: ref %i64) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc8_3.3(%self.param: ref %Cpp.long_long) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- unsigned_long_long.carbon
@@ -4018,6 +4078,8 @@ fn CopyUnsignedLongLong() {
 // CHECK:STDOUT:   %ULongLongResult.cpp_destructor.bound.loc16: <bound method> = bound_method %.loc16_107.3, constants.%ULongLongResult.cpp_destructor
 // CHECK:STDOUT:   %ULongLongResult.cpp_destructor.call.loc16: init %empty_tuple.type = call %ULongLongResult.cpp_destructor.bound.loc16(%.loc16_107.3)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc24_3.1(%self.param: ref %f32.9b3) = "no_op";
@@ -4025,11 +4087,15 @@ fn CopyUnsignedLongLong() {
 // CHECK:STDOUT: fn @Destroy.Op.loc24_3.2(%self.param: ref %f32.c73) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc24_3.3(%self.param: ref %array_type) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- copy_unsigned_long_long.carbon
@@ -4116,6 +4182,8 @@ fn CopyUnsignedLongLong() {
 // CHECK:STDOUT:   %Destroy.Op.bound.loc8: <bound method> = bound_method %a.var, constants.%Destroy.Op.1a2547.3
 // CHECK:STDOUT:   %Destroy.Op.call.loc8: init %empty_tuple.type = call %Destroy.Op.bound.loc8(%a.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc9_3.1(%self.param: ref %u64.builtin) = "no_op";
@@ -4123,10 +4191,14 @@ fn CopyUnsignedLongLong() {
 // CHECK:STDOUT: fn @Destroy.Op.loc9_3.2(%self.param: ref %u64) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc9_3.3(%self.param: ref %Cpp.unsigned_long_long) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/primitive_types/void_pointer.carbon

@@ -189,6 +189,8 @@ fn F(input: Cpp.void*) {
 // CHECK:STDOUT:     %p.patt: %pattern_type.712 = value_binding_pattern p [concrete = constants.%p.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- implicit_as_from_carbon_class_pointer_to_void_pointer.carbon
@@ -242,6 +244,8 @@ fn F(input: Cpp.void*) {
 // CHECK:STDOUT:     %p.patt: %pattern_type.712 = value_binding_pattern p [concrete = constants.%p.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- explicit_as_from_cpp_class_pointer_to_void_pointer.carbon
@@ -310,6 +314,8 @@ fn F(input: Cpp.void*) {
 // CHECK:STDOUT:     %p.patt: %pattern_type.712 = value_binding_pattern p [concrete = constants.%p.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- explicit_as_from_carbon_class_pointer_to_void_pointer.carbon
@@ -376,6 +382,8 @@ fn F(input: Cpp.void*) {
 // CHECK:STDOUT:     %p.patt: %pattern_type.712 = value_binding_pattern p [concrete = constants.%p.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_explicit_as_from_void_pointer_to_cpp_class_pointer.carbon
@@ -415,6 +423,8 @@ fn F(input: Cpp.void*) {
 // CHECK:STDOUT:     %p.patt: %pattern_type.de6 = value_binding_pattern p [concrete = constants.%p.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_explicit_as_from_void_pointer_to_carbon_class_pointer.carbon
@@ -443,6 +453,8 @@ fn F(input: Cpp.void*) {
 // CHECK:STDOUT:     %p.patt: %pattern_type.fcb = value_binding_pattern p [concrete = constants.%p.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- unsafe_as_from_void_pointer_to_cpp_class_pointer.carbon
@@ -502,6 +514,8 @@ fn F(input: Cpp.void*) {
 // CHECK:STDOUT:     %p.patt: %pattern_type.de6 = value_binding_pattern p [concrete = constants.%p.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- unsafe_as_from_void_pointer_to_carbon_class_pointer.carbon
@@ -553,5 +567,7 @@ fn F(input: Cpp.void*) {
 // CHECK:STDOUT:     %p.patt: %pattern_type.fcb = value_binding_pattern p [concrete = constants.%p.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/range_for.carbon

@@ -1085,17 +1085,23 @@ fn TestDriver(var no_begin_end: Cpp.NoBeginEnd,
 // CHECK:STDOUT:     %bound_method.loc34_19.8: <bound method> = bound_method %var, %specific_impl_fn.loc34_19.3
 // CHECK:STDOUT:     %Destroy.WithSelf.Op.call: init %empty_tuple.type = call %bound_method.loc34_19.8(%var)
 // CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !observes:
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc34_19.1(%self.param: ref %.1d6a7) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc34_19.2(%self.param: ref %MaybeUnformed.023) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc34_19.3(%self.param: ref bool) = "no_op";
@@ -1103,16 +1109,22 @@ fn TestDriver(var no_begin_end: Cpp.NoBeginEnd,
 // CHECK:STDOUT: fn @Destroy.Op.loc34_19.4(%self.param: ref %struct_type.value.has_value.ad0) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc34_19.5(%self.param: ref %DefaultOptionalStorage.970) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc34_19.6(%self.param: ref %Optional.e28) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @TestRangeFor(%m.param: ref %MutableRange, %c.param: %ConstRange) {
@@ -1265,6 +1277,8 @@ fn TestDriver(var no_begin_end: Cpp.NoBeginEnd,
 // CHECK:STDOUT:   %Destroy.Op.bound.loc49_19.2: <bound method> = bound_method %var.loc49, constants.%Destroy.Op.1a2547.10
 // CHECK:STDOUT:   %Destroy.Op.call.loc49_19.2: init %empty_tuple.type = call %Destroy.Op.bound.loc49_19.2(%var.loc49)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: specific @TestIterate(constants.%R.891) {
@@ -1712,17 +1726,23 @@ fn TestDriver(var no_begin_end: Cpp.NoBeginEnd,
 // CHECK:STDOUT:     %bound_method.loc44_29.8: <bound method> = bound_method %var, %specific_impl_fn.loc44_29.3
 // CHECK:STDOUT:     %Destroy.WithSelf.Op.call: init %empty_tuple.type = call %bound_method.loc44_29.8(%var)
 // CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !observes:
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc44_29.1(%self.param: ref %.98c) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc44_29.2(%self.param: ref %MaybeUnformed.02e) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc44_29.3(%self.param: ref bool) = "no_op";
@@ -1730,16 +1750,22 @@ fn TestDriver(var no_begin_end: Cpp.NoBeginEnd,
 // CHECK:STDOUT: fn @Destroy.Op.loc44_29.4(%self.param: ref %struct_type.value.has_value.761) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc44_29.5(%self.param: ref %DefaultOptionalStorage.84c) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc44_29.6(%self.param: ref %Optional.95f) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @TestRangeFor(%m.param: ref %MutableRange, %c.param: %ConstRange) {
@@ -1898,6 +1924,8 @@ fn TestDriver(var no_begin_end: Cpp.NoBeginEnd,
 // CHECK:STDOUT:   %Destroy.Op.bound.loc59_29.2: <bound method> = bound_method %var.loc59, constants.%Destroy.Op.1a2547.8
 // CHECK:STDOUT:   %Destroy.Op.call.loc59_29.2: init %empty_tuple.type = call %Destroy.Op.bound.loc59_29.2(%var.loc59)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: specific @TestIterate(constants.%R.de1) {
@@ -2261,17 +2289,23 @@ fn TestDriver(var no_begin_end: Cpp.NoBeginEnd,
 // CHECK:STDOUT:     %bound_method.loc24_19.8: <bound method> = bound_method %var, %specific_impl_fn.loc24_19.3
 // CHECK:STDOUT:     %Destroy.WithSelf.Op.call: init %empty_tuple.type = call %bound_method.loc24_19.8(%var)
 // CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !observes:
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc24_19.1(%self.param: ref %.cc0) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc24_19.2(%self.param: ref %MaybeUnformed.b7e) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc24_19.3(%self.param: ref bool) = "no_op";
@@ -2279,16 +2313,22 @@ fn TestDriver(var no_begin_end: Cpp.NoBeginEnd,
 // CHECK:STDOUT: fn @Destroy.Op.loc24_19.4(%self.param: ref %struct_type.value.has_value.ad9) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc24_19.5(%self.param: ref %DefaultOptionalStorage.541) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc24_19.6(%self.param: ref %Optional.f48) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @TestRangeFor(%c.param: %ConstRange) {
@@ -2362,6 +2402,8 @@ fn TestDriver(var no_begin_end: Cpp.NoBeginEnd,
 // CHECK:STDOUT:   %Destroy.Op.bound.loc38_19.2: <bound method> = bound_method %var, constants.%Destroy.Op.1a2547.10
 // CHECK:STDOUT:   %Destroy.Op.call.loc38_19.2: init %empty_tuple.type = call %Destroy.Op.bound.loc38_19.2(%var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: specific @TestIterate(constants.%R.7b2) {
@@ -2694,17 +2736,23 @@ fn TestDriver(var no_begin_end: Cpp.NoBeginEnd,
 // CHECK:STDOUT:     %bound_method.loc26_19.8: <bound method> = bound_method %var, %specific_impl_fn.loc26_19.3
 // CHECK:STDOUT:     %Destroy.WithSelf.Op.call: init %empty_tuple.type = call %bound_method.loc26_19.8(%var)
 // CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !observes:
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc26_19.1(%self.param: ref %.cc0) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc26_19.2(%self.param: ref %MaybeUnformed.b7e) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc26_19.3(%self.param: ref bool) = "no_op";
@@ -2712,16 +2760,22 @@ fn TestDriver(var no_begin_end: Cpp.NoBeginEnd,
 // CHECK:STDOUT: fn @Destroy.Op.loc26_19.4(%self.param: ref %struct_type.value.has_value.ad9) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc26_19.5(%self.param: ref %DefaultOptionalStorage.541) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc26_19.6(%self.param: ref %Optional.f48) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @TestRangeFor(%m.param: ref %MutableRange) {
@@ -2797,6 +2851,8 @@ fn TestDriver(var no_begin_end: Cpp.NoBeginEnd,
 // CHECK:STDOUT:   %Destroy.Op.bound.loc68_19.2: <bound method> = bound_method %var, constants.%Destroy.Op.1a2547.10
 // CHECK:STDOUT:   %Destroy.Op.call.loc68_19.2: init %empty_tuple.type = call %Destroy.Op.bound.loc68_19.2(%var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: specific @TestIterate(constants.%R.7b2) {
@@ -3157,17 +3213,23 @@ fn TestDriver(var no_begin_end: Cpp.NoBeginEnd,
 // CHECK:STDOUT:     %bound_method.loc31_31.8: <bound method> = bound_method %var, %specific_impl_fn.loc31_31.3
 // CHECK:STDOUT:     %Destroy.WithSelf.Op.call: init %empty_tuple.type = call %bound_method.loc31_31.8(%var)
 // CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !observes:
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc31_31.1(%self.param: ref %.b36) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc31_31.2(%self.param: ref %MaybeUnformed.669) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc31_31.3(%self.param: ref bool) = "no_op";
@@ -3175,16 +3237,22 @@ fn TestDriver(var no_begin_end: Cpp.NoBeginEnd,
 // CHECK:STDOUT: fn @Destroy.Op.loc31_31.4(%self.param: ref %struct_type.value.has_value.5a1) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc31_31.5(%self.param: ref %DefaultOptionalStorage.257) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc31_31.6(%self.param: ref %Optional.552) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @TestRangeFor(%c.param: %ConstRange) {
@@ -3267,6 +3335,8 @@ fn TestDriver(var no_begin_end: Cpp.NoBeginEnd,
 // CHECK:STDOUT:   %Destroy.Op.bound.loc45_31.2: <bound method> = bound_method %var, constants.%Destroy.Op.1a2547.8
 // CHECK:STDOUT:   %Destroy.Op.call.loc45_31.2: init %empty_tuple.type = call %Destroy.Op.bound.loc45_31.2(%var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: specific @TestIterate(constants.%R.623) {
@@ -3536,17 +3606,23 @@ fn TestDriver(var no_begin_end: Cpp.NoBeginEnd,
 // CHECK:STDOUT:     %bound_method.loc31_31.8: <bound method> = bound_method %var, %specific_impl_fn.loc31_31.3
 // CHECK:STDOUT:     %Destroy.WithSelf.Op.call: init %empty_tuple.type = call %bound_method.loc31_31.8(%var)
 // CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !observes:
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc31_31.1(%self.param: ref %.b36) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc31_31.2(%self.param: ref %MaybeUnformed.669) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc31_31.3(%self.param: ref bool) = "no_op";
@@ -3554,16 +3630,22 @@ fn TestDriver(var no_begin_end: Cpp.NoBeginEnd,
 // CHECK:STDOUT: fn @Destroy.Op.loc31_31.4(%self.param: ref %struct_type.value.has_value.5a1) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc31_31.5(%self.param: ref %DefaultOptionalStorage.257) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc31_31.6(%self.param: ref %Optional.be6) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @TestRangeFor(%m.param: ref %MutableRange) {
@@ -3596,6 +3678,8 @@ fn TestDriver(var no_begin_end: Cpp.NoBeginEnd,
 // CHECK:STDOUT:
 // CHECK:STDOUT: !for.done:
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: specific @TestIterate(constants.%R.623) {
@@ -3918,17 +4002,23 @@ fn TestDriver(var no_begin_end: Cpp.NoBeginEnd,
 // CHECK:STDOUT:     %bound_method.loc38_31.8: <bound method> = bound_method %var, %specific_impl_fn.loc38_31.3
 // CHECK:STDOUT:     %Destroy.WithSelf.Op.call: init %empty_tuple.type = call %bound_method.loc38_31.8(%var)
 // CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !observes:
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc38_31.1(%self.param: ref %.b36) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc38_31.2(%self.param: ref %MaybeUnformed.669) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc38_31.3(%self.param: ref bool) = "no_op";
@@ -3936,16 +4026,22 @@ fn TestDriver(var no_begin_end: Cpp.NoBeginEnd,
 // CHECK:STDOUT: fn @Destroy.Op.loc38_31.4(%self.param: ref %struct_type.value.has_value.5a1) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc38_31.5(%self.param: ref %DefaultOptionalStorage.257) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc38_31.6(%self.param: ref %Optional.552) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @TestRangeFor(%mc.param: ref %MutableAndConstRange) {
@@ -4030,6 +4126,8 @@ fn TestDriver(var no_begin_end: Cpp.NoBeginEnd,
 // CHECK:STDOUT:   %Destroy.Op.bound.loc80_32.2: <bound method> = bound_method %var, constants.%Destroy.Op.1a2547.8
 // CHECK:STDOUT:   %Destroy.Op.call.loc80_32.2: init %empty_tuple.type = call %Destroy.Op.bound.loc80_32.2(%var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: specific @TestIterate(constants.%R.623) {

toolchain/check/testdata/interop/cpp/stdlib/initializer_list.carbon

@@ -369,6 +369,8 @@ fn F() {
 // CHECK:STDOUT:   %initializer_list.cpp_destructor.call.loc8: init %empty_tuple.type = call %initializer_list.cpp_destructor.bound.loc8(%.loc8_50.18)
 // CHECK:STDOUT:   %Destroy.Op.call.loc8: init %empty_tuple.type = call constants.%Destroy.Op.bound(constants.%.981)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @initializer_list.initializer_list.loc8(%_.param: %array_type) -> out %return.param: %initializer_list = "cpp.std.initializer_list.make";
@@ -382,10 +384,14 @@ fn F() {
 // CHECK:STDOUT: fn @Destroy.Op.loc12_44.2(%self.param: ref %i32) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc12_44.3(%self.param: ref %array_type) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/stdlib/string_view.carbon

@@ -148,6 +148,8 @@ fn StarstWith(a: str, b: str) -> bool {
 // CHECK:STDOUT:   %addr: %ptr.e6f = addr_of %.loc8
 // CHECK:STDOUT:   %Consume__carbon_thunk.call: init %empty_tuple.type = call imports.%Consume__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @G() -> out %return.param: %str.3d4 {
@@ -159,6 +161,8 @@ fn StarstWith(a: str, b: str) -> bool {
 // CHECK:STDOUT:   %Produce__carbon_thunk.call: init %empty_tuple.type = call imports.%Produce__carbon_thunk.decl(%addr)
 // CHECK:STDOUT:   %.loc14: init %str.3d4 to %.loc13_11.1 = mark_in_place_init %Produce__carbon_thunk.call
 // CHECK:STDOUT:   return %.loc14 to %return.param
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- call_base_method.carbon
@@ -237,5 +241,7 @@ fn StarstWith(a: str, b: str) -> bool {
 // CHECK:STDOUT:   %starts_with__carbon_thunk.call: init %empty_tuple.type = call imports.%starts_with__carbon_thunk.decl(%a.ref, %addr.loc8_53.1, %addr.loc8_53.2)
 // CHECK:STDOUT:   %.loc8_53.2: init bool to %.loc8_53.1 = mark_in_place_init %starts_with__carbon_thunk.call
 // CHECK:STDOUT:   return %.loc8_53.2
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/template/alias_template.carbon

@@ -151,5 +151,7 @@ var a2: Cpp.Second(Cpp.B, Cpp.A) = Cpp.A.A();
 // CHECK:STDOUT:   %.loc10_44: init %A to %.loc10_1 = mark_in_place_init %A__carbon_thunk.call.loc10
 // CHECK:STDOUT:   assign file.%a2.var, %.loc10_44
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/template/argument_count.carbon

@@ -163,6 +163,8 @@ var too_many: Cpp.FixedSizePack(Cpp.A, Cpp.A).Inner(Cpp.B, Cpp.B, Cpp.B);
 // CHECK:STDOUT:   %T.as_type.as.DefaultOrUnformed.impl.Op.call: init %TwoTypes to %.loc7_1 = call %T.as_type.as.DefaultOrUnformed.impl.Op.specific_fn()
 // CHECK:STDOUT:   assign file.%x.var, %T.as_type.as.DefaultOrUnformed.impl.Op.call
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- pack.carbon
@@ -282,5 +284,7 @@ var too_many: Cpp.FixedSizePack(Cpp.A, Cpp.A).Inner(Cpp.B, Cpp.B, Cpp.B);
 // CHECK:STDOUT:   %T.as_type.as.DefaultOrUnformed.impl.Op.call.loc10: init %TypePack.186 to %.loc10_1 = call %T.as_type.as.DefaultOrUnformed.impl.Op.specific_fn.4()
 // CHECK:STDOUT:   assign file.%a3.var, %T.as_type.as.DefaultOrUnformed.impl.Op.call.loc10
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/template/class_template.carbon

@@ -109,5 +109,7 @@ var a: Cpp.A = Cpp.X(Cpp.A, Cpp.B).f({} as Cpp.B);
 // CHECK:STDOUT:   %.loc7_49: init %A to %.loc7_1 = mark_in_place_init %f__carbon_thunk.call
 // CHECK:STDOUT:   assign file.%a.var, %.loc7_49
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/template/concept.carbon

@@ -126,5 +126,7 @@ var x2: X(Cpp.IsLarge(Cpp.Large)) = X(true).Make();
 // CHECK:STDOUT:   %X.Make.call.loc12: init %X.7b4 to %.loc12_1 = call %X.Make.specific_fn.loc12()
 // CHECK:STDOUT:   assign file.%x2.var, %X.Make.call.loc12
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/template/non_type_param.carbon

@@ -206,6 +206,8 @@ fn G() -> i32 {
 // CHECK:STDOUT:   %.loc7_1: init %TwoNonType = converted %.loc7_32.1, %.loc7_32.2 [concrete = constants.%TwoNonType.val]
 // CHECK:STDOUT:   assign file.%x.var, %.loc7_1
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- dependent.carbon
@@ -285,5 +287,7 @@ fn G() -> i32 {
 // CHECK:STDOUT:   %.loc8_1: init %DependentNonType.d43 = converted %.loc8_54.1, %.loc8_54.2 [concrete = constants.%DependentNonType.val]
 // CHECK:STDOUT:   assign file.%y.var, %.loc8_1
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/template/template_template_param.carbon

@@ -125,6 +125,8 @@ var x: Cpp.TwoTemplates(Cpp.A, true);
 // CHECK:STDOUT:   %T.as_type.as.DefaultOrUnformed.impl.Op.call: init %TwoTemplates to %.loc7_1 = call %T.as_type.as.DefaultOrUnformed.impl.Op.specific_fn()
 // CHECK:STDOUT:   assign file.%x.var, %T.as_type.as.DefaultOrUnformed.impl.Op.call
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_template_mismatch.carbon
@@ -142,5 +144,7 @@ var x: Cpp.TwoTemplates(Cpp.A, true);
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   assign file.%x.var, <error>
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/template/type_param.carbon

@@ -109,6 +109,8 @@ var x: Cpp.TwoTypes(Cpp.A, {});
 // CHECK:STDOUT:   %T.as_type.as.DefaultOrUnformed.impl.Op.call: init %TwoTypes to %.loc7_1 = call %T.as_type.as.DefaultOrUnformed.impl.Op.specific_fn()
 // CHECK:STDOUT:   assign file.%x.var, %T.as_type.as.DefaultOrUnformed.impl.Op.call
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- char.carbon
@@ -156,5 +158,7 @@ var x: Cpp.TwoTypes(Cpp.A, {});
 // CHECK:STDOUT:   %T.as_type.as.DefaultOrUnformed.impl.Op.call: init %TwoTypes to %.loc7_1 = call %T.as_type.as.DefaultOrUnformed.impl.Op.specific_fn()
 // CHECK:STDOUT:   assign file.%x.var, %T.as_type.as.DefaultOrUnformed.impl.Op.call
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/template/var_template.carbon

@@ -159,5 +159,7 @@ let pwb: Cpp.B* = &Cpp.Wrap.r#var(Cpp.B);
 // CHECK:STDOUT:   %B.ref.loc10: type = name_ref B, imports.%B.decl [concrete = constants.%B]
 // CHECK:STDOUT:   %addr.loc10: %ptr.dc0 = addr_of imports.%var.var.302 [concrete = constants.%addr.cd4]
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/type_alias/import.carbon

@@ -153,6 +153,8 @@ fn H(var c: Cpp.C, var d: Cpp.D) {
 // CHECK:STDOUT:   %Destroy.Op.bound.loc8: <bound method> = bound_method %n.var, constants.%Destroy.Op.1a2547.3
 // CHECK:STDOUT:   %Destroy.Op.call.loc8: init %empty_tuple.type = call %Destroy.Op.bound.loc8(%n.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op.loc10(%self.param: ref %ptr.d08) = "no_op";
@@ -162,6 +164,8 @@ fn H(var c: Cpp.C, var d: Cpp.D) {
 // CHECK:STDOUT: fn @Destroy.Op.loc8_3.2(%self.param: ref %i32) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- use_class_typedef.carbon
@@ -246,6 +250,8 @@ fn H(var c: Cpp.C, var d: Cpp.D) {
 // CHECK:STDOUT:   %Destroy.Op.bound.loc9: <bound method> = bound_method %pd.var, constants.%Destroy.Op
 // CHECK:STDOUT:   %Destroy.Op.call.loc9: init %empty_tuple.type = call %Destroy.Op.bound.loc9(%pd.var)
 // CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @Destroy.Op(%self.param: ref %ptr.0a2) = "no_op";

toolchain/check/testdata/interop/cpp/var/import/global.carbon

@@ -182,6 +182,8 @@ fn MyF() {
 // CHECK:STDOUT:     %local_ref.patt: %pattern_type.8fa = value_binding_pattern local_ref [concrete = constants.%local_ref.patt]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_import_unsupported_type.carbon
@@ -229,5 +231,7 @@ fn MyF() {
 // CHECK:STDOUT:     %local.patt: <error> = value_binding_pattern local [concrete = <error>]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT:

toolchain/check/testdata/interop/cpp/var/import/namespace.carbon

@@ -75,5 +75,7 @@ fn F() {
 // CHECK:STDOUT:   %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
 // CHECK:STDOUT:   %c.ref: ref %C = name_ref c, imports.%c.var [concrete = imports.%c.var]
 // CHECK:STDOUT:   return
+// CHECK:STDOUT:
+// CHECK:STDOUT: !observes:
 // CHECK:STDOUT: }
 // CHECK:STDOUT: