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Fix mangling collision for C++ class template specializations (#7269)

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Carbon-side thunks (for example the `Copy`/`Destroy` witness thunks
generated for imported C++ types) are mangled by Carbon, and their names
incorporate a fingerprint of the involved types. The instruction
fingerprinter identifies a class only by its name and parent scope,
which is sufficient for Carbon classes but not for imported C++ classes:
different specializations of one class template (and other cases such as
types in anonymous namespaces) share a Carbon name and parent scope. As
a result, the thunks for two distinct specializations could mangle to
the same name, producing a single LLVM function with two definitions and
failing `verifyModule` during lowering.

When fingerprinting a class imported from C++, also include the Clang
mangled name of its type.

Test: toolchain/lower/testdata/interop/cpp/thunks.carbon gains a split
with two specializations of one class template, each requiring a thunk;
their thunks now get distinct mangled names instead of colliding.

Assisted-by: Claude Code

---------

Co-authored-by: Christopher Di Bella <cjdb.ns@gmail.com>
This commit is contained in:
Chandler Carruth
2026-05-30 08:13:00 +00:00
committed by GitHub
co-authored by Christopher Di Bella
parent 3ef128ac91
commit 8a59f2a76b
64 changed files with 4762 additions and 4330 deletions
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toolchain/check/testdata/interop/cpp/impls/copy.carbon
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+41 -41
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@@ -200,31 +200,31 @@ fn EqualWitnesses(p: Wrap(Cpp.Copyable)*) -> Wrap(Cpp.Copyable)* {
// CHECK:STDOUT: %Copy.type: type = facet_type <@Copy> [concrete]
// CHECK:STDOUT: %Copyable.Copyable.type: type = fn_type @Copyable.Copyable [concrete]
// CHECK:STDOUT: %Copyable.Copyable: %Copyable.Copyable.type = struct_value () [concrete]
// CHECK:STDOUT: %const.bd1: type = const_type %Copyable [concrete]
// CHECK:STDOUT: %ptr.f7a: type = ptr_type %const.bd1 [concrete]
// CHECK:STDOUT: %ptr.e16: type = ptr_type %Copyable [concrete]
// CHECK:STDOUT: %const.151: type = const_type %Copyable [concrete]
// CHECK:STDOUT: %ptr.765: type = ptr_type %const.151 [concrete]
// CHECK:STDOUT: %ptr.fc9: type = ptr_type %Copyable [concrete]
// CHECK:STDOUT: %Copyable__carbon_thunk.type: type = fn_type @Copyable__carbon_thunk [concrete]
// CHECK:STDOUT: %Copyable__carbon_thunk: %Copyable__carbon_thunk.type = struct_value () [concrete]
// CHECK:STDOUT: %Copyable.Op.type: type = fn_type @Copyable.Op [concrete]
// CHECK:STDOUT: %Copyable.Op: %Copyable.Op.type = struct_value () [concrete]
// CHECK:STDOUT: %custom_witness.b8df63.1: <witness> = custom_witness (%Copyable.Op), @Copy [concrete]
// CHECK:STDOUT: %Copy.facet.af5: %Copy.type = facet_value %Copyable, (%custom_witness.b8df63.1) [concrete]
// CHECK:STDOUT: %Copy.WithSelf.Op.type.b43: type = fn_type @Copy.WithSelf.Op, @Copy.WithSelf(%Copy.facet.af5) [concrete]
// CHECK:STDOUT: %.10e: type = fn_type_with_self_type %Copy.WithSelf.Op.type.b43, %Copy.facet.af5 [concrete]
// CHECK:STDOUT: %Copy.facet.0af: %Copy.type = facet_value %Copyable, (%custom_witness.b8df63.1) [concrete]
// CHECK:STDOUT: %Copy.WithSelf.Op.type.b36: type = fn_type @Copy.WithSelf.Op, @Copy.WithSelf(%Copy.facet.0af) [concrete]
// CHECK:STDOUT: %.8c1: type = fn_type_with_self_type %Copy.WithSelf.Op.type.b36, %Copy.facet.0af [concrete]
// CHECK:STDOUT: %ExplicitCopy: type = class_type @ExplicitCopy [concrete]
// CHECK:STDOUT: %ExplicitCopy.ExplicitCopy.type: type = fn_type @ExplicitCopy.ExplicitCopy [concrete]
// CHECK:STDOUT: %ExplicitCopy.ExplicitCopy: %ExplicitCopy.ExplicitCopy.type = struct_value () [concrete]
// CHECK:STDOUT: %const.8e8: type = const_type %ExplicitCopy [concrete]
// CHECK:STDOUT: %ptr.85a: type = ptr_type %const.8e8 [concrete]
// CHECK:STDOUT: %ptr.f9f: type = ptr_type %ExplicitCopy [concrete]
// CHECK:STDOUT: %const.869: type = const_type %ExplicitCopy [concrete]
// CHECK:STDOUT: %ptr.39a: type = ptr_type %const.869 [concrete]
// CHECK:STDOUT: %ptr.82f: type = ptr_type %ExplicitCopy [concrete]
// CHECK:STDOUT: %ExplicitCopy__carbon_thunk.type: type = fn_type @ExplicitCopy__carbon_thunk [concrete]
// CHECK:STDOUT: %ExplicitCopy__carbon_thunk: %ExplicitCopy__carbon_thunk.type = struct_value () [concrete]
// CHECK:STDOUT: %ExplicitCopy.Op.type: type = fn_type @ExplicitCopy.Op [concrete]
// CHECK:STDOUT: %ExplicitCopy.Op: %ExplicitCopy.Op.type = struct_value () [concrete]
// CHECK:STDOUT: %custom_witness.b8df63.2: <witness> = custom_witness (%ExplicitCopy.Op), @Copy [concrete]
// CHECK:STDOUT: %Copy.facet.4c2: %Copy.type = facet_value %ExplicitCopy, (%custom_witness.b8df63.2) [concrete]
// CHECK:STDOUT: %Copy.WithSelf.Op.type.4db: type = fn_type @Copy.WithSelf.Op, @Copy.WithSelf(%Copy.facet.4c2) [concrete]
// CHECK:STDOUT: %.3e7: type = fn_type_with_self_type %Copy.WithSelf.Op.type.4db, %Copy.facet.4c2 [concrete]
// CHECK:STDOUT: %Copy.facet.b31: %Copy.type = facet_value %ExplicitCopy, (%custom_witness.b8df63.2) [concrete]
// CHECK:STDOUT: %Copy.WithSelf.Op.type.baa: type = fn_type @Copy.WithSelf.Op, @Copy.WithSelf(%Copy.facet.b31) [concrete]
// CHECK:STDOUT: %.fcd: type = fn_type_with_self_type %Copy.WithSelf.Op.type.baa, %Copy.facet.b31 [concrete]
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: imports {
@@ -254,16 +254,16 @@ fn EqualWitnesses(p: Wrap(Cpp.Copyable)*) -> Wrap(Cpp.Copyable)* {
// CHECK:STDOUT: !entry:
// CHECK:STDOUT: %c.ref: %Copyable = name_ref c, %c
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: %impl.elem0: %.10e = impl_witness_access constants.%custom_witness.b8df63.1, element0 [concrete = constants.%Copyable.Op]
// CHECK:STDOUT: %impl.elem0: %.8c1 = impl_witness_access constants.%custom_witness.b8df63.1, element0 [concrete = constants.%Copyable.Op]
// CHECK:STDOUT: %bound_method: <bound method> = bound_method %c.ref, %impl.elem0
// CHECK:STDOUT: %.loc8_10.1: ref %Copyable = temporary_storage
// CHECK:STDOUT: %Op.ref: %Copyable.Copyable.type = name_ref Op, imports.%Copyable.Copyable.decl [concrete = constants.%Copyable.Copyable]
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: %.loc8_10.2: ref %Copyable = value_as_ref %c.ref
// CHECK:STDOUT: %addr.loc8_10.1: %ptr.e16 = addr_of %.loc8_10.2
// CHECK:STDOUT: %.loc8_10.3: %ptr.f7a = as_compatible %addr.loc8_10.1
// CHECK:STDOUT: %.loc8_10.4: %ptr.f7a = converted %addr.loc8_10.1, %.loc8_10.3
// CHECK:STDOUT: %addr.loc8_10.2: %ptr.e16 = addr_of %.loc6_40.1
// CHECK:STDOUT: %addr.loc8_10.1: %ptr.fc9 = addr_of %.loc8_10.2
// CHECK:STDOUT: %.loc8_10.3: %ptr.765 = as_compatible %addr.loc8_10.1
// CHECK:STDOUT: %.loc8_10.4: %ptr.765 = converted %addr.loc8_10.1, %.loc8_10.3
// CHECK:STDOUT: %addr.loc8_10.2: %ptr.fc9 = addr_of %.loc6_40.1
// 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
@@ -273,16 +273,16 @@ fn EqualWitnesses(p: Wrap(Cpp.Copyable)*) -> Wrap(Cpp.Copyable)* {
// CHECK:STDOUT: !entry:
// CHECK:STDOUT: %c.ref: %ExplicitCopy = name_ref c, %c
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: %impl.elem0: %.3e7 = impl_witness_access constants.%custom_witness.b8df63.2, element0 [concrete = constants.%ExplicitCopy.Op]
// CHECK:STDOUT: %impl.elem0: %.fcd = impl_witness_access constants.%custom_witness.b8df63.2, element0 [concrete = constants.%ExplicitCopy.Op]
// CHECK:STDOUT: %bound_method: <bound method> = bound_method %c.ref, %impl.elem0
// CHECK:STDOUT: %.loc14_10.1: ref %ExplicitCopy = temporary_storage
// CHECK:STDOUT: %Op.ref: %ExplicitCopy.ExplicitCopy.type = name_ref Op, imports.%ExplicitCopy.ExplicitCopy.decl [concrete = constants.%ExplicitCopy.ExplicitCopy]
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: %.loc14_10.2: ref %ExplicitCopy = value_as_ref %c.ref
// CHECK:STDOUT: %addr.loc14_10.1: %ptr.f9f = addr_of %.loc14_10.2
// CHECK:STDOUT: %.loc14_10.3: %ptr.85a = as_compatible %addr.loc14_10.1
// CHECK:STDOUT: %.loc14_10.4: %ptr.85a = converted %addr.loc14_10.1, %.loc14_10.3
// CHECK:STDOUT: %addr.loc14_10.2: %ptr.f9f = addr_of %.loc12_48.1
// CHECK:STDOUT: %addr.loc14_10.1: %ptr.82f = addr_of %.loc14_10.2
// CHECK:STDOUT: %.loc14_10.3: %ptr.39a = as_compatible %addr.loc14_10.1
// CHECK:STDOUT: %.loc14_10.4: %ptr.39a = converted %addr.loc14_10.1, %.loc14_10.3
// CHECK:STDOUT: %addr.loc14_10.2: %ptr.82f = addr_of %.loc12_48.1
// 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
@@ -301,17 +301,17 @@ fn EqualWitnesses(p: Wrap(Cpp.Copyable)*) -> Wrap(Cpp.Copyable)* {
// CHECK:STDOUT: %Copyable.Op.type: type = fn_type @Copyable.Op [concrete]
// CHECK:STDOUT: %Copyable.Op: %Copyable.Op.type = struct_value () [concrete]
// CHECK:STDOUT: %custom_witness.b8d: <witness> = custom_witness (%Copyable.Op), @Copy.1 [concrete]
// CHECK:STDOUT: %Copy.facet.af5: %Copy.type.62b = facet_value %Copyable, (%custom_witness.b8d) [concrete]
// CHECK:STDOUT: %Copy.specific_fn: <specific function> = specific_function %Copy, @Copy.loc6(%Copy.facet.af5) [concrete]
// CHECK:STDOUT: %Wrap.5b3: type = class_type @Wrap, @Wrap(%Copy.facet.af5) [concrete]
// CHECK:STDOUT: %ptr.6b6: type = ptr_type %Wrap.5b3 [concrete]
// CHECK:STDOUT: %Copy.impl_witness.54f: <witness> = impl_witness imports.%Copy.impl_witness_table.760, @ptr.as.Copy.impl(%Wrap.5b3) [concrete]
// CHECK:STDOUT: %ptr.as.Copy.impl.Op.type.24f: type = fn_type @ptr.as.Copy.impl.Op, @ptr.as.Copy.impl(%Wrap.5b3) [concrete]
// CHECK:STDOUT: %ptr.as.Copy.impl.Op.e89: %ptr.as.Copy.impl.Op.type.24f = struct_value () [concrete]
// CHECK:STDOUT: %Copy.facet.a96: %Copy.type.62b = facet_value %ptr.6b6, (%Copy.impl_witness.54f) [concrete]
// CHECK:STDOUT: %Copy.WithSelf.Op.type.166: type = fn_type @Copy.WithSelf.Op, @Copy.WithSelf(%Copy.facet.a96) [concrete]
// CHECK:STDOUT: %.d7b: type = fn_type_with_self_type %Copy.WithSelf.Op.type.166, %Copy.facet.a96 [concrete]
// CHECK:STDOUT: %ptr.as.Copy.impl.Op.specific_fn: <specific function> = specific_function %ptr.as.Copy.impl.Op.e89, @ptr.as.Copy.impl.Op(%Wrap.5b3) [concrete]
// CHECK:STDOUT: %Copy.facet.0af: %Copy.type.62b = facet_value %Copyable, (%custom_witness.b8d) [concrete]
// CHECK:STDOUT: %Copy.specific_fn: <specific function> = specific_function %Copy, @Copy.loc6(%Copy.facet.0af) [concrete]
// CHECK:STDOUT: %Wrap.cb4: type = class_type @Wrap, @Wrap(%Copy.facet.0af) [concrete]
// CHECK:STDOUT: %ptr.727: type = ptr_type %Wrap.cb4 [concrete]
// CHECK:STDOUT: %Copy.impl_witness.b80: <witness> = impl_witness imports.%Copy.impl_witness_table.760, @ptr.as.Copy.impl(%Wrap.cb4) [concrete]
// CHECK:STDOUT: %ptr.as.Copy.impl.Op.type.b3b: type = fn_type @ptr.as.Copy.impl.Op, @ptr.as.Copy.impl(%Wrap.cb4) [concrete]
// CHECK:STDOUT: %ptr.as.Copy.impl.Op.b43: %ptr.as.Copy.impl.Op.type.b3b = struct_value () [concrete]
// CHECK:STDOUT: %Copy.facet.86d: %Copy.type.62b = facet_value %ptr.727, (%Copy.impl_witness.b80) [concrete]
// CHECK:STDOUT: %Copy.WithSelf.Op.type.111: type = fn_type @Copy.WithSelf.Op, @Copy.WithSelf(%Copy.facet.86d) [concrete]
// CHECK:STDOUT: %.378: type = fn_type_with_self_type %Copy.WithSelf.Op.type.111, %Copy.facet.86d [concrete]
// CHECK:STDOUT: %ptr.as.Copy.impl.Op.specific_fn: <specific function> = specific_function %ptr.as.Copy.impl.Op.b43, @ptr.as.Copy.impl.Op(%Wrap.cb4) [concrete]
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: imports {
@@ -324,22 +324,22 @@ fn EqualWitnesses(p: Wrap(Cpp.Copyable)*) -> Wrap(Cpp.Copyable)* {
// CHECK:STDOUT: %Copy.ref: %Copy.type.543 = name_ref Copy, file.%Copy.decl [concrete = constants.%Copy]
// CHECK:STDOUT: %c.ref: %Copyable = name_ref c, %c
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: %Copy.facet: %Copy.type.62b = facet_value constants.%Copyable, (constants.%custom_witness.b8d) [concrete = constants.%Copy.facet.af5]
// CHECK:STDOUT: %.loc12: %Copy.type.62b = converted constants.%Copyable, %Copy.facet [concrete = constants.%Copy.facet.af5]
// CHECK:STDOUT: %Copy.specific_fn: <specific function> = specific_function %Copy.ref, @Copy.loc6(constants.%Copy.facet.af5) [concrete = constants.%Copy.specific_fn]
// CHECK:STDOUT: %Copy.facet: %Copy.type.62b = facet_value constants.%Copyable, (constants.%custom_witness.b8d) [concrete = constants.%Copy.facet.0af]
// CHECK:STDOUT: %.loc12: %Copy.type.62b = converted constants.%Copyable, %Copy.facet [concrete = constants.%Copy.facet.0af]
// CHECK:STDOUT: %Copy.specific_fn: <specific function> = specific_function %Copy.ref, @Copy.loc6(constants.%Copy.facet.0af) [concrete = constants.%Copy.specific_fn]
// 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:
// CHECK:STDOUT: fn @EqualWitnesses(%p.param: %ptr.6b6) -> out %return.param: %ptr.6b6 {
// CHECK:STDOUT: fn @EqualWitnesses(%p.param: %ptr.727) -> out %return.param: %ptr.727 {
// CHECK:STDOUT: !entry:
// CHECK:STDOUT: %p.ref: %ptr.6b6 = name_ref p, %p
// CHECK:STDOUT: %impl.elem0: %.d7b = impl_witness_access constants.%Copy.impl_witness.54f, element0 [concrete = constants.%ptr.as.Copy.impl.Op.e89]
// CHECK:STDOUT: %p.ref: %ptr.727 = name_ref p, %p
// CHECK:STDOUT: %impl.elem0: %.378 = impl_witness_access constants.%Copy.impl_witness.b80, element0 [concrete = constants.%ptr.as.Copy.impl.Op.b43]
// CHECK:STDOUT: %bound_method.loc20_10.1: <bound method> = bound_method %p.ref, %impl.elem0
// CHECK:STDOUT: %specific_fn: <specific function> = specific_function %impl.elem0, @ptr.as.Copy.impl.Op(constants.%Wrap.5b3) [concrete = constants.%ptr.as.Copy.impl.Op.specific_fn]
// CHECK:STDOUT: %specific_fn: <specific function> = specific_function %impl.elem0, @ptr.as.Copy.impl.Op(constants.%Wrap.cb4) [concrete = constants.%ptr.as.Copy.impl.Op.specific_fn]
// 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.6b6 = call %bound_method.loc20_10.2(%p.ref)
// CHECK:STDOUT: %ptr.as.Copy.impl.Op.call: init %ptr.727 = call %bound_method.loc20_10.2(%p.ref)
// CHECK:STDOUT: return %ptr.as.Copy.impl.Op.call
// CHECK:STDOUT: }
// CHECK:STDOUT: