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Destroy temporaries at the end of expression statements. (#7513)

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Instead of tracking the cleanup scope depth on entry to each scope,
track an "ambient" cleanup scope depth that's *after* the destructors of
local variables in that scope. This gets increased to include the
destructors of local variables when we create a name-binding
declaration. Then, when we reach a point where temporaries should be
destroyed, run cleanups that are after the ambient cleanup scope depth
on the stack. This happens:

* At the `;` of a statement expression.
* At the `)` of an `if` or `while` statement.
* After performing the implied `HasValue()` call in a `for` statement.

Per informal agreement with leads, this means we lifetime-extend all
temporaries created in the initializer of a name-binding declaration to
the full scope of that declaration, but that temporaries created in an
expression statement are destroyed at the `;`.
This commit is contained in:
Richard Smith
2026-07-16 15:12:39 +00:00
committed by GitHub
parent 81e495ee53
commit 703529fc55
37 changed files with 844 additions and 384 deletions
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toolchain/check/testdata/function/declaration/fail_import_incomplete_return.carbon
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+9 -9
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@@ -218,11 +218,11 @@ fn CallFAndGIncomplete() {
// CHECK:STDOUT: %D: type = class_type @D [concrete]
// CHECK:STDOUT: %empty_struct_type: type = struct_type {} [concrete]
// CHECK:STDOUT: %complete_type: <witness> = complete_type_witness %empty_struct_type [concrete]
// CHECK:STDOUT: %Destroy.type: type = facet_type <@Destroy> [concrete]
// CHECK:STDOUT: %Destroy.Op.type.1d8f74.2: type = fn_type @Destroy.Op.loc33_17.2 [concrete]
// CHECK:STDOUT: %Destroy.Op.1a2547.2: %Destroy.Op.type.1d8f74.2 = struct_value () [concrete]
// CHECK:STDOUT: %ReturnDUsed.type: type = fn_type @ReturnDUsed [concrete]
// CHECK:STDOUT: %ReturnDUsed: %ReturnDUsed.type = struct_value () [concrete]
// CHECK:STDOUT: %Destroy.type: type = facet_type <@Destroy> [concrete]
// CHECK:STDOUT: %Destroy.Op.type.1d8f74.2: type = fn_type @Destroy.Op.loc34_15.2 [concrete]
// CHECK:STDOUT: %Destroy.Op.1a2547.2: %Destroy.Op.type.1d8f74.2 = struct_value () [concrete]
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: imports {
@@ -279,14 +279,14 @@ fn CallFAndGIncomplete() {
// CHECK:STDOUT: %.loc33_17.1: ref %D = temporary_storage
// CHECK:STDOUT: %ReturnDUnused.call: init %D to %.loc33_17.1 = call %ReturnDUnused.ref()
// CHECK:STDOUT: %.loc33_17.2: ref %D = temporary %.loc33_17.1, %ReturnDUnused.call
// CHECK:STDOUT: %Destroy.Op.bound.loc33: <bound method> = bound_method %.loc33_17.2, constants.%Destroy.Op.1a2547.2
// CHECK:STDOUT: %Destroy.Op.call.loc33: init %empty_tuple.type = call %Destroy.Op.bound.loc33(%.loc33_17.2)
// CHECK:STDOUT: %ReturnDUsed.ref: %ReturnDUsed.type = name_ref ReturnDUsed, imports.%Main.ReturnDUsed [concrete = constants.%ReturnDUsed]
// CHECK:STDOUT: %.loc34_15.1: ref %D = temporary_storage
// CHECK:STDOUT: %ReturnDUsed.call: init %D to %.loc34_15.1 = call %ReturnDUsed.ref()
// CHECK:STDOUT: %.loc34_15.2: ref %D = temporary %.loc34_15.1, %ReturnDUsed.call
// CHECK:STDOUT: %Destroy.Op.bound.loc34: <bound method> = bound_method %.loc34_15.2, constants.%Destroy.Op.1a2547.2
// CHECK:STDOUT: %Destroy.Op.call.loc34: init %empty_tuple.type = call %Destroy.Op.bound.loc34(%.loc34_15.2)
// CHECK:STDOUT: %Destroy.Op.bound.loc33: <bound method> = bound_method %.loc33_17.2, constants.%Destroy.Op.1a2547.2
// CHECK:STDOUT: %Destroy.Op.call.loc33: init %empty_tuple.type = call %Destroy.Op.bound.loc33(%.loc33_17.2)
// CHECK:STDOUT: return
// CHECK:STDOUT: }
// CHECK:STDOUT:
@@ -296,12 +296,12 @@ fn CallFAndGIncomplete() {
// CHECK:STDOUT:
// CHECK:STDOUT: fn @ReturnDUnused [from "fail_incomplete_return.carbon"];
// CHECK:STDOUT:
// CHECK:STDOUT: fn @ReturnDUsed [from "fail_incomplete_return.carbon"];
// CHECK:STDOUT: fn @Destroy.Op.loc33_17.1(%self.param: ref %empty_struct_type) = "no_op";
// CHECK:STDOUT:
// CHECK:STDOUT: fn @Destroy.Op.loc34_15.1(%self.param: ref %empty_struct_type) = "no_op";
// CHECK:STDOUT:
// CHECK:STDOUT: fn @Destroy.Op.loc34_15.2(%self.param: ref %D) {
// CHECK:STDOUT: fn @Destroy.Op.loc33_17.2(%self.param: ref %D) {
// CHECK:STDOUT: !entry:
// CHECK:STDOUT: return
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: fn @ReturnDUsed [from "fail_incomplete_return.carbon"];
// CHECK:STDOUT: