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Correctly model NRVO returns (#7865)

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The AST doesn't really matter here, since it's NRVO, there's no actual
code to generate to return the value. But having a correct AST does
address at least one clang false-positive diagnostic:
```
error: stack memory associated with local variable 'return_storage' is returned
    3 | fn F() -> bool {
      |           ^
```
This commit is contained in:
David Blaikie
2026-09-29 21:06:48 +00:00
committed by GitHub
parent c2d9cde674
commit 99f910f179
2 changed files with 24 additions and 8 deletions
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toolchain/check/testdata/interop/cpp/function/export/thunk_ast.carbon
Vendored
+6 -5
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@@ -35,20 +35,21 @@ fn F(i: i32) -> i32 {
// CHECK:STDOUT: | | | `-ImplicitCastExpr {{0x[a-f0-9]+}} <col:21> 'const int' lvalue <NoOp>
// CHECK:STDOUT: | | | `-DeclRefExpr {{0x[a-f0-9]+}} <col:21> 'int' lvalue Var {{0x[a-f0-9]+}} 'return_storage' 'int'
// CHECK:STDOUT: | | `-ReturnStmt {{0x[a-f0-9]+}} <col:21> nrvo_candidate(Var {{0x[a-f0-9]+}} 'return_storage' 'int')
// CHECK:STDOUT: | | `-DeclRefExpr {{0x[a-f0-9]+}} <col:21> 'int' lvalue Var {{0x[a-f0-9]+}} 'return_storage' 'int'
// CHECK:STDOUT: | | `-ImplicitCastExpr {{0x[a-f0-9]+}} <col:21> 'int' <LValueToRValue>
// CHECK:STDOUT: | | `-DeclRefExpr {{0x[a-f0-9]+}} <col:21> 'int' lvalue Var {{0x[a-f0-9]+}} 'return_storage' 'int'
// CHECK:STDOUT: | |-AlwaysInlineAttr {{0x[a-f0-9]+}} <<invalid sloc>> Implicit always_inline
// CHECK:STDOUT: | `-InternalLinkageAttr {{0x[a-f0-9]+}} <<invalid sloc>> Implicit
// CHECK:STDOUT: |-FunctionDecl {{0x[a-f0-9]+}} <line:38:1, line:40:1> line:38:5 in thunk_with_args_and_return.carbon hidden G 'int (int)' external-linkage
// CHECK:STDOUT: |-FunctionDecl {{0x[a-f0-9]+}} <line:39:1, line:41:1> line:39:5 in thunk_with_args_and_return.carbon hidden G 'int (int)' external-linkage
// CHECK:STDOUT: | |-ParmVarDecl {{0x[a-f0-9]+}} <col:7, col:11> col:11 in thunk_with_args_and_return.carbon hidden used i 'int'
// CHECK:STDOUT: | `-CompoundStmt {{0x[a-f0-9]+}} <col:14, line:40:1>
// CHECK:STDOUT: | `-ReturnStmt {{0x[a-f0-9]+}} <line:39:3, col:21>
// CHECK:STDOUT: | `-CompoundStmt {{0x[a-f0-9]+}} <col:14, line:41:1>
// CHECK:STDOUT: | `-ReturnStmt {{0x[a-f0-9]+}} <line:40:3, col:21>
// CHECK:STDOUT: | `-CallExpr {{0x[a-f0-9]+}} <col:10, col:21> 'int'
// CHECK:STDOUT: | |-ImplicitCastExpr {{0x[a-f0-9]+}} <col:10, col:18> 'int (*)(int)' <FunctionToPointerDecay>
// CHECK:STDOUT: | | `-DeclRefExpr {{0x[a-f0-9]+}} <col:10, col:18> 'int (int)' lvalue Function {{0x[a-f0-9]+}} 'F' 'int (int)'
// CHECK:STDOUT: | | `-NestedNameSpecifier Namespace {{0x[a-f0-9]+}} 'Carbon'
// CHECK:STDOUT: | `-ImplicitCastExpr {{0x[a-f0-9]+}} <col:20> 'int' <LValueToRValue>
// CHECK:STDOUT: | `-DeclRefExpr {{0x[a-f0-9]+}} <col:20> 'int' lvalue ParmVar {{0x[a-f0-9]+}} 'i' 'int'
// CHECK:STDOUT: `-ImportDecl {{0x[a-f0-9]+}} <line:41:4> col:4 in thunk_with_args_and_return.carbon implicit thunk_with_args_and_return.carbon
// CHECK:STDOUT: `-ImportDecl {{0x[a-f0-9]+}} <line:42:4> col:4 in thunk_with_args_and_return.carbon implicit thunk_with_args_and_return.carbon
return i;
}