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C23 thread_local is mapping to C++ thread_local, not C11 _Thread_local #70068

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Fznamznon opened this issue Oct 24, 2023 · 4 comments · Fixed by #70107
Closed

C23 thread_local is mapping to C++ thread_local, not C11 _Thread_local #70068

Fznamznon opened this issue Oct 24, 2023 · 4 comments · Fixed by #70107
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accepts-invalid c23 clang:frontend Language frontend issues, e.g. anything involving "Sema" confirmed Verified by a second party

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@Fznamznon
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Per 6.7.1 p4

In the declaration of an object with block scope, if the declaration specifiers include thread_local,
they shall also include either static or extern.

gcc does complain.

Online demo https://godbolt.org/z/YorncrhKW

cc @AaronBallman
@Fznamznon Fznamznon added c clang:frontend Language frontend issues, e.g. anything involving "Sema" labels Oct 24, 2023
@llvmbot
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llvmbot commented Oct 24, 2023

@llvm/issue-subscribers-c

Author: Mariya Podchishchaeva (Fznamznon)

Per 6.7.1 p4 > In the declaration of an object with block scope, if the declaration specifiers include thread_local, they shall also include either static or extern.

gcc does complain.

Online demo https://godbolt.org/z/YorncrhKW

cc @AaronBallman

@llvmbot
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llvmbot commented Oct 24, 2023

@llvm/issue-subscribers-clang-frontend

Author: Mariya Podchishchaeva (Fznamznon)

Per 6.7.1 p4 > In the declaration of an object with block scope, if the declaration specifiers include thread_local, they shall also include either static or extern.

gcc does complain.

Online demo https://godbolt.org/z/YorncrhKW

cc @AaronBallman

@AaronBallman AaronBallman added c11 accepts-invalid confirmed Verified by a second party and removed c labels Oct 24, 2023
@llvmbot
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llvmbot commented Oct 24, 2023

@llvm/issue-subscribers-c11

Author: Mariya Podchishchaeva (Fznamznon)

Per 6.7.1 p4 > In the declaration of an object with block scope, if the declaration specifiers include thread_local, they shall also include either static or extern.

gcc does complain.

Online demo https://godbolt.org/z/YorncrhKW

cc @AaronBallman

@AaronBallman
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The root cause of this is that we enabled thread_local as a keyword in C23 mode and it is now mapping to the C++ thread_local semantics rather than the C11 _Thread_local semantics. You can see this in: https://godbolt.org/z/e89MsbG1E

@AaronBallman AaronBallman changed the title Clang doesn't complain about thread_local variable in file scope without extern or static. C23 thread_local is mapping to C++ thread_local, not C11 _Thread_local Oct 24, 2023
@AaronBallman AaronBallman added c23 and removed c11 labels Oct 24, 2023
@AaronBallman AaronBallman mentioned this issue Oct 24, 2023
Merged
AaronBallman added a commit to AaronBallman/llvm-project that referenced this issue Oct 24, 2023
@AaronBallman
[C23] Use thread_local semantics
9db10fc 
When implementing thread_local as a keyword in C23, we accidentally
started using C++11 thread_local semantics when using that keyword
instead of using C11 _Thread_local semantics.

This oversight is fixed by pretending the user wrote _Thread_local
instead. This doesn't have the best behavior in terms of diagnostics,
but it does correct the semantic behavior.

Fixes llvm#70068
AaronBallman added a commit that referenced this issue Oct 25, 2023
@AaronBallman
[C23] Use thread_local semantics (#70107)
66f4a13 
When implementing thread_local as a keyword in C23, we accidentally
started using C++11 thread_local semantics when using that keyword
instead of using C11 _Thread_local semantics.

This oversight is fixed by pretending the user wrote _Thread_local
instead. This doesn't have the best behavior in terms of diagnostics,
but it does correct the semantic behavior.

Fixes #70068
Fixes #69167
AaronBallman added a commit to AaronBallman/llvm-project that referenced this issue Oct 25, 2023
@AaronBallman
[C23] Use thread_local semantics (llvm#70107)
10e2ac1 
When implementing thread_local as a keyword in C23, we accidentally
started using C++11 thread_local semantics when using that keyword
instead of using C11 _Thread_local semantics.

This oversight is fixed by pretending the user wrote _Thread_local
instead. This doesn't have the best behavior in terms of diagnostics,
but it does correct the semantic behavior.

Fixes llvm#70068
Fixes llvm#69167
tru pushed a commit to llvm/llvm-project-release-prs that referenced this issue Oct 27, 2023
@AaronBallman @tru
[C23] Use thread_local semantics (#70107)
2a41d97 
When implementing thread_local as a keyword in C23, we accidentally
started using C++11 thread_local semantics when using that keyword
instead of using C11 _Thread_local semantics.

This oversight is fixed by pretending the user wrote _Thread_local
instead. This doesn't have the best behavior in terms of diagnostics,
but it does correct the semantic behavior.

Fixes llvm/llvm-project#70068
Fixes llvm/llvm-project#69167
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[C23] Use thread_local semantics AaronBallman/llvm-project
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