Skip to content

[libc++][Android] Always redirect <stdatomic.h> to <atomic> #143036

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 2 commits into
base: main
Choose a base branch
from
Open

[libc++][Android] Always redirect <stdatomic.h> to <atomic> #143036

Show file tree
Hide file tree
Changes from 1 commit
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
1e0457b
[libc++][Android] Always redirect <stdatomic.h> to <atomic>
rprichard Jun 4, 2025
44a5824
Move c++03 onto the same line as the other dialects
rprichard Jun 24, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
5 changes: 4 additions & 1 deletion libcxx/include/atomic
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -598,7 +598,10 @@ template <class T>
# define _LIBCPP_STDATOMIC_H_HAS_DEFINITELY_BEEN_INCLUDED 0
# endif

# if _LIBCPP_STD_VER < 23 && _LIBCPP_STDATOMIC_H_HAS_DEFINITELY_BEEN_INCLUDED
// The Android LLVM toolchain has historically allowed combining the <atomic>
// and <stdatomic.h> headers in dialects before C++23, so for backwards
// compatibility, preserve that ability when targeting Android.
# if _LIBCPP_STD_VER < 23 && !defined(__ANDROID__) && _LIBCPP_STDATOMIC_H_HAS_DEFINITELY_BEEN_INCLUDED
# error <atomic> is incompatible with <stdatomic.h> before C++23. Please compile with -std=c++23.
# endif

Expand Down
5 changes: 4 additions & 1 deletion libcxx/include/stdatomic.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -126,7 +126,10 @@ using std::atomic_signal_fence // see below
# pragma GCC system_header
# endif

# if defined(__cplusplus) && _LIBCPP_STD_VER >= 23
// The Android LLVM toolchain has historically allowed combining the <atomic>
// and <stdatomic.h> headers in dialects before C++23, so for backwards
// compatibility, preserve that ability when targeting Android.
# if defined(__cplusplus) && (_LIBCPP_STD_VER >= 23 || defined(__ANDROID__))

# include <atomic>
# include <version>
Expand Down
5 changes: 4 additions & 1 deletion libcxx/test/libcxx/atomics/atomics.syn/compatible_with_stdatomic.compile.pass.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,10 @@
//===----------------------------------------------------------------------===//

// UNSUPPORTED: no-threads
// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20

// On Android, libc++'s <stdatomic.h> header always redirects to <atomic>, even before C++23.
// UNSUPPORTED: c++03
Copy link
Contributor

@enh-google enh-google Jun 6, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

why is c++03 on a separate line now?

Copy link
Contributor Author

@rprichard rprichard Jun 8, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

It probably shouldn't be on a separate line -- it looks like libc++ does support <atomic> for C++03.

Though now I'm wondering if the UNSUPPORTED directive ought to be XFAIL instead. I think the libc++ project usually prefers XFAIL when we know that a test should fail.

Copy link
Contributor Author

@rprichard rprichard Jun 8, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I suppose UNSUPPORTED might be fine, though, because for previous language dialects, we have the incompatible_with_stdatomic.verify.cpp test already.

Copy link
Member

@ldionne ldionne Jun 12, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I think I'd move back c++03 on the same line as the other ones. I'm neutral on XFAIL vs UNSUPPORTED -- as you mention we already have a dedicated test for the inverse behavior.

// UNSUPPORTED: (c++11 || c++14 || c++17 || c++20) && !android

// This test verifies that <stdatomic.h> redirects to <atomic>.

Expand Down
3 changes: 3 additions & 0 deletions libcxx/test/libcxx/atomics/atomics.syn/incompatible_with_stdatomic.verify.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,9 @@
// UNSUPPORTED: no-threads
// REQUIRES: c++03 || c++11 || c++14 || c++17 || c++20

// On Android, libc++'s <stdatomic.h> header always redirects to <atomic>, even before C++23.
// XFAIL: android

// No diagnostic gets emitted when we build with modules.
// XFAIL: clang-modules-build

Expand Down
3 changes: 3 additions & 0 deletions libcxx/test/libcxx/atomics/stdatomic.h.syn/dont_hijack_header.cxx23.compile.pass.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,9 @@
// doesn't work at all if we don't use the <stdatomic.h> provided by libc++ in C++23 and above.
// XFAIL: (c++11 || c++14 || c++17 || c++20) && gcc

// On Android, libc++'s <stdatomic.h> header always redirects to <atomic>, even before C++23.
// XFAIL: android

#include <atomic>
#include <stdatomic.h>
#include <type_traits>
Expand Down
Loading