Exclude Apple platforms from _XOPEN_SOURCE definition#343
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mkruskal-google merged 9 commits intoJun 29, 2026
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_XOPEN_SOURCE 500 was added in google#266 to fix a QNX-specific compile error. On Apple platforms, defining it lowers __DARWIN_C_LEVEL, hiding C11 additions like quick_exit/at_quick_exit. GCC 15's libstdc++ <cstdlib> unconditionally re-exports these symbols, which fails to compile when they're hidden by this macro. Add __APPLE__ to the existing exclusion list alongside FreeBSD and OpenBSD, consistent with how those platforms are already handled. See abseil/abseil-cpp#2095
… with Bazel BUILD file
This reverts commit 3ae438d.
This reverts commit 433ab0e.
mkruskal-google
approved these changes
Jun 28, 2026
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This addresses the macOS+GCC15 build failure discussed in
abseil/abseil-cpp#2095, per @mkruskal-google's suggestion there.
Background
#265 added
_XOPEN_SOURCE 500to fix a QNX-specific compile error,excluding FreeBSD and OpenBSD. This wasn't tested against Apple
platforms at the time.
Problem
On Apple platforms, defining
_XOPEN_SOURCElowers__DARWIN_C_LEVEL,hiding C11 additions like
quick_exit/at_quick_exit. GCC 15'slibstdc++
<cstdlib>unconditionally re-exports these symbols, whichfails to compile when they're hidden:
error: 'quick_exit' has not been declared in '::'Fix
Add
__APPLE__to the existing exclusion list alongside FreeBSD andOpenBSD, consistent with how those platforms are already handled.
Testing
Verified with a CI workflow on a macos-latest runner + Homebrew GCC 15: