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[committed] libstdc++: Ignore _GLIBCXX_USE_POSIX_SEMAPHORE if not supported [PR116992]

Message ID 20241009124248.579260-1-jwakely@redhat.com
State New
Headers show
Series [committed] libstdc++: Ignore _GLIBCXX_USE_POSIX_SEMAPHORE if not supported [PR116992] | expand

Commit Message

Jonathan Wakely Oct. 9, 2024, 12:42 p.m. UTC 
Tested x86_64-linux. Pushed to trunk.

-- >8 --

If _GLIBCXX_HAVE_POSIX_SEMAPHRE is undefined then users get an error
when defining _GLIBCXX_USE_POSIX_SEMAPHORE. We can just ignore it
instead (and warn them it's being ignored).

This fixes a testsuite failure on hppa64-hp-hpux11.11 (and probably some
other targets):

FAIL: 30_threads/semaphore/platform_try_acquire_for.cc  -std=gnu++20 (test for excess errors)
Excess errors:
semaphore:49: error: '__semaphore_impl' has not been declared

libstdc++-v3/ChangeLog:

	PR libstdc++/116992
	* include/bits/semaphore_base.h (_GLIBCXX_USE_POSIX_SEMAPHORE):
	Undefine and issue a warning if POSIX sem_t is not supported.
	* testsuite/30_threads/semaphore/platform_try_acquire_for.cc:
	Prune new warning.
---
 libstdc++-v3/include/bits/semaphore_base.h                     | 3 +++
 .../testsuite/30_threads/semaphore/platform_try_acquire_for.cc | 2 ++
 2 files changed, 5 insertions(+)
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Patch

diff --git a/libstdc++-v3/include/bits/semaphore_base.h b/libstdc++-v3/include/bits/semaphore_base.h
index 9d73b37e60a..dd16d2c9249 100644
--- a/libstdc++-v3/include/bits/semaphore_base.h
+++ b/libstdc++-v3/include/bits/semaphore_base.h
@@ -45,6 +45,9 @@ 
 # include <cerrno>	// errno, EINTR, EAGAIN etc.
 # include <limits.h>	// SEM_VALUE_MAX
 # include <semaphore.h>	// sem_t, sem_init, sem_wait, sem_post etc.
+#elif defined(_GLIBCXX_USE_POSIX_SEMAPHORE)
+# warning "POSIX semaphore not available, ignoring _GLIBCXX_USE_POSIX_SEMAPHORE"
+# undef _GLIBCXX_USE_POSIX_SEMAPHORE
 #endif
 
 namespace std _GLIBCXX_VISIBILITY(default)
diff --git a/libstdc++-v3/testsuite/30_threads/semaphore/platform_try_acquire_for.cc b/libstdc++-v3/testsuite/30_threads/semaphore/platform_try_acquire_for.cc
index bf6cd142bf0..6d90564ea8a 100644
--- a/libstdc++-v3/testsuite/30_threads/semaphore/platform_try_acquire_for.cc
+++ b/libstdc++-v3/testsuite/30_threads/semaphore/platform_try_acquire_for.cc
@@ -5,3 +5,5 @@ 
 // { dg-add-options libatomic }
 
 #include "try_acquire_for.cc"
+
+// { dg-prune-output "ignoring _GLIBCXX_USE_POSIX_SEMAPHORE" }