[gcc r15-4211] libstdc++: Ignore _GLIBCXX_USE_POSIX_SEMAPHORE if not supported [PR116992]

[Jonathan Wakely via Gcc-cvs]

https://gcc.gnu.org/g:9a5ac633f0f49c819f2745584475051c9eb8f6e0

commit r15-4211-g9a5ac633f0f49c819f2745584475051c9eb8f6e0
Author: Jonathan Wakely <jwak...@redhat.com>
Date:   Mon Oct 7 10:22:24 2024 +0100

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

Diff:
---
 libstdc++-v3/include/bits/semaphore_base.h                             | 3 +++
 .../testsuite/30_threads/semaphore/platform_try_acquire_for.cc         | 2 ++
 2 files changed, 5 insertions(+)

diff --git a/libstdc++-v3/include/bits/semaphore_base.h 
b/libstdc++-v3/include/bits/semaphore_base.h
index 9d73b37e60a1..dd16d2c92498 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 bf6cd142bf01..6d90564ea8ac 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" }