From: Jonathan Wakely <jwakely@redhat.com>
Date: Tue, 9 Nov 2021 23:45:36 +0000 (+0000)
Subject: libstdc++: Disable gthreads weak symbols for glibc 2.34 [PR103133]
X-Git-Tag: basepoints/gcc-13~3205
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=80fe172ba9820199c2bbce5d0611ffca27823049;p=thirdparty%2Fgcc.git

libstdc++: Disable gthreads weak symbols for glibc 2.34 [PR103133]

Since Glibc 2.34 all pthreads symbols are defined directly in libc not
libpthread, and since Glibc 2.32 we have used __libc_single_threaded to
avoid unnecessary locking in single-threaded programs. This means there
is no reason to avoid linking to libpthread now, and so no reason to use
weak symbols defined in gthr-posix.h for all the pthread_xxx functions.

libstdc++-v3/ChangeLog:

	PR libstdc++/100748
	PR libstdc++/103133
	* config/os/gnu-linux/os_defines.h (_GLIBCXX_GTHREAD_USE_WEAK):
	Define for glibc 2.34 and later.
---

diff --git a/libstdc++-v3/config/os/gnu-linux/os_defines.h b/libstdc++-v3/config/os/gnu-linux/os_defines.h
index d5bb2a1886e3..3a0534541959 100644
--- a/libstdc++-v3/config/os/gnu-linux/os_defines.h
+++ b/libstdc++-v3/config/os/gnu-linux/os_defines.h
@@ -61,4 +61,10 @@
   (__gthread_active_p() ? __gthread_self() : (__gthread_t)1)
 #endif
 
+#if __GLIBC_PREREQ(2, 34)
+// Since glibc 2.34 all pthreads functions are usable without linking to
+// libpthread.
+# define _GLIBCXX_GTHREAD_USE_WEAK 0
+#endif
+
 #endif