Now that it's clear that glibc bug
<https://sourceware.org/bugzilla/show_bug.cgi?id=13701> will never be fixed,
it's time to update the corresponding cross-compilation guess in gnulib.
2019-08-29 Bruno Haible <br...@clisp.org>
lock: Fix cross-compilation guesses.
* m4/pthread_rwlock_rdlock.m4 (gl_PTHREAD_RWLOCK_RDLOCK_PREFER_WRITER):
Require AC_CANONICAL_HOST. When cross-compiling, guess no on most
platforms.
diff --git a/m4/pthread_rwlock_rdlock.m4 b/m4/pthread_rwlock_rdlock.m4
index 3c1d645..85e8dba 100644
--- a/m4/pthread_rwlock_rdlock.m4
+++ b/m4/pthread_rwlock_rdlock.m4
@@ -1,4 +1,4 @@
-# pthread_rwlock_rdlock.m4 serial 2
+# pthread_rwlock_rdlock.m4 serial 3
dnl Copyright (C) 2017-2019 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
@@ -29,11 +29,13 @@ dnl and SCHED_RR, see
dnl
http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_rwlock_rdlock.html
dnl but this test verifies the guarantee regardless of TPS and regardless of
dnl scheduling policy.
-dnl Glibc currently does not provide this guarantee, see
+dnl Glibc does not provide this guarantee (and never will on Linux), see
dnl https://sourceware.org/bugzilla/show_bug.cgi?id=13701
+dnl https://bugzilla.redhat.com/show_bug.cgi?id=1410052
AC_DEFUN([gl_PTHREAD_RWLOCK_RDLOCK_PREFER_WRITER],
[
AC_REQUIRE([gl_THREADLIB_EARLY])
+ AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
AC_CACHE_CHECK([whether pthread_rwlock_rdlock prefers a writer to a reader],
[gl_cv_pthread_rwlock_rdlock_prefer_writer],
[save_LIBS="$LIBS"
@@ -153,7 +155,25 @@ main ()
]])],
[gl_cv_pthread_rwlock_rdlock_prefer_writer=yes],
[gl_cv_pthread_rwlock_rdlock_prefer_writer=no],
- [gl_cv_pthread_rwlock_rdlock_prefer_writer="guessing yes"])
+ [case "$host_os" in
+ # Guess no on glibc systems.
+ *-gnu* | gnu*) gl_cv_pthread_rwlock_rdlock_prefer_writer="guessing
no" ;;
+ # Guess no on musl systems.
+ *-musl*) gl_cv_pthread_rwlock_rdlock_prefer_writer="guessing
no" ;;
+ # Guess no on bionic systems.
+ *-android*) gl_cv_pthread_rwlock_rdlock_prefer_writer="guessing
no" ;;
+ # Guess yes on native Windows with the mingw-w64
winpthreads library.
+ # Guess no on native Windows with the gnulib
windows-rwlock module.
+ mingw*) if test "$gl_use_threads" = yes || test
"$gl_use_threads" = posix; then
+ gl_cv_pthread_rwlock_rdlock_prefer_writer="guessing
yes"
+ else
+ gl_cv_pthread_rwlock_rdlock_prefer_writer="guessing
no"
+ fi
+ ;;
+ # If we don't know, assume the worst.
+ *) gl_cv_pthread_rwlock_rdlock_prefer_writer="guessing
no" ;;
+ esac
+ ])
LIBS="$save_LIBS"
])
case "$gl_cv_pthread_rwlock_rdlock_prefer_writer" in
