[PATCH] In configure.ac, try -lpthread in $LIBS instead of $CFLAGS to make picky linkers happy

From: Rainer M. Canavan <git@canavan.de>
Date: Nov 6, 2015, 01:11 UTC
Message-ID: <201511060111.tA61BbFX084361@tezro.nonet>
In-Reply-To: <vpqa8qwst4y.fsf@anie.imag.fr>

Some linkers, namely the one on IRIX are rather strict concerning the order or arguments for symbol resolution, i.e. no libraries listed before objects or other libraries on the command line are considered for symbol resolution. Therefore, -lpthread can't work if it's put in CFLAGS, because it will not be considered for resolving pthread_key_create in conftest.o. Use $LIBS instead.

Signed-off-by: Rainer Canavan <git@canavan.de>
---
 configure.ac | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index fd22d41..1f55009 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1149,7 +1149,12 @@ elif test -z "$PTHREAD_CFLAGS"; then
   # would then trigger compiler warnings on every single file we compile.
   for opt in "" -mt -pthread -lpthread; do
      old_CFLAGS="$CFLAGS"
-     CFLAGS="$opt $CFLAGS"
+     old_LIBS="$LIBS"
+     case "$opt" in
+        -l*)  LIBS="$opt $LIBS" ;;
+        *)    CFLAGS="$opt $CFLAGS" ;;
+     esac
+
      AC_MSG_CHECKING([for POSIX Threads with '$opt'])
      AC_LINK_IFELSE([PTHREADTEST_SRC],
 	[AC_MSG_RESULT([yes])
@@ -1161,6 +1166,7 @@ elif test -z "$PTHREAD_CFLAGS"; then
 	],
 	[AC_MSG_RESULT([no])])
       CFLAGS="$old_CFLAGS"
+      LIBS="$old_LIBS"
   done
   if test $threads_found != yes; then
     AC_CHECK_LIB([pthread], [pthread_create],

-- 
2.6.2