From: Simon Marchi <simon.marchi@efficios.com>
Date: Fri, 4 Oct 2019 16:18:05 +0000 (-0400)
Subject: m4: sync ax_pthread.m4 with autoconf archive
X-Git-Url: http://git.efficios.com/?p=babeltrace.git;a=commitdiff_plain;h=02c4ef49fb05d6e69053b54add5fe51ffd6f9aee

m4: sync ax_pthread.m4 with autoconf archive

Sync with [1].

In particular, this lets us configure with -Wunused-but-set-parameter.

[1] https://raw.githubusercontent.com/autoconf-archive/autoconf-archive/62e8491dbc174113a04fe910cad1e92e8a9e2164/m4/ax_pthread.m4

Change-Id: I496e3d9a8e896b04bf3cc87ddd41b1b144d23ee5
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/2128
Reviewed-by: Michael Jeanson <mjeanson@efficios.com>
Tested-by: jenkins <jenkins@lttng.org>
---

diff --git a/m4/ax_pthread.m4 b/m4/ax_pthread.m4
index 4920e073..0300e4ed 100644
--- a/m4/ax_pthread.m4
+++ b/m4/ax_pthread.m4
@@ -82,7 +82,7 @@
 #   modified version of the Autoconf Macro, you may extend this special
 #   exception to the GPL to apply to your modified version as well.
 
-#serial 25
+#serial 26
 
 AU_ALIAS([ACX_PTHREAD], [AX_PTHREAD])
 AC_DEFUN([AX_PTHREAD], [
@@ -371,7 +371,13 @@ for ax_pthread_try_flag in $ax_pthread_flags; do
 #                       if $ax_pthread_check_cond
 #                        error "$ax_pthread_check_macro must be defined"
 #                       endif
-                        static void routine(void *a) { a = 0; }
+                        static void *some_global = NULL;
+                        static void routine(void *a)
+                          {
+                             /* To avoid any unused-parameter or
+                                unused-but-set-parameter warning.  */
+                             some_global = a;
+                          }
                         static void *start_routine(void *a) { return a; }],
                        [pthread_t th; pthread_attr_t attr;
                         pthread_create(&th, 0, start_routine, 0);