From 027ff2052c6a97ec2833d4fab8999881d0ecec56 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Mon, 11 Feb 2013 10:15:34 +0200
Subject: Detect POSIX threads on MinGW-W64

---
 m4/threads.m4 | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

(limited to 'm4')

diff --git a/m4/threads.m4 b/m4/threads.m4
index 9a7da53..1609a04 100644
--- a/m4/threads.m4
+++ b/m4/threads.m4
@@ -22,7 +22,16 @@ if test x$threads = xcheck; then
           CXXFLAGS="$CXXFLAGS -mthreads"
           ;;
       esac
-      threads=win32
+
+      # Newer versions of GCC can be configured to use either Win32 or POSIX
+      # threads. It appears that -mthreads should be used in both cases but
+      # if the model is POSIX then GCC will also link -lpthread by default.
+      # Use that fact to test which model we have.
+      #
+      AC_TRY_LINK([#include <pthread.h>],
+                  [pthread_create(0,0,0,0);],
+		  [threads=posix],
+                  [threads=win32])
       ;;
     *)
       ACX_PTHREAD
-- 
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