[PATCH] Check whether pthread_sigmask is a simple macro

[Pavel Fedin]

 GNULib's pthread_sigmask() is configured and builds incorrectly on MinGW64. 
Configure
script detects it as
present, and this is technically correct, but:
--- cut ---
/* Windows has rudimentary signals support.  */
#define pthread_sigmask(H, S1, S2) 0
--- cut ---
 (see
http://sourceforge.net/p/mingw-w64/mingw-w64/ci/master/tree/mingw-w64-libraries/winpthread
s/include/pthread_signal.h)

 And this causes failure building gnulib's pthread_sigmask.c, because it tries 
to refer to
original pthread_sigmask()
after #undef'ing it.
 This patch recognizes that pthread_sigmask is a simple macro and there's no 
real function
behind it, and in this case it produces the following settings:
HAVE_PTHREAD_SIGMASK=0
LIB_PTHREAD_SIGMASK=''
REPLACE_PTHREAD_SIGMASK=1
 so that pthread_sigmask() is entirely emulated by GNULib.

 Related topic: 
http://lists.gnu.org/archive/html/bug-gnulib/2015-04/msg00065.html

Signed-off-by: Pavel Fedin <address@hidden>

m4/pthread_sigmask.m4 | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/m4/pthread_sigmask.m4 b/m4/pthread_sigmask.m4
index 5c17dfc..a974848 100644
--- a/m4/pthread_sigmask.m4
+++ b/m4/pthread_sigmask.m4
@@ -40,6 +40,30 @@ AC_DEFUN([gl_FUNC_PTHREAD_SIGMASK],
              LIBS="$gl_save_LIBS"
             ])
           if test $gl_cv_func_pthread_sigmask_in_LIBMULTITHREAD = yes; then
+            AC_CACHE_CHECK([whether pthread_sigmask is only a macro],
+              [gl_cv_func_pthread_sigmask_is_macro],
+              [gl_save_LIBS="$LIBS"
+               LIBS="$LIBS $LIBMULTITHREAD"
+               AC_LINK_IFELSE(
+                 [AC_LANG_PROGRAM(
+                    [[#include <pthread.h>
+                      #include <signal.h>
+                      #undef pthread_sigmask
+                    ]],
+                    [[return pthread_sigmask (0, (sigset_t *) 0, (sigset_t *) 
0);]])
+                 ],
+                 [gl_cv_func_pthread_sigmask_is_macro=no],
+                 [gl_cv_func_pthread_sigmask_is_macro=yes])
+               LIBS="$gl_save_LIBS"
+              ])
+            if test $gl_cv_func_pthread_sigmask_is_macro = yes; then
+              dnl On MinGW pthread_sigmask is just a macro which always return 
0.
+              dnl It does not exist as a real function, which is required by 
POSIX.
+              REPLACE_PTHREAD_SIGMASK=1
+              gl_cv_func_pthread_sigmask_in_LIBMULTITHREAD=no
+            fi
+          fi
+          if test $gl_cv_func_pthread_sigmask_in_LIBMULTITHREAD = yes; then
             dnl pthread_sigmask is available with -pthread or -lpthread.
             LIB_PTHREAD_SIGMASK="$LIBMULTITHREAD"
           else
--
Kind regards,
Pavel Fedin
Expert Engineer
Samsung Electronics Research center Russia