pthread: work around winpthread header pollution on mingw

Dan Berrange reported compilation failure of libvirt on Fedora 20
when cross-compiling to mingw; the problem was traced to bogus
macros in the winpthreads <pthread.h> header shipped as part of
mingw-headers 3.0.

  CC       util/libvirt_util_la-virerror.lo
In file included from /usr/i686-w64-mingw32/sys-root/mingw/include/sys/time.h:10:0,
                 from ../gnulib/lib/sys/time.h:39,
                 from ../gnulib/lib/sys/select.h:117,
                 from util/virutil.h:31,
                 from util/virerror.c:35:
../gnulib/lib/time.h:468:21: error: expected identifier or '(' before '{' token
 _GL_FUNCDECL_SYS (localtime_r, struct tm *, (time_t const *restrict __timer,
                     ^

Gnulib's time.h was already working around the pthread.h pollution,
but now that newer mingw has started providing struct timespec,
the workaround was no longer being hit.  Moving the pollution
workaround to the wrapper around the broken header solves the problem.

* lib/time.in.h: Move pthread workarounds...
* lib/pthread.in.h: ...here.
* m4/pthread.m4 (gl_PTHREAD_CHECK): Also build pthread.h when we
detect macro pollution on mingw.
* doc/posix-headers/pthread.texi (pthread.h): Document the problems.

Signed-off-by: Eric Blake <eblake@redhat.com>

diff --git a/ChangeLog b/ChangeLog
index b7c3e0f..d117e75 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2014-01-23  Eric Blake  <eblake@redhat.com>
+
+       pthread: work around winpthread header pollution on mingw
+       * lib/time.in.h: Move pthread workarounds...
+       * lib/pthread.in.h: ...here.
+       * m4/pthread.m4 (gl_PTHREAD_CHECK): Also build pthread.h when we
+       detect macro pollution on mingw.
+       * doc/posix-headers/pthread.texi (pthread.h): Document the problems.
+
 2014-01-22  Paul Eggert  <eggert@cs.ucla.edu>
 
        qacl: check for fchmod

diff --git a/doc/posix-headers/pthread.texi b/doc/posix-headers/pthread.texi
index 5fb1d2e..cb4d2b8 100644 (file)
--- a/doc/posix-headers/pthread.texi
+++ b/doc/posix-headers/pthread.texi
@@ -3,15 +3,22 @@
 
 POSIX specification:@* @url{http://www.opengroup.org/onlinepubs/9699919799/basedefs/pthread.h.html}
 
-Gnulib module: ---
+Gnulib module: pthread
 
 Portability problems fixed by Gnulib:
 @itemize
+@item
+This header pollutes the namespace with some broken macro
+implementations for various functions such as @code{strtok_r} and
+@code{gmtime_r}:
+mingw 3.0.
 @end itemize
 
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This header file is missing on some platforms:
-Minix 3.1.8, mingw, MSVC 9, BeOS.
+This header file is missing on some platforms; the replacement does
+not offer threads, so much as lightweight stubs that make conditional
+compilation easier for fallbacks to single-threaded programs.
+Minix 3.1.8, mingw 2.x, MSVC 9, BeOS.
 @end itemize

diff --git a/lib/pthread.in.h b/lib/pthread.in.h
index a8438df..764b346 100644 (file)
--- a/lib/pthread.in.h
+++ b/lib/pthread.in.h
@@ -36,6 +36,15 @@
 #include <stdlib.h>
 #undef __need_system_stdlib_h
 
+
+/* The pthreads-win32 <pthread.h> defines a couple of broken macros.  */
+#undef asctime_r
+#undef ctime_r
+#undef gmtime_r
+#undef localtime_r
+#undef rand_r
+#undef strtok_r
+
 #include <errno.h>
 #include <sched.h>
 #include <sys/types.h>

diff --git a/lib/time.in.h b/lib/time.in.h
index 1056139..98ca30d 100644 (file)
--- a/lib/time.in.h
+++ b/lib/time.in.h
@@ -48,20 +48,13 @@
 
 /* Some systems don't define struct timespec (e.g., AIX 4.1, Ultrix 4.3).
    Or they define it with the wrong member names or define it in <sys/time.h>
-   (e.g., FreeBSD circa 1997).  Stock Mingw does not define it, but the
-   pthreads-win32 library defines it in <pthread.h>.  */
+   (e.g., FreeBSD circa 1997).  Stock Mingw prior to 3.0 does not define it,
+   but the pthreads-win32 library defines it in <pthread.h>.  */
 # if ! @TIME_H_DEFINES_STRUCT_TIMESPEC@
 #  if @SYS_TIME_H_DEFINES_STRUCT_TIMESPEC@
 #   include <sys/time.h>
 #  elif @PTHREAD_H_DEFINES_STRUCT_TIMESPEC@
 #   include <pthread.h>
-/* The pthreads-win32 <pthread.h> also defines a couple of broken macros.  */
-#   undef asctime_r
-#   undef ctime_r
-#   undef gmtime_r
-#   undef localtime_r
-#   undef rand_r
-#   undef strtok_r
 #  else
 
 #   ifdef __cplusplus

diff --git a/m4/pthread.m4 b/m4/pthread.m4
index 2141e53..1ed0dd3 100644 (file)
--- a/m4/pthread.m4
+++ b/m4/pthread.m4
@@ -1,4 +1,4 @@
-# pthread.m4 serial 7
+# pthread.m4 serial 8
 dnl Copyright (C) 2009-2014 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -10,6 +10,19 @@ AC_DEFUN([gl_PTHREAD_CHECK],
    gl_CHECK_NEXT_HEADERS([pthread.h])
    if test $ac_cv_header_pthread_h = yes; then
      HAVE_PTHREAD_H=1
+     # mingw 3.0 uses winpthreads which installs broken macros via <pthread.h>
+     AC_CACHE_CHECK([whether <pthread.h> pollutes the namespace],
+      [gl_cv_header_pthread_h_pollution],
+      [AC_COMPILE_IFELSE(
+        [AC_LANG_PROGRAM(
+          [[#include <pthread.h>
+            #ifdef strtok_r
+            #error
+             break me
+            #endif
+          ]])],
+        [gl_cv_header_pthread_h_pollution=no],
+        [gl_cv_header_pthread_h_pollution=yes])])
    else
      HAVE_PTHREAD_H=0
    fi
@@ -31,6 +44,8 @@ AC_DEFUN([gl_PTHREAD_CHECK],
       test $ac_cv_type_pthread_spinlock_t != yes; then
      PTHREAD_H='pthread.h'
      AC_LIBOBJ([pthread])
+   elif test $gl_cv_header_pthread_h_pollution = yes; then
+     PTHREAD_H=pthread.h
    else
      PTHREAD_H=
    fi