Can't use -ansi with gcc 4.5.3 on Cygwin, at least through setup

setup version 2.763, because it disables some features in the
system system header files.  Added configure check, when using gcc,
for -ansi (and don't use -pedantic without it).

diff --git a/configure.ac b/configure.ac
index a0602df..8979fde 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -199,6 +199,25 @@ AC_CACHE_CHECK([whether compiler supports -Wno-pointer-sign], [nmh_cv_has_noptrs
  AC_TRY_COMPILE([],[],nmh_cv_has_noptrsign=yes,nmh_cv_has_noptrsign=no)
  CFLAGS="$nmh_saved_cflags"])
 
+dnl Can't use -ansi with gcc 4.5.3 on Cygwin, at least through setup
+dnl setup version 2.763, because it disables some features in the
+dnl system system header files and warns about them with -Wall.  Try
+dnl to test for that generally, though still with gcc.
+if test "$GCC" = yes; then
+  AC_CACHE_CHECK([whether we can use -ansi with gcc], [nmh_cv_has_dash_ansi],
+    [nmh_saved_cppflags="$CPPFLAGS"
+     nmh_saved_cflags="$CFLAGS"
+     CPPFLAGS="-D_GNU_SOURCE"
+     CFLAGS="-ansi -Wall -Werror"
+     AC_COMPILE_IFELSE([AC_LANG_PROGRAM([#include <time.h>],[tzset();])],
+       [nmh_cv_has_dash_ansi=yes],
+       [nmh_cv_has_dash_ansi=no])
+     CPPFLAGS="$nmh_saved_cppflags"
+     CFLAGS="$nmh_saved_cflags"])
+else
+  nmh_cv_has_dash_ansi=no
+fi
+
 dnl if the user hasn't specified CFLAGS, then
 dnl   if compiler is gcc, then
 dnl    use -O2 and some warning flags
@@ -208,7 +227,11 @@ dnl also use -Wno-pointer-sign, because gcc 4 now produces a lot of new
 dnl warnings which are probably mostly spurious and which in any case we
 dnl don't want to deal with now.
 if test "$nmh_cv_has_noptrsign" = "yes"; then
-    nmh_gcc_common_flags="-ansi -pedantic -Wall"
+    if test "$nmh_cv_has_dash_ansi" = "yes"; then
+        nmh_gcc_common_flags="-ansi -pedantic -Wall"
+    else
+        nmh_gcc_common_flags="-Wall"
+    fi
     if test "$nmh_cv_has_wextra" = "yes"; then
         nmh_gcc_warnflags="${nmh_gcc_common_flags} -Wextra -Wno-clobbered "\
 "-Wno-pointer-sign"