If the compile-test says

strerror_r doesn't work, then resort to a `run'-test that works on
BeOS and segfaults on DEC Unix.

diff --git a/m4/strerror_r.m4 b/m4/strerror_r.m4
index 34a2d246cf53add21954fd92c55a36e08c1aeb20..eab6916fae219a18f69b47ad0af26657b6331440 100644 (file)
--- a/m4/strerror_r.m4
+++ b/m4/strerror_r.m4
@@ -1,5 +1,7 @@
 #serial 1000
 # Experimental replacement for the function in the latest CVS autoconf.
+# If the compile-test says strerror_r doesn't work, then resort to a
+# `run'-test that works on BeOS and segfaults on DEC Unix.
 # Use with the error.c file in ../lib.
 
 undefine([AC_FUNC_STRERROR_R])
@@ -21,12 +23,6 @@ if test $ac_cv_func_strerror_r = yes; then
 #       if HAVE_STRING_H
 #        include <string.h>
 #       endif
-#ifndef HAVE_DECL_STRERROR_R
-"this configure-time declaration test was not run"
-#endif
-#if !HAVE_DECL_STRERROR_R
-char *strerror_r ();
-#endif
      ],
      [
        char buf;
@@ -35,6 +31,33 @@ char *strerror_r ();
      ac_cv_func_strerror_r_works=yes,
      ac_cv_func_strerror_r_works=no
     )
+    if test $ac_cv_func_strerror_r_works = no; then
+      # strerror_r seems not to work, but now we have to choose between
+      # systems that have relatively inaccessible declarations for the
+      # function.  BeOS and DEC UNIX 4.0 fall in this category, but the
+      # former has a strerror_r that returns char*, while the latter
+      # has a strerror_r that returns `int'.
+      # This test should segfault on the DEC system.
+      AC_TRY_RUN(
+       [
+#       include <stdio.h>
+#       include <string.h>
+
+       extern char *strerror_r ();
+
+       int
+       main ()
+       {
+         char buf[2];
+         char x = *strerror_r (0, buf, sizeof buf);
+         exit (x && !isalpha (x));
+       }
+       ],
+       ac_cv_func_strerror_r_works=yes,
+       ac_cv_func_strerror_r_works=no,
+       ac_cv_func_strerror_r_works=no)
+    fi
+
     if test $ac_cv_func_strerror_r_works = yes; then
       AC_DEFINE_UNQUOTED(HAVE_WORKING_STRERROR_R, 1,
         [Define to 1 if `strerror_r' returns a string.])