--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2007-02-05  Paul Eggert  <eggert@cs.ucla.edu>
+
+	* m4/regex.m4 (gl_REGEX): Check for glibc bug #3957.
+	Prefer returning from main to exiting from it.
+	Remove unnecessary parens after sizeof.
+
 2007-02-05  Bruno Haible  <bruno@clisp.org>
 
 	New module mbssep.

--- a/m4/regex.m4
+++ b/m4/regex.m4
@@ -1,4 +1,4 @@
-#serial 43
+#serial 44
 
 # Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2003, 2004, 2005,
 # 2006, 2007 Free Software Foundation, Inc.
@@ -29,8 +29,7 @@
     # If the system regex support is good enough that it passes the
     # following run test, then default to *not* using the included regex.c.
     # If cross compiling, assume the test would fail and use the included
-    # regex.c.  The first failing regular expression is from `Spencer ere
-    # test #75' in grep-2.3.
+    # regex.c.
     AC_CACHE_CHECK([for working re_compile_pattern],
 		   [gl_cv_func_re_compile_pattern_working],
       [AC_RUN_IFELSE(
@@ -74,68 +73,80 @@
 		}
 	    #endif
 
+	    /* This test is from glibc bug 3957, reported by Andrew Mackey.  */
+	    re_set_syntax (RE_SYNTAX_EGREP | RE_HAT_LISTS_NOT_NEWLINE);
+	    memset (&regex, 0, sizeof regex);
+	    s = re_compile_pattern ("a[^x]b", 6, &regex);
+	    if (s)
+	      return 1;
+
+	    /* This should fail, but succeeds for glibc-2.5.  */
+	    if (re_search (&regex, "a\nb", 3, 0, 3, &regs) != -1)
+	      return 1;
+
+	    /* This regular expression is from Spencer ere test number 75
+	       in grep-2.3.  */
 	    re_set_syntax (RE_SYNTAX_POSIX_EGREP);
-	    memset (&regex, 0, sizeof (regex));
+	    memset (&regex, 0, sizeof regex);
 	    for (i = 0; i <= UCHAR_MAX; i++)
 	      folded_chars[i] = i;
 	    regex.translate = folded_chars;
 	    s = re_compile_pattern ("a[[:@:>@:]]b\n", 11, &regex);
 	    /* This should fail with _Invalid character class name_ error.  */
 	    if (!s)
-	      exit (1);
+	      return 1;
 
-	    /* This should succeed, but does not for e.g. glibc-2.1.3.  */
-	    memset (&regex, 0, sizeof (regex));
+	    /* This should succeed, but does not for glibc-2.1.3.  */
+	    memset (&regex, 0, sizeof regex);
 	    s = re_compile_pattern ("{1", 2, &regex);
 
 	    if (s)
-	      exit (1);
+	      return 1;
 
 	    /* The following example is derived from a problem report
 	       against gawk from Jorge Stolfi <stolfi@ic.unicamp.br>.  */
-	    memset (&regex, 0, sizeof (regex));
+	    memset (&regex, 0, sizeof regex);
 	    s = re_compile_pattern ("[an\371]*n", 7, &regex);
 	    if (s)
-	      exit (1);
+	      return 1;
 
-	    /* This should match, but does not for e.g. glibc-2.2.1.  */
+	    /* This should match, but does not for glibc-2.2.1.  */
 	    if (re_match (&regex, "an", 2, 0, &regs) != 2)
-	      exit (1);
+	      return 1;
 
-	    memset (&regex, 0, sizeof (regex));
+	    memset (&regex, 0, sizeof regex);
 	    s = re_compile_pattern ("x", 1, &regex);
 	    if (s)
-	      exit (1);
+	      return 1;
 
-	    /* The version of regex.c in e.g. GNU libc-2.2.93 did not
-	       work with a negative RANGE argument.  */
+	    /* glibc-2.2.93 does not work with a negative RANGE argument.  */
 	    if (re_search (&regex, "wxy", 3, 2, -2, &regs) != 1)
-	      exit (1);
+	      return 1;
 
 	    /* The version of regex.c in older versions of gnulib
 	       ignored RE_ICASE.  Detect that problem too.  */
-	    memset (&regex, 0, sizeof (regex));
 	    re_set_syntax (RE_SYNTAX_EMACS | RE_ICASE);
+	    memset (&regex, 0, sizeof regex);
 	    s = re_compile_pattern ("x", 1, &regex);
 	    if (s)
-	      exit (1);
+	      return 1;
 
 	    if (re_search (&regex, "WXY", 3, 0, 3, &regs) < 0)
-	      exit (1);
+	      return 1;
 
 	    /* REG_STARTEND was added to glibc on 2004-01-15.
 	       Reject older versions.  */
 	    if (! REG_STARTEND)
-	      exit (1);
+	      return 1;
 
 	    /* Reject hosts whose regoff_t values are too narrow.
 	       These include glibc 2.3.5 on hosts with 64-bit ptrdiff_t
 	       and 32-bit int.  */
 	    if (sizeof (regoff_t) < sizeof (ptrdiff_t)
 		|| sizeof (regoff_t) < sizeof (ssize_t))
-	      exit (1);
+	      return 1;
 
-	    exit (0);]])],
+	    return 0;]])],
        [gl_cv_func_re_compile_pattern_working=yes],
        [gl_cv_func_re_compile_pattern_working=no],
        dnl When crosscompiling, assume it is not working.