1 files changed, 40 insertions, 4 deletions

diff --git a/m4/regex.m4 b/m4/regex.m4
index 850c572228a..1c7e562f6c6 100644
--- a/m4/regex.m4
+++ b/m4/regex.m4
@@ -1,4 +1,4 @@
-# serial 71
+# serial 73
 
 # Copyright (C) 1996-2001, 2003-2021 Free Software Foundation, Inc.
 #
@@ -246,7 +246,7 @@ AC_DEFUN([gl_REGEX],
                            & ~RE_CONTEXT_INVALID_DUP
                            & ~RE_NO_EMPTY_RANGES);
             memset (&regex, 0, sizeof regex);
-            s = re_compile_pattern ("[[:alnum:]_-]\\\\+$", 16, &regex);
+            s = re_compile_pattern ("[[:alnum:]_-]\\\\+\$", 16, &regex);
             if (s)
               result |= 32;
             else
@@ -264,14 +264,50 @@ AC_DEFUN([gl_REGEX],
                back reference.  */
             re_set_syntax (RE_SYNTAX_POSIX_EGREP);
             memset (&regex, 0, sizeof regex);
-            s = re_compile_pattern ("0|()0|\\1|0", 10, &regex);
+            s = re_compile_pattern ("0|()0|\\\\1|0", 10, &regex);
             if (!s)
-              result |= 64;
+              {
+                memset (&regs, 0, sizeof regs);
+                i = re_search (&regex, "x", 1, 0, 1, &regs);
+                if (i != -1)
+                  result |= 64;
+                if (0 <= i)
+                  {
+                    free (regs.start);
+                    free (regs.end);
+                  }
+                regfree (&regex);
+              }
             else
               {
                 if (strcmp (s, "Invalid back reference"))
                   result |= 64;
+              }
+
+            /* glibc bug 11053.  */
+            re_set_syntax (RE_SYNTAX_POSIX_BASIC);
+            memset (&regex, 0, sizeof regex);
+            static char const pat_sub2[] = "\\\\(a*\\\\)*a*\\\\1";
+            s = re_compile_pattern (pat_sub2, sizeof pat_sub2 - 1, &regex);
+            if (s)
+              result |= 64;
+            else
+              {
+                memset (&regs, 0, sizeof regs);
+                static char const data[] = "a";
+                int datalen = sizeof data - 1;
+                i = re_search (&regex, data, datalen, 0, datalen, &regs);
+                if (i != 0)
+                  result |= 64;
+                else if (regs.num_regs < 2)
+                  result |= 64;
+                else if (! (regs.start[0] == 0 && regs.end[0] == 1))
+                  result |= 64;
+                else if (! (regs.start[1] == 0 && regs.end[1] == 0))
+                  result |= 64;
                 regfree (&regex);
+                free (regs.start);
+                free (regs.end);
               }
 
 #if 0