[PATCH] getopt: avoid compiler warning during configure

[Eric Blake]

Some compilers (or warning settings within a compiler) rightfully
complain about assigning a string literal to a char *, since this
can lead to undefined behavior if those characters are modified.
Use the same casts as in the test file to avoid a spurious rejection
of a system getopt merely because of warnings.

* m4/getopt.m4 (gl_GETOPT_CHECK_HEADRS): Avoid problems with
assigning string literals to non-const pointer.

Signed-off-by: Eric Blake <address@hidden>
---
 ChangeLog    |    4 ++++
 m4/getopt.m4 |   44 ++++++++++++++++++++++----------------------
 2 files changed, 26 insertions(+), 22 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index e95d288..dbf0bea 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
 2011-07-07  Eric Blake  <address@hidden>

+       getopt: avoid compiler warning during configure
+       * m4/getopt.m4 (gl_GETOPT_CHECK_HEADRS): Avoid problems with
+       assigning string literals to non-const pointer.
+
        getopt-gnu: avoid crash in glibc getopt
        * m4/getopt.m4 (gl_GETOPT_CHECK_HEADRS): Detect the problem.
        * tests/test-getopt.h (test_getopt): Enhance test.
diff --git a/m4/getopt.m4 b/m4/getopt.m4
index db586bd..52dbb0f 100644
--- a/m4/getopt.m4
+++ b/m4/getopt.m4
@@ -1,4 +1,4 @@
-# getopt.m4 serial 36
+# getopt.m4 serial 37
 dnl Copyright (C) 2002-2006, 2008-2011 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -122,7 +122,7 @@ main ()
 {
   {
     int argc = 0;
-    char *argv[10];
+    const char *argv[10];
     int c;

     argv[argc++] = "program";
@@ -133,10 +133,10 @@ main ()
     optind = OPTIND_MIN;
     opterr = 0;

-    c = getopt (argc, argv, "ab");
+    c = getopt (argc, (char **) argv, "ab");
     if (!(c == 'a'))
       return 1;
-    c = getopt (argc, argv, "ab");
+    c = getopt (argc, (char **) argv, "ab");
     if (!(c == -1))
       return 2;
     if (!(optind == 2))
@@ -145,7 +145,7 @@ main ()
   /* Some internal state exists at this point.  */
   {
     int argc = 0;
-    char *argv[10];
+    const char *argv[10];
     int c;

     argv[argc++] = "program";
@@ -159,7 +159,7 @@ main ()
     optind = OPTIND_MIN;
     opterr = 0;

-    c = getopt (argc, argv, "+abp:q:");
+    c = getopt (argc, (char **) argv, "+abp:q:");
     if (!(c == -1))
       return 4;
     if (!(strcmp (argv[0], "program") == 0))
@@ -181,12 +181,12 @@ main ()
   }
   /* Detect MacOS 10.5, AIX 7.1 bug.  */
   {
-    char *argv[3] = { "program", "-ab", NULL };
+    const char *argv[3] = { "program", "-ab", NULL };
     optind = OPTIND_MIN;
     opterr = 0;
-    if (getopt (2, argv, "ab:") != 'a')
+    if (getopt (2, (char **) argv, "ab:") != 'a')
       return 13;
-    if (getopt (2, argv, "ab:") != '?')
+    if (getopt (2, (char **) argv, "ab:") != '?')
       return 14;
     if (optopt != 'b')
       return 15;
@@ -239,53 +239,53 @@ dnl is ambiguous with environment values that contain 
newlines.
                 and fails on MacOS X 10.5, AIX 5.2, HP-UX 11, IRIX 6.5,
                 OSF/1 5.1, Solaris 10.  */
              {
-               char *myargv[3];
+               const char *myargv[3];
                myargv[0] = "conftest";
                myargv[1] = "-+";
                myargv[2] = 0;
                opterr = 0;
-               if (getopt (2, myargv, "+a") != '?')
+               if (getopt (2, (char **) myargv, "+a") != '?')
                  result |= 1;
              }
              /* This code succeeds on glibc 2.8, mingw,
                 and fails on MacOS X 10.5, OpenBSD 4.0, AIX 5.2, HP-UX 11,
                 IRIX 6.5, OSF/1 5.1, Solaris 10, Cygwin 1.5.x.  */
              {
-               char *argv[] = { "program", "-p", "foo", "bar", NULL };
+               const char *argv[] = { "program", "-p", "foo", "bar", NULL };

                optind = 1;
-               if (getopt (4, argv, "p::") != 'p')
+               if (getopt (4, (char **) argv, "p::") != 'p')
                  result |= 2;
                else if (optarg != NULL)
                  result |= 4;
-               else if (getopt (4, argv, "p::") != -1)
+               else if (getopt (4, (char **) argv, "p::") != -1)
                  result |= 6;
                else if (optind != 2)
                  result |= 8;
              }
              /* This code succeeds on glibc 2.8 and fails on Cygwin 1.7.0.  */
              {
-               char *argv[] = { "program", "foo", "-p", NULL };
+               const char *argv[] = { "program", "foo", "-p", NULL };
                optind = 0;
-               if (getopt (3, argv, "-p") != 1)
+               if (getopt (3, (char **) argv, "-p") != 1)
                  result |= 16;
-               else if (getopt (3, argv, "-p") != 'p')
+               else if (getopt (3, (char **) argv, "-p") != 'p')
                  result |= 32;
              }
              /* This code fails on glibc 2.11.  */
              {
-               char *argv[] = { "program", "-b", "-a", NULL };
+               const char *argv[] = { "program", "-b", "-a", NULL };
                optind = opterr = 0;
-               if (getopt (3, argv, "+:a:b") != 'b')
+               if (getopt (3, (char **) argv, "+:a:b") != 'b')
                  result |= 64;
-               else if (getopt (3, argv, "+:a:b") != ':')
+               else if (getopt (3, (char **) argv, "+:a:b") != ':')
                  result |= 64;
              }
              /* This code dumps core on glibc 2.14.  */
              {
-               char *argv[] = { "program", "-W", "dummy", NULL };
+               const char *argv[] = { "program", "-W", "dummy", NULL };
                optind = opterr = 1;
-               if (getopt (3, argv, "W;") != 'W')
+               if (getopt (3, (char **) argv, "W;") != 'W')
                  result |= 128;
              }
              return result;
-- 
1.7.4.4