[PATCH] getopt: Indicate the problem with ambiguous options clearly.

[James Youngman]

---
 ChangeLog    |    6 ++++++
 lib/getopt.c |   25 +++++++++++++++++--------
 2 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 7faac2b..b593588 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2008-12-14  James Youngman  <address@hidden>
+
+       getopt: Indicate the problem with ambiguous options clearly. 
+       * lib/getopt.c (_getopt_internal_r): Print the first and second
+       possibility when there is an ambiguous match.
+
 2008-12-14  Bruno Haible  <address@hidden>
 
        Update doc for POSIX:2008.
diff --git a/lib/getopt.c b/lib/getopt.c
index f1e6d1f..107538f 100644
--- a/lib/getopt.c
+++ b/lib/getopt.c
@@ -480,8 +480,8 @@ _getopt_internal_r (int argc, char **argv, const char 
*optstring,
       char *nameend;
       const struct option *p;
       const struct option *pfound = NULL;
+      const struct option *pambig = NULL;
       int exact = 0;
-      int ambig = 0;
       int indfound = -1;
       int option_index;
 
@@ -512,19 +512,25 @@ _getopt_internal_r (int argc, char **argv, const char 
*optstring,
                     || pfound->has_arg != p->has_arg
                     || pfound->flag != p->flag
                     || pfound->val != p->val)
-             /* Second or later nonexact match found.  */
-             ambig = 1;
+             {
+               /* Second or later nonexact match found.  We remember
+                  it instead of breaking out of the loop in case
+                  there is a later exact match to be found.  */
+               pambig = p;
+             }
          }
 
-      if (ambig && !exact)
+      if (pambig && !exact)
        {
          if (print_errors)
            {
 #if defined _LIBC && defined USE_IN_LIBIO
              char *buf;
 
-             if (__asprintf (&buf, _("%s: option `%s' is ambiguous\n"),
-                             argv[0], argv[d->optind]) >= 0)
+             if (__asprintf (&buf, _("%s: option `%s' is ambiguous, "
+                                     "since for example it might mean --%s or 
--%s\n"),
+                             argv[0], argv[d->optind],
+                             pfound->name, pambig->name) >= 0)
                {
                  _IO_flockfile (stderr);
 
@@ -539,8 +545,11 @@ _getopt_internal_r (int argc, char **argv, const char 
*optstring,
                  free (buf);
                }
 #else
-             fprintf (stderr, _("%s: option `%s' is ambiguous\n"),
-                      argv[0], argv[d->optind]);
+             fprintf (stderr, _("%s: option `%s' is ambiguous, "
+                                "since for example it might mean --%s or 
--%s\n"),
+                      argv[0], argv[d->optind],
+                      pfound->name, pambig->name);
+             
 #endif
            }
          d->__nextchar += strlen (d->__nextchar);
-- 
1.5.6.5