diff-no-index: correctly diagnose error return from diff_opt_parse()

diff_opt_parse() returns the number of options parsed, or often
returns error() which is defined to return -1.  Yes, return value of
0 is "I did not process that option at all", which should cause the
caller to say that, but negative return should not be forgotten.

This bug caused "diff --no-index" to infinitely show the same error
message because the returned value was used to decrement the loop
control variable, e.g.

$ git diff --no-index --color=words a b
error: option `color' expects "always", "auto", or "never"
error: option `color' expects "always", "auto", or "never"
...

Instead, make it act like so:

$ git diff --no-index --color=words a b
error: option `color' expects "always", "auto", or "never"
fatal: invalid diff option/value: --color=words

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/diff-no-index.c b/diff-no-index.c
index 00a8eefde9aeb96592f5ed6455dbf5d3b16747c4..ecf929336d0c8d40862ad88ac188f5e18166c9f9 100644 (file)
--- a/diff-no-index.c
+++ b/diff-no-index.c
@@ -244,7 +244,7 @@ void diff_no_index(struct rev_info *revs,
                        i++;
                else {
                        j = diff_opt_parse(&revs->diffopt, argv + i, argc - i);
-                       if (!j)
+                       if (j <= 0)
                                die("invalid diff option/value: %s", argv[i]);
                        i += j;
                }