Subject: Re: [PATCH v2 1/3] rev-parse: correctly diagnose revision errors before "--"

From: Jonathan Nieder <[email-masked]>
Date: Fri, 6 Dec 2013 15:34:10 -0800

Jeff King wrote:

> Since rev-parse prefers revisions to files when parsing
> before the "--", we end up with the correct result (if such
> an argument is a revision, we parse it as one, and if it is
> not, it is an error either way).  However, we misdiagnose
> the errors:
>
>   $ git rev-parse foobar -- >/dev/null
>   fatal: ambiguous argument 'foobar': unknown revision or path not in the working tree.
>   Use '--' to separate paths from revisions, like this:
>   'git <command> [<revision>...] -- [<file>...]'
>
>   $ >foobar
>   $ git rev-parse foobar -- >/dev/null
>   fatal: bad flag '--' used after filename
>
> In both cases, we should know that the real error is that
> "foobar" is meant to be a revision, but could not be
> resolved.

Neat.

[...]
> --- a/builtin/rev-parse.c
> +++ b/builtin/rev-parse.c
> @@ -488,6 +488,7 @@ N_("git rev-parse --parseopt [options] -- [<args>...]\n"
>  int cmd_rev_parse(int argc, const char **argv, const char *prefix)
>  {
>  	int i, as_is = 0, verify = 0, quiet = 0, revs_count = 0, type = 0;
> +	int has_dashdash = 0;
>  	int output_prefix = 0;
>  	unsigned char sha1[20];
>  	const char *name = NULL;
> @@ -501,6 +502,13 @@ int cmd_rev_parse(int argc, const char **argv, const char *prefix)
>  	if (argc > 1 && !strcmp("-h", argv[1]))
>  		usage(builtin_rev_parse_usage);
>  
> +	for (i = 1; i < argc; i++) {
> +		if (!strcmp(argv[i], "--")) {
> +			has_dashdash = 1;
> +			break;
> +		}
> +	}
> +
>  	prefix = setup_git_directory();
>  	git_config(git_default_config, NULL);
>  	for (i = 1; i < argc; i++) {
> @@ -788,6 +796,8 @@ int cmd_rev_parse(int argc, const char **argv, const char *prefix)
>  		}
>  		if (verify)
>  			die_no_single_rev(quiet);
> +		if (has_dashdash)
> +			die("bad revision '%s'", arg);
>  		as_is = 1;

Yep, this is the "fall back to looking for a file" part of rev-parse,
so erroring out if there as a dashdash coming is the right thing to
do.  And a quick code search for "rev-parse.*\ --\ " reveals that
most callers would simply not be affected by this.

Thanks for a pleasant patch.

For what it's worth,
Reviewed-by: Jonathan Nieder <[email-masked]>