Re: [PATCH] commit: --amend -m '' silently fails to wipe message

> On Wed, Apr 06, 2016 at 06:15:03PM +0100, Adam Dinwoodie wrote:
> > `git commit --amend -m ''` seems to be an unambiguous request to blank a
> > commit message, but it actually leaves the commit message as-is.  That's
> > the case regardless of whether `--allow-empty-message` is specified, and
> > doesn't so much as drop a non-zero return code.
> > 
> > Add failing tests to show this behaviour.
> 
> Hmm. Is it just that we check "message.len", which cannot tell the
> difference between "-m was not given" and "-m was given the empty
> string"?
> 
> IOW, would this fix it?
> 
> diff --git a/builtin/commit.c b/builtin/commit.c
> index 109742e..3cdc44e 100644
> --- a/builtin/commit.c
> +++ b/builtin/commit.c
> @@ -695,7 +695,7 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
>  		}
>  	}
>  
> -	if (message.len) {
> +	if (have_option_m) {
>  		strbuf_addbuf(&sb, &message);
>  		hook_arg1 = "message";
>  	} else if (logfile && !strcmp(logfile, "-")) {
> 
> It passes the test suite and your two new tests, but I didn't look too
> deeply to see if there are other fallouts. I don't think anybody should
> be using it to counteract a previous "-m" or anything like that; we have
> "--no-message" for that.