Subject: Re: [PATCH 1/2] commit: add message options for rebase --autosquash

From: Stephen Boyd <[email-masked]>
Date: Fri, 17 Sep 2010 01:36:27 -0700

On 09/16/2010 06:39 PM, Pat Notz wrote:
> These options make it convenient to construct commit messages for use
> with 'rebase --autosquash'.  The resulting commit message will be
> "fixup! ..." or "squash! ..." where "..." is the subject line of the
> specified commit message.
> 
> Example usage:
>   $ git commit --fixup HEAD~2
>   $ git commit --squash HEAD~5
> 
> Signed-off-by: Pat Notz <[email-masked]>
> ---

So far I've been using an alias for these, but I suppose making them
real features of git could be worthwhile. What are the benefits with
this approach vs. an alias?

> @@ -863,7 +871,7 @@ static int parse_and_validate_options(int argc, const char *argv[],
>  	if (force_author && renew_authorship)
>  		die("Using both --reset-author and --author does not make sense");
>  
> -	if (logfile || message.len || use_message)
> +	if (logfile || message.len || use_message || fixup_message || squash_message)
>  		use_editor = 0;
>  	if (edit_flag)
>  		use_editor = 1;

The whole point of squash is to combine two commit texts, right?
Otherwise wouldn't you use --fixup where you throw away the text
eventually and thus don't want to open an editor?

> @@ -883,15 +891,19 @@ static int parse_and_validate_options(int argc, const char *argv[],
>  		f++;
>  	if (edit_message)
>  		f++;
> +	if (fixup_message)
> +		f++;
> +	if (squash_message)
> +		f++;
>  	if (logfile)
>  		f++;
>  	if (f > 1)
> -		die("Only one of -c/-C/-F can be used.");
> +		die("Only one of -c/-C/-F/--fixup/--squash can be used.");
>  	if (message.len && f > 0)
> -		die("Option -m cannot be combined with -c/-C/-F.");
> +		die("Option -m cannot be combined with -c/-C/-F/--fixup/--squash.");

Furthering that point, perhaps I want to squash this commit into another
commit using the commit text from yet another commit or just with an
extra note from the command line (-m). Perhaps this is where the benefit
over an alias comes in?

>  	if (edit_message)
>  		use_message = edit_message;
> -	if (amend && !use_message)
> +	if (amend && (!use_message && !fixup_message && !squash_message))
>  		use_message = "HEAD";
>  	if (!use_message && renew_authorship)
>  		die("--reset-author can be used only with -C, -c or --amend.");
> @@ -932,6 +944,23 @@ static int parse_and_validate_options(int argc, const char *argv[],
>  		if (enc != utf8)
>  			free(enc);
>  	}
> +	if (fixup_message || squash_message) {
> +		unsigned char sha1[20];
> +		struct commit *commit;
> +		const char * target_message = fixup_message ? fixup_message : squash_message;
> +		const char * msg_fmt = fixup_message ? "fixup! %s" : "squash! %s";

Style nit: stick the * to the variable.

I read this and became confused. fixup_message? target_message? Perhaps
it should be renamed to fixup_commit, squash_commit, target_commit?

> +		struct strbuf buf = STRBUF_INIT;
> +		struct pretty_print_context ctx = {0};
> +
> +		if (get_sha1(target_message, sha1))
> +			die("could not lookup commit %s", target_message);
> +		commit = lookup_commit_reference(sha1);
> +		if (!commit || parse_commit(commit))
> +			die("could not parse commit %s", target_message);
> +
> +		format_commit_message(commit, msg_fmt, &buf, &ctx);
> +		fixup_message_buffer = strbuf_detach(&buf, NULL);
> +	}
>  

Is it necessary to do this block of code here? Couldn't you lookup and
format the commit in prepare_to_commit()? Then we wouldn't have to
allocate another strbuf and the "message" code would be more centralized.