Re: Fwd: Possibly nicer pathspec syntax?

[Duy Nguyen <pclouds@gmail.com>]

On Thu, Feb 9, 2017 at 12:39 AM, Junio C Hamano <gitster@pobox.com> wrote:
> Duy Nguyen <pclouds@gmail.com> writes:
>
>> On Wed, Feb 8, 2017 at 12:12 PM, Linus Torvalds
>> <torvalds@linux-foundation.org> wrote:
>>> Two-patch series to follow.
>>
>> glossary-content.txt update for both patches would be nice.
>
> I am no longer worried about it as I saw somebody actually sent
> follow-up patches on this, but I want to pick your brain on one
> thing that is related to this codepath.
>
> We have PATHSPEC_PREFER_CWD and PATHSPEC_PREFER_FULL bits in flags,
> added at fc12261fea ("parse_pathspec: add PATHSPEC_PREFER_{CWD,FULL}
> flags", 2013-07-14), and I think the intent is some commands when
> given no pathspec work on all paths in the current subdirectory
> while others work on the full tree, regardless of where you are.
> "grep" is in the former camp, "log" is in the latter.  And there is
> a check to catch a bug in a caller that sets both.
>
> I am wondering about this hunk (this is from the original commit
> that added it):
>
>         if (!entry) {
>                 static const char *raw[2];
>
> +               if (flags & PATHSPEC_PREFER_FULL)
> +                       return;
> +
> +               if (!(flags & PATHSPEC_PREFER_CWD))
> +                       die("BUG: PATHSPEC_PREFER_CWD requires arguments");
> +
>                 pathspec->items = item = xmalloc(sizeof(*item));
>                 memset(item, 0, sizeof(*item));
>                 item->match = prefix;
>                 ... returns a single entry pathspec to cover cwd ...
>
> The BUG message is given when
>
>  - The command got no pathspec from the caller; and
>  - PATHSPEC_PREFER_FULL is not set; and
>  - PATHSPEC_PREFER_CWD is NOT set.
>
> but the message says that the caller must have args when it sets
> prefer-cwd.  Is this a simple typo?  If so what should it say?
>
>         die("BUG: one of PATHSPEC_PREFER_FULL or _CWD must be set");

Without reading through your next mail, I'd say "BUG: this command
requires arguments".

> Does this third possibility (i.e. a caller is allowed to pass
> "flags" that does not prefer either) exist to support a command
> where the caller MUST have at least one pathspec?  If that were the
> case, this wouldn't be a BUG but an end-user error, e.g.
>
>         die("at least one pathspec element is required");

Or this. Yes. I might have just been defensive at then and kept the
third option open.

> If you know offhand which callers pass neither of the two
> PATHSPEC_PREFER_* bits and remember for what purpose you allowed
> them to do so, please remind me.  I'll keep digging in the meantime.

I don't usually remember what I ate yesterday and this commit was from
2013 :D But I'll see if your findings spark anything in my brain.
-- 
Duy