Re: [PATCH] revision: set rev_input_given in handle_revision_arg()

[Junio C Hamano <gitster@pobox.com>]

Jeff King <peff@peff.net> writes:

> Subject: [PATCH] revision: set rev_input_given in handle_revision_arg()
>
> Commit 7ba826290a (revision: add rev_input_given flag, 2017-08-02) added
> a flag to rev_info to tell whether we got any revision arguments. As
> explained there, this is necessary because some revision arguments may
> not produce any pending traversal objects, but should still inhibit
> default behaviors (e.g., a glob that matches nothing).

Ah, that explains the symptom under discussion quite well; the topic
that introduced the commit was to fix "git log --tag=no-such-tag"
that used to default to HEAD.  We should be able to reuse the same
mechanism to prevent --stdin codepath from falling back to HEAD, of
course.

> However, it only set the flag in the globbing code, but not for
> revisions we get on the command-line or via stdin. This leads to two
> problems:
>
>   - the command-line code keeps its own separate got_rev_arg flag; this
>     isn't wrong, but it's confusing and an extra maintenance burden
>
>   - even specifically-named rev arguments might end up not adding any
>     pending objects: if --ignore-missing is set, then specifying a
>     missing object is a noop rather than an error.

Yup, nicely described.

> diff --git a/revision.c b/revision.c
> index 96630e3186..08c2ad23af 100644
> --- a/revision.c
> +++ b/revision.c

The patch of course looks straightforward and good.  Thanks.