Re: [PATCH] Fix git-bisect when show-branch is configured to run with pager

[Christian Couder <christian.couder@gmail.com>]

On Tue, Jul 27, 2021 at 8:26 PM Junio C Hamano <gitster@pobox.com> wrote:
>
> Junio C Hamano <gitster@pobox.com> writes:
>
> > Also, in the longer term, I suspect that we probably should stop
> > calling show-branch from this codepath and here is why.
>
> I wonder if it is just a simple matter of a few lines of code, like
> this?

Yeah, I also think it's a good idea.

> ---- >8 ------- >8 ------- >8 ------- >8 ------- >8 ----
> Subject: [PATCH] bisect: do not run show-branch just to show the current  commit
>
> In scripted versions of "git bisect", we used "git show-branch" to
> describe single commit in the bisect log and also to the interactive

s/single/ a single/

> user after checking out the next version to be tested.

[...]

> diff --git a/bisect.c b/bisect.c
> index af2863d044..2b8b6546e9 100644
> --- a/bisect.c
> +++ b/bisect.c
> @@ -23,7 +23,6 @@ static struct oid_array skipped_revs;
>  static struct object_id *current_bad_oid;
>
>  static const char *argv_checkout[] = {"checkout", "-q", NULL, "--", NULL};
> -static const char *argv_show_branch[] = {"show-branch", NULL, NULL};
>
>  static const char *term_bad;
>  static const char *term_good;
> @@ -729,6 +728,9 @@ static enum bisect_error bisect_checkout(const struct object_id *bisect_rev, int
>  {
>         char bisect_rev_hex[GIT_MAX_HEXSZ + 1];
>         enum bisect_error res = BISECT_OK;
> +       struct commit *commit;
> +       struct pretty_print_context pp = {0};
> +       struct strbuf commit_msg = STRBUF_INIT;
>
>         oid_to_hex_r(bisect_rev_hex, bisect_rev);
>         update_ref(NULL, "BISECT_EXPECTED_REV", bisect_rev, NULL, 0, UPDATE_REFS_DIE_ON_ERR);
> @@ -748,13 +750,11 @@ static enum bisect_error bisect_checkout(const struct object_id *bisect_rev, int
>                         return -abs(res);
>         }
>
> -       argv_show_branch[1] = bisect_rev_hex;
> -       res = run_command_v_opt(argv_show_branch, RUN_GIT_CMD);
> -       /*
> -        * Errors in `run_command()` itself, signaled by res < 0,
> -        * and errors in the child process, signaled by res > 0
> -        * can both be treated as regular BISECT_FAILURE (-1).
> -        */
> +       commit = lookup_commit_reference(the_repository, bisect_rev);
> +       format_commit_message(commit, "[%H] %s%n", &commit_msg, &pp);
> +       fputs(commit_msg.buf, stdout);
> +       strbuf_release(&commit_msg);
> +
>         return -abs(res);

Nice! Now, the above line can be simplified to:

         return BISECT_OK;

And the declaration of the `res` variable can be moved into the else
clause where it is used.
>  }