Re: [PATCH 1/3] refs: allow "HEAD" as decoration filter

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

On Tue, Jul 26 2022, Derrick Stolee via GitGitGadget wrote:

> From: Derrick Stolee <derrickstolee@github.com>
>
> The normalize_glob_ref() method was introduced in 65516f586b693 (log:
> add option to choose which refs to decorate, 2017-11-21) to help with
> decoration filters such as --decorate-refs=<filter> and
> --decorate-refs-exclude=<filter>. The method has not been used anywhere
> else.
>
> At the moment, it is impossible to specify HEAD as a decoration filter
> since normalize_glob_ref() prepends "refs/" to the filter if it isn't
> already there.
>
> Allow adding HEAD as a decoration filter by allowing the exact string
> "HEAD" to not be prepended with "refs/". Add a test in t4202-log.sh that
> would previously fail since the HEAD decoration would exist in the
> output.
>
> It is sufficient to only cover "HEAD" here and not include other special
> refs like REBASE_HEAD. This is because HEAD is the only ref outside of
> refs/* that is added to the list of decorations.
>
> Signed-off-by: Derrick Stolee <derrickstolee@github.com>
> ---
>  refs.c         | 4 ++--
>  t/t4202-log.sh | 6 ++++++
>  2 files changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/refs.c b/refs.c
> index 90bcb271687..ec3134e4842 100644
> --- a/refs.c
> +++ b/refs.c
> @@ -457,8 +457,8 @@ void normalize_glob_ref(struct string_list_item *item, const char *prefix,
>  
>  	if (prefix) {
>  		strbuf_addstr(&normalized_pattern, prefix);
> -	}
> -	else if (!starts_with(pattern, "refs/"))
> +	} else if (!starts_with(pattern, "refs/") &&
> +		   strcmp(pattern, "HEAD"))
>  		strbuf_addstr(&normalized_pattern, "refs/");

Arguably a digression for this series, but I think it would be very nice
to have a pre-step where we'd create some pre-step to centrally declare
these magical refs in some struct whose flags would cover these various
cases.

E.g. we have this hardcoded in should_autocreate_reflog(), in log-tree.c
(which AFAICT is the reference to "HEAD" here), refs.c etc. etc.