Re: [PATCH 6/7] refs: redefine special refs

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

Patrick Steinhardt <ps@pks.im> writes:

> Now that our list of special refs really only contains refs which have
> actually-special semantics, let's redefine what makes a special ref.

Yay.

>
> Signed-off-by: Patrick Steinhardt <ps@pks.im>
> ---
>  refs.c | 33 +++++++--------------------------
>  1 file changed, 7 insertions(+), 26 deletions(-)
>
> diff --git a/refs.c b/refs.c
> index 047c81b1c1..08a900a047 100644
> --- a/refs.c
> +++ b/refs.c
> @@ -1839,13 +1839,10 @@ static int refs_read_special_head(struct ref_store *ref_store,
>  static int is_special_ref(const char *refname)
>  {
>  	/*
> -	 * Special references get written and read directly via the filesystem
> -	 * by the subsystems that create them. Thus, they must not go through
> -	 * the reference backend but must instead be read directly. It is
> -	 * arguable whether this behaviour is sensible, or whether it's simply
> -	 * a leaky abstraction enabled by us only having a single reference
> -	 * backend implementation. But at least for a subset of references it
> -	 * indeed does make sense to treat them specially:
> +	 * Special references are refs that have different semantics compared
> +	 * to "normal" refs. These refs can thus not be stored in the ref
> +	 * backend, but must always be accessed via the filesystem. The
> +	 * following refs are special:
>  	 *
>  	 * - FETCH_HEAD may contain multiple object IDs, and each one of them
>  	 *   carries additional metadata like where it came from.
> @@ -1853,25 +1850,9 @@ static int is_special_ref(const char *refname)
>  	 * - MERGE_HEAD may contain multiple object IDs when merging multiple
>  	 *   heads.
>  	 *
> -	 * There are some exceptions that you might expect to see on this list
> -	 * but which are handled exclusively via the reference backend:
> -	 *
> -	 * - BISECT_EXPECTED_REV
> -	 *
> -	 * - CHERRY_PICK_HEAD
> -	 *
> -	 * - HEAD
> -	 *
> -	 * - ORIG_HEAD
> -	 *
> -	 * - "rebase-apply/" and "rebase-merge/" contain all of the state for
> -	 *   rebases, including some reference-like files. These are
> -	 *   exclusively read and written via the filesystem and never go
> -	 *   through the refdb.
> -	 *
> -	 * Writing or deleting references must consistently go either through
> -	 * the filesystem (special refs) or through the reference backend
> -	 * (normal ones).
> +	 * Reading, writing or deleting references must consistently go either
> +	 * through the filesystem (special refs) or through the reference
> +	 * backend (normal ones).
>  	 */
>  	static const char * const special_refs[] = {
>  		"FETCH_HEAD",