[PATCH v2 0/7] branch: --sort improvements

Addresses a comment Junio had on 3/5 in v1. Now there's leading patches moving the ref_sorting flags to a bitfield, which (agreeing with Junio) I think looks a bit better & should be more maintainable going forward.

While I was at it I squashed the 3/5 and 4/5 patches into one. It's less confusing to look at when we add the ref-filter.c sorting code in the same commit we're using it in. I also made the bitfield/xor checking/sanity BUG a bit less verbose & simpler to understand.

Ævar Arnfjörð Bjarmason (7):
  branch: change "--local" to "--list" in comment
  branch tests: add to --sort tests
  ref-filter: add braces to if/else if/else chain
  ref-filter: move "cmp_fn" assignment into "else if" arm
  ref-filter: move ref_sorting flags to a bitfield
  branch: sort detached HEAD based on a flag
  branch: show "HEAD detached" first under reverse sort

 builtin/branch.c         |  6 ++--
 builtin/for-each-ref.c   |  2 +-
 builtin/tag.c            |  2 +-
 ref-filter.c             | 75 ++++++++++++++++++++++++----------------
 ref-filter.h             | 13 ++++---
 t/t3203-branch-output.sh | 51 ++++++++++++++++++++++++++-
 wt-status.c              |  4 +--
 wt-status.h              |  2 --
 8 files changed, 111 insertions(+), 44 deletions(-)

Range-diff:
1:  c74e75dea90 = 1:  c74e75dea90 branch: change "--local" to "--list" in comment
2:  1fea125c7a6 = 2:  1fea125c7a6 branch tests: add to --sort tests
3:  11e6f274d2d < -:  ----------- ref-filter: add a "detached_head_first" sorting option
-:  ----------- > 3:  5cb44f0be40 ref-filter: add braces to if/else if/else chain
-:  ----------- > 4:  3e26cebe545 ref-filter: move "cmp_fn" assignment into "else if" arm
-:  ----------- > 5:  ad598fdc87c ref-filter: move ref_sorting flags to a bitfield
4:  faf9e23a13f ! 6:  af0c884b506 branch: use the "detached_head_first" sorting option
    @@ Metadata
     Author: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
     
      ## Commit message ##
    -    branch: use the "detached_head_first" sorting option
    +    branch: sort detached HEAD based on a flag
     
    -    Use the new ref_sorting_detached_head_first_all() sorting option in
    -    ref-filter.c to revert and amend 28438e84e04 (ref-filter: sort
    -    detached HEAD lines firstly, 2019-06-18).
    +    Change the ref-filter sorting of detached HEAD to check the
    +    FILTER_REFS_DETACHED_HEAD flag, instead of relying on the ref
    +    description filled-in by get_head_description() to start with "(",
    +    which in turn we expect to ASCII-sort before any other reference.
     
    -    In Chinese the fullwidth versions of punctuation like "()" are
    -    typically written as (U+FF08 fullwidth left parenthesis), (U+FF09
    -    fullwidth right parenthesis) instead. This form is used in both
    -    po/zh_{CN,TW}.po in most cases where "()" is translated in a string.
    -
    -    In 28438e84e04 the ability to translate this as part of the "git
    -    branch -l" output was removed because we'd like the detached line to
    -    appear first at the start of "git branch -l", e.g.:
    +    For context, we'd like the detached line to appear first at the start
    +    of "git branch -l", e.g.:
     
             $ git branch -l
             * (HEAD detached at <hash>)
               master
     
    -    Let's instead use the new ref_sorting_detached_head_first_all() in
    -    branch.c to say that we'd like these sorted before other entries.
    +    This doesn't change that, but improves on a fix made in
    +    28438e84e04 (ref-filter: sort detached HEAD lines firstly, 2019-06-18)
    +    and gives the Chinese translation the ability to use its preferred
    +    punctuation marks again.
    +
    +    In Chinese the fullwidth versions of punctuation like "()" are
    +    typically written as (U+FF08 fullwidth left parenthesis), (U+FF09
    +    fullwidth right parenthesis) instead[1]. This form is used in both
    +    po/zh_{CN,TW}.po in most cases where "()" is translated in a string.
    +
    +    Aside from that improvement to the Chinese translation, it also just
    +    makes for cleaner code that we mark any special cases in the ref_array
    +    we're sorting with flags and make the sort function aware of them,
    +    instead of piggy-backing on the general-case of strcmp() doing the
    +    right thing.
     
         As seen in the amended tests this made reverse sorting a bit more
         consistent. Before this we'd sometimes sort this message in the
    -    middle, now it's consistently at the beginning or end. Having it at
    -    the end doesn't make much sense either, but at least it behaves
    -    consistently now. A follow-up commit will make this behavior even
    -    better.
    +    middle, now it's consistently at the beginning or end, depending on
    +    whether we're doing a normal or reverse sort. Having it at the end
    +    doesn't make much sense either, but at least it behaves consistently
    +    now. A follow-up commit will make this behavior under reverse sorting
    +    even better.
     
         I'm removing the "TRANSLATORS" comments that were in the old code
         while I'm at it. Those were added in d4919bb288e (ref-filter: move
    @@ builtin/branch.c
     @@ builtin/branch.c: int cmd_branch(int argc, const char **argv, const char *prefix)
      		if (!sorting)
      			sorting = ref_default_sorting();
    - 		ref_sorting_icase_all(sorting, icase);
    -+		ref_sorting_detached_head_first_all(sorting, 1);
    + 		ref_sorting_set_sort_flags_all(sorting, REF_SORTING_ICASE, icase);
    ++		ref_sorting_set_sort_flags_all(
    ++			sorting, REF_SORTING_DETACHED_HEAD_FIRST, 1);
      		print_ref_list(&filter, sorting, &format);
      		print_columns(&output, colopts, NULL);
      		string_list_clear(&output, 0);
    @@ ref-filter.c: char *get_head_description(void)
      	return strbuf_detach(&desc, NULL);
      }
      
    +@@ ref-filter.c: int filter_refs(struct ref_array *array, struct ref_filter *filter, unsigned int
    + 	return ret;
    + }
    + 
    ++static int compare_detached_head(struct ref_array_item *a, struct ref_array_item *b)
    ++{
    ++	if (!(a->kind ^ b->kind))
    ++		BUG("ref_kind_from_refname() should only mark one ref as HEAD");
    ++	if (a->kind & FILTER_REFS_DETACHED_HEAD)
    ++		return -1;
    ++	else if (b->kind & FILTER_REFS_DETACHED_HEAD)
    ++		return 1;
    ++	BUG("should have died in the xor check above");
    ++	return 0;
    ++}
    ++
    + static int cmp_ref_sorting(struct ref_sorting *s, struct ref_array_item *a, struct ref_array_item *b)
    + {
    + 	struct atom_value *va, *vb;
    +@@ ref-filter.c: static int cmp_ref_sorting(struct ref_sorting *s, struct ref_array_item *a, stru
    + 	if (get_ref_atom_value(b, s->atom, &vb, &err))
    + 		die("%s", err.buf);
    + 	strbuf_release(&err);
    +-	if (s->sort_flags & REF_SORTING_VERSION) {
    ++	if (s->sort_flags & REF_SORTING_DETACHED_HEAD_FIRST &&
    ++	    ((a->kind | b->kind) & FILTER_REFS_DETACHED_HEAD)) {
    ++		cmp = compare_detached_head(a, b);
    ++	} else if (s->sort_flags & REF_SORTING_VERSION) {
    + 		cmp = versioncmp(va->s, vb->s);
    + 	} else if (cmp_type == FIELD_STR) {
    + 		int (*cmp_fn)(const char *, const char *);
    +
    + ## ref-filter.h ##
    +@@ ref-filter.h: struct ref_sorting {
    + 		REF_SORTING_REVERSE = 1<<0,
    + 		REF_SORTING_ICASE = 1<<1,
    + 		REF_SORTING_VERSION = 1<<2,
    ++		REF_SORTING_DETACHED_HEAD_FIRST = 1<<3,
    + 	} sort_flags;
    + };
    + 
     
      ## t/t3203-branch-output.sh ##
     @@ t/t3203-branch-output.sh: test_expect_success 'git branch `--sort=[-]objectsize` option' '
5:  b14a7b32cbf ! 7:  2497fffebf6 branch: show "HEAD detached" first under reverse sort
    @@ ref-filter.c: static int cmp_ref_sorting(struct ref_sorting *s, struct ref_array
      	int cmp;
     +	int cmp_detached_head = 0;
      	cmp_type cmp_type = used_atom[s->atom].type;
    - 	int (*cmp_fn)(const char *, const char *);
      	struct strbuf err = STRBUF_INIT;
    + 
     @@ ref-filter.c: static int cmp_ref_sorting(struct ref_sorting *s, struct ref_array_item *a, stru
    - 	     ^
    - 	     (b->kind & FILTER_REFS_DETACHED_HEAD))) {
    + 	if (s->sort_flags & REF_SORTING_DETACHED_HEAD_FIRST &&
    + 	    ((a->kind | b->kind) & FILTER_REFS_DETACHED_HEAD)) {
      		cmp = compare_detached_head(a, b);
     +		cmp_detached_head = 1;
    - 	} else if (s->version)
    + 	} else if (s->sort_flags & REF_SORTING_VERSION) {
      		cmp = versioncmp(va->s, vb->s);
    - 	else if (cmp_type == FIELD_STR)
    + 	} else if (cmp_type == FIELD_STR) {
     @@ ref-filter.c: static int cmp_ref_sorting(struct ref_sorting *s, struct ref_array_item *a, stru
      			cmp = 1;
      	}
      
    --	return (s->reverse) ? -cmp : cmp;
    -+	return (s->reverse && !cmp_detached_head) ? -cmp : cmp;
    +-	return (s->sort_flags & REF_SORTING_REVERSE) ? -cmp : cmp;
    ++	return (s->sort_flags & REF_SORTING_REVERSE && !cmp_detached_head)
    ++		? -cmp : cmp;
      }
      
      static int compare_refs(const void *a_, const void *b_, void *ref_sorting)