[PATCH v2 00/10] learn the "summary" pretty format

On this mailing list (and many others) the standard way to reference other commits with the "summary" format, e.g. "f86a374 ("pack-bitmap.c: fix a memleak", 2015-03-30)". Since it's so commonly used, let's standardise it as a pretty format.

Changes since v1:

* Replace more references to "sha1" with "hash"

* Clean up 8/10 by losing the allocation and making the subject less
  misleading

* Add tests in 7/10 to ensure 8/10 does not change any behaviour

Denton Liu (10):
  SubmittingPatches: use generic terms for hash
  pretty-formats.txt: use generic terms for hash
  revision: make get_revision_mark() return const pointer
  revision: change abbrev_commit_given to abbrev_commit_explicit
  pretty.c: inline initalize format_context
  pretty.c: extract functionality to repo_format_commit_generic()
  t4205: cover `git log --reflog -z` blindspot
  reflog-walk.c: move where the newline is added
  pretty: implement 'summary' format
  SubmittingPatches: use `--pretty=summary`

 Documentation/SubmittingPatches    |  8 ++-
 Documentation/pretty-formats.txt   | 25 ++++++---
 Documentation/pretty-options.txt   |  2 +-
 Documentation/rev-list-options.txt |  2 +-
 builtin/log.c                      | 30 ++++++++--
 log-tree.c                         | 15 +++--
 pretty.c                           | 74 ++++++++++++++++++++----
 pretty.h                           |  1 +
 reflog-walk.c                      |  8 ++-
 revision.c                         |  7 ++-
 revision.h                         |  6 +-
 t/t4205-log-pretty-formats.sh      | 90 ++++++++++++++++++++++++++++++
 12 files changed, 227 insertions(+), 41 deletions(-)

Range-diff against v1:
 -:  ---------- >  1:  b34e9aea56 SubmittingPatches: use generic terms for hash
 1:  dc88d700b8 =  2:  922cc6d849 pretty-formats.txt: use generic terms for hash
 2:  9d30c287fa =  3:  b31cffd5ef revision: make get_revision_mark() return const pointer
 3:  9ea8d676f7 =  4:  b970e52b57 revision: change abbrev_commit_given to abbrev_commit_explicit
 4:  21809581df =  5:  a2e90c78e6 pretty.c: inline initalize format_context
 5:  7f3a3b5828 =  6:  fd2bbcd169 pretty.c: extract functionality to repo_format_commit_generic()
 -:  ---------- >  7:  b5950823ce t4205: cover `git log --reflog -z` blindspot
 6:  004164c781 !  8:  05dc446d41 reflog-walk.c: don't print last newline with oneline
    @@ Metadata
     Author: Denton Liu <liu.denton@gmail.com>
     
      ## Commit message ##
    -    reflog-walk.c: don't print last newline with oneline
    +    reflog-walk.c: move where the newline is added
     
         In a future commit, we want to possibly be able to continue the reflog message on
         the same line without breaking the line. As a result, when
    @@ Commit message
     
         Add these missing newlines back in show_log().
     
    +    While we're at it, cuddle the else with the closing brace of the if to
    +    more closely match the existing style.
    +
         Signed-off-by: Denton Liu <liu.denton@gmail.com>
     
      ## log-tree.c ##
    @@ reflog-walk.c: void show_reflog_message(struct reflog_walk_info *reflog_info, in
      		get_reflog_selector(&selector, reflog_info, dmode, force_date, 0);
      		if (oneline) {
     -			printf("%s: %s", selector.buf, info->message);
    -+			struct strbuf message = STRBUF_INIT;
    -+			strbuf_addstr(&message, info->message);
    -+			strbuf_trim_trailing_newline(&message);
    -+			printf("%s: %s", selector.buf, message.buf);
    -+			strbuf_release(&message);
    - 		}
    - 		else {
    +-		}
    +-		else {
    ++			int len = strlen(info->message);
    ++			if (len > 0)
    ++				len--; /* strip away trailing newline */
    ++			printf("%s: %.*s", selector.buf, len, info->message);
    ++		} else {
      			printf("Reflog: %s (%s)\nReflog message: %s",
    + 			       selector.buf, info->email, info->message);
    + 		}
 7:  1e280b968c !  9:  e74eab6d21 pretty: implement 'summary' format
    @@ Commit message
         Documentation/SubmittingPatches as
     
                 If you want to reference a previous commit in the history of a stable
    -            branch, use the format "abbreviated sha1 (subject, date)",
    +            branch, use the format "abbreviated hash (subject, date)",
                 with the subject enclosed in a pair of double-quotes, like this:
     
                 ....
    @@ Documentation/pretty-formats.txt: This is designed to be as compact as possible.
     +	  <abbrev hash> ("<title line>", <short author date>)
     ++
     +This format is useful for referring to other commits when writing a new
    -+commit message. Although by default, '<abbrev sha1>' is used, this can
    ++commit message. Although by default, '<abbrev hash>' is used, this can
     +be overridden with '--no-abbrev'. In addition, '<short author date>' can
     +be overridden by with '--date='.
     +
    @@ pretty.h: enum cmit_fmt {
      	CMIT_FMT_USERFORMAT,
     
      ## t/t4205-log-pretty-formats.sh ##
    +@@ t/t4205-log-pretty-formats.sh: do
    + 	'
    + done
    + 
    +-test_expect_success 'NUL termination with --reflog --pretty=oneline' '
    +-	>expect &&
    +-	revs="$(git rev-list --reflog)" &&
    +-	for r in $revs
    +-	do
    +-		# trim trailing newline
    +-		output="$(git show -s --pretty=oneline "$r")" || return 1
    +-		printf "%s" "$output" >>expect
    +-		emit_nul >>expect
    +-	done &&
    +-	git log -z --pretty=oneline --reflog >actual &&
    +-	# no trailing NUL
    +-	test_cmp expect actual
    +-'
    ++for p in oneline summary
    ++do
    ++	test_expect_success "NUL termination with --reflog --pretty=$p" '
    ++		>expect &&
    ++		revs="$(git rev-list --reflog)" &&
    ++		for r in $revs
    ++		do
    ++			# trim trailing newline
    ++			output="$(git show -s --pretty='$p' "$r")" || return 1
    ++			printf "%s" "$output" >>expect
    ++			emit_nul >>expect
    ++		done &&
    ++		git log -z --pretty='$p' --reflog >actual &&
    ++		# no trailing NUL
    ++		test_cmp expect actual
    ++	'
    ++done
    + 
    + test_expect_success 'setup more commits' '
    + 	test_commit "message one" one one message-one &&
     @@ t/t4205-log-pretty-formats.sh: test_expect_success '%S in git log --format works with other placeholders (part
      	test_cmp expect actual
      '
 8:  80e7c4fc66 = 10:  3aaa7a318b SubmittingPatches: use `--pretty=summary`