[PATCH v5 0/2] diff: index-line: respect --abbrev in object's name

For diff-family, Git supports 2 different options for 2 different purposes, `--full-index' for showing diff-patch object's name in full, and `--abbrev' to customize the length of object names in diff-raw and diff-tree header lines, without any options to customise the length of object names in diff-patch format. When working with diff-patch format, we only have two options, either full index, or default abbrev length.

Although, that consistent is documented, it doesn't stop users from trying to use `--abbrev' with the hope of customising diff-patch's objects' name's abbreviation.

Let's resolve that inconsistency.

brian m. carlson (1):
  t4013: improve diff-post-processor logic

Đoàn Trần Công Danh (1):
  diff: index-line: respect --abbrev in object's name

 Documentation/diff-options.txt                |  9 +--
 diff.c                                        |  5 +-
 t/t4013-diff-various.sh                       | 63 ++++++++++++-------
 ...ff.diff-tree_--root_-p_--abbrev=10_initial | 29 +++++++++
 ...--root_-p_--full-index_--abbrev=10_initial | 29 +++++++++
 ...f.diff-tree_--root_-p_--full-index_initial | 29 +++++++++
 6 files changed, 138 insertions(+), 26 deletions(-)
 create mode 100644 t/t4013/diff.diff-tree_--root_-p_--abbrev=10_initial
 create mode 100644 t/t4013/diff.diff-tree_--root_-p_--full-index_--abbrev=10_initial
 create mode 100644 t/t4013/diff.diff-tree_--root_-p_--full-index_initial

Range-diff against v4:
1:  a52d0e59ec ! 1:  d7e0f13eba t4013: improve diff-post-processor logic
    @@ Commit message
         algorithm.
     
         However, we forgot to special case all-zero object names, which is
    -    special for not-exist objects, in consequence, we could't catch
    +    special for missing objects, in consequence, we could't catch
         possible future bugs where object names is all-zeros including but
    -    not limiting to:
    +    not limited to:
         * show intend-to-add entry
         * deleted entry
         * diff between index and working tree with new file
     
    -    In addition, in the incoming change, we would like to test for
    -    diff with 10 characters index, which is also not covered by current
    -    diff-processor logic.
    +    We also mistakenly munged file-modes as if they were object names
    +    abbreviated to 6 hexadecimal digits.
     
    -    Let's fix the bug for all-zero object names and extend object names'
    -    abbrev to 16 while we're at it.
    +    In addition, in the upcoming change, we would like to test for
    +    customizing the length of abbreviated blob objects on the index line,
    +    which is not supported by current diff-processor logic.
    +
    +    Let's fix the bug for all-zero object names, and file modes.
    +    While we're at it, support abbreviation of object names up to 16 bytes.
     
         Based-on-patch-by: Junio C Hamano <gitster@pobox.com>
         Signed-off-by: Junio C Hamano <gitster@pobox.com>
2:  3cec490500 ! 2:  a9eb73ceab diff: index-line: respect --abbrev in object's name
    @@ Commit message
         object names in diff-patch format. When working with diff-patch format,
         we only have two options, either full index, or default abbrev length.
     
    -    Although, that consistent is documented, it doesn't stop users from
    +    Although, that behaviour is documented, it doesn't stop users from
         trying to use `--abbrev' with the hope of customising diff-patch's
         objects' name's abbreviation.
     
    -    Let's resolve that inconsistency.
    +    Let's allow the blob object names shown on the "index" line to be
    +    abbreviated to arbitrary length given via the "--abbrev" option.
     
         To preserve backward compatibility with old script that specify both
    -    `--full-index' and `--abbrev', always shows full object id
    +    `--full-index' and `--abbrev', always show full object id
         if `--full-index' is specified.
     
         Signed-off-by: Đoàn Trần Công Danh <congdanhqx@gmail.com>
    @@ Documentation/diff-options.txt: endif::git-format-patch[]
     -	digits can be specified with `--abbrev=<n>`.
     +	lines, show only a partial prefix.
     +	In diff-patch output format, `--full-index` takes higher
    -+	precedent, i.e. if `--full-index` is specified, full blob
    ++	precedence, i.e. if `--full-index` is specified, full blob
     +	names will be shown regardless of `--abbrev`.
     +	Non default number of digits can be specified with `--abbrev=<n>`.