[PATCH v6 00/21] Add range-diff, a tbdiff lookalike

The incredibly useful git-tbdiff [https://github.com/trast/tbdiff] tool to compare patch series (say, to see what changed between two iterations sent to the Git mailing list) is slightly less useful for this developer due to the fact that it requires the hungarian and numpy Python packages which are for some reason really hard to build in MSYS2. So hard that I even had to give up, because it was simply easier to re-implement the whole shebang as a builtin command.

The project at https://github.com/trast/tbdiff seems to be dormant, anyway. Funny (and true) story: I looked at the open Pull Requests to see how active that project is, only to find to my surprise that I had submitted one in August 2015, and that it was still unanswered let alone merged.

While at it, I forward-ported AEvar's patch to force --decorate=no because git -p tbdiff would fail otherwise.

Side note: I work on implementing range-diff not only to make life easier for reviewers who have to suffer through v2, v3, ... of my patch series, but also to verify my changes before submitting a new iteration. And also, maybe even more importantly, I plan to use it to verify my merging-rebases of Git for Windows (for which I previously used to redirect the pre-rebase/post-rebase diffs vs upstream and then compare them using git diff --no-index). And of course any interested person can see what changes were necessary e.g. in the merging-rebase of Git for Windows onto v2.17.0 by running a command like:

        base=^{/Start.the.merging-rebase}
        tag=v2.17.0.windows.1
        pre=$tag$base^2
        git range-diff $pre$base..$pre $tag$base..$tag

The command uses what it calls the "dual color mode" (can be disabled via --no-dual-color) which helps identifying what actually changed: it prefixes lines with a - (and red background) that correspond to the first commit range, and with a + (and green background) that correspond to the second range. The rest of the lines will be colored according to the original diffs.

Changes since v4:

 * Fixed a typo in the commit message of "range-diff: add tests" that was
   introduced in v4.
 * White-space fixes.
 * Fixed the length of the first header underline in the man page.
 * Changed the preprocessor guard in linear-assignment.h to reflect the new
   name (instead of the old name, which was hungarian.h).
 * Likewise, changed the preprocessor guards in range-diff.h to hide the
   history of the thrice-renamed command.
 * Fixed indentation in the completion.
 * Instead of trying to paper over white-space error handling that does not
   apply to "diffs of diffs", dual color mode now simply disables all
   white-space warnings.
 * When showing the "single arg must be symmetric range" error message, git
   range-diff now also shows the usage.
 * Adjusted the commit message of "range-diff: adjust the output of the
   commit pairs" to avoid the surprise of the reviewer when onelines are
   printed all of a sudden, too.
 * "range-diff: adjust the output of the commit pairs" is now using a
   simpler way to print onelines.
 * We are now sandwiching the diff_opt_parse() loop between two 
   parse_options(), to make sure that we caught all options, and that the -- 
   separator is handled.
 * Adjusted the lookup_commit_reference() call to the newest master (it now
   takes a the_repository parameter).

Changes since v3:

 * The cover letter was adjusted to reflect the new reality (the command is
   called range-diff now, not branch-diff, and --dual-color is the default).
 * The documentation was adjusted a bit more in the patch that makes 
   --dual-color the default.
 * Clarified the calculation of the cost matrix, as per Stefan Beller's
   request.
 * The man page now spells out that merge commits are ignored in the commit
   ranges (not merges per se).
 * The code in linear-assignment.c was adjusted to use the SWAP() macro.
 * The commit message of the patch introducing the first rudimentary
   implementation no longer talks about the "Hungarian" algorithm, but about
   the "linear assignment algorithm" instead.
 * A bogus indentation change was backed out from the patch introducing the
   first rudimentary implementation.
 * Instead of merely warning about missing .. in the 2-parameter invocation,
   we now exit with the error message.
 * The diff_opt_parse() function is allowed to return a value larger than 1,
   indicating that more than just one command-line parameter was parsed. We
   now advance by the indicated value instead of always advancing exactly 1
   (which is still correct much of the time).
 * A lengthy if...else if...else if...else was simplified (from a logical
   point of view) by reordering it.
 * The unnecessarily static variable dashes was turned into a local variable
   of the caller.
 * The commit message talking about the new man page still referred to git
   branch --diff, which has been fixed.
 * A forgotten t7910 reference was changed to t3206.
 * An unbalanced double-tick was fixed in the man page.
 * Fixed grammar both of the commit message and the description of the 
   --no-dual-color option.
 * To fix the build, a blank man page is now introduced together with the
   new range-diff command, even if it is populated for real only at a later
   patch (i.e. at the same time as before).
 * The headaches Junio fears would be incurred by that simple workaround to
   avoid bogus white-space error reporting are fended off: a more complex
   patch is now in place that adds (and uses) a new white-space flag. Sadly,
   as is all too common when Junio "encourages" me to replace a simple
   workaround by something "proper", it caused all kinds of headaches to get
   this right, so I am rather less certain that the "proper" fix will cause
   us less headaches than the simple workaround would have done. But
   whatever.
 * The dual color mode now also dims the changes that are exclusively in the
   first specified commit range, and uses bold face on the changes
   exclusively in the second one. This matches the intuition when using 
   range-diff to compare an older iteration of a patch series to a newer
   one: the changes from the previous iteration that were replaced by new
   ones "fade", while the changes that replace them are "shiny new".

Changes since v2:

 * Right-aligned the patch numbers in the commit pairs.
 * Used ALLOC_ARRAY() in hungarian.c instead of xmalloc(sizeof()*size).
 * Changed compute_assignment()s return type from int to void, as it always
   succeeds.
 * Changed the Hungarian Algorithm to use an integer cost matrix.
 * Changed the --creation-weight option to --creation-factor where is an
   integer.
 * Retitled 1/19 and 2/19 to better conform with the current conventions, as
   pointed out (and suggested) by Junio.
 * Shut up Coverity, and at the same time avoided passing the unnecessary i 
   and j parameters to output_pair_header().
 * Removed support for the --no-patches option: we inherit diff_options'
   support for -s already (and much more).
 * Removed the ugly _INV enum values, and introduced a beautiful
   GIT_COLOR_REVERSE instead. This way, whatever the user configured as
   color.diff.new (or .old) will be used in reverse in the dual color mode.
 * Instead of overriding the fragment header color, the dual color mode will
   now reverse the "outer" fragment headers, too.
 * Turned the stand-alone branch-diff command into the --diff option of git
   branch. Adjusted pretty much all commit messages to account for this.
   This change should no longer be visible: see below.
 * Pretty much re-wrote the completion, to support the new --diff mode of
   git-branch. See below: it was reverted for range-diff.
 * Renamed t7910 to t3206, to be closer to the git-branch tests.
 * Ensured that git_diff_ui_config() gets called, and therefore color.diff.*
   respected.
 * Avoided leaking four_spaces.
 * Fixed a declaration in a for (;;) statement (which Junio had as a fixup!
   that I almost missed).
 * Renamed branch --diff, which had been renamed from branch-diff (which was
   picked to avoid re-using tbdiff) to range-diff.
 * Renamed hungarian.c and its header to linear-assignment.c
 * Made --dual-color the default, and changed it to still auto-detect
   whether color should be used rather than forcing it

Johannes Schindelin (20):
  linear-assignment: a function to solve least-cost assignment problems
  Introduce `range-diff` to compare iterations of a topic branch
  range-diff: first rudimentary implementation
  range-diff: improve the order of the shown commits
  range-diff: also show the diff between patches
  range-diff: right-trim commit messages
  range-diff: indent the diffs just like tbdiff
  range-diff: suppress the diff headers
  range-diff: adjust the output of the commit pairs
  range-diff: do not show "function names" in hunk headers
  range-diff: use color for the commit pairs
  color: add the meta color GIT_COLOR_REVERSE
  diff: add an internal option to dual-color diffs of diffs
  range-diff: offer to dual-color the diffs
  range-diff --dual-color: skip white-space warnings
  range-diff: populate the man page
  completion: support `git range-diff`
  range-diff: left-pad patch numbers
  range-diff: make --dual-color the default mode
  range-diff: use dim/bold cues to improve dual color mode

Thomas Rast (1):
  range-diff: add tests

 .gitignore                             |   1 +
 Documentation/config.txt               |   6 +-
 Documentation/git-range-diff.txt       | 252 +++++++++++
 Makefile                               |   3 +
 builtin.h                              |   1 +
 builtin/range-diff.c                   | 116 +++++
 color.h                                |   7 +
 command-list.txt                       |   1 +
 contrib/completion/git-completion.bash |  14 +
 diff.c                                 | 105 ++++-
 diff.h                                 |  10 +-
 git.c                                  |   1 +
 linear-assignment.c                    | 201 ++++++++
 linear-assignment.h                    |  22 +
 range-diff.c                           | 435 ++++++++++++++++++
 range-diff.h                           |   9 +
 t/.gitattributes                       |   1 +
 t/t3206-range-diff.sh                  | 145 ++++++
 t/t3206/history.export                 | 604 +++++++++++++++++++++++++
 19 files changed, 1915 insertions(+), 19 deletions(-)
 create mode 100644 Documentation/git-range-diff.txt
 create mode 100644 builtin/range-diff.c
 create mode 100644 linear-assignment.c
 create mode 100644 linear-assignment.h
 create mode 100644 range-diff.c
 create mode 100644 range-diff.h
 create mode 100755 t/t3206-range-diff.sh
 create mode 100644 t/t3206/history.export

base-commit: 1d89318c48d233d52f1db230cf622935ac3c69fa
Published-As: https://github.com/gitgitgadget/git/releases/tags/pr-1%2Fdscho%2Fbranch-diff-v6
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1/dscho/branch-diff-v6
Pull-Request: https://github.com/gitgitgadget/git/pull/1

Range-diff vs v5:

  1:  f168da3a3 =  1:  f168da3a3 linear-assignment: a function to solve least-cost assignment problems
  2:  33758f361 =  2:  33758f361 Introduce `range-diff` to compare iterations of a topic branch
  3:  08b8c3fc4 =  3:  08b8c3fc4 range-diff: first rudimentary implementation
  4:  7b9091968 =  4:  7b9091968 range-diff: improve the order of the shown commits
  5:  9e1e66007 !  5:  8515d2f75 range-diff: also show the diff between patches
     @@ -80,6 +80,8 @@
      +		else
      +			i += c;
      +	}
     ++	while (i < argc)
     ++		argv[j++] = argv[i++];
      +	argc = j;
      +	diff_setup_done(&diffopt);
      +
  6:  167ca02a3 =  6:  a10ca0163 range-diff: right-trim commit messages
  7:  ca8de8c75 =  7:  f81cbef2c range-diff: indent the diffs just like tbdiff
  8:  eb94d1982 =  8:  458090ffd range-diff: suppress the diff headers
  9:  6330afad9 =  9:  d3be03a44 range-diff: adjust the output of the commit pairs
 10:  c296675eb = 10:  94b44dfe6 range-diff: do not show "function names" in hunk headers
 11:  85e0ab82f = 11:  1477c58e4 range-diff: add tests
 12:  f48b62644 = 12:  32492c159 range-diff: use color for the commit pairs
 13:  1ad74f939 = 13:  969a196f4 color: add the meta color GIT_COLOR_REVERSE
 14:  39a0ecd28 = 14:  f1c86f606 diff: add an internal option to dual-color diffs of diffs
 15:  c32a24f6a = 15:  3c7b9f339 range-diff: offer to dual-color the diffs
 16:  05947781f = 16:  c56c51c8b range-diff --dual-color: skip white-space warnings
 17:  3147c4440 = 17:  8c5543a06 range-diff: populate the man page
 18:  b08e6d937 = 18:  16e3cf27b completion: support `git range-diff`
 19:  19406283e = 19:  d9b09abcf range-diff: left-pad patch numbers
 20:  6b3552386 = 20:  f6fd3955e range-diff: make --dual-color the default mode
 21:  ccf8c1bb2 = 21:  699cd712e range-diff: use dim/bold cues to improve dual color mode