[PATCH v4 0/3] Range diff with ranges lacking dotdot

In https://lore.kernel.org/git/20200306091933.mx2jmurmdnsjua4b@pengutronix.de/, it was reported that git range-diff does not handle commit ranges like rev^!. This patch series fixes that.

Changes since v3:

 * The revision machinery is now used directly to validate the commit
   ranges.

Changes since v2:

 * Move the helper function from revision.c to range-diff.c and rename it.
 * Use a regex to make it easier to understand what we're trying to match.
 * Fix the documentation that claimed that we used git merge-base internally
   when git range-diff parses ...-style arguments, which is not the case.

Changes since v1:

 * In addition to git range-diff, git format-patch --range-diff gets the
   same improvement.
 * The comment talking about ^@ was removed.
 * The parsing was made a bit safer (e.g. catching ! by its own as an
   invalid range).

Johannes Schindelin (3):
  range-diff/format-patch: refactor check for commit range
  range-diff/format-patch: handle commit ranges other than A..B
  range-diff(docs): explain how to specify commit ranges

 Documentation/git-range-diff.txt | 12 ++++++++++++
 builtin/log.c                    |  2 +-
 builtin/range-diff.c             |  9 +++++----
 range-diff.c                     | 22 ++++++++++++++++++++++
 range-diff.h                     |  8 ++++++++
 t/t3206-range-diff.sh            |  8 ++++++++
 6 files changed, 56 insertions(+), 5 deletions(-)

base-commit: 71ca53e8125e36efbda17293c50027d31681a41f
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-841%2Fdscho%2Frange-diff-with-ranges-lacking-dotdot-v4
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-841/dscho/range-diff-with-ranges-lacking-dotdot-v4
Pull-Request: https://github.com/gitgitgadget/git/pull/841

Range-diff vs v3:

 1:  b98fa94b8703 = 1:  b98fa94b8703 range-diff/format-patch: refactor check for commit range
 2:  0880ca587e63 ! 2:  448e6a64fa15 range-diff/format-patch: handle commit ranges other than A..B
     @@ Commit message
          described to specify commit ranges that `range-diff` does not yet
          accept: "<commit>^!" and "<commit>^-<n>".
      
     -    Let's accept them.
     +    Let's accept them, by parsing them via the revision machinery and
     +    looking for at least one interesting and one uninteresting revision in
     +    the resulting `pending` array.
      
          Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
      
       ## range-diff.c ##
     +@@
     + #include "pretty.h"
     + #include "userdiff.h"
     + #include "apply.h"
     ++#include "revision.h"
     + 
     + struct patch_util {
     + 	/* For the search for an exact match */
      @@ range-diff.c: int show_range_diff(const char *range1, const char *range2,
       
       int is_range_diff_range(const char *arg)
       {
      -	return !!strstr(arg, "..");
     -+	static regex_t *regex;
     -+
     -+	if (strstr(arg, ".."))
     -+		return 1;
     ++	char *copy = xstrdup(arg); /* setup_revisions() modifies it */
     ++	const char *argv[] = { "", copy, "--", NULL };
     ++	int i, positive = 0, negative = 0;
     ++	struct rev_info revs;
      +
     -+	/* match `<rev>^!` and `<rev>^-<n>` */
     -+	if (!regex) {
     -+		regex = xmalloc(sizeof(*regex));
     -+		if (regcomp(regex, "\\^(!|-[0-9]*)$", REG_EXTENDED) < 0)
     -+			BUG("could not compile range-diff regex");
     ++	init_revisions(&revs, NULL);
     ++	if (setup_revisions(3, argv, &revs, 0) == 1) {
     ++		for (i = 0; i < revs.pending.nr; i++)
     ++			if (revs.pending.objects[i].item->flags & UNINTERESTING)
     ++				negative++;
     ++			else
     ++				positive++;
      +	}
      +
     -+	return !regexec(regex, arg, 0, NULL, 0);
     ++	free(copy);
     ++	object_array_clear(&revs.pending);
     ++	return negative > 0 && positive > 0;
       }
      
       ## t/t3206-range-diff.sh ##
 3:  5ab9321a34ca = 3:  295fdc1cd32c range-diff(docs): explain how to specify commit ranges