[PATCH v5 0/4] branch: let --delete-merged find squash merged branches

Branches merged on GitHub with "Squash and merge" or "Rebase and merge" are never deleted by git branch --delete-merged, because their tips are not reachable from the upstream. This treats such a branch as merged when some upstream commit contains all of its changes, and names that commit in the output:

Deleted branch topic (was 1a2b3c4, landed as 9f8e7d6).

Changes in v5:

 * git branch -h lists --delete-integrated in the usage lines
 * Giving both --delete-merged and --delete-integrated dies with a short
   "cannot be used together" message instead of the full usage text

Changes in v4:

 * --delete-merged works as it does on master again: it only deletes
   branches whose tip is reachable from their upstream
 * New --delete-integrated <pattern> also deletes branches that were rebase
   or squash merged, including those squashed after upstream changed the
   same files. It replaces --squashed
 * New prep commit lets delete_branches() take a map of where each branch
   landed, so "landed as" is printed there
 * Added Junio's test that --delete-merged keeps a branch when an unrelated
   upstream commit adds an identical file
 * --dry-run works with either option, and the two options can't be combined

Changes in v3:

 * Split into multiple commits, one for rebase merges and one for squash
   merges.
 * By default a branch counts as merged when an upstream commit has its
   exact version of every file it changed. This never reads file contents,
   so it stays cheap in a partial clone. It finds rebase merges, and squash
   merges where upstream left those files alone.
 * Replace --no-squashed with an opt-in --squashed, which also finds
   branches merged after upstream changed the same files by merging those
   files.
 * Add a test for a rebase merge, and check that a squash onto changed files
   is kept without --squashed and deleted with it.

Changes in v2:

 * Diff each upstream commit once and share the result between all branches,
   faster than v1.
 * Fix a branch merged with a merge commit being reported as "landed as" the
   merge when another branch was searched first, and add a test for it. Show
   the topic commit itself in "landed as" for work that arrived through a
   merge.
 * Use git merge --squash as the example in the commit message and mention
   GitHub's squash and rebase buttons.
 * Add --no-squashed to skip the squash search.

Harald Nordgren (4):
  branch: move the deleteMerged opt-out check into a helper
  branch: let delete_branches() name where a branch landed
  branch: add --delete-integrated to delete rebase and squash merged
    branches
  branch: let --delete-integrated find branches merged onto changed
    files

 Documentation/config/branch.adoc |   8 +-
 Documentation/git-branch.adoc    |  22 +-
 builtin/branch.c                 | 360 +++++++++++++++++++++++++++++--
 t/t3200-branch.sh                | 218 +++++++++++++++++++
 4 files changed, 578 insertions(+), 30 deletions(-)

base-commit: 8d1b215c01512b9658d4525c54ff9b9245f9a7e8
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2425%2FHaraldNordgren%2Fbranch-delete-squashed-v5
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2425/HaraldNordgren/branch-delete-squashed-v5
Pull-Request: https://github.com/git/git/pull/2425

Range-diff vs v4:

 1:  1d01085b75 = 1:  090aec5725 branch: move the deleteMerged opt-out check into a helper
 2:  592562d7e7 = 2:  24180bf4a2 branch: let delete_branches() name where a branch landed
 3:  deb1e649cf ! 3:  bf30f57ceb branch: add --delete-integrated to delete rebase and squash merged branches
     @@ builtin/branch.c
       
       static const char * const builtin_branch_usage[] = {
       	N_("git branch [<options>] [-r | -a] [--merged] [--no-merged] [(--forked <branch>)...]"),
     +@@ builtin/branch.c: static const char * const builtin_branch_usage[] = {
     + 	N_("git branch [<options>] [-r | -a] [--format]"),
     + 	N_("git branch [<options>] (--delete-merged <pattern>)... "
     + 	   "[<branch-pattern>...]"),
     ++	N_("git branch [<options>] (--delete-integrated <pattern>)... "
     ++	   "[<branch-pattern>...]"),
     + 	NULL
     + };
     + 
      @@ builtin/branch.c: enum delete_branch_flags {
       	DELETE_BRANCH_SKIP_UNMERGED = (1 << 2),
       	DELETE_BRANCH_NO_HEAD_FALLBACK = (1 << 3),
     @@ builtin/branch.c: int cmd_branch(int argc,
       
       	if (filter.with_commit || filter.no_commit ||
      @@ builtin/branch.c: int cmd_branch(int argc,
     + 	    filter.points_at.nr || filter.forked.nr)
     + 		list = 1;
       
     ++	die_for_incompatible_opt2(!!delete_merged.nr, "--delete-merged",
     ++				  !!delete_integrated.nr, "--delete-integrated");
     ++
       	noncreate_actions = !!delete + !!rename + !!copy + !!new_upstream +
       			    !!show_current + !!list + !!edit_description +
      -			    !!unset_upstream + !!delete_merged.nr;
     @@ t/t3200-branch.sh: test_expect_success '--dry-run without --delete-merged is rej
       
      +test_expect_success '--delete-integrated cannot be combined with --delete-merged' '
      +	test_must_fail git -C forked branch --delete-merged origin/next \
     -+		--delete-integrated origin/next
     ++		--delete-integrated origin/next 2>err &&
     ++	test_grep "cannot be used together" err
      +'
      +
       test_done
 4:  19a9630c13 = 4:  9443055242 branch: let --delete-integrated find branches merged onto changed files