git/t/t6424-merge-unrelated-index-changes.sh
Elijah Newren aa77ce88ed merge: make restore_state() restore staged state too
There are multiple issues at play here:

  1) If `git merge` is invoked with staged changes, it should abort
     without doing any merging, and the user's working tree and index
     should be the same as before merge was invoked.
  2) Merge strategies are responsible for enforcing the index == HEAD
     requirement. (See 9822175d2b ("Ensure index matches head before
     invoking merge machinery, round N", 2019-08-17) for some history
     around this.)
  3) Merge strategies can bail saying they are not an appropriate
     handler for the merge in question (possibly allowing other
     strategies to be used instead).
  4) Merge strategies can make changes to the index and working tree,
     and have no expectation to clean up after themselves, *even* if
     they bail out and say they are not an appropriate handler for
     the merge in question.  (The `octopus` merge strategy does this,
     for example.)
  5) Because of (3) and (4), builtin/merge.c stashes state before
     trying merge strategies and restores it afterward.

Unfortunately, if users had staged changes before calling `git merge`,
builtin/merge.c could do the following:

   * stash the changes, in order to clean up after the strategies
   * try all the merge strategies in turn, each of which report they
     cannot function due to the index not matching HEAD
   * restore the changes via "git stash apply"

But that last step would have the net effect of unstaging the user's
changes.  Fix this by adding the "--index" option to "git stash apply".
While at it, also squelch the stash apply output; we already report
"Rewinding the tree to pristine..." and don't need a detailed `git
status` report afterwards.  Also while at it, switch to using strvec
so folks don't have to count the arguments to ensure we avoided an
off-by-one error, and so it's easier to add additional arguments to
the command.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-07-22 21:45:23 -07:00

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#!/bin/sh
test_description="merges with unrelated index changes"
. ./test-lib.sh
# Testcase for some simple merges
# A
# o-------o B
# \
# \-----o C
# \
# \---o D
# \
# \-o E
# \
# o F
# Commit A: some file a
# Commit B: adds file b, modifies end of a
# Commit C: adds file c
# Commit D: adds file d, modifies beginning of a
# Commit E: renames a->subdir/a, adds subdir/e
# Commit F: empty commit
test_expect_success 'setup trivial merges' '
test_seq 1 10 >a &&
git add a &&
test_tick && git commit -m A &&
git branch A &&
git branch B &&
git branch C &&
git branch D &&
git branch E &&
git branch F &&
git checkout B &&
echo b >b &&
echo 11 >>a &&
git add a b &&
test_tick && git commit -m B &&
git checkout C &&
echo c >c &&
git add c &&
test_tick && git commit -m C &&
git checkout D &&
test_seq 2 10 >a &&
echo d >d &&
git add a d &&
test_tick && git commit -m D &&
git checkout E &&
mkdir subdir &&
git mv a subdir/a &&
echo e >subdir/e &&
git add subdir &&
test_tick && git commit -m E &&
git checkout F &&
test_tick && git commit --allow-empty -m F
'
test_expect_success 'ff update' '
git reset --hard &&
git checkout A^0 &&
touch random_file && git add random_file &&
git merge E^0 &&
test_must_fail git rev-parse HEAD:random_file &&
test "$(git diff --name-only --cached E)" = "random_file" &&
test_path_is_file random_file &&
git rev-parse --verify :random_file
'
test_expect_success 'ff update, important file modified' '
git reset --hard &&
git checkout A^0 &&
mkdir subdir &&
touch subdir/e &&
git add subdir/e &&
test_must_fail git merge E^0 &&
test_path_is_file subdir/e &&
git rev-parse --verify :subdir/e &&
test_path_is_missing .git/MERGE_HEAD
'
test_expect_success 'resolve, trivial' '
git reset --hard &&
git checkout B^0 &&
touch random_file && git add random_file &&
test_must_fail git merge -s resolve C^0 &&
test_path_is_file random_file &&
git rev-parse --verify :random_file &&
test_path_is_missing .git/MERGE_HEAD
'
test_expect_success 'resolve, non-trivial' '
git reset --hard &&
git checkout B^0 &&
touch random_file && git add random_file &&
test_must_fail git merge -s resolve D^0 &&
test_path_is_file random_file &&
git rev-parse --verify :random_file &&
test_path_is_missing .git/MERGE_HEAD
'
test_expect_success 'resolve, trivial, related file removed' '
git reset --hard &&
git checkout B^0 &&
git rm a &&
test_path_is_missing a &&
test_must_fail git merge -s resolve C^0 &&
test_path_is_missing a &&
test_path_is_missing .git/MERGE_HEAD
'
test_expect_success 'resolve, non-trivial, related file removed' '
git reset --hard &&
git checkout B^0 &&
git rm a &&
test_path_is_missing a &&
# We also ask for recursive in order to turn off the "allow_trivial"
# setting in builtin/merge.c, and ensure that resolve really does
# correctly fail the merge (I guess this also tests that recursive
# correctly fails the merge, but the main thing we are attempting
# to test here is resolve and are just using the side effect of
# adding recursive to ensure that resolve is actually tested rather
# than the trivial merge codepath)
test_must_fail git merge -s resolve -s recursive D^0 &&
test_path_is_missing a &&
test_path_is_missing .git/MERGE_HEAD
'
test_expect_success 'recursive' '
git reset --hard &&
git checkout B^0 &&
touch random_file && git add random_file &&
test_must_fail git merge -s recursive C^0 &&
test_path_is_file random_file &&
git rev-parse --verify :random_file &&
test_path_is_missing .git/MERGE_HEAD
'
test_expect_success 'recursive, when merge branch matches merge base' '
git reset --hard &&
git checkout B^0 &&
touch random_file && git add random_file &&
test_must_fail git merge -s recursive F^0 &&
test_path_is_missing .git/MERGE_HEAD
'
test_expect_success 'merge-recursive, when index==head but head!=HEAD' '
git reset --hard &&
git checkout C^0 &&
# Make index match B
git diff C B -- | git apply --cached &&
test_when_finished "git clean -fd" && # Do not leave untracked around
# Merge B & F, with B as "head"
git merge-recursive A -- B F > out &&
test_i18ngrep "Already up to date" out
'
test_expect_success 'recursive, when file has staged changes not matching HEAD nor what a merge would give' '
git reset --hard &&
git checkout B^0 &&
mkdir subdir &&
test_seq 1 10 >subdir/a &&
git add subdir/a &&
git rev-parse --verify :subdir/a >expect &&
# We have staged changes; merge should error out
test_must_fail git merge -s recursive E^0 2>err &&
git rev-parse --verify :subdir/a >actual &&
test_cmp expect actual &&
test_i18ngrep "changes to the following files would be overwritten" err
'
test_expect_success 'recursive, when file has staged changes matching what a merge would give' '
git reset --hard &&
git checkout B^0 &&
mkdir subdir &&
test_seq 1 11 >subdir/a &&
git add subdir/a &&
git rev-parse --verify :subdir/a >expect &&
# We have staged changes; merge should error out
test_must_fail git merge -s recursive E^0 2>err &&
git rev-parse --verify :subdir/a >actual &&
test_cmp expect actual &&
test_i18ngrep "changes to the following files would be overwritten" err
'
test_expect_success 'octopus, unrelated file touched' '
git reset --hard &&
git checkout B^0 &&
touch random_file && git add random_file &&
test_must_fail git merge C^0 D^0 &&
test_path_is_missing .git/MERGE_HEAD &&
git rev-parse --verify :random_file &&
test_path_exists random_file
'
test_expect_success 'octopus, related file removed' '
git reset --hard &&
git checkout B^0 &&
git rm b &&
test_must_fail git merge C^0 D^0 &&
test_path_is_missing b &&
test_must_fail git rev-parse --verify :b &&
test_path_is_missing .git/MERGE_HEAD
'
test_expect_success 'octopus, related file modified' '
git reset --hard &&
git checkout B^0 &&
echo 12 >>a && git add a &&
git rev-parse --verify :a >expect &&
test_must_fail git merge C^0 D^0 &&
test_path_is_file a &&
git rev-parse --verify :a >actual &&
test_cmp expect actual &&
test_path_is_missing .git/MERGE_HEAD
'
test_expect_success 'ours' '
git reset --hard &&
git checkout B^0 &&
touch random_file && git add random_file &&
test_must_fail git merge -s ours C^0 &&
test_path_is_file random_file &&
git rev-parse --verify :random_file &&
test_path_is_missing .git/MERGE_HEAD
'
test_expect_success 'subtree' '
git reset --hard &&
git checkout B^0 &&
touch random_file && git add random_file &&
test_must_fail git merge -s subtree E^0 &&
test_path_is_file random_file &&
git rev-parse --verify :random_file &&
test_path_is_missing .git/MERGE_HEAD
'
test_expect_success 'avoid failure due to stat-dirty files' '
git reset --hard &&
git checkout B^0 &&
# Make "a" be stat-dirty
test-tool chmtime =+1 a &&
# stat-dirty file should not prevent stash creation in builtin/merge.c
git merge -s resolve -s recursive D^0
'
test_expect_success 'with multiple strategies, recursive or ort failure do not early abort' '
git reset --hard &&
git checkout B^0 &&
test_seq 0 10 >a &&
git add a &&
git rev-parse :a >expect &&
sane_unset GIT_TEST_MERGE_ALGORITHM &&
test_must_fail git merge -s recursive -s ort -s octopus C^0 >output 2>&1 &&
grep "Trying merge strategy recursive..." output &&
grep "Trying merge strategy ort..." output &&
grep "Trying merge strategy octopus..." output &&
grep "No merge strategy handled the merge." output &&
# Changes to "a" should remain staged
git rev-parse :a >actual &&
test_cmp expect actual
'
test_done