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eddd1a411d
builtin/merge.c says that when we are about to perform a merge:
...the index must be in sync with the head commit. The strategies are
responsible to ensure this.
merge-recursive has always relied on unpack_trees() to enforce this
requirement, except in the case of an "Already up to date!" merge.
unpack-trees.c does not actually enforce this requirement, though. It
allows for a pair of exceptions, in cases which it refers to as #14(ALT)
and #2ALT. Documentation/technical/trivial-merge.txt can be consulted for
the precise meanings of the various case numbers and their meanings for
unpack-trees.c, but we have a high-level description of the intent behind
these two exceptions in a combined and summarized form in
Documentation/git-merge.txt:
...[merge will] abort if there are any changes registered in the index
relative to the `HEAD` commit. (One exception is when the changed index
entries are in the state that would result from the merge already.)
While this high-level description does describe conditions under which it
would be safe to allow the index to diverge from HEAD, it does not match
what is actually implemented. In particular, unpack-trees.c has no
knowledge of renames, and these two exceptions were written assuming that
no renames take place. Once renames get into the mix, it is no longer
safe to allow the index to not match for #2ALT. We could modify
unpack-trees to only allow #14(ALT) as an exception, but that would be
more strict than required for the resolve strategy (since the resolve
strategy doesn't handle renames at all). Therefore, unpack_trees.c seems
like the wrong place to fix this.
Further, if someone fixes the combination of break and rename detection
and modifies merge-recursive to take advantage of the combination, then it
will also no longer be safe to allow the index to not match for #14(ALT)
when the recursive strategy is in use. Therefore, leaving one of the
exceptions in place with the recursive merge strategy feels like we are
just leaving a latent bug in the code for folks in the future to stumble
across.
It may be possible to fix both unpack-trees and merge-recursive in a way
that implements the exception as stated in Documentation/git-merge.txt,
but it would be somewhat complex, possibly also buggy at first, and
ultimately, not all that valuable. Instead, just enforce the requirement
stated in builtin/merge.c; error out if the index does not match the HEAD
commit, just like the 'ours' and 'octopus' strategies do.
Some testcase fixups were in order:
t7611: had many tests designed to show that `git merge --abort` could
not always restore the index and working tree to the state they
were in before the merge started. The tests that were associated
with having changes in the index before the merge started are no
longer applicable, so they have been removed.
t7504: had a few tests that had stray staged changes that were not
actually part of the test under consideration
t6044: We no longer expect stray staged changes to sometimes result
in the merge continuing. Also, fix a case where a merge
didn't abort but should have.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
216 lines
4.5 KiB
Bash
Executable file
216 lines
4.5 KiB
Bash
Executable file
#!/bin/sh
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test_description="merges with unrelated index changes"
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. ./test-lib.sh
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# Testcase for some simple merges
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# A
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# o-------o B
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# \
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# \-----o C
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# \
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# \---o D
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# \
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# \-o E
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# \
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# o F
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# Commit A: some file a
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# Commit B: adds file b, modifies end of a
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# Commit C: adds file c
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# Commit D: adds file d, modifies beginning of a
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# Commit E: renames a->subdir/a, adds subdir/e
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# Commit F: empty commit
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test_expect_success 'setup trivial merges' '
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test_seq 1 10 >a &&
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git add a &&
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test_tick && git commit -m A &&
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git branch A &&
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git branch B &&
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git branch C &&
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git branch D &&
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git branch E &&
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git branch F &&
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git checkout B &&
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echo b >b &&
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echo 11 >>a &&
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git add a b &&
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test_tick && git commit -m B &&
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git checkout C &&
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echo c >c &&
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git add c &&
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test_tick && git commit -m C &&
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git checkout D &&
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test_seq 2 10 >a &&
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echo d >d &&
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git add a d &&
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test_tick && git commit -m D &&
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git checkout E &&
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mkdir subdir &&
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git mv a subdir/a &&
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echo e >subdir/e &&
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git add subdir &&
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test_tick && git commit -m E &&
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git checkout F &&
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test_tick && git commit --allow-empty -m F
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'
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test_expect_success 'ff update' '
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git reset --hard &&
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git checkout A^0 &&
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touch random_file && git add random_file &&
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git merge E^0 &&
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test_must_fail git rev-parse HEAD:random_file &&
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test "$(git diff --name-only --cached E)" = "random_file"
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'
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test_expect_success 'ff update, important file modified' '
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git reset --hard &&
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git checkout A^0 &&
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mkdir subdir &&
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touch subdir/e &&
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git add subdir/e &&
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test_must_fail git merge E^0 &&
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test_path_is_missing .git/MERGE_HEAD
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'
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test_expect_success 'resolve, trivial' '
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git reset --hard &&
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git checkout B^0 &&
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touch random_file && git add random_file &&
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test_must_fail git merge -s resolve C^0 &&
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test_path_is_missing .git/MERGE_HEAD
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'
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test_expect_success 'resolve, non-trivial' '
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git reset --hard &&
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git checkout B^0 &&
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touch random_file && git add random_file &&
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test_must_fail git merge -s resolve D^0 &&
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test_path_is_missing .git/MERGE_HEAD
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'
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test_expect_success 'recursive' '
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git reset --hard &&
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git checkout B^0 &&
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touch random_file && git add random_file &&
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test_must_fail git merge -s recursive C^0 &&
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test_path_is_missing .git/MERGE_HEAD
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'
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test_expect_success 'recursive, when merge branch matches merge base' '
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git reset --hard &&
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git checkout B^0 &&
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touch random_file && git add random_file &&
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test_must_fail git merge -s recursive F^0 &&
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test_path_is_missing .git/MERGE_HEAD
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'
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test_expect_success 'merge-recursive, when index==head but head!=HEAD' '
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git reset --hard &&
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git checkout C^0 &&
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# Make index match B
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git diff C B -- | git apply --cached &&
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# Merge B & F, with B as "head"
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git merge-recursive A -- B F > out &&
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test_i18ngrep "Already up to date" out
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'
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test_expect_success 'recursive, when file has staged changes not matching HEAD nor what a merge would give' '
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git reset --hard &&
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git checkout B^0 &&
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mkdir subdir &&
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test_seq 1 10 >subdir/a &&
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git add subdir/a &&
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# We have staged changes; merge should error out
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test_must_fail git merge -s recursive E^0 2>err &&
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test_i18ngrep "changes to the following files would be overwritten" err
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'
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test_expect_success 'recursive, when file has staged changes matching what a merge would give' '
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git reset --hard &&
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git checkout B^0 &&
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mkdir subdir &&
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test_seq 1 11 >subdir/a &&
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git add subdir/a &&
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# We have staged changes; merge should error out
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test_must_fail git merge -s recursive E^0 2>err &&
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test_i18ngrep "changes to the following files would be overwritten" err
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'
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test_expect_success 'octopus, unrelated file touched' '
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git reset --hard &&
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git checkout B^0 &&
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touch random_file && git add random_file &&
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test_must_fail git merge C^0 D^0 &&
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test_path_is_missing .git/MERGE_HEAD
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'
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test_expect_success 'octopus, related file removed' '
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git reset --hard &&
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git checkout B^0 &&
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git rm b &&
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test_must_fail git merge C^0 D^0 &&
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test_path_is_missing .git/MERGE_HEAD
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'
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test_expect_success 'octopus, related file modified' '
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git reset --hard &&
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git checkout B^0 &&
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echo 12 >>a && git add a &&
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test_must_fail git merge C^0 D^0 &&
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test_path_is_missing .git/MERGE_HEAD
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'
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test_expect_success 'ours' '
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git reset --hard &&
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git checkout B^0 &&
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touch random_file && git add random_file &&
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test_must_fail git merge -s ours C^0 &&
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test_path_is_missing .git/MERGE_HEAD
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'
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test_expect_success 'subtree' '
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git reset --hard &&
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git checkout B^0 &&
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touch random_file && git add random_file &&
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test_must_fail git merge -s subtree E^0 &&
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test_path_is_missing .git/MERGE_HEAD
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'
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test_done
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