git/t/t6044-merge-unrelated-index-changes.sh
Elijah Newren 65170c07d4 merge-recursive: avoid incorporating uncommitted changes in a merge
builtin/merge.c contains this important requirement for merge strategies:
	/*
	 * At this point, we need a real merge.  No matter what strategy
	 * we use, it would operate on the index, possibly affecting the
	 * working tree, and when resolved cleanly, have the desired
	 * tree in the index -- this means that the index must be in
	 * sync with the head commit.  The strategies are responsible
	 * to ensure this.
	 */

merge-recursive does not do this check directly, instead it relies on
unpack_trees() to do it.  However, merge_trees() has a special check for
the merge branch exactly matching the merge base; when it detects that
situation, it returns early without calling unpack_trees(), because it
knows that the HEAD commit already has the correct result.  Unfortunately,
it didn't check that the index matched HEAD, so after it returned, the
outer logic ended up creating a merge commit that included something
other than HEAD.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-12-22 12:20:38 -08:00

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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_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_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_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_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_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_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_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_expect_success 'octopus, related file modified' '
git reset --hard &&
git checkout B^0 &&
echo 12 >>a && git add a &&
test_must_fail git merge C^0 D^0
'
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_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_done