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git/t/t4108-apply-threeway.sh
Junio C Hamano 57f183b698 apply: resolve trivial merge without hitting ll-merge with "--3way"
The ll_binary_merge() function assumes that the ancestor blob is
different from either side of the new versions, and always fails
the merge in conflict, unless -Xours or -Xtheirs is in effect.

The normal "merge" machineries all resolve the trivial cases
(e.g. if our side changed while their side did not, the result
is ours) without triggering the file-level merge drivers, so the
assumption is warranted.

The code path in "git apply --3way", however, does not check for
the trivial three-way merge situation and always calls the
file-level merge drivers.  This used to be perfectly OK back
when we always first attempted a straight patch application and
used the three-way code path only as a fallback.  Any binary
patch that can be applied as a trivial three-way merge (e.g. the
patch is based exactly on the version we happen to have) would
always cleanly apply, so the ll_binary_merge() that is not
prepared to see the trivial case would not have to handle such a
case.

This no longer is true after we made "--3way" to mean "first try
three-way and then fall back to straight application", and made
"git apply -3" on a binary patch that is based on the current
version no longer apply.

Teach "git apply -3" to first check for the trivial merge cases
and resolve them without hitting the file-level merge drivers.

Signed-off-by: Jerry Zhang <jerry@skydio.com>
[jc: stolen tests from Jerry's patch]
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-05 15:39:02 -07:00

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#!/bin/sh
test_description='git apply --3way'
GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
. ./test-lib.sh
print_sanitized_conflicted_diff () {
git diff HEAD >diff.raw &&
sed -e '
/^index /d
s/^\(+[<>|][<>|][<>|][<>|]*\) .*/\1/
' diff.raw
}
test_expect_success setup '
test_tick &&
test_write_lines 1 2 3 4 5 6 7 >one &&
cat one >two &&
git add one two &&
git commit -m initial &&
git branch side &&
test_tick &&
test_write_lines 1 two 3 4 5 six 7 >one &&
test_write_lines 1 two 3 4 5 6 7 >two &&
git commit -a -m main &&
git checkout side &&
test_write_lines 1 2 3 4 five 6 7 >one &&
test_write_lines 1 2 3 4 five 6 7 >two &&
git commit -a -m side &&
git checkout main
'
test_expect_success 'apply without --3way' '
git diff side^ side >P.diff &&
# should fail to apply
git reset --hard &&
git checkout main^0 &&
test_must_fail git apply --index P.diff &&
# should leave things intact
git diff-files --exit-code &&
git diff-index --exit-code --cached HEAD
'
test_apply_with_3way () {
# Merging side should be similar to applying this patch
git diff ...side >P.diff &&
# The corresponding conflicted merge
git reset --hard &&
git checkout main^0 &&
test_must_fail git merge --no-commit side &&
git ls-files -s >expect.ls &&
print_sanitized_conflicted_diff >expect.diff &&
# should fail to apply
git reset --hard &&
git checkout main^0 &&
test_must_fail git apply --index --3way P.diff &&
git ls-files -s >actual.ls &&
print_sanitized_conflicted_diff >actual.diff &&
# The result should resemble the corresponding merge
test_cmp expect.ls actual.ls &&
test_cmp expect.diff actual.diff
}
test_expect_success 'apply with --3way' '
test_apply_with_3way
'
test_expect_success 'apply with --3way with merge.conflictStyle = diff3' '
test_config merge.conflictStyle diff3 &&
test_apply_with_3way
'
test_expect_success 'apply with --3way with rerere enabled' '
test_config rerere.enabled true &&
# Merging side should be similar to applying this patch
git diff ...side >P.diff &&
# The corresponding conflicted merge
git reset --hard &&
git checkout main^0 &&
test_must_fail git merge --no-commit side &&
# Manually resolve and record the resolution
test_write_lines 1 two 3 4 five six 7 >one &&
git rerere &&
cat one >expect &&
# should fail to apply
git reset --hard &&
git checkout main^0 &&
test_must_fail git apply --index --3way P.diff &&
# but rerere should have replayed the recorded resolution
test_cmp expect one
'
test_expect_success 'apply -3 with add/add conflict setup' '
git reset --hard &&
git checkout -b adder &&
test_write_lines 1 2 3 4 5 6 7 >three &&
test_write_lines 1 2 3 4 5 6 7 >four &&
git add three four &&
git commit -m "add three and four" &&
git checkout -b another adder^ &&
test_write_lines 1 2 3 4 5 6 7 >three &&
test_write_lines 1 2 3 four 5 6 7 >four &&
git add three four &&
git commit -m "add three and four" &&
# Merging another should be similar to applying this patch
git diff adder...another >P.diff &&
git checkout adder^0 &&
test_must_fail git merge --no-commit another &&
git ls-files -s >expect.ls &&
print_sanitized_conflicted_diff >expect.diff
'
test_expect_success 'apply -3 with add/add conflict' '
# should fail to apply ...
git reset --hard &&
git checkout adder^0 &&
test_must_fail git apply --index --3way P.diff &&
# ... and leave conflicts in the index and in the working tree
git ls-files -s >actual.ls &&
print_sanitized_conflicted_diff >actual.diff &&
# The result should resemble the corresponding merge
test_cmp expect.ls actual.ls &&
test_cmp expect.diff actual.diff
'
test_expect_success 'apply -3 with add/add conflict (dirty working tree)' '
# should fail to apply ...
git reset --hard &&
git checkout adder^0 &&
echo >>four &&
cat four >four.save &&
cat three >three.save &&
git ls-files -s >expect.ls &&
test_must_fail git apply --index --3way P.diff &&
# ... and should not touch anything
git ls-files -s >actual.ls &&
test_cmp expect.ls actual.ls &&
test_cmp four.save four &&
test_cmp three.save three
'
test_expect_success 'apply -3 with ambiguous repeating file' '
git reset --hard &&
test_write_lines 1 2 1 2 1 2 1 2 1 2 1 >one_two_repeat &&
git add one_two_repeat &&
git commit -m "init one" &&
test_write_lines 1 2 1 2 1 2 1 2 one 2 1 >one_two_repeat &&
git commit -a -m "change one" &&
git diff HEAD~ >Repeat.diff &&
git reset --hard HEAD~ &&
test_write_lines 1 2 1 2 1 2 one 2 1 2 one >one_two_repeat &&
git commit -a -m "change surrounding one" &&
git apply --index --3way Repeat.diff &&
test_write_lines 1 2 1 2 1 2 one 2 one 2 one >expect &&
test_cmp expect one_two_repeat
'
test_expect_success 'apply with --3way --cached clean apply' '
# Merging side should be similar to applying this patch
git diff ...side >P.diff &&
# The corresponding cleanly applied merge
git reset --hard &&
git checkout main~ &&
git merge --no-commit side &&
git ls-files -s >expect.ls &&
# should succeed
git reset --hard &&
git checkout main~ &&
git apply --cached --3way P.diff &&
git ls-files -s >actual.ls &&
print_sanitized_conflicted_diff >actual.diff &&
# The cache should resemble the corresponding merge
# (both files at stage #0)
test_cmp expect.ls actual.ls &&
# However the working directory should not change
>expect.diff &&
test_cmp expect.diff actual.diff
'
test_expect_success 'apply with --3way --cached and conflicts' '
# Merging side should be similar to applying this patch
git diff ...side >P.diff &&
# The corresponding conflicted merge
git reset --hard &&
git checkout main^0 &&
test_must_fail git merge --no-commit side &&
git ls-files -s >expect.ls &&
# should fail to apply
git reset --hard &&
git checkout main^0 &&
test_must_fail git apply --cached --3way P.diff &&
git ls-files -s >actual.ls &&
print_sanitized_conflicted_diff >actual.diff &&
# The cache should resemble the corresponding merge
# (one file at stage #0, one file at stages #1 #2 #3)
test_cmp expect.ls actual.ls &&
# However the working directory should not change
>expect.diff &&
test_cmp expect.diff actual.diff
'
test_expect_success 'apply binary file patch' '
git reset --hard main &&
cp "$TEST_DIRECTORY/test-binary-1.png" bin.png &&
git add bin.png &&
git commit -m "add binary file" &&
cp "$TEST_DIRECTORY/test-binary-2.png" bin.png &&
git diff --binary >bin.diff &&
git reset --hard &&
# Apply must succeed.
git apply bin.diff
'
test_expect_success 'apply binary file patch with 3way' '
git reset --hard main &&
cp "$TEST_DIRECTORY/test-binary-1.png" bin.png &&
git add bin.png &&
git commit -m "add binary file" &&
cp "$TEST_DIRECTORY/test-binary-2.png" bin.png &&
git diff --binary >bin.diff &&
git reset --hard &&
# Apply must succeed.
git apply --3way --index bin.diff
'
test_expect_success 'apply full-index patch with 3way' '
git reset --hard main &&
cp "$TEST_DIRECTORY/test-binary-1.png" bin.png &&
git add bin.png &&
git commit -m "add binary file" &&
cp "$TEST_DIRECTORY/test-binary-2.png" bin.png &&
git diff --full-index >bin.diff &&
git reset --hard &&
# Apply must succeed.
git apply --3way --index bin.diff
'
test_done