format-patch: inform user that patch-id generation is unstable

I tried out 'git format-patch --base' with a set of commits that modifies more than one file. It turns out that the way this command is implemented it actually uses the unstable version of patch-id instead of the stable version that's documented. When I tried to modify the existing test to use 'git patch-id --stable' vs. 'git patch-id --unstable' I found that it didn't matter, the test still passed. Let's expand on the test here so it is a little more complicated and then use that to show that the patch-id generation is actually unstable vs. stable. Update the documentation as well. Cc: Xiaolong Ye <xiaolong.ye@intel.com> Signed-off-by: Stephen Boyd <sboyd@kernel.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Stephen Boyd committed Apr 26, 2019 at 16:51 UTC 6f93d261fa8ca6a84c2e03e20558c0ddca3c05c3
2 files changed +32 -6
Documentation/git-format-patch.txt
+1 -1
@@ -583,7 +583,7 @@ of 'base commit' in topological order before the patches can be applied.
583 The 'base commit' is shown as "base-commit: " followed by the 40-hex of
584 the commit object name. A 'prerequisite patch' is shown as
585 "prerequisite-patch-id: " followed by the 40-hex 'patch id', which can
586 -be obtained by passing the patch through the `git patch-id --stable`
586 +be obtained by passing the patch through the `git patch-id --unstable`
587 command.
588
589 Imagine that on top of the public commit P, you applied well-known
t/t4014-format-patch.sh
+31 -5
@@ -36,8 +36,27 @@ test_expect_success setup '
36 git checkout master &&
37 git diff-tree -p C2 | git apply --index &&
38 test_tick &&
39 - git commit -m "Master accepts moral equivalent of #2"
39 + git commit -m "Master accepts moral equivalent of #2" &&
40
41 + git checkout side &&
42 + git checkout -b patchid &&
43 + for i in 5 6 1 2 3 A 4 B C 7 8 9 10 D E F; do echo "$i"; done >file2 &&
44 + for i in 1 2 3 A 4 B C 7 8 9 10 D E F 5 6; do echo "$i"; done >file3 &&
45 + for i in 8 9 10; do echo "$i"; done >file &&
46 + git add file file2 file3 &&
47 + test_tick &&
48 + git commit -m "patchid 1" &&
49 + for i in 4 A B 7 8 9 10; do echo "$i"; done >file2 &&
50 + for i in 8 9 10 5 6; do echo "$i"; done >file3 &&
51 + git add file2 file3 &&
52 + test_tick &&
53 + git commit -m "patchid 2" &&
54 + for i in 10 5 6; do echo "$i"; done >file &&
55 + git add file &&
56 + test_tick &&
57 + git commit -m "patchid 3" &&
58 +
59 + git checkout master
60 '
61
62 test_expect_success "format-patch --ignore-if-in-upstream" '
@@ -1559,16 +1578,23 @@ test_expect_success 'format-patch -o overrides format.outputDirectory' '
1578 '
1579
1580 test_expect_success 'format-patch --base' '
1562 - git checkout side &&
1581 + git checkout patchid &&
1582 git format-patch --stdout --base=HEAD~3 -1 | tail -n 7 >actual1 &&
1583 git format-patch --stdout --base=HEAD~3 HEAD~.. | tail -n 7 >actual2 &&
1584 echo >expected &&
1585 echo "base-commit: $(git rev-parse HEAD~3)" >>expected &&
1567 - echo "prerequisite-patch-id: $(git show --patch HEAD~2 | git patch-id --stable | awk "{print \$1}")" >>expected &&
1568 - echo "prerequisite-patch-id: $(git show --patch HEAD~1 | git patch-id --stable | awk "{print \$1}")" >>expected &&
1586 + echo "prerequisite-patch-id: $(git show --patch HEAD~2 | git patch-id --unstable | awk "{print \$1}")" >>expected &&
1587 + echo "prerequisite-patch-id: $(git show --patch HEAD~1 | git patch-id --unstable | awk "{print \$1}")" >>expected &&
1588 signature >> expected &&
1589 test_cmp expected actual1 &&
1571 - test_cmp expected actual2
1590 + test_cmp expected actual2 &&
1591 + echo >fail &&
1592 + echo "base-commit: $(git rev-parse HEAD~3)" >>fail &&
1593 + echo "prerequisite-patch-id: $(git show --patch HEAD~2 | git patch-id --stable | awk "{print \$1}")" >>fail &&
1594 + echo "prerequisite-patch-id: $(git show --patch HEAD~1 | git patch-id --stable | awk "{print \$1}")" >>fail &&
1595 + signature >> fail &&
1596 + ! test_cmp fail actual1 &&
1597 + ! test_cmp fail actual2
1598 '
1599
1600 test_expect_success 'format-patch --base errors out when base commit is in revision list' '