[PATCH v4 2/7] merge-resolve: abort if index does not match HEAD
From: Elijah Newren via GitGitGadget <hidden>
Date: 2022-07-22 05:15:56
Subsystem:
the rest · Maintainer:
Linus Torvalds
From: Elijah Newren <redacted>
As noted in commit 9822175d2b ("Ensure index matches head before
invoking merge machinery, round N", 2019-08-17), we have had a very
long history of problems with failing to enforce the requirement that
index matches HEAD when starting a merge. One of the commits
referenced in the long tale of issues arising from lax enforcement of
this requirement was commit 55f39cf755 ("merge: fix misleading
pre-merge check documentation", 2018-06-30), which tried to document
the requirement and noted there were some exceptions. As mentioned in
that commit message, the `resolve` strategy was the one strategy that
did not have an explicit index matching HEAD check, and the reason it
didn't was that I wasn't able to discover any cases where the
implementation would fail to catch the problem and abort, and didn't
want to introduce unnecessary performance overhead of adding another
check.
Well, today I discovered a testcase where the implementation does not
catch the problem and so an explicit check is needed. Add a testcase
that previously would have failed, and update git-merge-resolve.sh to
have an explicit check. Note that the code is copied from 3ec62ad9ff
("merge-octopus: abort if index does not match HEAD", 2016-04-09), so
that we reuse the same message and avoid making translators need to
translate some new message.
Signed-off-by: Elijah Newren <redacted>
---
builtin/merge.c | 20 ++++++++++++++++++
git-merge-resolve.sh | 10 +++++++++
t/t6424-merge-unrelated-index-changes.sh | 26 ++++++++++++++++++++++++
3 files changed, 56 insertions(+)
diff --git a/builtin/merge.c b/builtin/merge.c
index 23170f2d2a6..13884b8e836 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c@@ -1599,6 +1599,26 @@ int cmd_merge(int argc, const char **argv, const char *prefix) */ refresh_cache(REFRESH_QUIET); if (allow_trivial && fast_forward != FF_ONLY) { + /* + * Must first ensure that index matches HEAD before + * attempting a trivial merge. + */ + struct tree *head_tree = get_commit_tree(head_commit); + struct strbuf sb = STRBUF_INIT; + + if (repo_index_has_changes(the_repository, head_tree, + &sb)) { + struct strbuf err = STRBUF_INIT; + strbuf_addstr(&err, "error: "); + strbuf_addf(&err, _("Your local changes to the following files would be overwritten by merge:\n %s"), + sb.buf); + strbuf_addch(&err, '\n'); + fputs(err.buf, stderr); + strbuf_release(&err); + strbuf_release(&sb); + return -1; + } + /* See if it is really trivial. */ git_committer_info(IDENT_STRICT); printf(_("Trying really trivial in-index merge...\n"));
diff --git a/git-merge-resolve.sh b/git-merge-resolve.sh
index 343fe7bccd0..77e93121bf8 100755
--- a/git-merge-resolve.sh
+++ b/git-merge-resolve.sh@@ -5,6 +5,16 @@ # # Resolve two trees, using enhanced multi-base read-tree. +. git-sh-setup + +# Abort if index does not match HEAD +if ! git diff-index --quiet --cached HEAD -- +then + gettextln "Error: Your local changes to the following files would be overwritten by merge" + git diff-index --cached --name-only HEAD -- | sed -e 's/^/ /' + exit 2 +fi + # The first parameters up to -- are merge bases; the rest are heads. bases= head= remotes= sep_seen= for arg
diff --git a/t/t6424-merge-unrelated-index-changes.sh b/t/t6424-merge-unrelated-index-changes.sh
index b6e424a427b..f35d3182b86 100755
--- a/t/t6424-merge-unrelated-index-changes.sh
+++ b/t/t6424-merge-unrelated-index-changes.sh@@ -114,6 +114,32 @@ test_expect_success 'resolve, non-trivial' ' 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 && + + test_must_fail git merge -s resolve 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 &&
--
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