Merge branch 'en/dirty-merge-fixes'

The recursive merge strategy did not properly ensure there was no
change between HEAD and the index before performing its operation,
which has been corrected.

* en/dirty-merge-fixes:
  merge: fix misleading pre-merge check documentation
  merge-recursive: enforce rule that index matches head before merging
  t6044: add more testcases with staged changes before a merge is invoked
  merge-recursive: fix assumption that head tree being merged is HEAD
  merge-recursive: make sure when we say we abort that we actually abort
  t6044: add a testcase for index matching head, when head doesn't match HEAD
  t6044: verify that merges expected to abort actually abort
  index_has_changes(): avoid assuming operating on the_index
  read-cache.c: move index_has_changes() from merge.c

1 files changed, 57 insertions, 10 deletions

diff --git a/t/t6044-merge-unrelated-index-changes.sh b/t/t6044-merge-unrelated-index-changes.sh
index 23b86fb977..5e3779ebc9 100755
--- a/t/t6044-merge-unrelated-index-changes.sh
+++ b/t/t6044-merge-unrelated-index-changes.sh
@@ -82,7 +82,8 @@ test_expect_success 'ff update, important file modified' '
 	touch subdir/e &&
 	git add subdir/e &&
 
-	test_must_fail git merge E^0
+	test_must_fail git merge E^0 &&
+	test_path_is_missing .git/MERGE_HEAD
 '
 
 test_expect_success 'resolve, trivial' '
@@ -91,7 +92,8 @@ test_expect_success 'resolve, trivial' '
 
 	touch random_file && git add random_file &&
 
-	test_must_fail git merge -s resolve C^0
+	test_must_fail git merge -s resolve C^0 &&
+	test_path_is_missing .git/MERGE_HEAD
 '
 
 test_expect_success 'resolve, non-trivial' '
@@ -100,7 +102,8 @@ test_expect_success 'resolve, non-trivial' '
 
 	touch random_file && git add random_file &&
 
-	test_must_fail git merge -s resolve D^0
+	test_must_fail git merge -s resolve D^0 &&
+	test_path_is_missing .git/MERGE_HEAD
 '
 
 test_expect_success 'recursive' '
@@ -109,7 +112,8 @@ test_expect_success 'recursive' '
 
 	touch random_file && git add random_file &&
 
-	test_must_fail git merge -s recursive C^0
+	test_must_fail git merge -s recursive C^0 &&
+	test_path_is_missing .git/MERGE_HEAD
 '
 
 test_expect_success 'recursive, when merge branch matches merge base' '
@@ -118,7 +122,45 @@ test_expect_success 'recursive, when merge branch matches merge base' '
 
 	touch random_file && git add random_file &&
 
-	test_must_fail git merge -s recursive F^0
+	test_must_fail git merge -s recursive F^0 &&
+	test_path_is_missing .git/MERGE_HEAD
+'
+
+test_expect_success 'merge-recursive, when index==head but head!=HEAD' '
+	git reset --hard &&
+	git checkout C^0 &&
+
+	# Make index match B
+	git diff C B -- | git apply --cached &&
+	# Merge B & F, with B as "head"
+	git merge-recursive A -- B F > out &&
+	test_i18ngrep "Already up to date" out
+'
+
+test_expect_success 'recursive, when file has staged changes not matching HEAD nor what a merge would give' '
+	git reset --hard &&
+	git checkout B^0 &&
+
+	mkdir subdir &&
+	test_seq 1 10 >subdir/a &&
+	git add subdir/a &&
+
+	# We have staged changes; merge should error out
+	test_must_fail git merge -s recursive E^0 2>err &&
+	test_i18ngrep "changes to the following files would be overwritten" err
+'
+
+test_expect_success 'recursive, when file has staged changes matching what a merge would give' '
+	git reset --hard &&
+	git checkout B^0 &&
+
+	mkdir subdir &&
+	test_seq 1 11 >subdir/a &&
+	git add subdir/a &&
+
+	# We have staged changes; merge should error out
+	test_must_fail git merge -s recursive E^0 2>err &&
+	test_i18ngrep "changes to the following files would be overwritten" err
 '
 
 test_expect_success 'octopus, unrelated file touched' '
@@ -127,7 +169,8 @@ test_expect_success 'octopus, unrelated file touched' '
 
 	touch random_file && git add random_file &&
 
-	test_must_fail git merge C^0 D^0
+	test_must_fail git merge C^0 D^0 &&
+	test_path_is_missing .git/MERGE_HEAD
 '
 
 test_expect_success 'octopus, related file removed' '
@@ -136,7 +179,8 @@ test_expect_success 'octopus, related file removed' '
 
 	git rm b &&
 
-	test_must_fail git merge C^0 D^0
+	test_must_fail git merge C^0 D^0 &&
+	test_path_is_missing .git/MERGE_HEAD
 '
 
 test_expect_success 'octopus, related file modified' '
@@ -145,7 +189,8 @@ test_expect_success 'octopus, related file modified' '
 
 	echo 12 >>a && git add a &&
 
-	test_must_fail git merge C^0 D^0
+	test_must_fail git merge C^0 D^0 &&
+	test_path_is_missing .git/MERGE_HEAD
 '
 
 test_expect_success 'ours' '
@@ -154,7 +199,8 @@ test_expect_success 'ours' '
 
 	touch random_file && git add random_file &&
 
-	test_must_fail git merge -s ours C^0
+	test_must_fail git merge -s ours C^0 &&
+	test_path_is_missing .git/MERGE_HEAD
 '
 
 test_expect_success 'subtree' '
@@ -163,7 +209,8 @@ test_expect_success 'subtree' '
 
 	touch random_file && git add random_file &&
 
-	test_must_fail git merge -s subtree E^0
+	test_must_fail git merge -s subtree E^0 &&
+	test_path_is_missing .git/MERGE_HEAD
 '
 
 test_done