Re: [PATCH] merge-tree: load default git config

[Felipe Contreras <felipe.contreras@gmail.com>]

Derrick Stolee wrote:
> On 5/10/2023 4:30 PM, Felipe Contreras wrote:
> > Derrick Stolee via GitGitGadget wrote:
> >> From: Derrick Stolee <derrickstolee@github.com>
> >>
> >> The 'git merge-tree' command handles creating root trees for merges
> >> without using the worktree. This is a critical operation in many Git
> >> hosts, as they typically store bare repositories.
> >>
> >> This builtin does not load the default Git config, which can have
> >> several important ramifications.
> > 
> > For the record, I had already sent a better version of this patch almost 2
> > years ago [1], not just for `git merge-tree`, but other commands as well.
> > 
> > The obvious fix was completely ignored by the maintainer.
> > 
> > The reason why it should be git_xmerge_config and not git_default_config, is
> > that merge.conflictstyle would not be parsed if you call git_default_config.
> 
> As mentioned by Elijah in a different thread, the merge machinery loads
> the merge config as needed. I confirmed by creating this test, which I
> may submit as an independent patch:
> 
> test_expect_success 'merge-tree respects merge.conflictstyle' '
> 	test_commit conflict-base &&
> 	for branch in left right
> 	do
> 		git checkout -b $branch conflict-base &&
> 		echo $branch >>conflict-base.t &&
> 		git add conflict-base.t &&
> 		git commit -m $branch || return 1
> 	done &&
> 
> 	test_must_fail git merge-tree left right >out1 &&
> 	test_must_fail git -c merge.conflictstyle=diff3 merge-tree left right >out2 &&
> 
> 	tree1=$(head -n 1 out1) &&
> 	tree2=$(head -n 1 out2) &&
> 
> 	git cat-file -p $tree1:conflict-base.t >conflict1 &&
> 	git cat-file -p $tree2:conflict-base.t >conflict2 &&
> 	! test_cmp conflict1 conflict2 &&
> 	! grep "||||||" conflict1 &&
> 	grep "||||||" conflict2
> '

This test is doing a real merge, not a trivial merge.

Try doing a trivial merge instead--which is what most of our testing framework
checks--and your test fails:
 
@@ -14,17 +14,12 @@ test_expect_success 'merge-tree respects merge.conflictstyle' '
                 git commit -m $branch || return 1
         done &&
 
-        test_must_fail git merge-tree left right >out1 &&
-        test_must_fail git -c merge.conflictstyle=diff3 merge-tree left right >out2 &&
+        test_expect_code 0 git merge-tree conflict-base left right >out1 &&
+        test_expect_code 0 git -c merge.conflictstyle=diff3 merge-tree conflict-base left right >out2 &&
 
-        tree1=$(head -n 1 out1) &&
-        tree2=$(head -n 1 out2) &&
-
-        git cat-file -p $tree1:conflict-base.t >conflict1 &&
-        git cat-file -p $tree2:conflict-base.t >conflict2 &&
-        ! test_cmp conflict1 conflict2 &&
-        ! grep "||||||" conflict1 &&
-        grep "||||||" conflict2
+        ! test_cmp out1 out2 &&
+        ! grep "||||||" out1 &&
+        grep "||||||" out2
 '

-- 
Felipe Contreras