[PATCH v2] merge-ort: initialize repo in index state

["John Cai via GitGitGadget" <gitgitgadget@gmail.com>]

From: John Cai <johncai86@gmail.com>

initialize_attr_index() does not initialize the repo member of
attr_index. Starting in 44451a2e5e (attr: teach "--attr-source=<tree>"
global option to "git", 2023-05-06), this became a problem because
istate->repo gets passed down the call chain starting in
git_check_attr(). This gets passed all the way down to
replace_refs_enabled(), which segfaults when accessing r->gitdir.

Fix this by initializing the repository in the index state.

Signed-off-by: John Cai <johncai86@gmail.com>
Helped-by: Christian Couder <christian.couder@gmail.com>
---
    merge-ort: initialize repo in index state
    
    initialize_attr_index() does not initialize the repo member of
    attr_index. Starting in 44451a2e5e (attr: teach "--attr-source=" global
    option to "git", 2023-05-06), this became a problem because istate->repo
    gets passed down the call chain starting in git_check_attr(). This gets
    passed all the way down to replace_refs_enabled(), which segfaults when
    accessing r->gitdir.
    
    Fix this by initializing the repository in the index state.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1583%2Fjohn-cai%2Fjc%2Fpopulate-repo-when-init-attr-index-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1583/john-cai/jc/populate-repo-when-init-attr-index-v2
Pull-Request: https://github.com/git/git/pull/1583

Range-diff vs v1:

 1:  80a18252b30 ! 1:  e178236064a merge-ort: initialize repo in index state
     @@ merge-ort.c: static void initialize_attr_index(struct merge_options *opt)
       	struct index_state *attr_index = &opt->priv->attr_index;
       	struct cache_entry *ce;
       
     -+	attr_index->repo = the_repository;
     ++	attr_index->repo = opt->repo;
       	attr_index->initialized = 1;
       
       	if (!opt->renormalize)
     @@ t/t4300-merge-tree.sh: EXPECTED
      +		test_commit initial file1 foo &&
      +		base=$(git rev-parse HEAD) &&
      +		git checkout -b brancha &&
     -+		echo bar>>file1 &&
     ++		echo bar >>file1 &&
      +		git commit -am "adding bar" &&
      +		source=$(git rev-parse HEAD) &&
     -+		echo baz>>file1 &&
     ++		git checkout @{-1} &&
     ++		git checkout -b branchb &&
     ++		echo baz >>file1 &&
      +		git commit -am "adding baz" &&
      +		merge=$(git rev-parse HEAD) &&
     -+		test_must_fail git --attr-source=HEAD merge-tree -z --write-tree \
     -+		--merge-base "$base" --end-of-options "$source" "$merge" >out &&
     -+		grep "Merge conflict in file1" out
     ++		git checkout -b gitattributes &&
     ++		test_commit "gitattributes" .gitattributes "file1 merge=union" &&
     ++		git checkout @{-1} &&
     ++		tree=$(git --attr-source=gitattributes merge-tree --write-tree \
     ++		--merge-base "$base" --end-of-options "$source" "$merge") &&
     ++		echo "foo\nbar\nbaz" >expect &&
     ++		git cat-file -p "$tree:file1" >actual &&
     ++		test_cmp expect actual
      +	)
      +'
      +


 merge-ort.c           |  1 +
 t/t4300-merge-tree.sh | 27 +++++++++++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/merge-ort.c b/merge-ort.c
index 7857ce9fbd1..36537256613 100644
--- a/merge-ort.c
+++ b/merge-ort.c
@@ -1902,6 +1902,7 @@ static void initialize_attr_index(struct merge_options *opt)
 	struct index_state *attr_index = &opt->priv->attr_index;
 	struct cache_entry *ce;
 
+	attr_index->repo = opt->repo;
 	attr_index->initialized = 1;
 
 	if (!opt->renormalize)
diff --git a/t/t4300-merge-tree.sh b/t/t4300-merge-tree.sh
index 57c4f26e461..2929ce3bf16 100755
--- a/t/t4300-merge-tree.sh
+++ b/t/t4300-merge-tree.sh
@@ -86,6 +86,33 @@ EXPECTED
 	test_cmp expected actual
 '
 
+test_expect_success '3-way merge with --attr-source' '
+	test_when_finished rm -rf 3-way &&
+	git init 3-way &&
+	(
+		cd 3-way &&
+		test_commit initial file1 foo &&
+		base=$(git rev-parse HEAD) &&
+		git checkout -b brancha &&
+		echo bar >>file1 &&
+		git commit -am "adding bar" &&
+		source=$(git rev-parse HEAD) &&
+		git checkout @{-1} &&
+		git checkout -b branchb &&
+		echo baz >>file1 &&
+		git commit -am "adding baz" &&
+		merge=$(git rev-parse HEAD) &&
+		git checkout -b gitattributes &&
+		test_commit "gitattributes" .gitattributes "file1 merge=union" &&
+		git checkout @{-1} &&
+		tree=$(git --attr-source=gitattributes merge-tree --write-tree \
+		--merge-base "$base" --end-of-options "$source" "$merge") &&
+		echo "foo\nbar\nbaz" >expect &&
+		git cat-file -p "$tree:file1" >actual &&
+		test_cmp expect actual
+	)
+'
+
 test_expect_success 'file change A, B (same)' '
 	git reset --hard initial &&
 	test_commit "change-a-b-same-A" "initial-file" "AAA" &&

base-commit: 493f4622739e9b64f24b465b21aa85870dd9dc09
-- 
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