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[PATCH v3] submodule: use the submodule repository to abbreviate commits

From
SGSrujith A Poojary via GitGitGadget <gitgitgadget@gmail.com>
Date
Oct 31, 2026, 19:24 UTC
Message-ID
<pull.2288.v3.git.1793474657981.gitgitgadget@gmail.com>
In-Reply-To
<pull.2288.git.1793435149942.gitgitgadget@gmail.com>
From: Srujith A Poojary <poojarysrujith@gmail.com>

The commit IDs shown in a submodule diff header belong to the submodule's object database. However, strbuf_add_unique_abbrev() uses the_repository, so it checks the superproject's object database when abbreviating those IDs.

Use the submodule repository when it is available, and fall back to the repository from the diff options when it is not.

Signed-off-by: Srujith A Poojary <poojarysrujith@gmail.com>
---
    [Outreachy PATCH] t4041: use submodule repository for commit
    abbreviations
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-2288%2Fpoojarysrujith%2Fmicroproject-git-libification-v3
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-2288/poojarysrujith/microproject-git-libification-v3
Pull-Request: https://github.com/gitgitgadget/git/pull/2288
Range-diff vs v2:
 1:  3133cd3017 ! 1:  a8c54b9292 Submodule: use the submodule repository to abbreviate commits
     @@ Metadata
      Author: Srujith A Poojary <poojarysrujith@gmail.com>
      
       ## Commit message ##
     -    Submodule: use the submodule repository to abbreviate commits
     +    submodule: use the submodule repository to abbreviate commits
      
          The commit IDs shown in a submodule diff header belong to the
          submodule's object database. However, strbuf_add_unique_abbrev()
 submodule.c                      |  5 +++--
 t/t4041-diff-submodule-option.sh | 18 ++++++++++++++++++
 2 files changed, 21 insertions(+), 2 deletions(-)
diff --git a/submodule.c b/submodule.c
index 6fcb606f7e..1302c11ddf 100644
--- a/submodule.c
+++ b/submodule.c
@@ -543,6 +543,7 @@ static void show_submodule_header(struct diff_options *o,
 		struct commit **left, struct commit **right,
 		struct commit_list **merge_bases)
 {
+	struct repository *repo = sub ? sub : o->repo;
 	const char *message = NULL;
 	struct strbuf sb = STRBUF_INIT;
 	int fast_forward = 0, fast_backward = 0;
@@ -599,9 +600,9 @@ static void show_submodule_header(struct diff_options *o,
 
 output_header:
 	strbuf_addf(&sb, "Submodule %s ", path);
-	strbuf_add_unique_abbrev(&sb, one, DEFAULT_ABBREV);
+	strbuf_repo_add_unique_abbrev(&sb, repo, one, DEFAULT_ABBREV);
 	strbuf_addstr(&sb, (fast_backward || fast_forward) ? ".." : "...");
-	strbuf_add_unique_abbrev(&sb, two, DEFAULT_ABBREV);
+	strbuf_repo_add_unique_abbrev(&sb, repo, two, DEFAULT_ABBREV);
 	if (message)
 		strbuf_addf(&sb, " %s\n", message);
 	else
diff --git a/t/t4041-diff-submodule-option.sh b/t/t4041-diff-submodule-option.sh
index 4dd4954260..e80472af32 100755
--- a/t/t4041-diff-submodule-option.sh
+++ b/t/t4041-diff-submodule-option.sh
@@ -14,6 +14,24 @@ export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
 . ./test-lib.sh
 
+test_expect_success SHA1 'submodule commit abbreviation uses submodule object database' '
+	test_when_finished "rm -rf collision-super" &&
+	git init -q collision-super &&
+	git init -q collision-super/sm1 &&
+	printf "0\n1\n2\n3\n4\n5\n6\n7\n8\n9\n\nb1rwzyc3\n" >collision-super/sm1/a0blgqsjc &&
+	git -C collision-super/sm1 add a0blgqsjc &&
+	tree=$(git -C collision-super/sm1 write-tree) &&
+	commit1=$(GIT_AUTHOR_DATE="1112911993 -0700" GIT_COMMITTER_DATE="1112911993 -0700" git -C collision-super/sm1 commit-tree "$tree" -m a2onsxbvj) &&
+	commit2=$(printf "child\n" | GIT_AUTHOR_DATE="1112912053 -0700" GIT_COMMITTER_DATE="1112912053 -0700" git -C collision-super/sm1 commit-tree "$tree" -p "$commit1") &&
+	git -C collision-super/sm1 checkout -q "$commit2" &&
+	git -C collision-super update-index --add --cacheinfo 160000,"$commit1",sm1 &&
+	git -C collision-super commit -q -m "Add submodule" &&
+	git -C collision-super diff --submodule=log >actual &&
+	printf "Submodule sm1 0000000000e..%s:\n  > child\n" \
+		"$(git -C collision-super/sm1 rev-parse --short "$commit2")" >expected &&
+	test_cmp expected actual
+'
+
 # Test non-UTF-8 encoding in case iconv is available.
 if test_have_prereq ICONV
 then

base-commit: 50fe5cc63f9cd6e89b87a2c9ccf96a444f4cfdb7
-- 
gitgitgadget
Previous: Srujith Poojary
Message 7 of 7 in “t4041: use submodule repository for commit abbreviations”
  1. [Outreachy PATCH] t4041: use submodule repository for commit abbreviationsSrujith A Poojary via GitGitGadget, Oct 31, 2026
  2. Okhuomon AjayiOct 31, 2026
  3. Srujith PoojaryOct 31, 2026
  4. Submodule: use the submodule repository to abbreviate commitsSrujith A Poojary via GitGitGadget, Oct 31, 2026
  5. Okhuomon AjayiOct 31, 2026
  6. Srujith PoojaryOct 31, 2026
  7. submodule: use the submodule repository to abbreviate commitsSrujith A Poojary via GitGitGadget, Oct 31, 2026

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