[PATCH v2] Submodule: use the submodule repository to abbreviate commits

["Srujith A Poojary via GitGitGadget" <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-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-2288/poojarysrujith/microproject-git-libification-v2
Pull-Request: https://github.com/gitgitgadget/git/pull/2288

Range-diff vs v1:

 1:  7b2af1b46a ! 1:  3133cd3017 [Outreachy PATCH] t4041: use submodule repository for commit abbreviations
     @@ Metadata
      Author: Srujith A Poojary <poojarysrujith@gmail.com>
      
       ## Commit message ##
     -    [Outreachy PATCH] t4041: use submodule repository for commit abbreviations
     +    Submodule: use the submodule repository to abbreviate commits
      
     -    Use the submodule repository when abbreviating commit IDs in
     -    submodule diff headers, so uniqueness is checked against the
     -    correct object database.
     +    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>
      
       ## submodule.c ##
      @@ submodule.c: 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;
     +@@ submodule.c: 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);
     -+	if (sub)
     -+		strbuf_repo_add_unique_abbrev(&sb, sub, one, DEFAULT_ABBREV);
     -+	else
     -+		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);
     -+	if (sub)
     -+		strbuf_repo_add_unique_abbrev(&sb, sub, two, DEFAULT_ABBREV);
     -+	else
     -+		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


 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
-- 
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