[PATCH] ls-files: support --recurse-submodules --stage

[Jonathan Tan <jonathantanmy@google.com>]

e77aa336f1 ("ls-files: optionally recurse into submodules", 2016-10-10)
taught ls-files the --recurse-submodules argument, but only in a limited
set of circumstances. In particular, --stage was unsupported, perhaps
because there was no repo_find_unique_abbrev(), which was only
introduced in 8bb95572b0 ("sha1-name.c: add
repo_find_unique_abbrev_r()", 2019-04-16). This function is needed for
using --recurse-submodules with --stage.

Now that we have repo_find_unique_abbrev(), teach support for this
combination of arguments.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
---
I got the similar-hashing object contents from Ævar's work in [1].

[1] https://lore.kernel.org/git/patch-v7-1.6-28c01b7f8a5-20220111T130811Z-avarab@gmail.com/
---
 Documentation/git-ls-files.txt         |  2 +-
 builtin/ls-files.c                     |  4 ++--
 t/t3007-ls-files-recurse-submodules.sh | 20 +++++++++++++++++++-
 3 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/Documentation/git-ls-files.txt b/Documentation/git-ls-files.txt
index 48cc7c0b6f..0dabf3f0dd 100644
--- a/Documentation/git-ls-files.txt
+++ b/Documentation/git-ls-files.txt
@@ -156,7 +156,7 @@ a space) at the start of each line:
 
 --recurse-submodules::
 	Recursively calls ls-files on each active submodule in the repository.
-	Currently there is only support for the --cached mode.
+	Currently there is only support for the --cached and --stage modes.
 
 --abbrev[=<n>]::
 	Instead of showing the full 40-byte hexadecimal object
diff --git a/builtin/ls-files.c b/builtin/ls-files.c
index f7ea56cc63..e791b65e7e 100644
--- a/builtin/ls-files.c
+++ b/builtin/ls-files.c
@@ -244,7 +244,7 @@ static void show_ce(struct repository *repo, struct dir_struct *dir,
 			printf("%s%06o %s %d\t",
 			       tag,
 			       ce->ce_mode,
-			       find_unique_abbrev(&ce->oid, abbrev),
+			       repo_find_unique_abbrev(repo, &ce->oid, abbrev),
 			       ce_stage(ce));
 		}
 		write_eolinfo(repo->index, ce, fullname);
@@ -726,7 +726,7 @@ int cmd_ls_files(int argc, const char **argv, const char *cmd_prefix)
 		setup_work_tree();
 
 	if (recurse_submodules &&
-	    (show_stage || show_deleted || show_others || show_unmerged ||
+	    (show_deleted || show_others || show_unmerged ||
 	     show_killed || show_modified || show_resolve_undo || with_tree))
 		die("ls-files --recurse-submodules unsupported mode");
 
diff --git a/t/t3007-ls-files-recurse-submodules.sh b/t/t3007-ls-files-recurse-submodules.sh
index 4a08000713..3d2da360d1 100755
--- a/t/t3007-ls-files-recurse-submodules.sh
+++ b/t/t3007-ls-files-recurse-submodules.sh
@@ -34,6 +34,25 @@ test_expect_success 'ls-files correctly outputs files in submodule' '
 	test_cmp expect actual
 '
 
+test_expect_success '--stage' '
+	# In order to test hash abbreviation, write two objects that have the
+	# same first 4 hexadecimal characters in their (SHA-1) hashes.
+	echo brocdnra >submodule/c &&
+	git -C submodule commit -am "update c" &&
+	echo brigddsv >submodule/c &&
+	git -C submodule commit -am "update c again" &&
+
+	cat >expect <<-\EOF &&
+	100644 6da7 0	.gitmodules
+	100644 7898 0	a
+	100644 6178 0	b/b
+	100644 dead9 0	submodule/c
+	EOF
+
+	git ls-files --stage --recurse-submodules --abbrev=4 >actual &&
+	test_cmp expect actual
+'
+
 test_expect_success 'ls-files correctly outputs files in submodule with -z' '
 	lf_to_nul >expect <<-\EOF &&
 	.gitmodules
@@ -292,7 +311,6 @@ test_incompatible_with_recurse_submodules () {
 test_incompatible_with_recurse_submodules --deleted
 test_incompatible_with_recurse_submodules --modified
 test_incompatible_with_recurse_submodules --others
-test_incompatible_with_recurse_submodules --stage
 test_incompatible_with_recurse_submodules --killed
 test_incompatible_with_recurse_submodules --unmerged
 
-- 
2.35.1.473.g83b2b277ed-goog