rm: absorb a submodules git dir before deletion

When deleting a submodule, we need to keep the actual git directory around,
such that we do not lose local changes in there and at a later checkout
of the submodule we don't need to clone it again.

Now that the functionality is available to absorb the git directory of a
submodule, rewrite the checking in git-rm to not complain, but rather
relocate the git directories inside the superproject.

An alternative solution was discussed to have a function
`depopulate_submodule`. That would couple the check for its git directory
and possible relocation before the the removal, such that it is less
likely to miss the check in the future.  But the indirection with such
a function added seemed also complex. The reason for that was that this
possible move of the git directory was also implemented in
`ok_to_remove_submodule`, such that this function could truthfully
answer whether it is ok to remove the submodule.

The solution proposed here defers all these checks to the caller.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

2 files changed, 36 insertions, 87 deletions

diff --git a/builtin/rm.c b/builtin/rm.c
index 5a5a66272b..20635dca94 100644
--- a/builtin/rm.c
+++ b/builtin/rm.c
@@ -59,27 +59,9 @@ static void print_error_files(struct string_list *files_list,
 	}
 }
 
-static void error_removing_concrete_submodules(struct string_list *files, int *errs)
-{
-	print_error_files(files,
-			  Q_("the following submodule (or one of its nested "
-			     "submodules)\n"
-			     "uses a .git directory:",
-			     "the following submodules (or one of their nested "
-			     "submodules)\n"
-			     "use a .git directory:", files->nr),
-			  _("\n(use 'rm -rf' if you really want to remove "
-			    "it including all of its history)"),
-			  errs);
-	string_list_clear(files, 0);
-}
-
-static int check_submodules_use_gitfiles(void)
+static void submodules_absorb_gitdir_if_needed(const char *prefix)
 {
 	int i;
-	int errs = 0;
-	struct string_list files = STRING_LIST_INIT_NODUP;
-
 	for (i = 0; i < list.nr; i++) {
 		const char *name = list.entry[i].name;
 		int pos;
@@ -99,12 +81,9 @@ static int check_submodules_use_gitfiles(void)
 			continue;
 
 		if (!submodule_uses_gitfile(name))
-			string_list_append(&files, name);
+			absorb_git_dir_into_superproject(prefix, name,
+				ABSORB_GITDIR_RECURSE_SUBMODULES);
 	}
-
-	error_removing_concrete_submodules(&files, &errs);
-
-	return errs;
 }
 
 static int check_local_mod(struct object_id *head, int index_only)
@@ -120,7 +99,6 @@ static int check_local_mod(struct object_id *head, int index_only)
 	int errs = 0;
 	struct string_list files_staged = STRING_LIST_INIT_NODUP;
 	struct string_list files_cached = STRING_LIST_INIT_NODUP;
-	struct string_list files_submodule = STRING_LIST_INIT_NODUP;
 	struct string_list files_local = STRING_LIST_INIT_NODUP;
 
 	no_head = is_null_oid(head);
@@ -219,13 +197,8 @@ static int check_local_mod(struct object_id *head, int index_only)
 		else if (!index_only) {
 			if (staged_changes)
 				string_list_append(&files_cached, name);
-			if (local_changes) {
-				if (S_ISGITLINK(ce->ce_mode) &&
-				    !submodule_uses_gitfile(name))
-					string_list_append(&files_submodule, name);
-				else
-					string_list_append(&files_local, name);
-			}
+			if (local_changes)
+				string_list_append(&files_local, name);
 		}
 	}
 	print_error_files(&files_staged,
@@ -247,8 +220,6 @@ static int check_local_mod(struct object_id *head, int index_only)
 			  &errs);
 	string_list_clear(&files_cached, 0);
 
-	error_removing_concrete_submodules(&files_submodule, &errs);
-
 	print_error_files(&files_local,
 			  Q_("the following file has local modifications:",
 			     "the following files have local modifications:",
@@ -342,6 +313,9 @@ int cmd_rm(int argc, const char **argv, const char *prefix)
 			exit(0);
 	}
 
+	if (!index_only)
+		submodules_absorb_gitdir_if_needed(prefix);
+
 	/*
 	 * If not forced, the file, the index and the HEAD (if exists)
 	 * must match; but the file can already been removed, since
@@ -358,9 +332,6 @@ int cmd_rm(int argc, const char **argv, const char *prefix)
 			oidclr(&oid);
 		if (check_local_mod(&oid, index_only))
 			exit(1);
-	} else if (!index_only) {
-		if (check_submodules_use_gitfiles())
-			exit(1);
 	}
 
 	/*
@@ -389,32 +360,20 @@ int cmd_rm(int argc, const char **argv, const char *prefix)
 	 */
 	if (!index_only) {
 		int removed = 0, gitmodules_modified = 0;
-		struct strbuf buf = STRBUF_INIT;
 		for (i = 0; i < list.nr; i++) {
 			const char *path = list.entry[i].name;
 			if (list.entry[i].is_submodule) {
-				if (is_empty_dir(path)) {
-					if (!rmdir(path)) {
-						removed = 1;
-						if (!remove_path_from_gitmodules(path))
-							gitmodules_modified = 1;
-						continue;
-					}
-				} else {
-					strbuf_reset(&buf);
-					strbuf_addstr(&buf, path);
-					if (!remove_dir_recursively(&buf, 0)) {
-						removed = 1;
-						if (!remove_path_from_gitmodules(path))
-							gitmodules_modified = 1;
-						strbuf_release(&buf);
-						continue;
-					} else if (!file_exists(path))
-						/* Submodule was removed by user */
-						if (!remove_path_from_gitmodules(path))
-							gitmodules_modified = 1;
-					/* Fallthrough and let remove_path() fail. */
-				}
+				struct strbuf buf = STRBUF_INIT;
+
+				strbuf_addstr(&buf, path);
+				if (remove_dir_recursively(&buf, 0))
+					die(_("could not remove '%s'"), path);
+				strbuf_release(&buf);
+
+				removed = 1;
+				if (!remove_path_from_gitmodules(path))
+					gitmodules_modified = 1;
+				continue;
 			}
 			if (!remove_path(path)) {
 				removed = 1;
@@ -423,7 +382,6 @@ int cmd_rm(int argc, const char **argv, const char *prefix)
 			if (!removed)
 				die_errno("git rm: '%s'", path);
 		}
-		strbuf_release(&buf);
 		if (gitmodules_modified)
 			stage_updated_gitmodules();
 	}
diff --git a/t/t3600-rm.sh b/t/t3600-rm.sh
index 14f0edca2b..030d6c32ae 100755
--- a/t/t3600-rm.sh
+++ b/t/t3600-rm.sh
@@ -585,26 +585,22 @@ test_expect_success 'rm of a conflicted unpopulated submodule succeeds' '
 	test_cmp expect actual
 '
 
-test_expect_success 'rm of a populated submodule with a .git directory fails even when forced' '
+test_expect_success 'rm of a populated submodule with a .git directory migrates git dir' '
 	git checkout -f master &&
 	git reset --hard &&
 	git submodule update &&
 	(cd submod &&
 		rm .git &&
 		cp -R ../.git/modules/sub .git &&
-		GIT_WORK_TREE=. git config --unset core.worktree
+		GIT_WORK_TREE=. git config --unset core.worktree &&
+		rm -r ../.git/modules/sub
 	) &&
-	test_must_fail git rm submod &&
-	test -d submod &&
-	test -d submod/.git &&
-	git status -s -uno --ignore-submodules=none > actual &&
-	! test -s actual &&
-	test_must_fail git rm -f submod &&
-	test -d submod &&
-	test -d submod/.git &&
-	git status -s -uno --ignore-submodules=none > actual &&
-	! test -s actual &&
-	rm -rf submod
+	git rm submod 2>output.err &&
+	! test -d submod &&
+	! test -d submod/.git &&
+	git status -s -uno --ignore-submodules=none >actual &&
+	test -s actual &&
+	test_i18ngrep Migrating output.err
 '
 
 cat >expect.deepmodified <<EOF
@@ -689,24 +685,19 @@ test_expect_success 'rm of a populated nested submodule with a nested .git direc
 	git submodule update --recursive &&
 	(cd submod/subsubmod &&
 		rm .git &&
-		cp -R ../../.git/modules/sub/modules/sub .git &&
+		mv ../../.git/modules/sub/modules/sub .git &&
 		GIT_WORK_TREE=. git config --unset core.worktree
 	) &&
-	test_must_fail git rm submod &&
-	test -d submod &&
-	test -d submod/subsubmod/.git &&
-	git status -s -uno --ignore-submodules=none > actual &&
-	! test -s actual &&
-	test_must_fail git rm -f submod &&
-	test -d submod &&
-	test -d submod/subsubmod/.git &&
-	git status -s -uno --ignore-submodules=none > actual &&
-	! test -s actual &&
-	rm -rf submod
+	git rm submod 2>output.err &&
+	! test -d submod &&
+	! test -d submod/subsubmod/.git &&
+	git status -s -uno --ignore-submodules=none >actual &&
+	test -s actual &&
+	test_i18ngrep Migrating output.err
 '
 
 test_expect_success 'checking out a commit after submodule removal needs manual updates' '
-	git commit -m "submodule removal" submod &&
+	git commit -m "submodule removal" submod .gitmodules &&
 	git checkout HEAD^ &&
 	git submodule update &&
 	git checkout -q HEAD^ 2>actual &&