submodule: teach rm to remove submodules unless they contain a git directory

Currently using "git rm" on a submodule - populated or not - fails with
this error:

	fatal: git rm: '<submodule path>': Is a directory

This made sense in the past as there was no way to remove a submodule
without possibly removing unpushed parts of the submodule's history
contained in its .git directory too, so erroring out here protected the
user from possible loss of data.

But submodules cloned with a recent git version do not contain the .git
directory anymore, they use a gitfile to point to their git directory
which is safely stored inside the superproject's .git directory. The work
tree of these submodules can safely be removed without losing history, so
let's teach git to do so.

Using rm on an unpopulated submodule now removes the empty directory from
the work tree and the gitlink from the index. If the submodule's directory
is missing from the work tree, it will still be removed from the index.

Using rm on a populated submodule using a gitfile will apply the usual
checks for work tree modification adapted to submodules (unless forced).
For a submodule that means that the HEAD is the same as recorded in the
index, no tracked files are modified and no untracked files that aren't
ignored are present in the submodules work tree (ignored files are deemed
expendable and won't stop a submodule's work tree from being removed).
That logic has to be applied in all nested submodules too.

Using rm on a submodule which has its .git directory inside the work trees
top level directory will just error out like it did before to protect the
repository, even when forced. In the future git could either provide a
message informing the user to convert the submodule to use a gitfile or
even attempt to do the conversion itself, but that is not part of this
change.

Signed-off-by: Jens Lehmann <Jens.Lehmann@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 343 insertions, 0 deletions

diff --git a/t/t3600-rm.sh b/t/t3600-rm.sh
index 9fd28bcf3..97254e8d3 100755
--- a/t/t3600-rm.sh
+++ b/t/t3600-rm.sh
@@ -262,4 +262,347 @@ test_expect_success 'rm removes subdirectories recursively' '
 	! test -d dir
 '
 
+cat >expect <<EOF
+D  submod
+EOF
+
+cat >expect.modified <<EOF
+ M submod
+EOF
+
+test_expect_success 'rm removes empty submodules from work tree' '
+	mkdir submod &&
+	git update-index --add --cacheinfo 160000 $(git rev-parse HEAD) submod &&
+	git config -f .gitmodules submodule.sub.url ./. &&
+	git config -f .gitmodules submodule.sub.path submod &&
+	git submodule init &&
+	git add .gitmodules &&
+	git commit -m "add submodule" &&
+	git rm submod &&
+	test ! -e submod &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'rm removes removed submodule from index' '
+	git reset --hard &&
+	git submodule update &&
+	rm -rf submod &&
+	git rm submod &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'rm removes work tree of unmodified submodules' '
+	git reset --hard &&
+	git submodule update &&
+	git rm submod &&
+	test ! -d submod &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'rm of a populated submodule with different HEAD fails unless forced' '
+	git reset --hard &&
+	git submodule update &&
+	(cd submod &&
+		git checkout HEAD^
+	) &&
+	test_must_fail git rm submod &&
+	test -d submod &&
+	test -f submod/.git &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect.modified actual &&
+	git rm -f submod &&
+	test ! -d submod &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'rm of a populated submodule with modifications fails unless forced' '
+	git reset --hard &&
+	git submodule update &&
+	(cd submod &&
+		echo X >empty
+	) &&
+	test_must_fail git rm submod &&
+	test -d submod &&
+	test -f submod/.git &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect.modified actual &&
+	git rm -f submod &&
+	test ! -d submod &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'rm of a populated submodule with untracked files fails unless forced' '
+	git reset --hard &&
+	git submodule update &&
+	(cd submod &&
+		echo X >untracked
+	) &&
+	test_must_fail git rm submod &&
+	test -d submod &&
+	test -f submod/.git &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect.modified actual &&
+	git rm -f submod &&
+	test ! -d submod &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'setup submodule conflict' '
+	git reset --hard &&
+	git submodule update &&
+	git checkout -b branch1 &&
+	echo 1 >nitfol &&
+	git add nitfol &&
+	git commit -m "added nitfol 1" &&
+	git checkout -b branch2 master &&
+	echo 2 >nitfol &&
+	git add nitfol &&
+	git commit -m "added nitfol 2" &&
+	git checkout -b conflict1 master &&
+	(cd submod &&
+		git fetch &&
+		git checkout branch1
+	) &&
+	git add submod &&
+	git commit -m "submod 1" &&
+	git checkout -b conflict2 master &&
+	(cd submod &&
+		git checkout branch2
+	) &&
+	git add submod &&
+	git commit -m "submod 2"
+'
+
+cat >expect.conflict <<EOF
+UU submod
+EOF
+
+test_expect_success 'rm removes work tree of unmodified conflicted submodule' '
+	git checkout conflict1 &&
+	git reset --hard &&
+	git submodule update &&
+	test_must_fail git merge conflict2 &&
+	git rm submod &&
+	test ! -d submod &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'rm of a conflicted populated submodule with different HEAD fails unless forced' '
+	git checkout conflict1 &&
+	git reset --hard &&
+	git submodule update &&
+	(cd submod &&
+		git checkout HEAD^
+	) &&
+	test_must_fail git merge conflict2 &&
+	test_must_fail git rm submod &&
+	test -d submod &&
+	test -f submod/.git &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect.conflict actual &&
+	git rm -f submod &&
+	test ! -d submod &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'rm of a conflicted populated submodule with modifications fails unless forced' '
+	git checkout conflict1 &&
+	git reset --hard &&
+	git submodule update &&
+	(cd submod &&
+		echo X >empty
+	) &&
+	test_must_fail git merge conflict2 &&
+	test_must_fail git rm submod &&
+	test -d submod &&
+	test -f submod/.git &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect.conflict actual &&
+	git rm -f submod &&
+	test ! -d submod &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'rm of a conflicted populated submodule with untracked files fails unless forced' '
+	git checkout conflict1 &&
+	git reset --hard &&
+	git submodule update &&
+	(cd submod &&
+		echo X >untracked
+	) &&
+	test_must_fail git merge conflict2 &&
+	test_must_fail git rm submod &&
+	test -d submod &&
+	test -f submod/.git &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect.conflict actual &&
+	git rm -f submod &&
+	test ! -d submod &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'rm of a conflicted populated submodule with a .git directory fails even when forced' '
+	git checkout conflict1 &&
+	git reset --hard &&
+	git submodule update &&
+	(cd submod &&
+		rm .git &&
+		cp -a ../.git/modules/sub .git &&
+		GIT_WORK_TREE=. git config --unset core.worktree
+	) &&
+	test_must_fail git merge conflict2 &&
+	test_must_fail git rm submod &&
+	test -d submod &&
+	test -d submod/.git &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect.conflict actual &&
+	test_must_fail git rm -f submod &&
+	test -d submod &&
+	test -d submod/.git &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect.conflict actual &&
+	git merge --abort &&
+	rm -rf submod
+'
+
+test_expect_success 'rm of a conflicted unpopulated submodule succeeds' '
+	git checkout conflict1 &&
+	git reset --hard &&
+	test_must_fail git merge conflict2 &&
+	git rm submod &&
+	test ! -d submod &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'rm of a populated submodule with a .git directory fails even when forced' '
+	git checkout -f master &&
+	git reset --hard &&
+	git submodule update &&
+	(cd submod &&
+		rm .git &&
+		cp -a ../.git/modules/sub .git &&
+		GIT_WORK_TREE=. git config --unset core.worktree
+	) &&
+	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
+'
+
+cat >expect.deepmodified <<EOF
+ M submod/subsubmod
+EOF
+
+test_expect_success 'setup subsubmodule' '
+	git reset --hard &&
+	git submodule update &&
+	(cd submod &&
+		git update-index --add --cacheinfo 160000 $(git rev-parse HEAD) subsubmod &&
+		git config -f .gitmodules submodule.sub.url ../. &&
+		git config -f .gitmodules submodule.sub.path subsubmod &&
+		git submodule init &&
+		git add .gitmodules &&
+		git commit -m "add subsubmodule" &&
+		git submodule update subsubmod
+	) &&
+	git commit -a -m "added deep submodule"
+'
+
+test_expect_success 'rm recursively removes work tree of unmodified submodules' '
+	git rm submod &&
+	test ! -d submod &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'rm of a populated nested submodule with different nested HEAD fails unless forced' '
+	git reset --hard &&
+	git submodule update --recursive &&
+	(cd submod/subsubmod &&
+		git checkout HEAD^
+	) &&
+	test_must_fail git rm submod &&
+	test -d submod &&
+	test -f submod/.git &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect.modified actual &&
+	git rm -f submod &&
+	test ! -d submod &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'rm of a populated nested submodule with nested modifications fails unless forced' '
+	git reset --hard &&
+	git submodule update --recursive &&
+	(cd submod/subsubmod &&
+		echo X >empty
+	) &&
+	test_must_fail git rm submod &&
+	test -d submod &&
+	test -f submod/.git &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect.modified actual &&
+	git rm -f submod &&
+	test ! -d submod &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'rm of a populated nested submodule with nested untracked files fails unless forced' '
+	git reset --hard &&
+	git submodule update --recursive &&
+	(cd submod/subsubmod &&
+		echo X >untracked
+	) &&
+	test_must_fail git rm submod &&
+	test -d submod &&
+	test -f submod/.git &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect.modified actual &&
+	git rm -f submod &&
+	test ! -d submod &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'rm of a populated nested submodule with a nested .git directory fails even when forced' '
+	git reset --hard &&
+	git submodule update --recursive &&
+	(cd submod/subsubmod &&
+		rm .git &&
+		cp -a ../../.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
+'
+
 test_done