[PATCH/RFC] git submodule: add submodules with git add -f <path>

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

Change `git submodule add' to add the new submodule <path> with `git
add --force'.

I keep my /etc in .git with a .gitignore that contains just
"*". I.e. `git status' will ignore everything that isn't in the tree
already. When I do:

    git submodule add <url> hlagh

git-submodule will get as far as checking out the remote repository
into hlagh, but it'll die right afterwards when it fails to add the
new path:

    The following paths are ignored by one of your .gitignore files:
    hlagh
    Use -f if you really want to add them.
    fatal: no files added
    Failed to add submodule 'hlagh'

Currently there's no way to add a submodule in this situation other
than to remove the ignored path from the .gitignore while I'm at it.

That's silly, when you run `git submodule add' you're explicitly
saying that you want to add something *new* to the repository. Instead
it should just add the path with `git add --force'.

Initially I implemented this by adding new -f and --force options to
`git submodule add'. But if the --force option isn't supplied it'll
get as far as cloning `hlagh', but won't add it.

So the first thing the user has to do is to remove `hlagh' and then
try again with the --force option.

That sucks, it should just add the path to begin with. I can't think
of any usecase where you've gone through the trouble of typing out
`git submodule add ..', but wish to be overriden by a `gitignore'. The
submodule semantics should be more like `git init', not `git add'.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 Documentation/git-submodule.txt |    4 ++++
 git-submodule.sh                |    4 ++--
 t/t7400-submodule-basic.sh      |   24 +++++++++++++++++++++++-
 3 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/Documentation/git-submodule.txt b/Documentation/git-submodule.txt
index cdabfd2..76a832a 100644
--- a/Documentation/git-submodule.txt
+++ b/Documentation/git-submodule.txt
@@ -95,6 +95,10 @@ is the superproject and submodule repositories will be kept
 together in the same relative location, and only the
 superproject's URL needs to be provided: git-submodule will correctly
 locate the submodule using the relative URL in .gitmodules.
++
+The submodule will be added with "git add --force <path>". I.e. git
+doesn't care if the new path is in a `gitignore`. Your invocation of
+"git submodule add" is considered enough to override it.
 
 status::
 	Show the status of the submodules. This will print the SHA-1 of the
diff --git a/git-submodule.sh b/git-submodule.sh
index d9950c2..ad2417d 100755
--- a/git-submodule.sh
+++ b/git-submodule.sh
@@ -234,12 +234,12 @@ cmd_add()
 		) || die "Unable to checkout submodule '$path'"
 	fi
 
-	git add "$path" ||
+	git add --force "$path" ||
 	die "Failed to add submodule '$path'"
 
 	git config -f .gitmodules submodule."$path".path "$path" &&
 	git config -f .gitmodules submodule."$path".url "$repo" &&
-	git add .gitmodules ||
+	git add --force .gitmodules ||
 	die "Failed to register submodule '$path'"
 }
 
diff --git a/t/t7400-submodule-basic.sh b/t/t7400-submodule-basic.sh
index 97ff074..d9f2785 100755
--- a/t/t7400-submodule-basic.sh
+++ b/t/t7400-submodule-basic.sh
@@ -42,7 +42,8 @@ test_expect_success 'setup - hide init subdirectory' '
 '
 
 test_expect_success 'setup - repository to add submodules to' '
-	git init addtest
+	git init addtest &&
+	git init addtest-ignore
 '
 
 # The 'submodule add' tests need some repository to add as a submodule.
@@ -85,6 +86,27 @@ test_expect_success 'submodule add' '
 	test_cmp empty untracked
 '
 
+test_expect_success 'submodule add to .gitignored path' '
+	echo "refs/heads/master" >expect &&
+	>empty &&
+
+	(
+		cd addtest-ignore &&
+		# Does not use test_commit due to the ignore
+		echo "*" > .gitignore &&
+		git add --force .gitignore &&
+		git commit -m"Ignore everything" &&
+		git submodule add "$submodurl" submod &&
+		git submodule init
+	) &&
+
+	rm -f heads head untracked &&
+	inspect addtest/submod ../.. &&
+	test_cmp expect heads &&
+	test_cmp expect head &&
+	test_cmp empty untracked
+'
+
 test_expect_success 'submodule add --branch' '
 	echo "refs/heads/initial" >expect-head &&
 	cat <<-\EOF >expect-heads &&
-- 
1.7.2.rc1.192.g262ff.dirty