[PATCH] submodule: resolve insteadof-aliases when matching remote

["Éric NICOLAS" <ccjmne@gmail.com>]

When ca62f524c1 introduced a mechanism to identify which remote is to be
used by a submodule, we had it compare the URL stored in the .gitmodules
inventory to those of each available remote.

However, when using URL aliasing via url.<base>.insteadOf, we store
in .gitmodules the URL pre-resolution of the alias, whereas the
corresponding remote set up in the submodule reports using the
*resolved* URL.  This mechanism therefore fails to find a match then,
and resorts to the fallback logic, which does use either the only
configured remote if there is only one, or attempts using "origin"
otherwise.

Resolve the alias in the URL inventoried in .gitmodules before comparing
it against those of the corresponding submodule's configured remotes.

Signed-off-by: Éric NICOLAS <ccjmne@gmail.com>
---
 remote.c                    | 15 ++++++++++++---
 t/t7406-submodule-update.sh | 21 +++++++++++++++++++++
 2 files changed, 33 insertions(+), 3 deletions(-)

diff --git a/remote.c b/remote.c
index b17648d6ef..ae187fb3d6 100644
--- a/remote.c
+++ b/remote.c
@@ -1821,17 +1821,26 @@ const char *repo_default_remote(struct repository *repo)
 
 const char *repo_remote_from_url(struct repository *repo, const char *url)
 {
+	char *rewritten_url;
+	const char *url_to_match;
+	const char *remote_name = NULL;
+
 	read_config(repo, 0);
+	rewritten_url = alias_url(url, &repo->remote_state->rewrites);
+	url_to_match = rewritten_url ? rewritten_url : url;
 
 	for (int i = 0; i < repo->remote_state->remotes_nr; i++) {
 		struct remote *remote = repo->remote_state->remotes[i];
 		if (!remote)
 			continue;
 
-		if (remote_has_url(remote, url))
-			return remote->name;
+		if (remote_has_url(remote, url_to_match)) {
+			remote_name = remote->name;
+			break;
+		}
 	}
-	return NULL;
+	free(rewritten_url);
+	return remote_name;
 }
 
 int branch_has_merge_config(struct branch *branch)
diff --git a/t/t7406-submodule-update.sh b/t/t7406-submodule-update.sh
index 9554720152..84e2cbbef9 100755
--- a/t/t7406-submodule-update.sh
+++ b/t/t7406-submodule-update.sh
@@ -256,6 +256,27 @@ test_expect_success 'submodule update --remote should fetch upstream changes' '
 	)
 '
 
+test_expect_success 'submodule update --remote resolves URL rewrites' '
+	test_config_global "url.$(pwd)/.insteadOf" local: &&
+	mkdir aliased-super aliased-submodule &&
+	(
+		cd aliased-submodule &&
+		git init &&
+		echo line >file &&
+		git add file &&
+		git commit -m "Initial commit"
+	) &&
+	(
+		cd aliased-super &&
+		git init &&
+		git submodule add local:aliased-submodule submodule &&
+		git submodule update --force submodule &&
+		git -C submodule remote rename origin upstream &&
+		git -C submodule remote add fork user@host &&
+		git submodule update --remote submodule
+	)
+'
+
 test_expect_success 'submodule update --remote should fetch upstream changes with .' '
 	(
 		cd super &&
-- 
2.55.0