submodule-config: keep shallow recommendation around

The shallow field will be used in a later patch by `submodule update`.
To differentiate between the actual depth (which may be different),
we name it `recommend_shallow` as the field in the .gitmodules file
is only a recommendation by the project.

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

submodule-config.c

@@ -199,6 +199,7 @@ static struct submodule *lookup_or_create_by_name(struct submodule_cache *cache,
 	submodule->update_strategy.command = NULL;
 	submodule->fetch_recurse = RECURSE_SUBMODULES_NONE;
 	submodule->ignore = NULL;
+	submodule->recommend_shallow = -1;
 
 	hashcpy(submodule->gitmodules_sha1, gitmodules_sha1);
 
@@ -353,6 +354,14 @@ static int parse_config(const char *var, const char *value, void *data)
 		else if (parse_submodule_update_strategy(value,
 			 &submodule->update_strategy) < 0)
 				die(_("invalid value for %s"), var);
+	} else if (!strcmp(item.buf, "shallow")) {
+		if (!me->overwrite && submodule->recommend_shallow != -1)
+			warn_multiple_config(me->commit_sha1, submodule->name,
+					     "shallow");
+		else {
+			submodule->recommend_shallow =
+				git_config_bool(var, value);
+		}
 	}
 
 	strbuf_release(&name);

submodule-config.h

@@ -18,6 +18,7 @@ struct submodule {
 	struct submodule_update_strategy update_strategy;
 	/* the sha1 blob id of the responsible .gitmodules file */
 	unsigned char gitmodules_sha1[20];
+	int recommend_shallow;
 };
 
 int parse_fetch_recurse_submodules_arg(const char *opt, const char *arg);