fetch: honor the user-provided refspecs when pruning refs

If the user gave us refspecs on the command line, we should use those
when deciding whether to prune a ref instead of relying on the
refspecs in the config.

Previously, running

    git fetch --prune origin refs/heads/master:refs/remotes/origin/master

would delete every other ref under the origin namespace because we
were using the refspec to filter the available refs but using the
configured refspec to figure out if a ref had been deleted on the
remote. This is clearly the wrong thing to do.

Change prune_refs and get_stale_heads to simply accept a list of
references and a list of refspecs. The caller of either function needs
to decide what refspecs should be used to decide whether a ref is
stale.

Signed-off-by: Carlos Martín Nieto <cmn@elego.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/fetch.c

@@ -540,10 +540,10 @@ static int fetch_refs(struct transport *transport, struct ref *ref_map)
 	return ret;
 }
 
-static int prune_refs(struct transport *transport, struct ref *ref_map)
+static int prune_refs(struct refspec *refs, int ref_count, struct ref *ref_map)
 {
 	int result = 0;
-	struct ref *ref, *stale_refs = get_stale_heads(transport->remote, ref_map);
+	struct ref *ref, *stale_refs = get_stale_heads(refs, ref_count, ref_map);
 	const char *dangling_msg = dry_run
 		? _("   (%s will become dangling)\n")
 		: _("   (%s has become dangling)\n");
@@ -734,8 +734,12 @@ static int do_fetch(struct transport *transport,
 		free_refs(ref_map);
 		return 1;
 	}
-	if (prune)
-		prune_refs(transport, ref_map);
+	if (prune) {
+		if (ref_count)
+			prune_refs(refs, ref_count, ref_map);
+		else
+			prune_refs(transport->remote->fetch, transport->remote->fetch_refspec_nr, ref_map);
+	}
 	free_refs(ref_map);
 
 	/* if neither --no-tags nor --tags was specified, do automated tag

builtin/remote.c

@@ -349,7 +349,8 @@ static int get_ref_states(const struct ref *remote_refs, struct ref_states *stat
 		else
 			string_list_append(&states->tracked, abbrev_branch(ref->name));
 	}
-	stale_refs = get_stale_heads(states->remote, fetch_map);
+	stale_refs = get_stale_heads(states->remote->fetch,
+				     states->remote->fetch_refspec_nr, fetch_map);
 	for (ref = stale_refs; ref; ref = ref->next) {
 		struct string_list_item *item =
 			string_list_append(&states->stale, abbrev_branch(ref->name));

remote.c

@@ -1678,36 +1678,47 @@ struct ref *guess_remote_head(const struct ref *head,
 }
 
 struct stale_heads_info {
-	struct remote *remote;
 	struct string_list *ref_names;
 	struct ref **stale_refs_tail;
+	struct refspec *refs;
+	int ref_count;
 };
 
 static int get_stale_heads_cb(const char *refname,
 	const unsigned char *sha1, int flags, void *cb_data)
 {
 	struct stale_heads_info *info = cb_data;
-	struct refspec refspec;
-	memset(&refspec, 0, sizeof(refspec));
-	refspec.dst = (char *)refname;
-	if (!remote_find_tracking(info->remote, &refspec)) {
-		if (!((flags & REF_ISSYMREF) ||
-		    string_list_has_string(info->ref_names, refspec.src))) {
-			struct ref *ref = make_linked_ref(refname, &info->stale_refs_tail);
-			hashcpy(ref->new_sha1, sha1);
-		}
+	struct refspec query;
+	memset(&query, 0, sizeof(struct refspec));
+	query.dst = (char *)refname;
+
+	if (query_refspecs(info->refs, info->ref_count, &query))
+		return 0; /* No matches */
+
+	/*
+	 * If we did find a suitable refspec and it's not a symref and
+	 * it's not in the list of refs that currently exist in that
+	 * remote we consider it to be stale.
+	 */
+	if (!((flags & REF_ISSYMREF) ||
+	      string_list_has_string(info->ref_names, query.src))) {
+		struct ref *ref = make_linked_ref(refname, &info->stale_refs_tail);
+		hashcpy(ref->new_sha1, sha1);
 	}
+
+	free(query.src);
 	return 0;
 }
 
-struct ref *get_stale_heads(struct remote *remote, struct ref *fetch_map)
+struct ref *get_stale_heads(struct refspec *refs, int ref_count, struct ref *fetch_map)
 {
 	struct ref *ref, *stale_refs = NULL;
 	struct string_list ref_names = STRING_LIST_INIT_NODUP;
 	struct stale_heads_info info;
-	info.remote = remote;
 	info.ref_names = &ref_names;
 	info.stale_refs_tail = &stale_refs;
+	info.refs = refs;
+	info.ref_count = ref_count;
 	for (ref = fetch_map; ref; ref = ref->next)
 		string_list_append(&ref_names, ref->name);
 	sort_string_list(&ref_names);

remote.h

@@ -164,6 +164,6 @@ struct ref *guess_remote_head(const struct ref *head,
 			      int all);
 
 /* Return refs which no longer exist on remote */
-struct ref *get_stale_heads(struct remote *remote, struct ref *fetch_map);
+struct ref *get_stale_heads(struct refspec *refs, int ref_count, struct ref *fetch_map);
 
 #endif

t/t5510-fetch.sh

@@ -86,7 +86,7 @@ test_expect_success 'fetch --prune on its own works as expected' '
 	test_must_fail git rev-parse origin/extrabranch
 '
 
-test_expect_failure 'fetch --prune with a branch name keeps branches' '
+test_expect_success 'fetch --prune with a branch name keeps branches' '
 	cd "$D" &&
 	git clone . prune-branch &&
 	cd prune-branch &&
@@ -96,7 +96,7 @@ test_expect_failure 'fetch --prune with a branch name keeps branches' '
 	git rev-parse origin/extrabranch
 '
 
-test_expect_failure 'fetch --prune with a namespace keeps other namespaces' '
+test_expect_success 'fetch --prune with a namespace keeps other namespaces' '
 	cd "$D" &&
 	git clone . prune-namespace &&
 	cd prune-namespace &&