Merge branch 'yn/worktree-ambiguous-remote-advice' into jch

'git worktree add' did not prevent DWIM behavior when '-b' or '-B' was
specified, which has been corrected.

* yn/worktree-ambiguous-remote-advice:
  worktree add: treat multiple matches with --guess-remote as an error
  worktree add: improve message for ambiguous remote branch name
  checkout: improve message for ambiguous remote branch name
  checkout: extract function to display advice for ambiguous remotes

Documentation/config/worktree.adoc

@@ -5,8 +5,9 @@
 	set to true, `worktree add` tries to find a remote-tracking
 	branch whose name uniquely matches the new branch name.  If
 	such a branch exists, it is checked out and set as "upstream"
-	for the new branch.  If no such match can be found, it falls
+	for the new branch.  If multiple matches are found, the command
-	back to creating a new branch from the current `HEAD`.
+	fails.  If no such match can be found, it falls back to
+	creating a new branch from the current `HEAD`.
 
 `worktree.useRelativePaths`::
 	Link worktrees using relative paths (when "`true`") or absolute

Documentation/git-worktree.adoc

@@ -219,7 +219,9 @@ To remove a locked worktree, specify `--force` twice.
 	of creating a new branch from `HEAD`, if there exists a tracking
 	branch in exactly one remote matching the basename of _<path>_,
 	base the new branch on the remote-tracking branch, and mark
-	the remote-tracking branch as "upstream" from the new branch.
+	the remote-tracking branch as "upstream" from the new branch. If
+	there are multiple matches, the command fails. If there is no
+	match, the command falls back to creating a new branch from `HEAD`.
 +
 This can also be set up as the default behaviour by using the
 `worktree.guessRemote` config option.

builtin/checkout.c

@@ -1343,13 +1343,51 @@ enum checkout_command {
 	CHECKOUT_RESTORE = 3,
 };
 
+static void advise_disambiguating_remotes(enum checkout_command which_command,
+					  const char *branch,
+					  const struct string_list *matched_remote_names)
+{
+	const char *cmdname;
+	struct string_list_item *item;
+
+	switch (which_command) {
+	case CHECKOUT_CHECKOUT:
+		cmdname = "checkout";
+		break;
+	case CHECKOUT_SWITCH:
+		cmdname = "switch";
+		break;
+	default:
+		BUG("command <%d> should not reach advise_disambiguating_remotes",
+		    which_command);
+		break;
+	}
+
+	advise(_("Branch name '%s' appears in multiple remotes:"), branch);
+	for_each_string_list_item(item, matched_remote_names) {
+		advise(_("  %s"), item->string);
+	}
+	advise(_("If you meant to check out a remote tracking branch on <remote>,\n"
+		 "you can do so by fully qualifying the name with the --track option:\n"
+		 "\n"
+		 "    git %s --track <remote>/%s\n"
+		 "\n"
+		 "If you'd like to always have checkouts of an ambiguous name prefer\n"
+		 "one remote, e.g. the 'origin' remote, consider setting\n"
+		 "checkout.defaultRemote=origin in your config."),
+	       cmdname, branch);
+}
+
 static char *parse_remote_branch(const char *arg,
 				 struct object_id *rev,
 				 int could_be_checkout_paths,
 				 enum checkout_command which_command)
 {
 	int num_matches = 0;
-	char *remote = unique_tracking_name(arg, rev, &num_matches);
+	struct string_list matched_remote_names = STRING_LIST_INIT_DUP;
+
+	char *remote = unique_tracking_name(arg, rev, &num_matches,
+					    &matched_remote_names);
 
 	if (remote && could_be_checkout_paths) {
 		die(_("'%s' could be both a local file and a tracking branch.\n"
@@ -1358,37 +1396,15 @@ static char *parse_remote_branch(const char *arg,
 	}
 
 	if (!remote && num_matches > 1) {
-	    if (advice_enabled(ADVICE_CHECKOUT_AMBIGUOUS_REMOTE_BRANCH_NAME)) {
+		if (advice_enabled(ADVICE_CHECKOUT_AMBIGUOUS_REMOTE_BRANCH_NAME))
-		    const char *cmdname;
+			advise_disambiguating_remotes(which_command, arg,
-
+						      &matched_remote_names);
-		    switch (which_command) {
+		die(_("'%s' matched multiple (%d) remote tracking branches"),
-		    case CHECKOUT_CHECKOUT:
+		    arg, num_matches);
-			    cmdname = "checkout";
-			    break;
-		    case CHECKOUT_SWITCH:
-			    cmdname = "switch";
-			    break;
-		    default:
-			    BUG("command <%d> should not reach parse_remote_branch",
-				which_command);
-			    break;
-		    }
-
-		    advise(_("If you meant to check out a remote tracking branch on, e.g. 'origin',\n"
-			     "you can do so by fully qualifying the name with the --track option:\n"
-			     "\n"
-			     "    git %s --track origin/<name>\n"
-			     "\n"
-			     "If you'd like to always have checkouts of an ambiguous <name> prefer\n"
-			     "one remote, e.g. the 'origin' remote, consider setting\n"
-			     "checkout.defaultRemote=origin in your config."),
-			   cmdname);
-	    }
-
-	    die(_("'%s' matched multiple (%d) remote tracking branches"),
-		arg, num_matches);
 	}
 
+	string_list_clear(&matched_remote_names, 0);
+
 	return remote;
 }
 

builtin/worktree.c

@@ -764,7 +764,26 @@ static int dwim_orphan(const struct add_opts *opts, int opt_track, int remote)
 	return 1;
 }
 
-static char *dwim_branch(const char *path, char **new_branch)
+static void advise_disambiguating_remotes(const char *path, const char *branch,
+					  const struct string_list *matched_remote_names)
+{
+	struct string_list_item *item;
+
+	advise(_("Branch name '%s' appears in multiple remotes:"), branch);
+	for_each_string_list_item(item, matched_remote_names) {
+		advise(_("  %s"), item->string);
+	}
+	advise(_("If you meant to create a worktree from a remote tracking branch on\n"
+		 "<remote>, you can do so by:\n"
+		 "\n"
+		 "    git worktree add -b %s %s <remote>/%s\n"
+		 "\n"
+		 "If you'd like to always prefer some remote, e.g. 'origin',\n"
+		 "consider setting checkout.defaultRemote=origin in your config."),
+	       branch, path, branch);
+}
+
+static char *dwim_branch(const struct add_opts *opts, const char *path, char **new_branch)
 {
 	int n;
 	int branch_exists;
@@ -782,7 +801,21 @@ static char *dwim_branch(const char *path, char **new_branch)
 	*new_branch = branchname;
 	if (guess_remote) {
 		struct object_id oid;
-		char *remote = unique_tracking_name(*new_branch, &oid, NULL);
+		char *remote;
+		int num_matches = 0;
+		struct string_list matched_remote_names = STRING_LIST_INIT_DUP;
+
+		remote = unique_tracking_name(*new_branch, &oid, &num_matches,
+					      &matched_remote_names);
+		if (!remote && num_matches > 1) {
+			if (!opts->quiet &&
+			    advice_enabled(ADVICE_CHECKOUT_AMBIGUOUS_REMOTE_BRANCH_NAME))
+				advise_disambiguating_remotes(path, *new_branch,
+							      &matched_remote_names);
+			die(_("'%s' matched multiple (%d) remote tracking branches"),
+			    *new_branch, num_matches);
+		}
+		string_list_clear(&matched_remote_names, 0);
 		return remote;
 	}
 	return NULL;
@@ -890,7 +923,7 @@ static int add(int ac, const char **av, const char *prefix,
 		opts.orphan = dwim_orphan(&opts, !!opt_track, 0);
 	} else if (ac < 2) {
 		/* DWIM: Guess branch name from path. */
-		char *s = dwim_branch(path, &new_branch_to_free);
+		char *s = dwim_branch(&opts, path, &new_branch_to_free);
 		if (s)
 			branch = branch_to_free = s;
 		new_branch = new_branch_to_free;
@@ -901,17 +934,29 @@ static int add(int ac, const char **av, const char *prefix,
 		if (!strcmp(branch, "HEAD"))
 			can_use_local_refs(&opts);
 	} else if (ac == 2) {
-		struct object_id oid;
 		struct commit *commit;
-		char *remote;
 
 		commit = lookup_commit_reference_by_name(branch);
 		if (!commit) {
-			remote = unique_tracking_name(branch, &oid, NULL);
+			struct object_id oid;
+			char *remote;
+			int num_matches = 0;
+			struct string_list matched_remote_names = STRING_LIST_INIT_DUP;
+
+			remote = unique_tracking_name(branch, &oid, &num_matches,
+						      &matched_remote_names);
 			if (remote) {
 				new_branch = branch;
 				branch = new_branch_to_free = remote;
+			} else if (num_matches > 1) {
+				if (!opts.quiet &&
+				    advice_enabled(ADVICE_CHECKOUT_AMBIGUOUS_REMOTE_BRANCH_NAME))
+					advise_disambiguating_remotes(path, branch,
+								      &matched_remote_names);
+				die(_("'%s' matched multiple (%d) remote tracking branches"),
+				    branch, num_matches);
 			}
+			string_list_clear(&matched_remote_names, 0);
 		}
 
 		if (!strcmp(branch, "HEAD"))

checkout.c

@@ -8,6 +8,7 @@
 #include "checkout.h"
 #include "config.h"
 #include "strbuf.h"
+#include "string-list.h"
 
 struct tracking_name_data {
 	/* const */ char *src_ref;
@@ -17,6 +18,7 @@ struct tracking_name_data {
 	const char *default_remote;
 	char *default_dst_ref;
 	struct object_id *default_dst_oid;
+	struct string_list *remote_names;
 };
 
 #define TRACKING_NAME_DATA_INIT { 0 }
@@ -39,6 +41,8 @@ static int check_tracking_name(struct remote *remote, void *cb_data)
 		oidcpy(dst, cb->dst_oid);
 		cb->default_dst_oid = dst;
 	}
+	if (cb->remote_names)
+		string_list_append(cb->remote_names, remote->name);
 	if (cb->dst_ref) {
 		free(query.dst);
 		return 0;
@@ -48,14 +52,19 @@ static int check_tracking_name(struct remote *remote, void *cb_data)
 }
 
 char *unique_tracking_name(const char *name, struct object_id *oid,
-			   int *dwim_remotes_matched)
+			   int *dwim_remotes_matched,
+			   struct string_list *dwim_remote_names)
 {
 	struct tracking_name_data cb_data = TRACKING_NAME_DATA_INIT;
 	const char *default_remote = NULL;
-	if (!repo_config_get_string_tmp(the_repository, "checkout.defaultremote", &default_remote))
+
+	if (!repo_config_get_string_tmp(the_repository,
+					"checkout.defaultremote",
+					&default_remote))
 		cb_data.default_remote = default_remote;
 	cb_data.src_ref = xstrfmt("refs/heads/%s", name);
 	cb_data.dst_oid = oid;
+	cb_data.remote_names = dwim_remote_names;
 	for_each_remote(check_tracking_name, &cb_data);
 	if (dwim_remotes_matched)
 		*dwim_remotes_matched = cb_data.num_matches;

checkout.h

@@ -3,6 +3,8 @@
 
 #include "hash.h"
 
+struct string_list;
+
 /*
  * Check if the branch name uniquely matches a branch name on a remote
  * tracking branch.  Return the name of the remote if such a branch
@@ -10,6 +12,7 @@
  */
 char *unique_tracking_name(const char *name,
 			   struct object_id *oid,
-			   int *dwim_remotes_matched);
+			   int *dwim_remotes_matched,
+			   struct string_list *dwim_remote_names);
 
 #endif /* CHECKOUT_H */

t/t2400-worktree-add.sh

@@ -634,12 +634,12 @@ test_expect_success '"add" <path> <branch> does not dwim with -b' '
 test_expect_success '"add" <path> <branch> dwims with checkout.defaultRemote' '
 	test_when_finished rm -rf repo_upstream repo_dwim foo &&
 	setup_remote_repo repo_upstream repo_dwim &&
-	git init repo_dwim &&
 	(
 		cd repo_dwim &&
 		git remote add repo_upstream2 ../repo_upstream &&
 		git fetch repo_upstream2 &&
-		test_must_fail git worktree add ../foo foo &&
+		test_must_fail git worktree add ../foo foo 2>error.actual &&
+		test_grep "matched multiple (2) remote tracking branches" error.actual &&
 		git -c checkout.defaultRemote=repo_upstream worktree add ../foo foo &&
 		git status -uno --porcelain >status.actual &&
 		test_must_be_empty status.actual
@@ -679,6 +679,19 @@ test_expect_success 'git worktree add --guess-remote sets up tracking' '
 		test_cmp_rev refs/remotes/repo_a/foo refs/heads/foo
 	)
 '
+
+test_expect_success 'git worktree add --guess-remote fails if there are multiple matches' '
+	test_when_finished rm -rf repo_a repo_b foo &&
+	setup_remote_repo repo_a repo_b &&
+	(
+		cd repo_b &&
+		git remote add repo_a2 ../repo_a &&
+		git fetch repo_a2 &&
+		test_must_fail git worktree add --guess-remote ../foo 2>actual &&
+		test_grep "matched multiple (2) remote tracking branches" actual
+	)
+'
+
 test_expect_success 'git worktree add --guess-remote sets up tracking (quiet)' '
 	test_when_finished rm -rf repo_a repo_b foo &&
 	setup_remote_repo repo_a repo_b &&