Merge branch 'ab/checkout-default-remote'

"git checkout" and "git worktree add" learned to honor
checkout.defaultRemote when auto-vivifying a local branch out of a
remote tracking branch in a repository with multiple remotes that
have tracking branches that share the same names.

* ab/checkout-default-remote:
  checkout & worktree: introduce checkout.defaultRemote
  checkout: add advice for ambiguous "checkout <branch>"
  builtin/checkout.c: use "ret" variable for return
  checkout: pass the "num_matches" up to callers
  checkout.c: change "unique" member to "num_matches"
  checkout.c: introduce an *_INIT macro
  checkout.h: wrap the arguments to unique_tracking_name()
  checkout tests: index should be clean after dwim checkout

2 files changed, 35 insertions, 10 deletions

diff --git a/builtin/checkout.c b/builtin/checkout.c
index 2862765..2de10d2 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -23,6 +23,7 @@
 #include "resolve-undo.h"
 #include "submodule-config.h"
 #include "submodule.h"
+#include "advice.h"
 
 static const char * const checkout_usage[] = {
 	N_("git checkout [<options>] <branch>"),
@@ -879,7 +880,8 @@ static int parse_branchname_arg(int argc, const char **argv,
 				int dwim_new_local_branch_ok,
 				struct branch_info *new_branch_info,
 				struct checkout_opts *opts,
-				struct object_id *rev)
+				struct object_id *rev,
+				int *dwim_remotes_matched)
 {
 	struct tree **source_tree = &opts->source_tree;
 	const char **new_branch = &opts->new_branch;
@@ -911,8 +913,10 @@ static int parse_branchname_arg(int argc, const char **argv,
 	 *   (b) If <something> is _not_ a commit, either "--" is present
 	 *       or <something> is not a path, no -t or -b was given, and
 	 *       and there is a tracking branch whose name is <something>
-	 *       in one and only one remote, then this is a short-hand to
-	 *       fork local <something> from that remote-tracking branch.
+	 *       in one and only one remote (or if the branch exists on the
+	 *       remote named in checkout.defaultRemote), then this is a
+	 *       short-hand to fork local <something> from that
+	 *       remote-tracking branch.
 	 *
 	 *   (c) Otherwise, if "--" is present, treat it like case (1).
 	 *
@@ -973,7 +977,8 @@ static int parse_branchname_arg(int argc, const char **argv,
 			recover_with_dwim = 0;
 
 		if (recover_with_dwim) {
-			const char *remote = unique_tracking_name(arg, rev);
+			const char *remote = unique_tracking_name(arg, rev,
+								  dwim_remotes_matched);
 			if (remote) {
 				*new_branch = arg;
 				arg = remote;
@@ -1110,6 +1115,7 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
 	struct branch_info new_branch_info;
 	char *conflict_style = NULL;
 	int dwim_new_local_branch = 1;
+	int dwim_remotes_matched = 0;
 	struct option options[] = {
 		OPT__QUIET(&opts.quiet, N_("suppress progress reporting")),
 		OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
@@ -1222,7 +1228,8 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
 			opts.track == BRANCH_TRACK_UNSPECIFIED &&
 			!opts.new_branch;
 		int n = parse_branchname_arg(argc, argv, dwim_ok,
-					     &new_branch_info, &opts, &rev);
+					     &new_branch_info, &opts, &rev,
+					     &dwim_remotes_matched);
 		argv += n;
 		argc -= n;
 	}
@@ -1264,8 +1271,26 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
 	}
 
 	UNLEAK(opts);
-	if (opts.patch_mode || opts.pathspec.nr)
-		return checkout_paths(&opts, new_branch_info.name);
-	else
+	if (opts.patch_mode || opts.pathspec.nr) {
+		int ret = checkout_paths(&opts, new_branch_info.name);
+		if (ret && dwim_remotes_matched > 1 &&
+		    advice_checkout_ambiguous_remote_branch_name)
+			advise(_("'%s' matched more than one remote tracking branch.\n"
+				 "We found %d remotes with a reference that matched. So we fell back\n"
+				 "on trying to resolve the argument as a path, but failed there too!\n"
+				 "\n"
+				 "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 checkout --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."),
+			       argv[0],
+			       dwim_remotes_matched);
+		return ret;
+	} else {
 		return checkout_branch(&opts, &new_branch_info);
+	}
 }
diff --git a/builtin/worktree.c b/builtin/worktree.c
index 5c7d2bb..a763dbd 100644
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -412,7 +412,7 @@ static const char *dwim_branch(const char *path, const char **new_branch)
 	if (guess_remote) {
 		struct object_id oid;
 		const char *remote =
-			unique_tracking_name(*new_branch, &oid);
+			unique_tracking_name(*new_branch, &oid, NULL);
 		return remote;
 	}
 	return NULL;
@@ -484,7 +484,7 @@ static int add(int ac, const char **av, const char *prefix)
 
 		commit = lookup_commit_reference_by_name(branch);
 		if (!commit) {
-			remote = unique_tracking_name(branch, &oid);
+			remote = unique_tracking_name(branch, &oid, NULL);
 			if (remote) {
 				new_branch = branch;
 				branch = remote;