branch: improve error log on branch not found by checking remotes refs

New git users may want to locally delete remote-tracking branches but
don't really understand how they are distinguished from branches by git.
Then one may naively try:
`git branch -d foo/bar` and get a correct error `branch foo/bar not
found` but hard to understand for a newbie, this patch aims to guide one
in such case.

when failing to delete a branch with `git branch -d <branch>` because
of branch not found, try to find a **remote refs** matching `<branch>`
and if so, add an hint:
`Did you forget --remote?` to the error message

Signed-off-by: Clement Mabileau <mabileau.clement@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/branch.c b/builtin/branch.c
index f63fd45edb96b513c24e1a9cd7c8a55e5a5f7b13..5f035dd5969b80039f4f63973f89a8490d896610 100644 (file)
--- a/builtin/branch.c
+++ b/builtin/branch.c
@@ -216,10 +216,11 @@ static int delete_branches(int argc, const char **argv, int force, int kinds,
        struct string_list refs_to_delete = STRING_LIST_INIT_DUP;
        struct string_list_item *item;
        int branch_name_pos;
+       const char *fmt_remotes = "refs/remotes/%s";
 
        switch (kinds) {
        case FILTER_REFS_REMOTES:
-               fmt = "refs/remotes/%s";
+               fmt = fmt_remotes;
                /* For subsequent UI messages */
                remote_branch = 1;
                allowed_interpret = INTERPRET_BRANCH_REMOTE;
@@ -263,9 +264,25 @@ static int delete_branches(int argc, const char **argv, int force, int kinds,
                                        | RESOLVE_REF_ALLOW_BAD_NAME,
                                        &oid, &flags);
                if (!target) {
-                       error(remote_branch
-                             ? _("remote-tracking branch '%s' not found.")
-                             : _("branch '%s' not found."), bname.buf);
+                       if (remote_branch) {
+                               error(_("remote-tracking branch '%s' not found."), bname.buf);
+                       } else {
+                               char *virtual_name = mkpathdup(fmt_remotes, bname.buf);
+                               char *virtual_target = resolve_refdup(virtual_name,
+                                                       RESOLVE_REF_READING
+                                                       | RESOLVE_REF_NO_RECURSE
+                                                       | RESOLVE_REF_ALLOW_BAD_NAME,
+                                                       &oid, &flags);
+                               FREE_AND_NULL(virtual_name);
+
+                               if (virtual_target)
+                                       error(_("branch '%s' not found.\n"
+                                               "Did you forget --remote?"),
+                                               bname.buf);
+                               else
+                                       error(_("branch '%s' not found."), bname.buf);
+                               FREE_AND_NULL(virtual_target);
+                       }
                        ret = 1;
                        continue;
                }