[PATCH v3] branch: improve error log on branch not found by checking remotes refs

From: Clement Mabileau <mabileau.clement@gmail.com>

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

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1476%2Fctmbl%2Fbranch%2Fdeletion%2Fimprove-error-msg-v3
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1476/ctmbl/branch/deletion/improve-error-msg-v3
Pull-Request: https://github.com/git/git/pull/1476

Range-diff vs v2:

 1:  eb95695ace2 ! 1:  0774f182b50 branch: improve error log on branch not found by checking remotes refs
     @@
       ## Metadata ##
     -Author: ctmbl <mabileau.clement@gmail.com>
     +Author: Clement Mabileau <mabileau.clement@gmail.com>
      
       ## Commit message ##
          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:
     +    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>
     @@ builtin/branch.c: static int delete_branches(int argc, const char **argv, int fo
       	struct string_list refs_to_delete = STRING_LIST_INIT_DUP;
       	struct string_list_item *item;
       	int branch_name_pos;
     -+	char* FMT_REMOTES = "refs/remotes/%s";
     -+	char* FMT_BRANCHES = "refs/heads/%s";
     ++	const char *fmt_remotes = "refs/remotes/%s";
       
       	switch (kinds) {
       	case FILTER_REFS_REMOTES:
      -		fmt = "refs/remotes/%s";
     -+		fmt = FMT_REMOTES;
     ++		fmt = fmt_remotes;
       		/* For subsequent UI messages */
       		remote_branch = 1;
       		allowed_interpret = INTERPRET_BRANCH_REMOTE;
     -@@ builtin/branch.c: static int delete_branches(int argc, const char **argv, int force, int kinds,
     - 		force = 1;
     - 		break;
     - 	case FILTER_REFS_BRANCHES:
     --		fmt = "refs/heads/%s";
     -+		fmt = FMT_BRANCHES;
     - 		allowed_interpret = INTERPRET_BRANCH_LOCAL;
     - 		break;
     - 	default:
      @@ builtin/branch.c: static int delete_branches(int argc, const char **argv, int force, int kinds,
       					| RESOLVE_REF_ALLOW_BAD_NAME,
       					&oid, &flags);
     @@ builtin/branch.c: static int delete_branches(int argc, const char **argv, int fo
      -			error(remote_branch
      -			      ? _("remote-tracking branch '%s' not found.")
      -			      : _("branch '%s' not found."), bname.buf);
     -+			char* MISSING_REMOTE_REF_ERROR_MSG = "remote-tracking branch '%s' not found.";
     -+			char* MISSING_BRANCH_ERROR_MSG = "branch '%s' not found.";
     -+			char* MISSING_BRANCH_HINT_MSG = "branch '%s' not found.\n"
     -+											"Did you forget --remote?";
     -+
      +			if (remote_branch) {
     -+				error(_(MISSING_REMOTE_REF_ERROR_MSG), bname.buf);
     ++				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,
     ++				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(_(MISSING_BRANCH_HINT_MSG), bname.buf);
     ++					error(_("branch '%s' not found.\n"
     ++						"Did you forget --remote?"),
     ++						bname.buf);
      +				else
     -+					error(_(MISSING_BRANCH_ERROR_MSG), bname.buf);
     ++					error(_("branch '%s' not found."), bname.buf);
     ++				FREE_AND_NULL(virtual_target);
      +			}
       			ret = 1;
       			continue;

 builtin/branch.c | 25 +++++++++++++++++++++----
 1 file changed, 21 insertions(+), 4 deletions(-)