[PATCH] bookmarks: reject bookmark names that unambiguously resolve to a node (BC)

[Yuya Nishihara]

On Mon, 22 May 2017 19:44:52 -0400, Augie Fackler wrote:
> # HG changeset patch
> # User Augie Fackler <augie at google.com>
> # Date 1495495092 14400
> #      Mon May 22 19:18:12 2017 -0400
> # Node ID 2b2ecc8ef94635e26ba41246db5bd693e6078481
> # Parent  8db2feb04cebc1878c6232dd2650f2c5468d350e
> bookmarks: reject bookmark names that unambiguously resolve to a node (BC)
> 
> I just burned myself on this today because I left out the -r in my `hg
> bookmark` command, which then left me confused because I didn't notice
> the bookmark I created in the wrong place that was silently shadowing
> the revision I was trying to check out. Let's just reject this without
> --force to avoid user confusion.
> 
> This patch only enforces the check on bookmark names 4 characters long
> or longer. We can tweak that if we'd like, I selected that since
> that's the fewest characters shortest will use in the templater
> output, but it does increase the odds that an otherwise-valid bookmark
> will become unusable later (eg 'cafe' which currently only matches
> hidden revisions in my clone of Mercurial.) I think the inconvenience
> on short hex-friendly words is worth the extra sanity for users in the
> long term.

I like the idea, but the new behavior might be a bit confusing because
the conflicted names aren't statically predictable. It might also cause
problems in scripting and automation use.

So, how about showing a warning message?

> diff --git a/mercurial/commands.py b/mercurial/commands.py
> --- a/mercurial/commands.py
> +++ b/mercurial/commands.py
> @@ -968,6 +968,10 @@ def bookmark(ui, repo, *names, **opts):
>              and not force):
>              raise error.Abort(
>                  _("a bookmark cannot have the name of an existing branch"))
> +        if len(mark) > 3 and mark in repo and not force:

repo.__contains__() may raise error.LookupError if mark is an ambiguous hash.