[PATCH] revsets: makes follow() supports file patterns (issue4757)

[Yuya Nishihara]

On Sun, 23 Aug 2015 11:52:21 +0200, liscju wrote:
> # HG changeset patch
> # User liscju <piotr.listkiewicz at gmail.com>
> # Date 1440083972 -7200
> #      Thu Aug 20 17:19:32 2015 +0200
> # Branch bug4757#followRevset
> # Node ID 4bd021d45c66503b7d6a01ebcc1711722e10f264
> # Parent  d9d3d49c4cf77049d12920980e91bf8e4a4ecda2
> revsets: makes follow() supports file patterns (issue4757)
> 
> Before this patch, follow only supports full, exact filenames.
> This patch makes follow argument to be treated like file
> pattern same way like log treats their arguments.
> 
> It preserves current behaviour of follow() matching files
> against the repository root, not current working directory.
> 
> diff -r d9d3d49c4cf7 -r 4bd021d45c66 mercurial/revset.py
> --- a/mercurial/revset.py	Tue Aug 18 18:38:56 2015 -0500
> +++ b/mercurial/revset.py	Thu Aug 20 17:19:32 2015 +0200
> @@ -1037,34 +1037,36 @@
>      return limit(repo, subset, x)
>  
>  def _follow(repo, subset, x, name, followfirst=False):
> -    l = getargs(x, 0, 1, _("%s takes no arguments or a filename") % name)
> +    l = getargs(x, 0, 1, _("%s takes no arguments or a pattern") % name)
>      c = repo['.']
>      if l:
> -        x = getstring(l[0], _("%s expected a filename") % name)
> -        if x in c:
> -            cx = c[x]
> -            s = set(ctx.rev() for ctx in cx.ancestors(followfirst=followfirst))
> -            # include the revision responsible for the most recent version
> -            s.add(cx.introrev())
> -        else:
> -            return baseset()
> +        x = getstring(l[0], _("%s expected a pattern") % name)
> +        wctx = repo[None]
> +        matcher = matchmod.match(repo.root, '', [x], ctx=wctx)

It makes other kind of patterns to be evaluated relative to the repository
root, not cwd. That is different from what the doc says.

https://selenic.com/repo/hg/file/tip/mercurial/match.py#l103

If we really want to preserve the current behavior, perhaps we can use
default='path'.

BTW, do we need wctx here?