[PATCH 2 of 2] dirstate: normalize on case insensitive filesystems on Mac (issue1663)

[Simon Heimberg]

Am Mittwoch, den 22.07.2009, 14:04 -0500 schrieb Matt Mackall:
> On Wed, 2009-07-22 at 15:22 +0200, Simon Heimberg wrote:
> > # HG changeset patch
> > # User Simon Heimberg <simohe at besonet.ch>
> > # Date 1248264291 -7200
> > # Node ID f812e62a12b68c035b1aef3b3732f8486c376373
> > # Parent  ca876099803a9e71497d9deaee3c9fb7ff47ee81
> > dirstate: normalize on case insensitive filesystems on Mac (issue1663)
> > 
> > os.path.normcase does not change the path on Mac OS X (uses possix module)
> > 
> > diff -r ca876099803a -r f812e62a12b6 mercurial/dirstate.py
> > --- a/mercurial/dirstate.py	Mit Jul 22 12:52:02 2009 +0200
> > +++ b/mercurial/dirstate.py	Mit Jul 22 14:04:51 2009 +0200
> > @@ -351,8 +351,14 @@
> >          except KeyError:
> >              self._ui.warn(_("not in dirstate: %s\n") % f)
> >  
> > +    _usenormcase = os.path.normcase("A") == "a"
> > +
> >      def _normalize(self, path, knownpath):
> > -        norm_path = os.path.normcase(path)
> > +        if self._usenormcase:
> > +            norm_path = os.path.normcase(path)
> > +        else:
> > +            #case insensitive filesystem on Mac OS X
> > +            norm_path = path.lower()
> 
> You're going to have to be more clever than lower(), I'm afraid.
> Consider a file named 'Ä' and the possibility that your local character
> set might be set to MacRoman. There's also the whole issue of Unicode
> normalization.
> 
This is as clever as os.path.normcase in windows and mac (not OS X) (see
ntpath.py and macpath.py from python). We could use macpath.normcase for
being upgraded when python is.

> I think we need to have a more general facility for dealing with all
> forms of folding (ie any non-direct filename matching/mangling) that
> allows us to deal with all the stupid Windowsisms and Macisms.
> Case-folding is just the most commonplace form of it.
> 
Maybe this could happen too on linux or unix when a special file system 
is mounted or with some mount options.

More general is good, but I do not have an idea how to do it. Any hint?
What are other cases of folding?