From: Jeff King <peff@peff.net>
Date: Mon, 02 Feb 2009 12:41:40 GMT
Subject: Re: [PATCH] builtin-blame.c: Use utf8_strwidth for author's names
Message-ID: <20090202124139.GA8325@sigio.peff.net>
In-Reply-To: <7v8wopmizw.fsf@gitster.siamese.dyndns.org>

On Sun, Feb 01, 2009 at 10:48:51PM -0800, Junio C Hamano wrote:

> > I do not know what encoding the author is at that point, but if you cannot 
> > be sure that it is UTF-8, using utf8_strwidth() is just as wrong as the 
> > current code, IMHO.
> 
> That is true, but then we are not losing anything.
> 
> This codepath is not about the payload (the contents of the files) but the
> author name part of the commit log message, and UTF-8 would probably be
> the only sensible encoding to standardize on.
> 
> If your project uses UTF-8 for everybody, great, we will align them better
> than we did before.  If not, sorry, you will get a different misaligned
> names.
> 
> That assumes utf8_width() does not barf when fed an invalid byte sequence,
> but I did not think it is that fragile (I didn't actually audit the
> codepath, though).

We should be able to know the encoding (we call reencode_commit_message,
but we don't bother to save the result). It should be trivial to do:

int strwidth(const char *s, const char *encoding)
{
  if (!strcmp(encoding, "utf-8"))
    return utf8_strwidth(s);
  /* ideally, else if (some_other_encoding_family) */
  else
    return strlen(s);
}

Then utf-8 is fixed, and other encodings keep identical behavior (and
don't even waste cycles on utf-8 decoding). And it should be obvious to
anyone who wants to add a width detector for their pet encoding where it
should go.

-Peff