bug#37633: Column part interpreted wrong in compilation mode

[Eli Zaretskii]

> Date: Sun, 6 Oct 2019 14:31:12 +0200
> From: Anton Ertl <anton@mips.complang.tuwien.ac.at>
> Cc: bernd@net2o.de, 37633@debbugs.gnu.org, anton@mips.complang.tuwien.ac.at
> 
> On Sat, Oct 05, 2019 at 07:16:53PM +0300, Eli Zaretskii wrote:
> > For byte offsets in external text we have bufferpos-to-filepos, but
> > that requires us to know the encoding of the external text.  We need
> > to find a reasonable way of getting that.  Suggestions and patches
> > welcome.
> 
> It's the encoding that you assumed for the text when you loaded the
> file into the buffer.

I'm not sure this is correct.  You are saying that the compiler counts
bytes in the original file, not in its output (which might be encoded
differently).  Do we have conclusive evidence that this is always
true?

> the byte position does not depend on the encoding (unlike the
> character position).

??? The same Latin-1 characters encoded in ISO-8859-1 and in UTF-8
will yield a different number of bytes.  So I don't think I understand
how can you say the above.