Re: C++ mode and c-beginning-of-current-token

[Herbert Euler]

> > Please try the same thing with Emacs 22 started with
> > "--unibyte" argument.  The same error is signalled.
> >
> > So, the bug has been in the original code of skip_chars
> > (where it handles a unibyte case) in Emacs 22.  Could
> > someone please fix it in Emacs 22?  Then, I'll do the same
> > fix on emacs-unicode-2.
>
> FWIW, I couldn't find problems with the attached patch.


> *** syntax.c    Wed Jan 17 09:31:10 2007
> --- syntax.c    Thu May 17 11:15:42 2007
> ***************
> *** 1672,1678 ****
>                   if (! fastmap[(int) SYNTAX (p[-1])])
>                     break;
>                   p--, pos--;
> !                 UPDATE_SYNTAX_TABLE_BACKWARD (pos - 1);
>                 }
>           }
>         }
> --- 1672,1678 ----
>                   if (! fastmap[(int) SYNTAX (p[-1])])
>                     break;
>                   p--, pos--;
> !                 UPDATE_SYNTAX_TABLE_BACKWARD (pos);
>                 }
>           }
>         }

Can I ask a silly question, too?  There are two "calling"s of
UPDATE_SYNTAX_TABLE_BACKWARD in `skip_chars', one with the "argument"
(pos), the other with (pos - 1).  To me, the second one does not look
like a typo, but a correct piece of code on purpose.  Yes, changing it
from (pos - 1) to (pos) works, but it seems to be dangerous to me.

UPDATE_SYNTAX_TABLE_BACKWARD also updates `gl_state' by setting its
members `forward_i' and `backward_i'.  Perhaps (pos - 1) is for
keeping these two members at right positions.  Different "argument"s
passed to UPDATE_SYNTAX_TABLE_BACKWARD sets the two intervals
differently.  There are still some details I did not make clear, so I
am still confused now.

Regards,
Guanpeng Xu

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