cpplib: Charconsts and escape sequences

[Zack Weinberg]

On Fri, May 03, 2002 at 09:50:36PM +0100, Neil Booth wrote:
> This patch is further preparation for cpplib having a correct
> implementation of arithmetic to the correct target-precision,
> so that, in particular, it has no dependence on HOST_*_INT
> macros.

I like this.  You should test it with a sparc-sun-solaris2.8 target;
that's the situation where the lex_charconst issue shows up.  (It has
a combination of 64-bit HOST_WIDE_INT and a bizarre definition of
WCHAR_TYPE.)  A cross-compiler will work fine.

Cleaning up the interface to cpp_parse_escape/cpp_interpret_charconst
is a Good Thing.  The bitmask mess was asking for trouble.

I'm not sure if two-integer arithmetic is really what we want.  There
are known situations where a 32-bit host needs to do 128-bit
arithmetic; I think we currently deal with that by forcing
HOST_WIDE_INT to be "long long" when it comes up.  A real
multiple-precision library would be better.  (I don't think any of
these situations affect cpplib, but if we're going to do this we might
as well do it right.)

zw