Re: proposed Opengroup action for c99 command (XCU ERN 76)

[Joe Buck <Joe dot Buck at synopsys dot COM>]

On Wed, Sep 14, 2005 at 01:50:19PM -0700, Paul Eggert wrote:
> In response Joseph S. Myers pointed out that this action would require
> c99 to use interpretation B of section 5.2.1 (page 20) of the C99 Rationale
> <http://www.open-std.org/jtc1/sc22/wg14/www/C99RationaleV5.10.pdf>.
> The Rationale says C preprocessors can be implemented in three ways:
> 
>   A.  Convert everything to UCNs in basic source characters as soon
>       as possible, that is, in translation phase 1.  (This is what
>       C++ requires, apparently.)
> 
>   B.  Use native encodings where possible, UCNs otherwise.
> 
>   C.  Convert everything to wide characters as soon as possible
>       using an internal encoding that encompasses the entire source
>       character set and all UCNs.
>
> The C99 standardizers chose (B), but said implementations could also
> use (A) or (C) because the C99 standard gives almost unlimited freedom
> in translation phase 1 for compilers to do whatever transformations
> they like.
> 
> However, the proposed action for the c99 command would close this
> escape hatch, forcing interpretation (B) for c99 implementations.
> 
> So my question is: Is it a burden on GCC to require interpretation (B)?

This is written in terms of internal implementation rather than visible
behavior.  Can you provide an example that lets us distinguish a compiler
that uses method A, from a compiler that uses method B?  If "where
possible" in B simply means "in cases where otherwise the user could 
tell that we aren't doing A", then there would be no observable
difference.