Re: [boost] [wave] problem with long long suffixes

From: Paul Mensonides (pmenso57_at_[hidden])
Date: 2005-11-23 04:51:00

> -----Original Message-----
> From: boost-bounces_at_[hidden] 
> [mailto:boost-bounces_at_[hidden]] On Behalf Of Alexey Bakhvalov

> It would be ok if Wave tool printed this warning and 
> preprocessing continued outputting two tokens '11' and 'LL'. 
> Instead of this it throws wave::cpplexer::lexing_exception 
> and stops preprocessing as if '11LL' is invalid character sequence.
> '11LL' is in no way different from '11ABC' and the latter 
> produces two tokens as expected.

Both '11LL' and '11ABC' are valid _preprocessing tokens_.  However, with long
long support, the former is a valid _token_ but the latter is not.  At the point
where preprocessing tokens are converted into tokens, an error should occur, not
two tokens.  That point is directly between where preprocessing ends and the
rest of the phases of translation.  Normally, a standalone preprocessor doesn't
go all the way in the conversion phase, but Wave does because it is producing
tokens by going into phase 7.  IMO, there are only two options here: 1) Wave
should yield preprocessing tokens instead of tokens, or 2) Wave should yield an
error trying to translate '11ABC' into a token (or '11LL' if long long is not
explicitly enabled--it isn't part of standard C++ yet).

> This kind of behavior leads to some problems. For example, 
> you can't use Boost.Wave for preprocessing many of the boost 
> files without enabling support for long long suffixes because 
> boost/limit.hpp uses them (but they are ifdef'ed away if you 
> define some macroses).

Personally, I think that Wave should produce preprocessing tokens.  An iterator
adaptor could be applied to produce tokens (or more accurately, do the checking
that tokens require).

Regards,
Paul Mensonides