Re: [boost] Another patch for long long in gcc -std=c++98

From: Aaron W. LaFramboise (aaronrabiddog51_at_[hidden])
Date: 2004-08-18 13:05:38

John Maddock wrote:
> How about something like:
> 
> BOOST_EXTENSION(x)
> 
> which expands to "__extension__ x" on gcc and "x" otherwise?
> 
> Then we can use BOOST_EXTENSION(long long) where necessary.

This is what I initially tried to do.  However, it is difficult to make
work.

Consider:

template<typename T> class myclass {
};
__extension__ template<> class myclass<long long> {
};

Note the placement of __extension__.  This is the only place that
__extension__ can be placed that it will make the error go away, and not
trigger a parse error.

Simply prefixing "long long" with __extension__ does not, in general,
work.  With complicated source lines, the placement of __extension__ may
be entirely non-obvious.  It is possible, for certain constructs, that
there is no appropriate way that __extension__ might be added.  In fact,
the documentation is not clear on exactly how __extension__ is supposed
to be placed, as (in my reading) its description does not correspond
with actual usage:
http://gcc.gnu.org/onlinedocs/gcc-3.4.1/gcc/Alternate-Keywords.html

Using __extension__ at each instance of long long would require anyone
using long long in Boost headers to know particular characteristics of
GCC in this regard, which I think is unacceptable.  I think a typedef is
the only way to shield the rest of Boost from this issue.

Aaron W. LaFramboise