Re: [boost] BOOST_WORKAROUND and gcc warnings

From: John Maddock (john_at_[hidden])
Date: 2007-08-25 11:32:37

Peter Dimov wrote:
> John Maddock:
>
>> Is the proposal here: http://svn.boost.org/trac/boost/ticket/1130 a
>> viable way of fixing the pesky gcc warnings from BOOST_WORKAROUND?
>
> It works for me.

That was my first thought, however, on reflection it looks fragile: with 
this change BOOST_WORKAROUND when applied to an unknown pp-symbol will 
always silently return 0, which isn't what we want to have happen :-(

What if we reverse the logic a little:

# define BOOST_WORKAROUND(symbol, test) \
(0 == (BOOST_WORKAROUND_GUARD_ ## symbol) && \
(symbol != 0) && (1 % (( (symbol test) ) + 1)))

Which (I hope!) has no change to current behaviour if 
BOOST_WORKAROUND_GUARD_ ## symbol is not defined.

Then for common pp-symbols we add:

#define BOOST_WORKAROUND_GUARD_BOOST_MSVC !defined(BOOST_MSVC)

And hopefully the warnings get suppressed: at least in the common cases.

John.