Re: [boost] [c++0x] OK to merge cpp0x branch config changes to trunk?

Subject: Re: [boost] [c++0x] OK to merge cpp0x branch config changes to trunk?
From: Beman Dawes (bdawes_at_[hidden])
Date: 2009-02-22 08:40:28

Steven Watanabe wrote:
> AMDG
> 
> Mathias Gaunard wrote:
>> Beman Dawes wrote:
>>> See http://svn.boost.org/svn/boost/branches/cpp0x
>>>
>>> This branch adds the following config macros:
>>>
>>> [...]             BOOST_NO_DECLTYPE                    [...]
>>
>> I see that this macro is defined for GCC 4.3+ when std=c++0x is not used.
>> However, decltype is still available with __decltype__ outside of 
>> C++0x experimental mode.
>>
>> Would a
>> #define decltype __decltype__
>> on this compiler not be a better idea?
> 
> No it wouldn't.  A BOOST_DECLTYPE macro would
> be acceptable, but effectively overriding the default -std
> is not a good idea, as it can affect user code.

Agreed.

When we in effect alter the behavior of a compiler and/or language, it 
is far less confusing to users to do it in a loud and noisy fashion 
(BOOST_DECLTYPE) than silently (#define decltype __decltype__). Macros 
that silently change language features have a long history of unintended 
consequences.

--Beman