V3 PATCH: numeric_limits<> support, fix PR/3865

[Joseph S. Myers]

On 1 Sep 2002, Gabriel Dos Reis wrote:

> | If we do this, let's leave the macros undocumented so that third
> | party code doesn't come to rely on them.
> 
> I have no problem with that.  I thought gccint.texi was for GCC
> developers only and I was "obliged" by some conventions to document
> them. 

If an extension is used only by GCC libraries and headers, it should still 
be documented, with a statement that it is only to be used by GCC 
libraries and headers.  The documentation currently says that the _BIT__ 
macros should not be used directly; I see no need for any change in that 
regard.  If the __TARGET_ macros also should not be used directly, an 
appropriate note should be added to their documentation.

-- 
Joseph S. Myers
jsm28@cam.ac.uk