Re: [boost] WCHAR_MAX not defined on openbsd

Subject: Re: [boost] WCHAR_MAX not defined on openbsd
From: Kim Barrett (kab.conundrums_at_[hidden])
Date: 2010-08-16 13:44:03

On Aug 16, 2010, at 1:17 PM, Bo Persson wrote:

> Kim Barrett wrote:
>> On Aug 15, 2010, at 12:09 PM, John Maddock wrote:
>>> The std doesn't specify that some magic macro has to be defined
>>> before WCHAR_MAX gets defined
>> 
>> The C++ standard doesn't, but the C99 standard does!  See footnote
>> in 7.18.2 Limits of specified-width integer types.  This is one of
>> several places where C99 added features to C89 and notes that "C++
>> implementations should define these macros only when ..." some
>> specified macro is defined before the relevant header is included.
>> 
>> And of course that specified behavior is probably quite wrong for
>> C++0x, but the C99 standard doesn't mention the scope of that
>> behavior.  And to add to the confusion, it is worded as a "should"
>> rather than a "shall".
>> 
> 
> It is wrong for C++0x, which specifically mentions that the macros are 
> NOT to be used in <cstdint>.
> §18.4.1

That's not how I read 18.4.1.  Quoting from n3092 (the most recent
draft I happen to have handy), 18.4.1/2 says

    The header defines all functions, types, and macros the same as
    7.18 in the C standard. [Note: The macros defined by <cstdint> are
    provided unconditionally.  In particular, the symbols
    __STDC_LIMIT_MACROS and __STDC_CONSTANT_MACROS (mentioned in
    footnotes 219, 220, and 222 in the C standard) play no role in
    C++. -- end note]

I read that as saying that macros such as WCHAR_MAX are always defined
by <cstdint>, irrespective of any definitions (or lack thereof) for
__STDC_LIMIT_MACROS.