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>. ยง18.4.1
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.