[Webkit-unassigned] [Bug 59249] Colliding isinf/isnan between C99 and C++0x with GCC 4.6.0

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=59249





--- Comment #6 from Xan Lopez <xan.lopez at gmail.com>  2011-04-22 23:19:22 PST ---
(In reply to comment #5)
> (From update of attachment 90792 [details])
> View in context: https://bugs.webkit.org/attachment.cgi?id=90792&action=review
> 
> > Source/JavaScriptCore/ChangeLog:9
> > +        Don't use "using namespace std;" in files where isnan or isinf are
> > +        used, since it can lead to ambiguity in C++0x compilers. See the
> 
> This is not a very maintainable rule, and following it makes the code base less consistent. I hope that there is a better solution.

I can't really think of any, but there might be. My proposed long-term solution of getting rid of math.h and always using std:: in front of the functions also requires not to use "using namespace std;", at least in the files where isnan/isinf are called, so it wouldn't be a huge improvement in that regard, I suppose.

> 
> Is this a gcc bug, or expected behavior?

The spec, AFAICU, leaves undefined whether or not the functions are also present in the global namespace (on top of being in std::), so I don't think it's a bug but just the way it happens to be on GCC. For details see section 17.6.1.2 (4) of http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2010/n3092.pdf

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