Clang complains unsigned integer arithmetic overflows

[llvmbot]

Bugzilla Link	3942
Resolution	FIXED
Resolved on	Mar 12, 2010 00:57
Version	unspecified
OS	NetBSD
Reporter	LLVM Bugzilla Contributor
CC	@efriedma-quic

Extended Description

one e.g.

#if 5U << 63
#endif

[efriedma-quic]

The affected operators are binary +, -, *, and <<. I'm not entirely sure we want to change this, though... are there any realistic use cases for unsigned overflow in a preprocessor expression?

[llvmbot]

For multiplication (and hence <<) I can see it being used to condition on object/memory sizes. Dunno about + and -, but I think consistency between CPP arithmetic and front end arithmetic should be the goal as the rules for both are largely identical, certainly when it comes to overflow.

[lattner]

I tend to agree with Neil that it is good to make the PP and sema rules be as similar as possible.

[efriedma-quic]

Fixed in r71960.