[cfe-commits] libc++ and const expr.

[Sebastian Redl]

On 04.02.2012, at 19:06, Howard Hinnant wrote:

> On Feb 4, 2012, at 12:52 PM, Howard Hinnant wrote:
> 
>> On Feb 4, 2012, at 12:04 PM, Eli Friedman wrote:
>>> 
>>> [expr.shift]p2: [...] if E1 has a signed type and non-negative value,
>>> and E1×2E2 is representable in the result type, then that is the
>>> resulting value; otherwise, the behavior is undefined.
>>> 
>>> -Eli
>> 
>> I see, you're point is that I've walked into undefined territory because I set the sign bit on the long long?  Does changing 1LL to 1ULL make the compiler happy?
> 
> Another question:  Is there a motivation for giving the compile time behavior of these operations a different behavior than they would have at run time?

The runtime behavior is undefined. Do you really want the compile time behavior to be the same?

As a side note, I think the diagnostics here could still be improved.

Sebastian
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