[cfe-commits] r44058 - in /cfe/trunk: Sema/SemaExpr.cpp test/Sema/floating-point-compare.c

[Chris Lattner]

On Nov 14, 2007, at 3:36 AM, Neil Booth wrote:

> Ted Kremenek wrote:-
>
>>> More generally, should it be suppressed for comparisons against
>>> any FP constant that is exact as written?
>>>
>>> Neil.
>>
>> I'm not certain.  Also, I wonder if the following two cases should be
>> treated separately:
>>
>>   x == 0.0
>>
>> and
>>
>>  x == 3.14159  (or any non-zero constant)
>>
>> The first case still isn't really kosher either, but suppressing
>> warnings for explicit tests against 0.0 probably will suppress more
>> false positives than the number of false negatives it will cause.
>
> Indeed, and same for 1.0 and -1.0 etc.  All those numbers are exact
> as written.
>
>> I think the second case is far more likely to be an error.
>
> 3.14159 is not exact as written so would be diagnosed under my
> proposal.

This is an interesting proposal.  Is there any way to tell that the  
value is inexact?

-Chris