[cfe-dev] new warnings

[Sebastian Redl]

Florian Weimer wrote:
> * Mike Stump:
>
>   
>> ?  [ toquote the the C rules, as my fingers for some reason didn't  
>> find the C++ rules in seconds ]
>>     
>
> The C++ rules are different.  I think the warning is bogus in C++ mode.
> [basic.lval] rules out most of the strict aliasing analysis, AFAIK.
>   
Here's the 3.10/15, which discusses aliasing:

If a program attempts to access the stored value of an object through an 
lvalue of other than one of the fol-
lowing types the behavior is undefined48):
— the dynamic type of the object,
— a cv-qualified version of the dynamic type of the object,
— a type that is the signed or unsigned type corresponding to the 
dynamic type of the object,
— a type that is the signed or unsigned type corresponding to a 
cv-qualified version of the dynamic type of
    the object,
— an aggregate or union type that includes one of the aforementioned 
types among its members (includ-
    ing, recursively, a member of a subaggregate or contained union),
— a type that is a (possibly cv-qualified) base class type of the 
dynamic type of the object,
— a char or unsigned char type.

48) The intent of this list is to specify those circumstances in which 
an object may or may not be aliased.