Re: linux/kernel.h (&_x == &_y); why

[Momchil Velikov <velco@fadata.bg>]

>>>>> "Jan" == Jan Hudec <bulb@ucw.cz> writes:

Jan> On Tue, Dec 02, 2003 at 15:12:52 -0800, John Tyner wrote:
>> I believe that it is so that gcc will throw a warning if the two types 
>> are not compatible.

Jan> Actualy, it should throw a warning if they are not exactly the same,
Jan> because if they are not, the comparsion breaks aliasing rules.
Jan> Especially it should throw a warning if one is signed and the other is
Jan> not.

Aliasing rules are NOT like this.  See below:

[#7] An object shall have its stored value accessed only by an lvalue
     expression that has one of the following types:73)

  -- a type compatible with the effective type of the object,

  -- a qualified version of a type compatible with the effective type
     of the object,

  -- a type that is the signed or unsigned type corresponding to the
     effective type of the object,

  -- a type that is the signed or unsigned type corresponding to a
     qualified version of the effective type of the object,

  -- an aggregate or union type that includes one of the
     aforementioned types among its members (including, recursively, a
     member of a subaggregate or contained union), or

  -- a character type.

~velco
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