Comment # 1 on bug 1178241 from Aaron Puchert

To quote C11 [1], 6.3.2.3.6:

> Any pointer type may be converted to an integer type. Except as previously
> specified, the result is implementation-defined. If the result cannot be
> represented in the integer type, the behavior is undefined. The result need
> not be in the range of values of any integer type.

So this is warning about undefined behavior.

However, 7.20.1.4 comes to the rescue:

> The following type designates a signed integer type with the property that any
> valid pointer to void can be converted to this type, then converted back to
> pointer to void, and the result will compare equal to the original pointer:
>     intptr_t
> The following type designates an unsigned integer type with the property that
> any valid pointer to void can be converted to this type, then converted back
> to pointer to void, and the result will compare equal to the original pointer:
>     uintptr_t
> These types are optional.

[1] http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf