size_t vs uintptr_t

[deadalnix via Digitalmars-d]

On Tuesday, 14 June 2016 at 23:19:12 UTC, Walter Bright wrote:
> On 6/14/2016 3:38 PM, Guillaume Boucher wrote:
>> Isn't it guaranteed that x.sizeof >= x.alignof?  (At least it 
>> is in C and C++.)
>> So the alignment should be of type size_t and not of type 
>> uintptr_t.
>>
>> Also in general cast(uint)ptr%alignment is wrong since 
>> alignment does not need
>> to be 32 bit.  However, cast(size_t)ptr%alignment is be 
>> correct in any case.
>
> There is no conceivable case where alignment will be > 32 bits, 
> nor not being a power of 2.

There are many cases in which alignment in 64bits.

There is nothing that says that x.sizeof >= x.alignof must be 
respected, but really, if you don't respect that, you are simply 
wasting space and cache without getting any benefit (the purpose 
of alignment is to avoid store/load across cache lines).