C `restrict` keyword in D

[Johan Engelen via Digitalmars-d]

On Monday, 4 September 2017 at 14:28:14 UTC, Dukc wrote:
> On Sunday, 3 September 2017 at 03:04:58 UTC, Uknown wrote:
>> In C, the `restrict` keyword implies that 2 or more pointer 
>> arguments in a function call do not point to the same data.
>
> I really don't see where the restrict keyword is needed at all, 
> neither in C nor in D. If you want to imply to the compiler 
> that there is no need to reload the pointed data between uses, 
> just assign it to a local.

It's need for auto-vectorization, for example.

I would support an LDC PR for adding a magic UDA to be able to 
attach 'restrict' with C-semantics to function parameters. E.g.
```
  // add restrict to parameters 1 and 2
void foo(int, int*, int*) @restrict(1,2)
```

-Johan