The difference between T[] opIndex() and T[] opSlice()

[Paul Backus]

On Tuesday, 3 October 2023 at 13:07:00 UTC, Steven Schveighoffer 
wrote:
>
> Now, you can define a further `opIndexAssign(T val, size_t 
> idx)`. However, now you lose capabilities like `a[0]++`, which 
> I don't think has a possibility of implementing using an 
> `opIndex` operator, and it would be pretty ugly if you had to.

Works for me, with both `++` and `+=`: 
https://run.dlang.io/is/JckTVG

AST output confirms that these are lowered to use `opIndex`.

Looking at the spec, it seems like `opIndex` would only be 
pre-empted here if you overloaded `opIndexUnary` (for `++`) 
and/or `opIndexOpAssign` (for `+=`).