Issue 1974 - What's your opinion?

[kinke]

On Thursday, 24 October 2019 at 08:02:28 UTC, RazvanN wrote:
> What are your thoughts on this? Should be close the issue as an 
> invalid one?

I'm clearly in favor of the filed issue, i.e., see it as valid. 
This is for consistency with primitive types, and lvalue-ness is 
IMO a clear intrinsic requirement for a (bin)assign operator's 
left hand side:

```
struct S { int i; }

struct O
{
     int i;
     void opOpAssign(string op)(int) {}
}

T make(T)() { return cast(T) 1; }

void foo()
{
     make!int() += 2; // Error: `make()` is not an lvalue and 
cannot be modified
     make!S() += 2;   // Error: `make()` is not an lvalue and 
cannot be modified
     make!O() += 2;   // compiles
}
```

Allowing rvalues for an explicit opOpAssign!"+" call is IMO fine, 
but not when using the operator, as that's just a leaking 
implementation detail.