[Issue 24510] New: Perfect forwarding and explicit move should be compiler intrinsic and have operators

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=24510

          Issue ID: 24510
           Summary: Perfect forwarding and explicit move should be
                    compiler intrinsic and have operators
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: qs.il.paperinik at gmail.com

Perfect forwarding parameters of parameters and explicit move requires
importing modules (that I have to look up every time and make no sense
naming-wise) and is quite unpleasant to look at in code. Last but not least,
the current implemenation of explicit move is ctfe-hostile, which makes no
sense as the compiler actually can move objects at ctfe. Both operations don’t
deserve that; they’re safe and useful.

My suggestion would be to make move (and forward, which boils down to either a
no-op or an explicit move) a compiler intrinsic. For both of them, there should
be unary operators: I suggest `>>` for forward and `<<` for move.

```d
f(move(x));
// becomes
f(<<x);

f(forward!xs);
// becomes
f(>>xs);
// xs can be a pack!
```

They’re both unary prefix operators with the same precedence as the other unary
prefix operators.

Rationale for the operator symbols:
They look very much alike, but that’s happenstance. `>>` looks like the the
"fast forward" icon. `<<` looks like an arrow pointing away from the object and
indicates: "Whatever is in here goes out of it."

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