[Issue 13773] std.traits.ReturnType does not resolve inout

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=13773

--- Comment #1 from Kenji Hara <k.hara.pg at gmail.com> ---
I think this should be marked as invalid or changed as a compiler enhancement,
because:

1. ReturnType takes an alias (through the index 0 of the TupleParameter).

2. Currently alias parameter cannot handle the runtime context of the
expression,
  so ReturnType!(m.keys), ReturnType!(c.keys), and ReturnType!(i.keys) are 
  perfectly same with ReturnType!(Foo.keys).

3. The return type of Foo.keys is inout(int)[].

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