return parameter not supported

[MartinNowak]

///
module test;

///
ref int foo(return ref int a) @safe
{
    return a;
}

///
int* foo(return scope int* a) @safe
{
    return a;
}

///
ref int* foo(scope return ref int* a) @safe
{
    return a;
}

///
struct S
{
@safe:
    ///
    ref S foo() return
    {
        return this;
    }

    ///
    S foo() return scope
    {
        return this;
    }

    ///
    ref S foo() return scope
    {
        return this;
    }

    int* p;
}

[MartinNowak]

duplicate of #181