[Issue 23278] New: Can't pass alias member to a function

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=23278

          Issue ID: 23278
           Summary: Can't pass alias member to a function
           Product: D
           Version: D2
          Hardware: All
                OS: Windows
            Status: NEW
          Severity: normal
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: msnmancini at hotmail.com

This trivial code fails to compile with the error message: 
`onlineapp.Test2.mxString!(oops).mxString` need `this` to access member
`mxString`

```d
class Test2
{
    string oops;
    mixin(mxString!(oops));
}
enum mxString(alias c)()
{
    return "";
}
```

This should compile as there is no dependent usage on "this". Plus, the message
is obviously wrong as there is no member named `mxString`.

A real use case for that is:
```d
enum mxString(alias c)()
{
    return typeof(c).stringof~" "~c.stringof~c.stringof~";";
}
```
Which does not depends on "this", as some code like `mxString!(typeof(oops),
oops.stringof)` would work.

Mixin template does not have this limitation, so, I believe a normal function
should not too.

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