"alias this" does not work with opEquals()

[dlangBugzillaToGithub]

Victor Porton (@vporton) reported this on 2019-01-02T07:09:31Z

Transferred from https://issues.dlang.org/show_bug.cgi?id=19538

Description

This program does not compile. I think it should do.

---
struct X {
    string m;
    alias m this;
    bool opEquals(const X s) const {
        return true;
    }
}

void main() {
    X* x = new X("");
    assert(*x == "");
}
---

$ dmd --version
DMD64 D Compiler v2.080.1
Copyright (C) 1999-2018 by The D Language Foundation, All Rights Reserved written by Walter Bright
$ dmd test.d
test.d(11): Error: function test.X.opEquals(const(X) s) const is not callable using argument types (string)
test.d(11):        cannot pass argument "" of type string to parameter const(X) s