[Issue 13113] cannot build druntime's gc.d with -debug=INVARIANT, bad @nogc inference?

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=13113

--- Comment #3 from Rainer Schuetze <r.sagitario at gmx.de> ---
>Does reverting the invariant portion of [1] allow it to compile?

I haven't actually reverted the code, but commenting out the contents of
Gcx.invariant didn't help. Commenting out the destructor of Treap DOES help.

Here is a further reduction of the test case:

class Gcx
{
    invariant() {}

    Treap!int tr;
}

struct Treap(E)
{
    ~this() {} // no error if this line is removed
}

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