module a;
import b;
import c;

class A {
	static __gshared A a;
	void f(B b) {}
	void g(C c) {} // <- Error: identifier 'C' is not defined
}

////////////
module b;
import a;
class B { void f(A x = A.a) {} }

////////////
module c;
import a;
class C { void f(A x = A.a) {} }



There is no problem if class A, B and C are in the same module.
So this dependency is valid and the error is specific for inter-module circular dependency.

If default parameter "= A.a" for B.f is removed, it goes well.
There is no problem if A.a appeared in the body of B.f.

It seems that the compiler tries to recognize the semantics of default parameter A.a when it is reading declaration of B.f.
Default parameters are usually hint for the expressions which call the functions with default parameters, this behavior is inexplicable.


This error is a regression between 2.031 and 2.032.