If you have to mark the method as abstract, it should produce an error while compiling, not on linking. I had to figure out the problem because I didn't get any error when compiling. On big projects have descriptive errors is a must.

//version = WORKS;

interface I {
	void test();
}

abstract class A : I {
	version (WORKS) {
		// Works
		abstract void test();
	} else {
		// Error 42: Symbol Undefined _D2aa1A4testMFZv
		void test();
	}
}

class B : A {
	void test() {
	}
}

int main(string[] args) {
	return 0;
}