module remedy.math.matrix;

struct Vector4
{
	float x = 0.0f;
	float y = 0.0f;
	float z = 0.0f;
	float w = 0.0f;

	static immutable zero =		Vector4( 0.0f, 0.0f, 0.0f, 0.0f );
	static immutable one =		Vector4( 1.0f, 1.0f, 1.0f, 1.0f );
	static immutable right =	Vector4( 1.0f, 0.0f, 0.0f, 0.0f );
	static immutable up =		Vector4( 0.0f, 1.0f, 0.0f, 0.0f );
	static immutable forward =	Vector4( 0.0f, 0.0f, 1.0f, 0.0f );
	static immutable origin =	Vector4( 0.0f, 0.0f, 0.0f, 0.0f );
	static immutable identity =	Vector4( 0.0f, 0.0f, 0.0f, 1.0f );
}

struct Matrix4
{
	union
	{
		struct
		{
			Vector4 x = Vector4.right;
			Vector4 y = Vector4.up;
			Vector4 z = Vector4.forward;
			Vector4 t = Vector4.zero;
		}
		float[16] m;
		Vector4[4] v;
	}

	static immutable Matrix4 identity = Matrix4.init;
}



The final line causes the error:
  static immutable Matrix4 identity = Matrix4.init;

Remove the initialisation ( = Matrix4.init), and it works fine.