I find typedef useful still. While trying to create something like a typedef using a struct with "alias this", I have found this problem: struct Typedef(T) { T data; alias data this; } alias int[] TA1; typedef int[] TA2; alias Typedef!(int[]) TA3; immutable TA1 a1; immutable TA2 a2; TA3 a3a; immutable TA3 a3b; static this() { a1 = [1, 2, 3]; // OK a2 = [1, 2, 3]; // OK a3a = [1, 2, 3]; // OK a3b = [1, 2, 3]; // line 16, error } void main() {} DMD 2.057beta gives: test.d(16): Error: cannot implicitly convert expression ([1,2,3]) of type int[] to immutable(Typedef!(int[]))
I think this is a same issue with bug 6174. The assignment expression a3b = [1, 2, 3]; is translated to a3b.data = [1, 2, 3]; , and current dmd does not allow indirect initialization of members with assignment. *** This issue has been marked as a duplicate of issue 6174 ***