mixin template T() { void f(C) {} } class C { mixin T V; void f(C) {} } void main() {} a.d(7): Error: class a.C use of a.C.T!().f(C _param_0) hidden by C is deprecated _V._f(C) is inserted to class C by mixin within MixinIndentifier, it is not naked f(C). Because C.V.f(C) and C.f(C) are not conflict.
Fixed by dmd 2.056.