Bug 1834 – typedeffed primitaves can't lose their constancy

Just try compiling this: void main() { string s = "hello world"; char c = s[0]; // OK typedef char mychar; alias invariant(mychar)[] mystring; mystring t = cast(mystring)("hello world"); mychar d = t[0]; // Not OK } The way I see it, either both of the lines I've commented should compile, or both should fail to compile. But the second one (mychar d = t[0]) causes the following error: cannot implicitly convert expression (t[0u]) of type invariant(mychar) to mychar So ... you can implicitly convert invariant(char) to char, but you can't convert invariant(mychar) to mychar - even though the latter is just a typedef of the former. This makes it impossible to define a "new kind of char". (Or any primitive type). I understand that /in general/ you don't want invariant(T) to implicitly cast to T, but typedefs of primitive types? That's going too far. Ideally you want to say "if T does not contain any pointers then const(T) and invariant(T) may implicitly cast to T". This bug is preventing development on one of my projects.

Works in dmd 2.011 (no errors for either case).