Bug 8718 – Template mixin + string mixin name collision

From the (simplified) discussion @ http://forum.dlang.org/thread/[email protected] ---- mixin template T(string s) { void f() { mixin("++" ~ s ~ ";"); //L5 } } struct S { int x; } void main() { S a; S s; mixin T!("a.x"); mixin T!("s.x"); //L18 } ---- main.d(5): Error: undefined identifier 'x', did you mean 'struct S'? main.d(18): Error: mixin main.main.T!("s.x") error instantiating ---- When trying to instantiate the template mixin T the second time with "s.x", the compiler gets confused because the name of the string parameter is also "s", making "s.x" illegal. I think this is a catch 22: - On the one hand, the code generated by the template is, AFAIK, genuinely illegal, as s shadows the outside world's s, and the generated "s.x" is indeed illegal. - On the other hand, I think it is not conceivable to tell a client "your code failed to work, because you declared your variable with the same name as the argument of a function: You are not allowed to call your variable s because it's taken." WHAT? Not sure what to make of this...

I don't think this is a bug... If you use mixins, you may get symbol conflicts.

I think this is working correctly, with the template parameter shadowing the local variable. It is fairly easy to work around by either renaming the variable or using alias parameters instead of string mixins.