Can a parameter of a template template parameter c

Question

Is this legal C++?

template <typename T, template <typename T> class>
struct S { };

Clang (3.7.1) rejects it, complaining the second T shadows the first T. GCC seems not to care about it and I think that's reasonable. I think it is only the number of parameters that matters in a template template parameter.

• http://goo.gl/51bHVG (gcc.godbolt.org)

Answer 1

No. [temp.local]/6:

A template-parameter shall not be redeclared within its scope (including nested scopes).