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)
No. [temp.local]/6:
A template-parameter shall not be redeclared within its scope (including nested scopes).
来源：https://stackoverflow.com/questions/35744299/can-a-parameter-of-a-template-template-parameter-cause-shadowing