Daniel Frey <d.frey@gmx.de> wrote: [...] I tried following code: #include <iostream> template <typename T> class V {}; template <template <typename> class T> struct B {}; struct D : B<V> {}; template <typename T> void f (const B<T>&) { std::cout << typeid(T).name() << std::endl; } int main() { D d; f (d); } According to Comeau compiler and GCC this program is invalid. I have following error messages (from GCC 3.3.1): T246.cpp:6: error: type/value mismatch at argument 1 in template parameter list for `template<template<class> class T> struct B' T246.cpp:6: error: expected a class template, got `T' T246.cpp:7: error: ISO C++ forbids declaration of `parameter' with no type T246.cpp: In function `int main()': T246.cpp:13: error: no matching function for call to `f(D&)' (from Comeau online 4.3.3 beta) "ComeauTest.c", line 6: error: template parameter "T" is not a class template void f (const B<T>&) ^ "ComeauTest.c", line 13: error: no instance of function template "f" matches the argument list The argument types that you used are: (D) f (d); ^ ... however it compiles under VC71, and the output of this program is: class V I think that's a surprise? B.