[c++] weird conflict with template template parameter taking subtype of previous parameter as a non-type ordinal

[charles James Leonardo]

Binary package hint: gcc-4.5

The following code will not compile:

template <int i>
struct LabelTypeMap { typedef int type_t; };

template <bool>
struct Hold { typedef int type; };

template<typename Holder, template<typename Holder::type> class typeMap>
struct Whatever { };

template <bool Enable>
struct Now { typedef Whatever<Hold<Enable>, LabelTypeMap> concrete_t; };

int main()
{ Now<true>::concrete_t t; };

i get these errors:

 error: type/value mismatch at argument 2 in template parameter list for ‘template<class Holder, template<typename Holder::type <anonymous> > class typeMap> struct Whatever’
expected a template of type ‘template<typename Holder::type <anonymous> > class typeMap’, got ‘template<int i> struct LabelTypeMap’

Hint: if i replace this:

template <bool Enable>
struct Now { typedef Whatever<Hold<Enable>, LabelTypeMap> concrete_t; };

with this:
template <bool Enable>
struct Now { typedef Whatever<Hold<true>, LabelTypeMap> concrete_t; };

it builds just fine.

tested versions:
g++ (Ubuntu/Linaro 4.4.4-14ubuntu5) 4.4.5
g++-4.5 (Ubuntu/Linaro 4.5.1-7ubuntu2) 4.5.1

Description: Ubuntu 10.10
Release: 10.10