Error when inheriting from templated class and calling templated function - c++

Question

I've got some template code that I'm modifying and I've run into an odd error that I can't work around. I was able to recreate the problem with the below simpler (but admittedly pointless) code snippet:
struct Widget
{
};
template <typename A>
class Foo
{
public:
template <int numA>
inline bool funcCall()
{
return numA > 0;
}
inline bool funcCallNoTemplate()
{
return false;
}
};
template <typename B>
class Bar : public Foo<B>
{
public:
// doesn't work
bool concrete()
{
return Foo<B>::funcCall<5>();
}
// works fine
bool other()
{
return Foo<B>::funcCallNoTemplate();
}
};
int main()
{
Bar<Widget> b;
b.concrete();
b.other();
return 0;
}
The error I get with GCC 4.7 is the following (line 30 is the body of Bar::concrete):
example.cxx: In member function ‘bool Bar<B>::concrete()’:
example.cxx:30: error: expected primary-expression before ‘)’ token
example.cxx: In member function ‘bool Bar<B>::concrete() [with B = Widget]’:
example.cxx:43: instantiated from here
example.cxx:30: error: invalid operands of types ‘<unresolved overloaded function type>’ and ‘int’ to binary ‘operator<’
It seems like the compiler can't even parse this correctly, am I missing something here that makes that line completely bogus?

Answer 1

It seems like the compiler can't even parse this correctly, am I missing something here that makes that line completely bogus?
Yes. You need to use the template disambiguator:
return Foo<B>::template funcCall<5>();
// ^^^^^^^^
This way you will tell the compiler to parse the dependent name funcCall as the name of a member function template, and the subsequent angular brackets as delimiters for the corresponding template arguments.
Without it, funcCall will be parsed as the name of a data member, while < and > will be parsed as less-than and greater-than, respectively.