Should typename be before or after const in C++?

Question

Should I write:

template<class T> class Foo {
    typename const T* x;
};

or:

template<class T> class Foo {
    const typename T* x;
};

Answer 1

typename is not used like this, so both cases are invalid and should produce a compilation error, like this:

main.cpp:4:20: error: expected a qualified name after 'typename'
    const typename T* x;
                   ^

Here you would need something like T::myType to go on.

Or even this, which is worse:

main.cpp:4:14: error: expected a qualified name after 'typename'
    typename const T* x;
             ^
main.cpp:4:14: error: expected member name or ';' after declaration specifiers

Relevant example in expected a qualified name after 'typename'.

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The keyword typename was introduced to specify that the identifier that follows is a type

Read more in: Officially, what is typename for?