I figured an explicit instantiation request would automatically instantiate all base class members also, but I get a linker error: unresolved external symbol "public: void Base<int>::foo(int)" when building this code using Visual Studio 2008 or 2010.

Note that adding a call to foo() inside bar() forces the compiler to instantiate Base<int>::bar() and the build succeeds, so it appears that the compiler has all the necessary information to instantiate foo().

Obviously, explicitly instantiating Base<int> in source.cpp allows the build to succeed, but it seems silly to need to explicitly instantiate any dependent base classes whenever explicitly instantiating a derived class.

Is this normal? I couldn't find what the standard says regarding this issue.

header.h

template<typename T>
class Base {
public:
    void foo();
};

template<typename T>
class Derived : public Base<T> {
public:
    void bar();
};

source.cpp

#include "header.h"

template<typename T>
void Base<T>::foo() { }

template<typename T>
void Derived<T>::bar() {
    // this->foo();   // adding this forces instantiation of foo()???
}

template class Derived<int>;

main.cpp

#include "header.h"

int main() {
    Derived<int> d;
    d.foo(); // Linker Error: unresolved external symbol "public: void Base<int>::foo(int)"
}

Edit:

It looks like the Standard says only members of a class get instantiated by an explicit class instantiation, so the linker error is justified in my example.

Note that a class is defined by class-head { member-specification } and "The member-specification in a class definition declares the full set of members of

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