Hi folks,
Look at the following example code:
template<typename>
class Base
{
typedef int ValueType;
};
template<typename ValueType>
struct Derived : public Base<ValueType>
{
Derived(ValueType);
};
Derived<float> obj(1);
This code compiles cleanly with GCC 4.7.2 and Clang 3.5 (Xcode 6.2).
However, it fails to compile with Visual Studio 2013, complaining that it
cannot access private typedef "Base<ValueType>::ValueType".
Furthermore, if you make the private typedef public:
template<typename>
class Base
{
public:
typedef int ValueType;
};
It compiles on all three compilers, but the produces different answers.
GCC and clang result in ValueType=float in the Derived constructor
definition, whereas Visual Studio 2013 results in ValueType=int in the
Derived constructor definition.
What does the standard say should happen in these cases? Which compiler(s)
are closer to implementing the standard behavior?
The standard is clear (see C++11 section 14.6.1 paragraph 9) about what
happens when "Base" is not a template, but it seems more vague about when
"Base" is a template (which the example above seems to demonstrate).
Sincerely,
Jonathan Jones
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