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Template argument name resolution and compiler discrepancies

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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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Template argument name resolution and compiler discrepancies Jonathan Jones <jhjones1969@googlemail.com> - 2015-09-12 11:24 -0600
  Re: Template argument name resolution and compiler discrepancies Bo Persson <bop@gmb.dk> - 2015-09-13 07:51 -0600

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