[cfe-users] inserted-name bug?

[Jens B. Jorgensen]

Compiling the attached sample produces:

clang_inserted_name_bug.cpp:34:45: error: template argument for template
      template parameter must be a class template or type alias template
                typedef TraitChooser_t<TRAITS, BASE_TYPE, TemplClass> Traits;
                                                          ^
clang_inserted_name_bug.cpp:35:55: error: template argument for template
      template parameter must be a class template or type alias template
                typedef BASE_TYPE<TraitChooser_t<TRAITS, BASE_TYPE, Temp...
                                                                    ^
2 errors generated.

I think this is incorrect as even though TemplClass becomes an injected-class-name when used in the template-argument-list where a template parameter goes it should get the template, not the class. Others discuss here:

https://stackoverflow.com/questions/12810630/how-do-i-refer-to-a-class-template-as-a-template-from-within-its-own-class-def

--
Jens B. Jorgensen jorgensen at kcg.com<mailto:jorgensen at kcg.com>
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// build with: clang++ -c -std=c++11 clang_inserted_name_bug.cpp

#include <type_traits>
	template <typename TRAITS, typename DERIVEDTYPE>
	struct DerivedTraits : public TRAITS
	{
		typedef DERIVEDTYPE DerivedType;
		static constexpr bool hasDerived() { return true; }
	};


	template <typename TRAITS, template <typename> class DERIVEDTYPE>
	struct TraitChooser
	{
		typedef typename std::conditional<TRAITS::hasDerived(), TRAITS, DerivedTraits<TRAITS, DERIVEDTYPE<TRAITS> > >::type TraitType;
	};


	template<template<typename> class BASE_TYPE, template<typename, template<typename> class> class DERIVED_TEMPLATE>
	struct BaseClassTransformer
	{
		template<typename TRAITS>
		using Result = DERIVED_TEMPLATE<TRAITS, BASE_TYPE>;
	};

	template<
		typename Traits,
		template<typename> class BASE_TYPE,
		template<typename, template<typename> class> class DERIVED_TEMPLATE> using TraitChooser_t = typename TraitChooser<Traits, BaseClassTransformer<BASE_TYPE, DERIVED_TEMPLATE>::template Result>::TraitType;


	template <typename TRAITS, template<typename> class BASE_TYPE>
	class TemplClass : public BASE_TYPE<TraitChooser_t<TRAITS, BASE_TYPE, TemplClass>>
	{
	public:
		typedef TraitChooser_t<TRAITS, BASE_TYPE, TemplClass> Traits;
		typedef BASE_TYPE<TraitChooser_t<TRAITS, BASE_TYPE, TemplClass>> base_t;
	};

	struct Traits
	{
		constexpr static bool hasDerived() { return false; }
	};

	template <typename T>
	class BaseClass
	{
	};
		
void instantiate()
{
	TemplClass<Traits, BaseClass> tc;
}