using std::__enable_if template as constructor parameter

[Michal Bukovský]

Hello,

     I try use std::__enable_if as class constructor but gcc don't see
     this constructor while I try use it. Then I write small bit of code,
     which I think, is same and gcc don't compile this too.

     template <typename>
     struct is_allowed {};

     template <>
     struct is_allowed<int> { typedef int type; };

     class SomeObject {
     public:
         template <typename Type>
         SomeObject(const typename is_allowed<Type>::type &) {}
     };

     int main(int /*argc*/, char *[] /*argv*/) {
         SomeObject o(1);
     }

     Gcc says:

     a.cc: In function ‘int main(int, char**)’:
     a.cc:112: error: no matching function for call to ‘SomeObject::SomeObject(int)’
     a.cc:105: note: candidates are: SomeObject::SomeObject(const SomeObject&)

     I can't understand why gcc don't instantiate constructor template
     SomeObject::SomeObject<>?

     Can anybody explain me this?

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Michal Bukovský
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