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Template template parameters and variadic templates with gcc 4.4

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情深已故
情深已故 2021-01-11 12:47

I\'m using gcc 4.4 on Debian squeeze. Consider the following code.

#include 
#include 
using std::map;
using std::string;

// Args l
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  • 太阳男子
    太阳男子 (楼主)
    2021-01-11 13:53

    I don't think variadic template parameters can match non-variadic arguments in g++4.4, so you need to overload your foo function with a non-variadic version.

    Also keep in mind that map actually has more than two template parameters, and therefor wont match the new foo-function either.

    This addition to your example should clarify it:

    #include 
#include 
using std::map;
using std::string;

// Args lets the user specify additional explicit template arguments
template  class C,
          typename... Args>
C foo() {
  C x;
  return x;
}

template class C, typename Arg>
C foo() {
  return C();
}

template class A {};

template class B {};

int main(void) {
  map a = foo(); // fails.
  A x = foo();
  B y = foo();
}

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