How to make a function accept certain parameters using templates and concepts

I want to write a function that accepts a certain number of parameters using constant templates, for example:

template<int count>
void foo(int... args) { ... }

foo<1>(0); // success
foo<2>(0); // error
foo<3>(0, 0, 0); // success

count in templates decides how many parameters it can accept.

I tried to write a prototype like this

template <int a, int b>
concept equal = (a == b);

template <int size>
void foo(int... args) requires equal<sizeof...(args), size>
{ ... }

and it fails to complie. What is the correct way to do it, or is there a simplier method.

thanks very much

Solution

int... args is not the way to have int arg0, int arg1, .., int argN

int... is used for number0, number1, ..., numberN
as in std::integer_sequence<int, 4, 8, 15, 16, 23, 42>

You might do:

template<int count, std::same_as<int> ...Ints>
void foo(Ints... args) requires (sizeof...(args) == count)
{
  // ...
}