Re: Array size validity and SFINAE

Am 25.02.26 um 17:08 schrieb Andrey Tarasevich:

   #include <iostream>
    struct S { static constexpr int N = -1; };
    template <typename T> void foo(int [T::N])
   {
     std::cout << "array" << std::endl;
   }
    template <typename T> void foo(...)
   {
     std::cout << "..." << std::endl;
   }
    int main()
   {
     foo<int>(0);
   }
 GCC outputs "array", Clang and MSVC output "..."

You are taking an array by value. This might not be the intention and might take a slice. Since the array index is unsigned -1 is UB or in fact expand to UINT_MAX.
If you write
   template <typename T> void foo(int (&)[T::N])
gcc will also output ...
I am unsure whether the overload resolution should take place before the other checks.
Marcel

Date	Sujet	#		Auteur
25 Feb 26	Array size validity and SFINAE	9		Andrey Tarasevich
1 Mar 26	Re: Array size validity and SFINAE	5		Marcel Mueller
1 Mar 26	Re: Array size validity and SFINAE	3		Andrey Tarasevich
2 Mar 26	Re: Array size validity and SFINAE	2		Chris M. Thomasson
2 Mar 26	Re: Array size validity and SFINAE	1		Andrey Tarasevich
2 Mar 26	Re: Array size validity and SFINAE	1		Bonita Montero
2 Mar 26	Re: Array size validity and SFINAE	3		Tim Rentsch
2 Mar 26	Re: Array size validity and SFINAE	2		Andrey Tarasevich
3 Mar 26	Re: Array size validity and SFINAE	1		Tim Rentsch

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