Simplified static_assert 

The static_assert macro helps identify assert failures during compile time. This feature has been supported since C++11; however, the static_assert macro used to take a mandatory assertion failure message till, which is now made optional in C++17.

The following example demonstrates the use of static_assert with and without the message:

#include <iostream>
#include <type_traits>
using namespace std;

int main ( ) {

        const int x = 5, y = 5;

        static_assert ( 1 == 0, "Assertion failed" );
        static_assert ( 1 == 0 );
        static_assert ( x == y );

        return 0;
}

The output of the preceding program is as follows:

g++-7 staticassert.cpp -std=c++17
staticassert.cpp: In function ‘int main()’:
staticassert.cpp:7:2: error: static assertion failed: Assertion failed
  static_assert ( 1 == 0, "Assertion failed" );
  
staticassert.cpp:8:2: error: static assertion failed
  static_assert ( 1 == 0 );

From the preceding output, you can see that the message, Assertion failed, appears as part of the compilation error, while in the second compilation the default compiler error message appears, as we didn't supply an assertion failure message. When there is no assertion failure, the assertion error message will not appear as demonstrated in static_assert ( x == y ).  This feature is inspired by the C++ community from the BOOST C++ library.