std::SignedIntegral
From cppreference.com
Defined in header <concepts>


template < class T > concept SignedIntegral = std::Integral<T> && std::is_signed_v<T>; 
(since C++20)  
The concept SignedIntegral<T>
is satisfied if and only if T
is an integral type and std::is_signed_v<T> is true.
Notes
SignedIntegral<T>
may be satisfied by a type that is not a signed integer type, for example, char (on a system where char is signed).
See also
(C++11) 
checks if a type is an integral type (class template) 
(C++11) 
checks if a type is a signed arithmetic type (class template) 