Use `constexpr` functions to compute values at compile time

Reason

A function is the most obvious and conventional way of expressing the computation of a value. Often a constexpr function implies less compile-time overhead than alternatives.

Note

"Traits" techniques are mostly replaced by template aliases to compute types and constexpr functions to compute values.

Example

template<typename T>
    // requires Number<T>
constexpr T pow(T v, int n)   // power/exponential
{
    T res = 1;
    while (n--) res *= v;
    return res;
}

constexpr auto f7 = pow(pi, 7);

Enforcement

• Flag template metaprograms yielding a value. These should be replaced with constexpr functions.