Comparing constexpr function parameter in constexpr-if condition causes error

Question

I\'m trying to compare a function parameter inside a constexpr-if statement.

Here is a simple example:

constexpr bool test_int(const int i) {
  if c         


        

Answer 1

A constexpr function can be called with non-constexpr arguments, in which case it behaves like a normal function, so the code must still compile as if it were not constexpr.

In short, there's nothing in test_int_no_if that depends on i being constexpr, while in test_int(), there is. ("constexpr if" only works with compile time expressions.)