The body of constexpr function not a return-statement

Question

In the following program, I have added an explicit return statement in func(), but the compiler gives me the following error:

m.cpp: In         


        

Answer 1

Prior to C++14, the body of a constexpr function must consist solely of a return statement: it cannot have any other statements inside it. This works in C++11 :

constexpr int func (int x) 
{
  return x < 0 ? -x : x;
}

In C++14 and up, what you wrote is legal, as are most other statements.

Source.