The complement of true is true, except when it's false

With such example:

  bool Complement( bool x )
  {
      return ~x;
  }

  test.cpp:3:10: warning: ‘~’ on an expression of type bool [-Wbool-operation]
    return ~x;

C++ is a true spiritual successor to Perl, in a way. It can express anything and everything, its syntax is arcane, as is its logic. Most of the time, of course, what you see is what you get, until the moment when what you see is what you don't get.

They should have defined true as -1 (all bits set) instead, as in some other languages like Forth and BASIC.

In any field of characteristic 2, every element is its own negative. So on the surface this makes sense, notwithstanding the unintuitive enum corner case behaviour

I wonder if [[=std::bitmask_type]] also enables compiler warnings that a switch statement is not exhaustive if it does not cover all possible flag combinations.

I thought attributes were reserved for compiler-specific semantics like calling conventions. Here they're just being used as stropping for a language feature with syntactic significance!