[fpc-devel] Dangerous optimization in CASE..OF

[Martok]

Booleans are not enums in Delphi (not even ordinals), but their own little
thing. "if boolean_expr" is always a jz/jnz, no matter what. They are defined as
0=FALSE and "everything else"=TRUE

However:

var
  b : boolean;
begin
  b:=boolean(3);
  if b = True then
    writeln(true)
  else if b = False then
    writeln(false)
  else
    writeln(ord(b));
end.

That writes 3, which is why your should never compare on the boolean lexicals.
Some Winapi functions returning longbool rely on that.

Wait, that was a trick question, wasn't it?