https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106128
Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Resolution|--- |INVALID Status|UNCONFIRMED |RESOLVED --- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> --- >its internals What do you mean internals? When you do a static cast anything to a bool, it is always converted to "!= 0". This is not an internal part of GCC but part of the language. GCC is not warning about the constant version because it know exactly that 0.0 != 0.0 will be true at compile time as it is considered an constant expression as required by the C++ standard. clang does not have -Wfloat-equal so there is nothing to compare against here. Also note comparing against 0.0 will have -0.0 be equal too. Which might not be what you wnated either.