[Bug c++/35852] -Wconversion rejects bitwise negation and assignment, cannot cast around

[manu at gcc dot gnu dot org]

------- Comment #5 from manu at gcc dot gnu dot org  2008-08-22 13:53 -------
This is the current situation as of revision 139373.

typedef unsigned short  ushort;

enum {
        FOO = 0x13
};

template <typename T>
inline
void
andnot(T& lv, const T& rv) {
  lv &= ~rv; // -Wconversion  int(lv) & ~(int(rv))
}

int
main(int, char*[]) {
  ushort x = 99;
  x = ~FOO;               // -Wsign-conversion -20 -> unsigned short
  x &= ~FOO;              // -Wconversion int(x) & ~(int(19)) -> unsigned short
  x = x & ~FOO;           // -Wconversion int(x) & ~(int(19)) -> unsigned short
  x = x & ushort(~FOO);   // no warning
  x = x & ushort(~ushort(FOO));   // no warning
  x &= static_cast<ushort>(~FOO); // no warning
  x &= ~x;                        // no warning
  andnot(x, ushort(FOO)); // instantiated from here
  return x;
}

I don't see what is wrong with the warnings. Would you mind elaborating?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35852