trac 21887 some forgotten cases

src/sage/rings/complex_interval.pyx

@@ -1406,7 +1406,7 @@ cdef class ComplexIntervalFieldElement(sage.structure.element.FieldElement):
             sage: bool(CIF(RIF(-1, 1), RIF(-1, 1)))
             True
         """
-        return self.real().__bool__() or self.imag().__bool__()
+        return bool(self.real()) or bool(self.imag())
 
     cpdef _richcmp_(left, right, int op):
         r"""

src/sage/rings/function_field/function_field_element.pyx

@@ -560,7 +560,7 @@ cdef class FunctionFieldElement_rational(FunctionFieldElement):
         """
         return repr(self._x)
 
-    def __bool__(self):
+    def __nonzero__(self):
         """
         EXAMPLES::
 

src/sage/rings/polynomial/polynomial_element.pyx

@@ -8976,7 +8976,7 @@ cdef class Polynomial_generic_dense(Polynomial):
         """
         return make_generic_polynomial, (self._parent, self.__coeffs)
 
-    def __bool__(self):
+    def __nonzero__(self):
         return len(self.__coeffs) > 0
 
     cdef int __normalize(self) except -1:

src/sage/rings/polynomial/polynomial_modn_dense_ntl.pyx

@@ -1604,7 +1604,7 @@ cdef class Polynomial_dense_modn_ntl_ZZ(Polynomial_dense_mod_n):
                 return n
         return infinity
 
-    def __bool__(self):
+    def __nonzero__(self):
         """
         TESTS::