private void convertExpression(PsiExpression expr, PsiType toType, PsiType fromType, boolean isCovariantPosition, PsiMember member) {
    final TypeConversionDescriptorBase conversion = myRules.findConversion(fromType, toType, member, expr, isCovariantPosition, this);

    if (conversion == null) {
      markFailedConversion(toType, expr);
    }
    else {
      setConversionMapping(expr, conversion);
    }
  }
private void convertExpression(PsiExpression expr, PsiType toType, PsiType fromType, boolean isCovariantPosition, PsiMember member)