code: OperatorSymbol resolveUnary(DiagnosticPosition pos, JCTree.Tag tag, Type op) {
          return resolve(tag,
                  unaryOperators,
                  unop -> unop.test(op),
                  unop -> unop.resolve(op),
                  () -> reportErrorIfNeeded(pos, tag, op));
      }
docs: Entry point for resolving a unary operator given an operator tag and an argument type.