*  @param optag     The tag of the operation tree.
     *  @param env       The environment current at the operation.
     *  @param argtypes  The types of the operands.
     */
    Symbol resolveOperator(DiagnosticPosition pos, int optag,
                           Env<AttrContext> env, List<Type> argtypes) {
        startResolution();
        Name name = treeinfo.operatorName(optag);
        Symbol sym = findMethod(env, syms.predefClass.type, name, argtypes,
                                null, false, false, true);
        if (boxingEnabled && sym.kind >= WRONG_MTHS)
            sym = findMethod(env, syms.predefClass.type, name, argtypes,
                             null, true, false, true);
        return access(sym, pos, env.enclClass.sym.type, name,
                      false, argtypes, null);
    }