Method visit

src/ast/ast_const_folding.cpp:849–852

            func = f;
        }
        virtual FunctionPtr visit ( Function * that ) override {
            func = nullptr;
            return Visitor::visit(that);
        }
    // turn static assert into nada or report error
        virtual ExpressionPtr visit(ExprStaticAssert * expr) override {
            auto cond = expr->arguments[0];