问精神X3，两个规则在组合成一个之后不会编译。

EN

namespace x3 = boost::spirit::x3;

struct Expression;

struct FunctionExpression {
    std::string functionName;
    std::vector<x3::forward_ast<Expression>> inputs;
};

struct Expression: x3::variant<int, double, bool, FunctionExpression> {
    using base_type::base_type;
    using base_type::operator=;
};

rule<struct basic_exp_class, ast::Expression> const
    basic_exp = "basic_exp";
rule<struct exp_pair_class, std::vector<ast::Expression>> const 
    exp_pair = "exp_pair";
rule<struct range_class, ast::FunctionExpression> const 
    range = "range";

auto const basic_exp_def = double_ | int_ | bool_;
auto const exp_pair_def = basic_expr >> ',' >> basic_expr;
auto const range_def = attr("computeRange") >> '{' >> exp_pair >> '}';

BOOST_SPIRIT_DEFINE(basic_expr, exp_pair_def, range_def);

rule<struct basic_exp_class, ast::Expression> const
    basic_exp = "basic_exp";
rule<struct range_class, ast::FunctionExpression> const 
    range = "range";

auto const basic_exp_def = double_ | int_ | bool_;
auto const range_def = attr("computeRange") >> '{' >> (
    basic_exp >> ',' >> basic_exp
) >> '}';

BOOST_SPIRIT_DEFINE(basic_expr, range_def);

spirit/include/boost/spirit/home/x3/operator/detail/sequence.hpp:149:9: error: static assertion failed: Size of the passed attribute is less than expected.
     static_assert(
     ^~~~~~~~~~~~~

// If you got an error here, then you are trying to pass
// a fusion sequence with the wrong number of elements
// as that expected by the (sequence) parser.