编译器无法识别重载的构造函数C ++

我正在尝试为基本的编译器创建符号表。我的Symbol类中有2个构造函数，一个有4个参数，一个有5个。我有一个简单的main函数，它试图创建一个Symbol对象，接受4个参数，然后再创建5个参数。编译器抱怨Symbol b具有5个参数：

error: no matching function for call to ‘Symbol::Symbol(std::string&, std::string&, int, kind, int)’
symbol.h:14: note: candidates are: Symbol::Symbol(const Symbol::string&, const Symbol::string&, int, kind)
 symbol.h:6: note:                 Symbol::Symbol(const Symbol&)

我不确定为什么说没有匹配的函数，因为它在那里。尽管我不确定“ const Symbol :: string＆”是否不同于“ std :: string＆”会导致某些问题，或者如果出现这种情况该如何解决。

这是主要的：

int main(){
    string x="x";
    string y="y";
    Symbol a(x,"int",0,SCALAR);
    Symbol b(y,"char",0,ARRAY,5);

    //operator << is overloaded
    cout << a << endl;
    cout << b << endl;
    return 0;
}

symbol.h：

#ifndef SYMBOL_H
#define SYMBOL_H
#include "type.h"
#include <string>

class Symbol{
    typedef std::string string;
    string _name;
    Type _type;

public:
    const string& getName() const;
    const Type& getType() const;
    Symbol(const string& name, const string& specifier, int indirection, kind kind); 
    Symbol(const string& name, const string& specifier, int indirection, kind kind, int length); 
};

std::ostream& operator<<(std::ostream& ostr, const Symbol& symbol);

#endif /*SYMBOL_H*/

symbol.cpp

#include "symbol.h"
#include <iostream>
using namespace std;

/*other member function definitions*/

Symbol::Symbol(const string& name, const string& specifier, int indirection, kind kind)
{
    _name = name;
    Type a(specifier,indirection,kind);
    _type = a;
}

Symbol::Symbol(const string& name, const string& specifier, int indirection, kind kind, int length)
{
    _name = name;

    /*Type is another class that holds the description of the type of the     
     *particular variable, function,etc. declaration
     */

    Type a(specifier,indirection,kind,length);
    _type = a;
}