Compilation error when including eigen library - c++

Question

I'm currently using eigen library, and this is the only file that I include eigen:
Kraftwerk2.cpp:
#include "Kraftwerk2.h"
Kraftwerk2::Kraftwerk2(int n){ //n: num instances
Connectivity_mat.resize(n,n);
}
int Kraftwerk2::Parse_Inst_Name(string s){ //input: String("M12"), output: int 12
return stoi(s.substr(1));
}
void Kraftwerk2::Generate_Connectivity_matrix(unordered_map<string, net> map){
for(auto& it : map){
int n =it.second.net_pin.size();
for(int i=0; i<n; i++){
for(int j=i+1; j<n; j++){
Connectivity_mat(i,j) = Connectivity_mat(i,j) +1;
}
}
}
}
void Kraftwerk2::Print_Mat(){
IOFormat CleanFmt(4, 0, ", ", "\n", "[", "]");
cout << Connectivity_mat.format(CleanFmt);
}
Kraftwerk2.h:
#include <iostream>
#include <Eigen/Core>
#include "module.h"
using namespace std;
// unordered_map<string, instance> instances;
// unordered_map<string, net> nets;
using namespace Eigen;
class Kraftwerk2{
public:
Kraftwerk2(int);
MatrixXd Connectivity_mat;
int Parse_Inst_Name(string);
void Generate_Connectivity_matrix(unordered_map<string, net>);
void Print_Mat();
};
And I use makefile for compiling:
(I'm pretty new to makefile, so if there's something I can improve, please tell me)
(Eigen is installed in the working directory ./eigen)
# CC and CFLAGS are varilables
CC = g++
CFLAGS = -c
OPTFLAGS = -O2
DBGFLAGS = -g -D_DEBUG_ON_
# make all
all : bin/partition
#echo -n "make complete!"
# optimized version
bin/partition: main_opt.o FM.o partition.o module.o Kraftwerk2.o
$(CC) $(OPTFLAGS) main_opt.o FM.o partition.o module.o Kraftwerk2.o -o bin/partition
main_opt.o: src/main.cpp src/FM_alg.h src/partition.h src/module.h src/Kraftwerk2.h
$(CC) -I ./eigen $< -o $#
FM.o: src/FM_alg.cpp src/FM_alg.h
$(CC) $(CFLAGS) $(OPTFLAGS) $< -o $#
partition.o: src/partition.cpp src/partition.h
$(CC) $(CFLAGS) $(OPTFLAGS) $< -o $#
Kraftwerk2.o: src/Kraftwerk2.cpp src/Kraftwerk2.h
$(CC) ./eigen $(CFLAGS) $(OPTFLAGS) $< -o $#
module.o: src/module.cpp src/module.h
$(CC) $(CFLAGS) $(OPTFLAGS) $< -o $#
# clean all the .o and executable files
clean:
rm -rf *.o lib/*.a lib/*.o bin/*
However, when I make, the terminal seems to output some error that comes form the library itself(???
g++ -I ./eigen src/main.cpp -o main_opt.o
In file included from ./eigen/Eigen/Core:269,
from src/Kraftwerk2.h:2,
from src/main.cpp:4:
./eigen/Eigen/src/Core/util/IndexedViewHelper.h:69:23: error: declaration of ‘template<class first> constexpr Eigen::Index Eigen::internal::first(const first&)’ shadows template parameter
69 | EIGEN_CONSTEXPR Index first(const T& x) EIGEN_NOEXCEPT { return x.first(); }
| ^~~~~
./eigen/Eigen/src/Core/util/IndexedViewHelper.h:68:10: note: template parameter ‘first’ declared here
68 | template<typename T>
| ^~~~~~~~
make: *** [makefile:15: main_opt.o] Error 1
I would be so appreciated if anybody can tell me what's wrong with this.