Problem with move assignment in C++. Illegal instruction: 4

I’m writing a simple Matrix class, and I’ve defined, among others, an operator+ overloading and a move assignment. It looks like something happens when the two of them interact, but I can’t find where I am wrong. Here’s my code (I’ve deleted everything superfluous, and just left what is needed to show the bug). The problematic line is at the end, in the main:

#include <iostream>
#define DEF -1

using namespace std;
//----- Matrix -----//
class Matrix{
private:
    float **matrixpp;
    int dim_r;
    int dim_c;

public:
    Matrix(int d_r = DEF, int d_c = 0);   
    Matrix(const Matrix&);
    Matrix(Matrix&&);
    Matrix& operator=(Matrix&&);
    ~Matrix();

    Matrix operator+(const Matrix&);

    void print();
    void fill();

};

//----- Matrix -----//
Matrix::Matrix(int d_r, int d_c){

    if(d_r == DEF){
        do{
            cout << "number of rows: ";
            cin >> dim_r;
            if(dim_r <= 0){
                cout << "ERROR" << endl;
            }
        }
        while(dim_r <= 0);

        do{
            cout << "Number of columns: ";
            cin >> dim_c;
            if(dim_c <= 0){
                cout << "ERROR" << endl;
            }
        }
        while(dim_c <= 0);


    }
    else{
        dim_r = d_r;
        dim_c = d_c;
    }

    matrixpp = new float*[dim_r];

    for(int i = 0; i < dim_r; i++){
        matrixpp[i] = new float[dim_c];
    }

    for(int r = 0; r < dim_r; r++){
        for(int c = 0; c < dim_c; c++){
            matrixpp[r][c] = 0;
        }
    }
}

Matrix::Matrix(const Matrix& tocopy)
:matrixpp(tocopy.matrixpp), dim_r(tocopy.dim_r), dim_c(tocopy.dim_c)
{

    matrixpp = new float*[dim_r];

    for(int i = 0; i < dim_r; i++){
        matrixpp[i] = new float[dim_c];
    }

    for(int r = 0; r < dim_r; r++){
        for(int c = 0; c < dim_c; c++){
            matrixpp[r][c] = tocopy.matrixpp[r][c];
        }
    }
}

Matrix::Matrix(Matrix&& tomove)
:matrixpp(tomove.matrixpp), dim_r(tomove.dim_r), dim_c(tomove.dim_c)
{
    tomove.matrixpp = nullptr;

}

Matrix& Matrix::operator=(Matrix&& tomove){

    cout << "--- MA ---" << endl;
    matrixpp = tomove.matrixpp;
    dim_r = tomove.dim_r;
    dim_c = tomove.dim_c;

    tomove.matrixpp = nullptr;
}

Matrix::~Matrix(){

    if(matrixpp != nullptr){
        for(int i = 0; i < dim_r; i++){
            delete[] matrixpp[i];
        }
        delete[] matrixpp;
    }
}

Matrix Matrix::operator+(const Matrix& m){

    if(this->dim_r == m.dim_r && this->dim_c == m.dim_c){
        Matrix new_m(m.dim_r, m.dim_c);

        for(int r = 0; r < new_m.dim_r; r++){
            for(int c = 0; c < new_m.dim_c; c++){
                new_m.matrixpp[r][c] = this->matrixpp[r][c] + m.matrixpp[r][c];
            }
        }

        return new_m;
    }
    else{
        cout << "ERROR" << endl;
    }
}

void Matrix::print(){
    int temp;

    for(int r = 0; r < dim_r; r++){
        for(int c = 0; c < dim_c; c++){
            cout << matrixpp[r][c] << " ";

        }
        cout << endl;
    }
    cout << endl;
}

void Matrix::fill(){
    float temp;

    for(int r = 0; r < dim_r; r++){
        for(int c = 0; c < dim_c; c++){
            cout << "new value: " << endl;
            this->print();
            cin >> temp;
            matrixpp[r][c] = temp;
            system("clear");
        }
    }
}

//-------- Main -------//
int main(){

    Matrix m0;
    m0.fill();
    Matrix m1(0);

    m1 = m0+m0; // problematic line

    //m1.print();

}

It gives me the error when the move assignment is called to move the result of m0+m0 in m1.

If I compile my code with g++ on a Mac, the error given is just “Illegal instruction: 4”, nothing more, nothing less. If I do it on a Linux, the error given is:

In member function ‘Matrix Matrix::operator+(const Matrix&)’: p.cpp:90:16: error: use of deleted function ‘constexpr Matrix::Matrix(const Matrix&)’ return new_m; ^~~~~ p.cpp:9:7: note: ‘constexpr Matrix::Matrix(const Matrix&)’ is implicitly declared as deleted because ‘Matrix’ declares a move constructor or move assignment operator class Matrix{ ^~~~~~

Thank you in advance!