C++ code compiled with g++ works, but XCode fails - c++

Question

I'm trying to compile a small C++ example in XCode 12.5.1 using the linear algebra library armadillo, which I've installed without problems:
//example.cpp
#include <armadillo>
#include <iostream>
using namespace std;
using namespace arma;
int
main(int argc, char** argv)
{
cout << "Armadillo version: " << arma_version::as_string() << endl;
cx_vec eigval;
cx_mat eigvec;
mat A(3,3,fill::zeros);
eig_gen(eigval, eigvec, A);
cout << A << "\n";
cout << eigval << "\n";
cout << eigvec << "\n";
return 0;
}
Specifically, I'm trying to figure out why the inclusion function eig_gen() gives me linking errors in XCode (removing the function call allows for proper compilation):
Undefined symbols for architecture x86_64:
"_dgeev_", referenced from:
void arma::lapack::geev<double>(char*, char*, int*, double*, int*, double*, double*, double*, int*, double*, int*, double*, int*, int*) in main.o
"_dgeevx_", referenced from:
void arma::lapack::geevx<double>(char*, char*, char*, char*, int*, double*, int*, double*, double*, double*, int*, double*, int*, int*, int*, double*, double*, double*, double*, double*, int*, int*, int*) in main.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Since if I compile the program using g++ on the command line,g++ example.cpp -o example -std=c++11 -O2 -larmadillo, the compilation is successful and the program outputs:
Armadillo version: 10.6.2 (Keep Calm)
0 0 0
0 0 0
0 0 0
(0,0)
(0,0)
(0,0)
(+1.000e+00,+0.000e+00) (+1.000e+00,-0.000e+00) (0,0)
(+0.000e+00,+1.000e+00) (+0.000e+00,-1.000e+00) (0,0)
(0,0) (0,0) (+1.000e+00,+0.000e+00)
The only change I made to XCode's default linking setup (the project is a Command Line Tool project) is to include /usr/local/include in System Header Search Paths, so that I can use the code's first line #include <armadillo>.
Any suggestions as to why XCode specifically might be giving me this error?
############################### Update
I've noticed that if I place the definition #define ARMA_DONT_USE_WRAPPER in the fist line of the program above #include <armadillo>, then the command-line compilation using g++ also outputs the same linking errors. This suggests to me that the error is related to armadillo.