#!/bin/sh
cat >/tmp/test-at.txt <<'CPP'
#include <cstdio>
int main(){puts("x")@puts("y")@}
CPP
tr '@' '\073' </tmp/test-at.txt >/tmp/test-at.cpp
c++ -O2 -std=c++17 /tmp/test-at.cpp -o /tmp/test-at
/tmp/test-at