attempt to fix CI

.gitlab-ci.yml

@@ -1,5 +1,9 @@
 image: conanio/clang7
 
+variables:
+  CC: /usr/bin/clang
+  CXX: /usr/bin/clang++
+
 build:
   stage: build
   before_script:

src/main.cc

@@ -1,6 +1,24 @@
 #include <iostream>
+#include <opencv2/core/core.hpp>
+#include <opencv2/highgui/highgui.hpp>
+
+using namespace std;
 
 int main(int argc, char **argv) {
-  std::cout << "Hello World!\n";
+  if (argc != 2) {
+    cout << " Usage: display_image ImageToLoadAndDisplay" << endl;
+    return -1;
+  }
+
+  cv::Mat image = cv::imread(argv[1], cv::IMREAD_COLOR); // Read the file
+
+  if (!image.data) // Check for invalid input
+  {
+    cout << "Could not open or find the image" << std::endl;
+    return -1;
+  } else {
+    cout << "Loaded image!\n";
+  }
+
   return 0;
 }