[libc++] Add missing 'return 0' from main functions in tests

Author: ldionne

libcxx/test/libcxx/algorithms/alg.sorting/pstl.is_partitioned.pass.cpp

@@ -26,4 +26,6 @@ int main(int, char**) {
     return i < 5;
   }));
   assert(call_count == std::size(a));
+
+  return 0;
 }

libcxx/test/libcxx/algorithms/robust_against_using_non_transparent_comparators.pass.cpp

@@ -58,7 +58,7 @@ struct Iterator {
   T* ptr_;
 };
 
-int main() {
+int main(int, char**) {
   int array[5] = {1, 2, 3, 4, 5};
   Iterator<int> first(array);
   Iterator<int> middle(array + 3);
@@ -74,4 +74,6 @@ int main() {
   (void)std::min_element(first, last);
   (void)std::minmax_element(first, last);
   (void)std::upper_bound(first, last, 3);
+
+  return 0;
 }

libcxx/test/std/thread/thread.stoptoken/stopcallback/dtor.pass.cpp

@@ -163,4 +163,6 @@ int main(int, char**) {
     ss.request_stop(); // the callbacks deletes itself. if the destructor blocks, it would be deadlock
     assert(holder.callback_ == nullptr);
   }
+
+  return 0;
 }

libcxx/test/std/utilities/expol/policies.compile.pass.cpp

@@ -47,4 +47,6 @@ int main(int, char**) {
 #if TEST_STD_VER >= 20
   use(std::execution::unseq);
 #endif
+
+  return 0;
 }