Add deterministic C++ reference adapter

tests/fixtures/reference-cpp/src/main.cpp

@@ -0,0 +1,17 @@
+#include "../include/config.hpp"
+
+namespace demo {
+
+int execute(int value) {
+    Config config{value};
+    if (value == 0) {
+        return effective_limit(config);
+    }
+    return normalize(value);
+}
+
+}  // namespace demo
+
+int main() {
+    return demo::execute(3);
+}

tests/fixtures/reference-cpp/src/worker.cpp

@@ -0,0 +1,17 @@
+#include "../include/config.hpp"
+
+namespace demo {
+
+class Worker {
+public:
+    int run(int value) {
+        for (int attempt = 0; attempt < 2; ++attempt) {
+            if (value > attempt) {
+                return effective_limit(Config{value});
+            }
+        }
+        return 0;
+    }
+};
+
+}  // namespace demo