wip

src/libexpr/eval.cc

@@ -939,6 +939,10 @@ void EvalState::resetFileCache()
 
 void EvalState::eval(Expr * e, Value & v)
 {
+    auto sayHello = evalSettings.generateCallgraph;
+    if(sayHello) {
+         std::cout << "hello here?" << std::endl;
+    }
     e->eval(*this, baseEnv, v);
 }
 

src/libexpr/eval.hh

@@ -445,6 +445,11 @@ struct EvalSettings : Config
 
     Setting<bool> useEvalCache{this, true, "eval-cache",
         "Whether to use the flake evaluation cache."};
+
+    Setting<bool> generateCallgraph{this, false, "callgraph-profile",
+        R"(
+          TODO write some documentation about that.
+        )"};
 };
 
 extern EvalSettings evalSettings;