Fix uninitialised collect_callsites field in call_grapht

This only affected people using both collect_callsites and a call graph restricted to
those functions reachable from a particular root function, hence slipping through the net.

Author: smowton

src/analyses/call_graph.cpp

@@ -74,7 +74,8 @@ static void forall_callsites(
 call_grapht::call_grapht(
   const goto_functionst &goto_functions,
   const irep_idt &root,
-  bool collect_callsites)
+  bool collect_callsites):
+  collect_callsites(collect_callsites)
 {
   std::stack<irep_idt, std::vector<irep_idt>> pending_stack;
   pending_stack.push(root);

unit/analyses/call_graph.cpp

@@ -164,6 +164,28 @@ SCENARIO("call_graph",
       }
     }
 
+    WHEN("A call graph is constructed with both a specific root and call-site tracking")
+    {
+      call_grapht call_graph_with_specific_root =
+        call_grapht::create_from_root_function(goto_model, "B", true);
+
+      THEN("The graph should contain nodes for only B, C and D")
+      {
+        call_grapht::nodest correct_value {"B", "C", "D"};
+        REQUIRE(call_graph_with_specific_root.nodes == correct_value);
+      }
+      THEN("Only B -> C and B -> D edges should exist, each with one callsite")
+      {
+        const auto &check_callsites=call_graph_with_specific_root.callsites;
+        call_grapht::edgest correct_value { {"B", "C"}, {"B", "D"} };
+        REQUIRE(call_graph_with_specific_root.edges == correct_value);
+        for(const auto &edge : call_graph_with_specific_root.edges)
+        {
+          REQUIRE(check_callsites.at(edge).size()==1);
+        }
+      }
+    }
+
     WHEN("A call-graph is constructed rooted at B")
     {
       call_grapht call_graph_from_b =