dfcc_loop_nesting_grapht: cleanup loop includes

Directly refer to the classes rather than going through a series of
(member) typedefs and one header that is rather unrelated.

Author: tautschnig

src/goto-instrument/contracts/dynamic-frames/dfcc_loop_nesting_graph.cpp

@@ -12,12 +12,12 @@ Date: March 2023
 
 #include "dfcc_loop_nesting_graph.h"
 
-#include <util/invariant.h>
+#include <analyses/natural_loops.h>
 
 dfcc_loop_nesting_graph_nodet::dfcc_loop_nesting_graph_nodet(
   const goto_programt::targett &head,
   const goto_programt::targett &latch,
-  const loopt &instructions)
+  const loop_templatet<goto_programt::targett> &instructions)
   : head(head), latch(latch), instructions(instructions)
 {
 }

src/goto-instrument/contracts/dynamic-frames/dfcc_loop_nesting_graph.h

@@ -18,7 +18,7 @@ Date: March 2023
 
 #include <util/graph.h>
 
-#include <goto-instrument/loop_utils.h>
+#include <analyses/loop_analysis.h>
 
 class messaget;
 
@@ -29,16 +29,17 @@ struct dfcc_loop_nesting_graph_nodet : public graph_nodet<empty_edget>
   dfcc_loop_nesting_graph_nodet(
     const goto_programt::targett &head,
     const goto_programt::targett &latch,
-    const loopt &instructions);
+    const loop_templatet<goto_programt::targett> &instructions);
 
   /// Loop head instruction
-  goto_programt::targett head;
+  const goto_programt::targett head;
 
   /// Loop latch instruction
-  goto_programt::targett latch;
+  const goto_programt::targett latch;
 
   /// Set of loop instructions
-  loopt instructions;
+  /// Should be `const`, but this doesn't work with Visual Studio.
+  loop_templatet<goto_programt::targett> instructions;
 };
 
 typedef grapht<dfcc_loop_nesting_graph_nodet> dfcc_loop_nesting_grapht;