clone in situ compiled terms

src/prolog/machine/machine_state.rs

@@ -268,8 +268,7 @@ impl MachineState {
     }
 }
 
-fn try_in_situ_lookup(name: ClauseName, arity: usize, indices: &IndexStore)
-                      -> Option<usize>
+fn try_in_situ_lookup(name: ClauseName, arity: usize, indices: &IndexStore) -> Option<usize>
 {
     match indices.in_situ_code_dir.get(&(name.clone(), arity)) {
         Some(p) => Some(*p),

src/prolog/machine/mod.rs

@@ -149,14 +149,15 @@ impl CodeRepo {
             cl.name().map(|name| (name, arity))
         }).ok_or(SessionError::NamelessEntry)?;
 
-        let p   = self.in_situ_code.len();
+        let p = self.in_situ_code.len();
         in_situ_code_dir.insert((name, arity), p);
 
         let mut cg = CodeGenerator::<DebrayAllocator>::new(true, flags);
-        let mut decl_code = cg.compile_predicate(&decl.0)?;
-
+        // clone the decl to avoid the need to wipe its register cells later.
+        let mut decl_code = cg.compile_predicate(&decl.0.clone())?;        
+        
         compile_appendix(&mut decl_code, queue, true, flags)?;
-
+                
         self.in_situ_code.extend(decl_code.into_iter());
         Ok(())
     }

src/prolog/machine/term_expansion.rs

@@ -104,7 +104,7 @@ impl ExpansionAdditionResult {
 impl<'a, R: Read> Drop for TermStream<'a, R> {
     fn drop(&mut self) {
         self.indices.in_situ_code_dir.clear();
-        self.code_repo.in_situ_code.clear();        
+        self.code_repo.in_situ_code.clear();
         discard_result!(self.rollback_expansion_code());
     }
 }
@@ -322,7 +322,6 @@ impl MachineState {
             };
 
             output.push_char('.');
-
             self.reset();
             Some(output.result())
         }