bugfix: set assignment type for actual parameters correctly

Author: Daniel Kroening

regression/cbmc/compact-trace/test.desc

@@ -5,6 +5,6 @@ activate-multi-line-match
 ^EXIT=10$
 ^SIGNAL=0$
 ^↳ main\.c:10 main\(\)\n  12: x=1 .*$
-^↳ main.c:13 bar\(0\)\n  13: bar_a=0 .*\n  5: x=2 .*\n  6: x=3 .*$
+^↳ main\.c:13 bar\(0\)\n  5: x=2 .*\n  6: x=3 .*$
 --
 ^warning: ignoring

src/goto-symex/symex_function_call.cpp

@@ -125,7 +125,21 @@ void goto_symext::parameter_assignments(
         }
       }
 
-      symex_assign(state, code_assignt(lhs, rhs));
+      assignment_typet assignment_type;
+
+      // We hide if we are in a hidden function.
+      if(state.top().hidden_function)
+        assignment_type =
+          symex_targett::assignment_typet::HIDDEN_ACTUAL_PARAMETER;
+      else
+        assignment_type =
+          symex_targett::assignment_typet::VISIBLE_ACTUAL_PARAMETER;
+
+      clean_expr(lhs, state, true);
+      clean_expr(rhs, state, false);
+
+      guardt guard;
+      symex_assign_rec(state, lhs, nil_exprt(), rhs, guard, assignment_type);
     }
 
     if(it1!=arguments.end())