Syntax error when trying to use inductive predicate

Question

I am trying to use the example of an inductive predicate taken from the webpage https://frama-c.com/acsl_tutorial_index.html:

#include <stddef.h>
#include <stdlib.h>

typedef struct _list { int element; struct _list* next; } list; 

/*@ inductive reachable{L} (list* root, list* node) { 
       case root_reachable{L}: 
         \forall list* root; reachable(root,root); 
       case next_reachable{L}: 
         \forall list* root, *node; 
         \valid(root) ==>
            reachable(root−>next, node) ==> 
              reachable(root,node); 
     } 
*/ 

However, I get a compilation error:

$ frama-c -wp -wp-rte -wp-split list.c
[kernel] Parsing list.c (with preprocessing)
[kernel:annot-error] list.c:12: Warning: unexpected token '>'
[kernel] User Error: warning annot-error treated as fatal error.
[kernel] User Error: stopping on file "list.c" that has errors. Add '-kernel-msg-key pp'
  for preprocessing command.
[kernel] Frama-C aborted: invalid user input.

The error I get seems to be for root->next.

If I try the following it works:

/*@ inductive reachable{L} (list* root, list* node) {
      case empty{L}: \forall struct List* l; reachable(l, l);
      case non_empty{L}: \forall list *l1,*l2;
        \valid(l1) && reachable(l1->next, l2) ==> reachable(l1, l2);
    }
*/

Perhaps I've done something wrong? Although all I have tried to do is to copy and paste the tutorial code. Any help appreciated.

Answer 1

It is indeed hard to spot, but the − just before the incriminated > is not a standard ASCII dash - but one of its countless unicode variant. This is what gets Frama-C confused. Of course this does not happen in handwritten code where you have a normal -.