list-c++, set-c++, oset-c++, map-c++, omap-c++: Don't fool the compiler.

Reported by Akim Demaille in
<https://lists.gnu.org/archive/html/bug-bison/2020-05/msg00102.html>.

* lib/gl_list.hh (gl_List::iterator::next): Avoid a reinterpret_cast.
* lib/gl_set.hh (gl_Set::iterator::next): Likewise.
* lib/gl_oset.hh (gl_OSet::iterator::next): Likewise.
* lib/gl_map.hh (gl_Map::iterator::next): Likewise.
* lib/gl_omap.hh (gl_OMap::iterator::next): Likewise.

1 files changed, 14 insertions, 2 deletions

diff --git a/lib/gl_list.hh b/lib/gl_list.hh
index b19bda71b1..8b0ccad1ba 100644
--- a/lib/gl_list.hh
+++ b/lib/gl_list.hh
@@ -351,13 +351,25 @@ public:
        the iterator and returns true.
        Otherwise, returns false.  */
     bool next (ELTYPE *& elt)
-      { return gl_list_iterator_next (&_state, reinterpret_cast<const void **>(&elt), NULL); }
+      {
+        const void *next_elt;
+        bool has_next = gl_list_iterator_next (&_state, &next_elt, NULL);
+        if (has_next)
+          elt = static_cast<ELTYPE *>(next_elt);
+        return has_next;
+      }
 
     /* If there is a next element, stores the next element in ELT, stores its
        node in *NODEP if NODEP is non-NULL, advances the iterator and returns true.
        Otherwise, returns false.  */
     bool next (ELTYPE *& elt, gl_list_node_t *nodep)
-      { return gl_list_iterator_next (&_state, reinterpret_cast<const void **>(&elt), nodep); }
+      {
+        const void *next_elt;
+        bool has_next = gl_list_iterator_next (&_state, &next_elt, nodep);
+        if (has_next)
+          elt = static_cast<ELTYPE *>(next_elt);
+        return has_next;
+      }
 
     ~iterator ()
       { gl_list_iterator_free (&_state); }