some fixes in response to miri

src/lib/builtins.pl

@@ -568,7 +568,6 @@ parse_options_list(Options, Selector, DefaultPairs, OptionValues, Stub) :-
                                                 % maplist isn't
                                                 % declared as a
                                                 % meta-predicate yet
-       '$debug_hook',
        catch(lists:maplist(Selector, Options, OptionPairs0),
              error(E, _),
              builtins:throw(error(E, Stub))) ->

src/machine/heap.rs

@@ -1281,3 +1281,17 @@ pub(crate) fn to_local_code_ptr(heap: &Heap, addr: HeapCellValue) -> Option<usiz
         }
     )
 }
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn heap_manipulation() {
+        let mut heap = Heap::new();
+
+        for idx in 0 .. 10 {
+            heap.push_cell(heap_loc_as_cell!(idx)).unwrap();
+        }
+    }
+}

src/machine/machine_state_impl.rs

@@ -267,16 +267,6 @@ impl MachineState {
         unifier.unify_atom(atom, value);
     }
 
-    pub fn unify_list(&mut self, l1: usize, value: HeapCellValue) {
-        let mut unifier = DefaultUnifier::from(self);
-        unifier.unify_list(l1, value);
-    }
-
-    pub fn unify_partial_string(&mut self, pstr_loc: usize, value: HeapCellValue) {
-        let mut unifier = DefaultUnifier::from(self);
-        unifier.unify_partial_string(pstr_loc, value);
-    }
-
     pub fn unify_char(&mut self, c: char, value: HeapCellValue) {
         let mut unifier = DefaultUnifier::from(self);
         unifier.unify_char(c, value);

src/machine/stack.rs

@@ -228,7 +228,7 @@ impl Stack {
 
             for idx in 0..num_cells {
                 ptr::write(
-                    (new_ptr as usize + offset) as *mut HeapCellValue,
+                    new_ptr.byte_add(offset) as *mut HeapCellValue,
                     stack_loc_as_cell!(OrFrame, b, idx),
                 );
 

src/types.rs

@@ -97,8 +97,7 @@ impl ConsPtr {
 
     #[inline(always)]
     pub fn as_ptr(self) -> *mut u8 {
-        let addr: u64 = self.ptr();
-        addr as usize as *mut _
+        unsafe { mem::transmute::<_, *mut u8>(self.ptr()) }
     }
 
     #[inline(always)]
@@ -676,23 +675,22 @@ impl UntypedArenaPtr {
     }
 
     #[inline]
-    pub fn get_ptr(self) -> *const u8 {
-        let addr: u64 = self.ptr();
-        addr as usize as *const u8
+    pub fn get_ptr(self) -> *const ArenaHeader {
+        unsafe { mem::transmute::<_, *const ArenaHeader>(self.ptr()) }
     }
 
     #[inline]
     pub fn get_tag(self) -> ArenaHeaderTag {
         unsafe {
             debug_assert!(!self.get_ptr().is_null());
-            let header = *(self.get_ptr() as *const ArenaHeader);
+            let header = *self.get_ptr();
             header.get_tag()
         }
     }
 
     #[inline]
     pub fn payload_offset(self) -> *const u8 {
-        unsafe { self.get_ptr().add(mem::size_of::<ArenaHeader>()) }
+        unsafe { self.get_ptr().byte_add(mem::size_of::<ArenaHeader>()) as *const _ }
     }
 
     /// # Safety