fix bug in DeleteAttribute

2019-02-02 19:25:12 -07:00
parent a28c8934f3
commit f51405bc04
5 changed files with 90 additions and 37 deletions
--- a/src/prolog/machine/system_calls.rs
+++ b/src/prolog/machine/system_calls.rs
@@ -210,7 +210,7 @@ impl MachineState {
                    if let Addr::Lis(l2) = self.store(self.deref(Addr::HeapCell(l1 + 1))) {
                        let addr = self.heap[l1 + 1].as_addr(l1 + 1);                        
                        self.heap[l1 + 1] = HeapCellValue::Addr(Addr::HeapCell(l2 + 1));
-                        self.trail(TrailRef::AttrVarLink(l2 + 1, addr));
+                        self.trail(TrailRef::AttrVarLink(l1 + 1, addr));
                    }
                }                
            },