From 7ea7e5c9519c70954d8bf722ee2a1b828c725917 Mon Sep 17 00:00:00 2001
From: Mark Thom <markjordanthom@gmail.com>
Date: Sat, 13 Mar 2021 23:22:24 -0700
Subject: [PATCH] remove intra-module predicates from module code directory
 when module is being re-defined (#848)

---
 src/lib/tabling/wrapper.pl |  4 ++--
 src/machine/load_state.rs  | 23 +++++++++++++++++++++++
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/src/lib/tabling/wrapper.pl b/src/lib/tabling/wrapper.pl
index 7925a667..4aad452a 100644
--- a/src/lib/tabling/wrapper.pl
+++ b/src/lib/tabling/wrapper.pl
@@ -56,8 +56,8 @@
 %% table(PIList) :-
 %% 	throw(error(context_error(nodirective, table(PIList)), _)).
 
-instantiation_error(Var) :-
-        throw(error(instantiation_error(Var), _)).
+%% instantiation_error(Var) :-
+%%         throw(error(instantiation_error(Var), _)).
 
 wrappers(Var) -->
 	{ var(Var), !,
diff --git a/src/machine/load_state.rs b/src/machine/load_state.rs
index 96f88d04..4e9d2033 100644
--- a/src/machine/load_state.rs
+++ b/src/machine/load_state.rs
@@ -473,6 +473,27 @@ impl<'a> LoadState<'a> {
         }
     }
 
+    pub(super) fn remove_replaced_module(&mut self, module_name: ClauseName) {
+        let removed_module = match self.wam.indices.modules.remove(&module_name) {
+            Some(module) => module,
+            None => return,
+        };
+
+        for (key, code_index) in &removed_module.code_dir {
+            if code_index.get() != IndexPtr::Undefined {
+                let old_index_ptr = code_index.replace(IndexPtr::Undefined);
+
+                self.retraction_info.push_record(
+                    RetractionRecord::ReplacedModulePredicate(
+                        module_name.clone(), key.clone(), old_index_ptr,
+                    ),
+                );
+            }
+        }
+
+        self.wam.indices.modules.insert(module_name, removed_module);
+    }
+
     pub(super) fn remove_module_exports(&mut self, module_name: ClauseName) {
         let removed_module = match self.wam.indices.modules.remove(&module_name) {
             Some(module) => module,
@@ -884,7 +905,9 @@ impl<'a> LoadState<'a> {
 
     pub(crate) fn add_module(&mut self, module_decl: ModuleDecl, listing_src: ListingSource) {
         let module_name = module_decl.name.clone();
+
         self.remove_module_exports(module_name.clone());
+        self.remove_replaced_module(module_name.clone());
 
         match self.wam.indices.modules.get_mut(&module_name) {
             Some(module) => {
-- 
2.54.0