# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1693913607 -7200
# Node ID 06335a0e411366319ffbf4115086b8161d0cc28b
# Parent  4e68e347740990566bbbb76eff27f559fda20df7
Prevent inadvertent object copying during __data__ attribute assignment.

diff -r 4e68e3477409 -r 06335a0e4113 access_plan.py
--- a/access_plan.py	Tue Sep 05 01:32:12 2023 +0200
+++ b/access_plan.py	Tue Sep 05 13:33:27 2023 +0200
@@ -241,12 +241,14 @@
             attrname = self.get_first_attribute_name()
             assigning = self.assigning_first_attribute()
 
+            store = attrname != "__data__" and "__store_via_attr_ref" or "__store_via_attr_ref__"
+
             # Access via the accessor's class.
 
             if self.first_method == "relative-class":
                 if assigning:
                     emit(("<set_attr_ref>", ("__get_class_attr_ref", accessor, attrname)))
-                    emit(("__store_via_attr_ref", "<attr_ref>", "<assexpr>"))
+                    emit((store, "<attr_ref>", "<assexpr>"))
                 else:
                     accessor = ("__load_via_class", accessor, attrname)
 
@@ -255,7 +257,7 @@
             elif self.first_method == "relative-object":
                 if assigning:
                     emit(("<set_attr_ref>", ("__get_object_attr_ref", accessor, attrname)))
-                    emit(("__store_via_attr_ref", "<attr_ref>", "<assexpr>"))
+                    emit((store, "<attr_ref>", "<assexpr>"))
                 else:
                     accessor = ("__load_via_object", accessor, attrname)
 
@@ -280,7 +282,7 @@
             elif self.first_method == "check-object":
                 if assigning:
                     emit(("<set_attr_ref>", ("__check_and_get_object_attr_ref", accessor, attrname)))
-                    emit(("__store_via_attr_ref", "<attr_ref>", "<assexpr>"))
+                    emit((store, "<attr_ref>", "<assexpr>"))
                 else:
                     accessor = ("__check_and_load_via_object", accessor, attrname)
 
@@ -290,7 +292,7 @@
             elif self.first_method == "check-object-class":
                 if assigning:
                     emit(("<set_attr_ref>", ("__check_and_get_object_attr_ref", accessor, attrname)))
-                    emit(("__store_via_attr_ref", "<attr_ref>", "<assexpr>"))
+                    emit((store, "<attr_ref>", "<assexpr>"))
                 else:
                     accessor = ("__check_and_load_via_any", accessor, attrname)
 
@@ -334,16 +336,18 @@
 
                 if num_remaining > 1 or self.final_method in ("access", "access-invoke", "assign"):
 
+                    store = attrname != "__data__" and "__store_via_attr_ref" or "__store_via_attr_ref__"
+
                     if traversal_mode == "class":
                         if assigning:
                             emit(("<set_attr_ref>", ("__get_class_attr_ref", accessor, attrname)))
-                            emit(("__store_via_attr_ref", "<attr_ref>", "<assexpr>"))
+                            emit((store, "<attr_ref>", "<assexpr>"))
                         else:
                             accessor = ("__load_via_class", accessor, attrname)
                     else:
                         if assigning:
                             emit(("<set_attr_ref>", ("__get_object_attr_ref", accessor, attrname)))
-                            emit(("__store_via_attr_ref", "<attr_ref>", "<assexpr>"))
+                            emit((store, "<attr_ref>", "<assexpr>"))
                         else:
                             accessor = ("__load_via_object", accessor, attrname)
 
@@ -392,11 +396,12 @@
                     # Constrain instructions involving certain special
                     # attribute names.
 
+                    store = attrname != "__data__" and "__store_via_attr_ref" or "__store_via_attr_ref__"
                     to_search = attrname != "__data__" and "any" or "object"
 
                     if assigning:
                         emit(("<set_attr_ref>", ("__check_and_get_object_attr_ref", accessor, attrname)))
-                        emit(("__store_via_attr_ref", "<attr_ref>", "<assexpr>"))
+                        emit((store, "<attr_ref>", "<assexpr>"))
                     else:
                         accessor = ("__check_and_load_via_%s" % to_search, accessor, attrname)
 
@@ -423,8 +428,9 @@
 
             if self.final_method == "static-assign":
                 parent, attrname = self.origin.rsplit(".", 1)
+                store = attrname != "__data__" and "__store_via_attr_ref" or "__store_via_attr_ref__"
                 emit(("<set_attr_ref>", ("__get_object_attr_ref", parent, attrname)))
-                emit(("__store_via_attr_ref", "<attr_ref>", "<assexpr>"))
+                emit((store, "<attr_ref>", "<assexpr>"))
 
             # Invoked attributes employ a separate context.
 
diff -r 4e68e3477409 -r 06335a0e4113 transresults.py
--- a/transresults.py	Tue Sep 05 01:32:12 2023 +0200
+++ b/transresults.py	Tue Sep 05 13:33:27 2023 +0200
@@ -101,6 +101,8 @@
 
         if self.expr:
 
+            store = self.attrname != "__data__" and "__store_via_attr_ref" or "__store_via_attr_ref__"
+
             # Eliminate assignments between constants.
 
             if self.static_ref and self.expr.static():
@@ -109,14 +111,14 @@
             # Qualified names must be converted into parent-relative assignments.
 
             elif self.parent:
-                return "__store_via_attr_ref(__get_object_attr_ref(&%s, %s), %s)" % (
-                    encode_path(self.parent), self.attrname, self.expr)
+                return "%s(__get_object_attr_ref(&%s, %s), %s)" % (
+                    store, encode_path(self.parent), self.attrname, self.expr)
 
             # All other assignments involve the names as they were given.
             # To support value replacement, a special operation is used.
 
             else:
-                return "__set_attr(&%s, %s)" % (self.attrname, self.expr)
+                return "%s(&%s, %s)" % (store, self.attrname, self.expr)
 
         # Expressions.