[GR-36519] fix GetItemNode specialization on list subclassing

PullRequest: graalpython/2118

Author: cosminbasca

graalpython/com.oracle.graal.python.test/src/tests/test_list_subclassing.py

@@ -1,4 +1,4 @@
-# Copyright (c) 2018, 2021, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2018, 2022, Oracle and/or its affiliates. All rights reserved.
 # DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 #
 # The Universal Permissive License (UPL), Version 1.0
@@ -78,3 +78,20 @@ def __init__(self, a, b=None):
     assert l == [20]
     l = MyList(10, b=30)
     assert l == [30]
+
+
+def test_list_custom_getitem():
+    class MyList(list):
+        def __init__(self, it, mapping):
+            list.__init__(self, it)
+            self.mapping = mapping
+
+        def __getitem__(self, key):
+            idx = key
+            if key in self.mapping:
+                idx = self.mapping[idx]
+            return list.__getitem__(self, idx)
+
+    l = MyList([1, 2, 3, 4], {"a": 1, "b": 2})
+    assert l[1] == 2
+    assert l["a"] == 2

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/nodes/subscript/GetItemNode.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017, 2021, Oracle and/or its affiliates.
+ * Copyright (c) 2017, 2022, Oracle and/or its affiliates.
  * Copyright (c) 2013, Regents of the University of California
  *
  * All rights reserved.
@@ -85,6 +85,10 @@ public static GetItemNode create(ExpressionNode primary, ExpressionNode slice) {
         return GetItemNodeGen.create(primary, slice);
     }
 
+    protected LookupAndCallBinaryNode createLookupAndCallGetItemNode() {
+        return LookupAndCallBinaryNode.create(SpecialMethodSlot.GetItem);
+    }
+
     @Override
     public StatementNode makeWriteNode(ExpressionNode rhs) {
         return SetItemNode.create(getPrimary(), getSlice(), rhs);
@@ -101,9 +105,10 @@ Object doBuiltinList(VirtualFrame frame, PList primary, Object index,
     @SuppressWarnings("unused")
     @Specialization(guards = {"!indexCheckNode.execute(index)", "!isPSlice(index)"}, limit = "1")
     public Object doListError(VirtualFrame frame, PList primary, Object index,
+                    @Cached("createLookupAndCallGetItemNode()") LookupAndCallBinaryNode lookupAndCallGetItem,
                     @SuppressWarnings("unused") @Cached PyIndexCheckNode indexCheckNode,
                     @Cached PRaiseNode raiseNode) {
-        throw raiseNode.raise(TypeError, ErrorMessages.OBJ_INDEX_MUST_BE_INT_OR_SLICES, "list", index);
+        return lookupAndCallGetItem.executeObject(frame, primary, index);
     }
 
     @Specialization(guards = {"indexCheckNode.execute(index) || isPSlice(index)", "isBuiltinTuple.profileIsAnyBuiltinObject(primary)"}, limit = "1")