fix: metadata journal can rollback incorrectly

tests/ast/test_metadata_journal.py

@@ -0,0 +1,82 @@
+from vyper.ast.metadata import NodeMetadata
+from vyper.exceptions import VyperException
+
+
+def test_metadata_journal_basic():
+    m = NodeMetadata()
+
+    m["x"] = 1
+    assert m["x"] == 1
+
+
+def test_metadata_journal_commit():
+    m = NodeMetadata()
+
+    with m.enter_typechecker_speculation():
+        m["x"] = 1
+
+    assert m["x"] == 1
+
+
+def test_metadata_journal_exception():
+    m = NodeMetadata()
+
+    m["x"] = 1
+    try:
+        with m.enter_typechecker_speculation():
+            m["x"] = 2
+            m["x"] = 3
+
+            assert m["x"] == 3
+            raise VyperException("dummy exception")
+
+    except VyperException:
+        pass
+
+    # rollback upon exception
+    assert m["x"] == 1
+
+
+def test_metadata_journal_rollback_inner():
+    m = NodeMetadata()
+
+    m["x"] = 1
+    with m.enter_typechecker_speculation():
+        m["x"] = 2
+
+        try:
+            with m.enter_typechecker_speculation():
+                m["x"] = 3
+                m["x"] = 4  # test multiple writes
+
+                assert m["x"] == 4
+                raise VyperException("dummy exception")
+
+        except VyperException:
+            pass
+
+    assert m["x"] == 2
+
+
+def test_metadata_journal_rollback_outer():
+    m = NodeMetadata()
+
+    m["x"] = 1
+    try:
+        with m.enter_typechecker_speculation():
+            m["x"] = 2
+
+            with m.enter_typechecker_speculation():
+                m["x"] = 3
+                m["x"] = 4  # test multiple writes
+
+            assert m["x"] == 4
+
+            m["x"] = 5
+
+            raise VyperException("dummy exception")
+
+    except VyperException:
+        pass
+
+    assert m["x"] == 1

vyper/ast/metadata.py

@@ -17,8 +17,11 @@ def __init__(self):
         self._node_updates: list[dict[tuple[int, str, Any], NodeMetadata]] = []
 
     def register_update(self, metadata, k):
+        KEY = (id(metadata), k)
+        if KEY in self._node_updates[-1]:
+            return
         prev = metadata.get(k, self._NOT_FOUND)
-        self._node_updates[-1][(id(metadata), k)] = (metadata, prev)
+        self._node_updates[-1][KEY] = (metadata, prev)
 
     @contextlib.contextmanager
     def enter(self):