Fix tracemalloc.Snapshot.filter_traces() for tuple traces storage

Snapshot.filter_traces() assumed the internal traces container supports .copy(),
which fails if a Snapshot is constructed with tuple traces.
Fix: use list(self.traces._traces) in the no-filter branch to make a shallow copy
without depending on the container type.
Add a regression test that constructs a Snapshot with tuple storage and verifies
filter_traces(()) works.

Signed-off-by: Yongtao Huang <yongtaoh2022@gmail.com>

Author: hyongtao-code

Lib/test/test_tracemalloc.py

@@ -446,6 +446,13 @@ def test_filter_traces(self):
 
         self.assertRaises(TypeError, snapshot.filter_traces, filter1)
 
+    def test_filter_traces_no_filter_tuple_storage(self):
+        snapshot, _snapshot2 = create_snapshots()
+        snap = tracemalloc.Snapshot(tuple(snapshot.traces._traces),
+                                    snapshot.traceback_limit)
+        snap2 = snap.filter_traces(())
+        self.assertEqual(snap2.traces._traces, list(snap.traces._traces))
+
     def test_filter_traces_domain(self):
         snapshot, snapshot2 = create_snapshots()
         filter1 = tracemalloc.Filter(False, "a.py", domain=1)

Lib/tracemalloc.py

@@ -471,7 +471,7 @@ def filter_traces(self, filters):
                                                 exclude_filters,
                                                 trace)]
         else:
-            new_traces = self.traces._traces.copy()
+            new_traces = list(self.traces._traces)
         return Snapshot(new_traces, self.traceback_limit)
 
     def _group_by(self, key_type, cumulative):