Accept bytes-like input in pyexpat.Parse (#9187)

Assisted-by: Codex:GPT-6

extra_tests/snippets/stdlib_pyexpat.py

@@ -21,3 +21,30 @@ for separator, expected_name, expected_attribute in (
             else {expected_attribute: "v", "a": "u"}
         )
         assert starts[1][1] == expected_attributes
+
+# Parse accepts contiguous buffer objects, including views of mutable input.
+for xml in (bytearray(b"<r>ok</r>"), memoryview(b"<r>ok</r>")):
+    parser = expat.ParserCreate()
+    text = []
+    parser.CharacterDataHandler = text.append
+    assert parser.Parse(xml, True) == 1
+    assert "".join(text) == "ok"
+
+try:
+    expat.ParserCreate().Parse(memoryview(b"<r/>")[::2], True)
+except BufferError:
+    pass
+else:
+    raise AssertionError("Parse accepted a non-contiguous buffer")
+
+# Keep the export alive through callbacks without retaining its read lock.
+xml = bytearray(b"<r/>")
+parser = expat.ParserCreate()
+parser.StartElementHandler = lambda *_: xml.extend(b" ")
+try:
+    parser.Parse(xml, True)
+except BufferError:
+    pass
+else:
+    raise AssertionError("Parse released its input buffer before the callback")
+xml.extend(b" ")