fix(python): honor version-specific code equality

Fixes #6547

src/python/PythonPycParser.test.ts

@@ -918,6 +918,68 @@ it("accepts code objects as set members and dictionary keys", () => {
   expect(pythonPycSchema.safeParse(report).success).toBe(true);
 });
 
+it("uses the code equality fields for each CPython layout", () => {
+  const codeCollections = (
+    layout: "py38" | "py311",
+    different: boolean,
+  ): [Buffer, Buffer] => {
+    const lineA = marshalCode(layout, {
+      name: "f",
+      filename: "fixture.py",
+      firstlineno: 1,
+      linetable: Buffer.from([2, 1]),
+    });
+    const lineB = marshalCode(layout, {
+      name: "f",
+      filename: "fixture.py",
+      firstlineno: 1,
+      linetable: Buffer.from([2, different ? 2 : 1]),
+    });
+    const frozenSet = Buffer.concat([
+      Buffer.from([0x3e]),
+      u32(2),
+      lineA,
+      lineB,
+    ]);
+    const dict = Buffer.concat([
+      Buffer.from([0x7b]),
+      lineA,
+      Buffer.from([0x4e]),
+      lineB,
+      Buffer.from([0x54, 0x30]),
+    ]);
+    return [frozenSet, dict];
+  };
+  for (const [magic, layout] of [
+    [3413, "py38"],
+    [3439, "py38"],
+  ] as const) {
+    const [frozenSet, dict] = codeCollections(layout, true);
+    const report = parse(
+      Buffer.concat([
+        pythonPycHeader(magic),
+        marshalCode(layout, { consts: [frozenSet, dict] }),
+      ]),
+    );
+    expect(root(report).consts).toEqual([
+      { kind: "frozenset", length: 1 },
+      { kind: "dict", length: 1 },
+    ]);
+  }
+
+  const [frozenSet, dict] = codeCollections("py311", true);
+  const py312 = parse(
+    Buffer.concat([
+      pythonPycHeader(3531),
+      marshalCode("py311", { consts: [frozenSet, dict] }),
+    ]),
+  );
+  expect(root(py312).consts).toEqual([
+    { kind: "frozenset", length: 2 },
+    { kind: "dict", length: 2 },
+  ]);
+});
+
 it("keeps the first dictionary key when a later key compares equal", () => {
   const key = (filename: string): Buffer =>
     marshalCode("py311", {

src/python/PythonPycParser.ts

@@ -1156,8 +1156,12 @@ class MarshalReader {
       `${node.bytecode.bytes}:${node.bytecode.sha256}`,
       this.#constKeyItems(material.consts),
       ...nameTables,
-      material.linetable,
-      material.exceptiontable,
+      // CPython started including line and exception tables in code equality
+      // with the 3.11 code layout; earlier layouts still retain their digests
+      // in CodeEquality, but those fields do not affect container identity.
+      ...(this.layout === "py311"
+        ? [material.linetable, material.exceptiontable]
+        : []),
     ];
     const key = this.#boundedJoin(
       "",

tests/acceptance/pythonPycCli.test.ts

@@ -61,6 +61,62 @@ cliTest(
   },
 );
 
+cliTest(
+  "counts code keys using the selected CPython equality rules",
+  async ({ cli }) => {
+    const root = await createTestTempDirectory("rea-python-pyc-equality-");
+    const cases = [
+      { magic: 3413, layout: "py38" as const, lengths: [1, 1] },
+      { magic: 3439, layout: "py38" as const, lengths: [1, 1] },
+      { magic: 3531, layout: "py311" as const, lengths: [2, 2] },
+    ];
+    for (const [index, testCase] of cases.entries()) {
+      const code = (linetable: Buffer) =>
+        marshalCode(testCase.layout, {
+          name: "f",
+          filename: "fixture.py",
+          firstlineno: 1,
+          linetable,
+        });
+      const frozenSet = Buffer.concat([
+        Buffer.from([0x3e]),
+        Buffer.from([2, 0, 0, 0]),
+        code(Buffer.from([2, 1])),
+        code(Buffer.from([2, 2])),
+      ]);
+      const dict = Buffer.concat([
+        Buffer.from([0x7b]),
+        code(Buffer.from([2, 1])),
+        Buffer.from([0x4e]),
+        code(Buffer.from([2, 2])),
+        Buffer.from([0x54, 0x30]),
+      ]);
+      const path = join(root, `case-${index}.pyc`);
+      await writeFile(
+        path,
+        Buffer.concat([
+          pythonPycHeader(testCase.magic),
+          marshalCode(testCase.layout, { consts: [frozenSet, dict] }),
+        ]),
+      );
+      const result = await cli.run({
+        arguments: ["inspect-python-pyc", path, "--json"],
+      });
+      expect(result.exitCode, result.stderr).toBe(0);
+      const evidence = toolContract("inspect_python_pyc").outputSchema.parse(
+        result.json,
+      );
+      expect(
+        evidence.normalized_result.code_objects[0]?.consts.map((value) =>
+          value.kind === "frozenset" || value.kind === "dict"
+            ? value.length
+            : null,
+        ),
+      ).toEqual(testCase.lengths);
+    }
+  },
+);
+
 cliTest(
   "resolves a relative pyc path against the working directory",
   async ({ cli }) => {