[3.13] gh-130851: Don't crash when deduping unusual code constants (GH-130853) (#130880)

The bytecode compiler only generates a few different types of constants,
like str, int, tuple, slices, etc. Users can construct code objects with
various unusual constants, including ones that are not hashable or not
even constant.

The free threaded build previously crashed with a fatal error when
confronted with these constants. Instead, treat distinct objects of
otherwise unhandled types as not equal for the purposes of deduplication.
(cherry picked from commit 2905690a91)

Co-authored-by: Sam Gross <colesbury@gmail.com>

Lib/test/test_code.py

@@ -596,6 +596,23 @@ class CodeConstsTest(unittest.TestCase):
 
         self.assertTrue(globals["func1"]() is globals["func2"]())
 
+    @cpython_only
+    def test_unusual_constants(self):
+        # gh-130851: Code objects constructed with constants that are not
+        # types generated by the bytecode compiler should not crash the
+        # interpreter.
+        class Unhashable:
+            def __hash__(self):
+                raise TypeError("unhashable type")
+
+        class MyInt(int):
+            pass
+
+        code = compile("a = 1", "<string>", "exec")
+        code = code.replace(co_consts=(1, Unhashable(), MyInt(1), MyInt(1)))
+        self.assertIsInstance(code.co_consts[1], Unhashable)
+        self.assertEqual(code.co_consts[2], code.co_consts[3])
+
 
 class CodeWeakRefTest(unittest.TestCase):