gh-132775: Add _PyFunction_GetXIData() (gh-133481)

Lib/test/test_crossinterp.py

@@ -758,6 +758,40 @@ class CodeTests(_GetXIDataTests):
         ])
 
 
+class ShareableFuncTests(_GetXIDataTests):
+
+    MODE = 'func'
+
+    def test_stateless(self):
+        self.assert_roundtrip_not_equal([
+            *defs.STATELESS_FUNCTIONS,
+            # Generators can be stateless too.
+            *defs.FUNCTION_LIKE,
+        ])
+
+    def test_not_stateless(self):
+        self.assert_not_shareable([
+            *(f for f in defs.FUNCTIONS
+              if f not in defs.STATELESS_FUNCTIONS),
+        ])
+
+    def test_other_objects(self):
+        self.assert_not_shareable([
+            None,
+            True,
+            False,
+            Ellipsis,
+            NotImplemented,
+            9999,
+            'spam',
+            b'spam',
+            (),
+            [],
+            {},
+            object(),
+        ])
+
+
 class PureShareableScriptTests(_GetXIDataTests):
 
     MODE = 'script-pure'