Merge remote-tracking branch 'upstream/main' into tail-call

Author: Fidget-Spinner

Doc/glossary.rst

@@ -658,6 +658,9 @@ Glossary
       and therefore it is never deallocated while the interpreter is running.
       For example, :const:`True` and :const:`None` are immortal in CPython.
 
+      Immortal objects can be identified via :func:`sys._is_immortal`, or
+      via :c:func:`PyUnstable_IsImmortal` in the C API.
+
    immutable
       An object with a fixed value.  Immutable objects include numbers, strings and
       tuples.  Such an object cannot be altered.  A new object has to

Doc/library/sys.rst

@@ -855,6 +855,11 @@ always available. Unless explicitly noted otherwise, all variables are read-only
    reflect the actual number of references.  Consequently, do not rely
    on the returned value to be accurate, other than a value of 0 or 1.
 
+   .. impl-detail::
+
+      :term:`Immortal <immortal>` objects with a large reference count can be
+      identified via :func:`_is_immortal`.
+
    .. versionchanged:: 3.12
       Immortal objects have very large refcounts that do not match
       the actual number of references to the object.
@@ -1264,6 +1269,24 @@ always available. Unless explicitly noted otherwise, all variables are read-only
 
    .. versionadded:: 3.12
 
+.. function:: _is_immortal(op)
+
+   Return :const:`True` if the given object is :term:`immortal`, :const:`False`
+   otherwise.
+
+   .. note::
+
+      Objects that are immortal (and thus return ``True`` upon being passed
+      to this function) are not guaranteed to be immortal in future versions,
+      and vice versa for mortal objects.
+
+   .. versionadded:: next
+
+   .. impl-detail::
+
+      This function should be used for specialized purposes only.
+      It is not guaranteed to exist in all implementations of Python.
+
 .. function:: _is_interned(string)
 
    Return :const:`True` if the given string is "interned", :const:`False`

Doc/whatsnew/3.14.rst

@@ -649,9 +649,13 @@ sys
   which only exists in specialized builds of Python, may now return objects
   from other interpreters than the one it's called in.
 
+* Add :func:`sys._is_immortal` for determining if an object is :term:`immortal`.
+  (Contributed by Peter Bierma in :gh:`128509`.)
+
 * On FreeBSD, :data:`sys.platform` doesn't contain the major version anymore.
   It is always ``'freebsd'``, instead of ``'freebsd13'`` or ``'freebsd14'``.
 
+
 sys.monitoring
 --------------
 

Lib/test/test_capi/test_frame.py

@@ -0,0 +1,56 @@
+import sys
+import unittest
+from test.support import import_helper
+
+
+_testcapi = import_helper.import_module('_testcapi')
+
+
+class FrameTest(unittest.TestCase):
+    def getframe(self):
+        return sys._getframe()
+
+    def test_frame_getters(self):
+        frame = self.getframe()
+        self.assertEqual(frame.f_locals, _testcapi.frame_getlocals(frame))
+        self.assertIs(frame.f_globals, _testcapi.frame_getglobals(frame))
+        self.assertIs(frame.f_builtins, _testcapi.frame_getbuiltins(frame))
+        self.assertEqual(frame.f_lasti, _testcapi.frame_getlasti(frame))
+
+    def test_getvar(self):
+        current_frame = sys._getframe()
+        x = 1
+        self.assertEqual(_testcapi.frame_getvar(current_frame, "x"), 1)
+        self.assertEqual(_testcapi.frame_getvarstring(current_frame, b"x"), 1)
+        with self.assertRaises(NameError):
+            _testcapi.frame_getvar(current_frame, "y")
+        with self.assertRaises(NameError):
+            _testcapi.frame_getvarstring(current_frame, b"y")
+
+        # wrong name type
+        with self.assertRaises(TypeError):
+            _testcapi.frame_getvar(current_frame, b'x')
+        with self.assertRaises(TypeError):
+            _testcapi.frame_getvar(current_frame, 123)
+
+    def getgenframe(self):
+        yield sys._getframe()
+
+    def test_frame_get_generator(self):
+        gen = self.getgenframe()
+        frame = next(gen)
+        self.assertIs(gen, _testcapi.frame_getgenerator(frame))
+
+    def test_frame_fback_api(self):
+        """Test that accessing `f_back` does not cause a segmentation fault on
+        a frame created with `PyFrame_New` (GH-99110)."""
+        def dummy():
+            pass
+
+        frame = _testcapi.frame_new(dummy.__code__, globals(), locals())
+        # The following line should not cause a segmentation fault.
+        self.assertIsNone(frame.f_back)
+
+
+if __name__ == "__main__":
+    unittest.main()