[pull] main from python:main

Doc/deprecations/pending-removal-in-3.15.rst

@@ -60,7 +60,7 @@ Pending removal in Python 3.15
 
 * :mod:`types`:
 
-  * :class:`types.CodeType`: Accessing :attr:`~codeobject.co_lnotab` was
+  * :class:`types.CodeType`: Accessing :attr:`!codeobject.co_lnotab` was
     deprecated in :pep:`626`
     since 3.10 and was planned to be removed in 3.12,
     but it only got a proper :exc:`DeprecationWarning` in 3.12.

Doc/deprecations/pending-removal-in-future.rst

@@ -47,7 +47,7 @@ although there is currently no date scheduled for their removal.
 
 * :mod:`codecs`: use :func:`open` instead of :func:`codecs.open`. (:gh:`133038`)
 
-* :attr:`codeobject.co_lnotab`: use the :meth:`codeobject.co_lines` method
+* :attr:`!codeobject.co_lnotab`: use the :meth:`codeobject.co_lines` method
   instead.
 
 * :mod:`datetime`:

Doc/library/dis.rst

@@ -400,7 +400,7 @@ operation is being performed, so the intermediate analysis object isn't useful:
 
    .. versionchanged:: 3.10
       The :pep:`626` :meth:`~codeobject.co_lines` method is used instead of the
-      :attr:`~codeobject.co_firstlineno` and :attr:`~codeobject.co_lnotab`
+      :attr:`~codeobject.co_firstlineno` and :attr:`!codeobject.co_lnotab`
       attributes of the :ref:`code object <code-objects>`.
 
    .. versionchanged:: 3.13

Doc/library/inspect.rst

@@ -195,10 +195,6 @@ attributes (see :ref:`import-mod-attrs` for module attributes):
 |                 |                   | read more :ref:`here      |
 |                 |                   | <inspect-module-co-flags>`|
 +-----------------+-------------------+---------------------------+
-|                 | co_lnotab         | encoded mapping of line   |
-|                 |                   | numbers to bytecode       |
-|                 |                   | indices                   |
-+-----------------+-------------------+---------------------------+
 |                 | co_freevars       | tuple of names of free    |
 |                 |                   | variables (referenced via |
 |                 |                   | a function's closure)     |

Doc/reference/datamodel.rst

@@ -926,6 +926,7 @@ Attribute assignment updates the module's namespace dictionary, e.g.,
    single: __doc__ (module attribute)
    single: __annotations__ (module attribute)
    single: __annotate__ (module attribute)
+   single: __lazy_modules__ (module attribute)
    pair: module; namespace
 
 .. _import-mod-attrs:
@@ -1121,6 +1122,20 @@ the following writable attributes:
 
    .. versionadded:: 3.14
 
+.. attribute:: module.__lazy_modules__
+
+   A container (an object implementing :meth:`~object.__contains__`) of fully
+   qualified module name strings.  When defined
+   at module scope, any regular :keyword:`import` statement in that module whose
+   target module name appears in this container is treated as a
+   :ref:`lazy import <lazy-imports>`, as if the :keyword:`lazy` keyword had
+   been used.  Imports inside functions, class bodies, or
+   :keyword:`try`/:keyword:`except`/:keyword:`finally` blocks are unaffected.
+
+   See :ref:`lazy-modules-compat` for details and examples.
+
+   .. versionadded:: 3.15
+
 Module dictionaries
 ^^^^^^^^^^^^^^^^^^^
 
@@ -1461,7 +1476,6 @@ indirectly) to mutable objects.
    single: co_filename (code object attribute)
    single: co_firstlineno (code object attribute)
    single: co_flags (code object attribute)
-   single: co_lnotab (code object attribute)
    single: co_name (code object attribute)
    single: co_names (code object attribute)
    single: co_nlocals (code object attribute)
@@ -1534,14 +1548,6 @@ Special read-only attributes
    * - .. attribute:: codeobject.co_firstlineno
      - The line number of the first line of the function
 
-   * - .. attribute:: codeobject.co_lnotab
-     - A string encoding the mapping from :term:`bytecode` offsets to line
-       numbers. For details, see the source code of the interpreter.
-
-       .. deprecated:: 3.12
-          This attribute of code objects is deprecated, and may be removed in
-          Python 3.15.
-
    * - .. attribute:: codeobject.co_stacksize
      - The required stack size of the code object
 

Doc/reference/simple_stmts.rst

@@ -920,6 +920,56 @@ See :pep:`810` for the full specification of lazy imports.
 
 .. versionadded:: 3.15
 
+.. _lazy-modules-compat:
+
+Compatibility via ``__lazy_modules__``
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. index::
+   single: __lazy_modules__
+
+As an alternative to using the :keyword:`lazy` keyword, a module can opt
+into lazy loading for specific imports by defining a module-level
+:attr:`~module.__lazy_modules__` variable.  When present, it must be a
+container of fully qualified module name strings.  Any regular (non-``lazy``)
+:keyword:`import` statement at module scope whose target appears in
+:attr:`!__lazy_modules__` is treated as a lazy import, exactly as if the
+:keyword:`lazy` keyword had been used.
+
+This provides a way to enable lazy loading for specific dependencies without
+changing individual ``import`` statements. This is useful when supporting
+Python versions older than 3.15 while using lazy imports in 3.15+::
+
+   __lazy_modules__ = ["json", "pathlib"]
+
+   import json     # loaded lazily (name is in __lazy_modules__)
+   import os       # loaded eagerly (name not in __lazy_modules__)
+
+   import pathlib  # loaded lazily
+
+Relative imports are resolved to their absolute name before the lookup, so
+:attr:`!__lazy_modules__` must always contain fully qualified module names.
+
+For ``from``-style imports, the relevant name is the module following
+``from``, not the names of its members::
+
+   # In mypackage/mymodule.py
+   __lazy_modules__ = ["mypackage", "mypackage.sub.utils"]
+
+   from . import helper         # loaded lazily: . resolves to mypackage
+   from .sub.utils import func  # loaded lazily: .sub.utils resolves to mypackage.sub.utils
+   import json                  # loaded eagerly (not in __lazy_modules__)
+
+Imports inside functions, class bodies, or
+:keyword:`try`/:keyword:`except`/:keyword:`finally` blocks are always eager,
+regardless of :attr:`!__lazy_modules__`.
+
+Setting ``-X lazy_imports=none`` (or the :envvar:`PYTHON_LAZY_IMPORTS`
+environment variable to ``none``) overrides :attr:`!__lazy_modules__` and
+forces all imports to be eager.
+
+.. versionadded:: 3.15
+
 .. _future:
 
 Future statements

Doc/whatsnew/3.10.rst

@@ -402,7 +402,7 @@ Tracing events, with the correct line number, are generated for all lines of cod
 The :attr:`~frame.f_lineno` attribute of frame objects will always contain the
 expected line number.
 
-The :attr:`~codeobject.co_lnotab` attribute of
+The :attr:`!codeobject.co_lnotab` attribute of
 :ref:`code objects <code-objects>` is deprecated and
 will be removed in 3.12.
 Code that needs to convert from offset to line number should use the new

Doc/whatsnew/3.12.rst

@@ -1347,7 +1347,7 @@ Deprecated
   ``int``, convert to int explicitly: ``~int(x)``. (Contributed by Tim Hoffmann
   in :gh:`103487`.)
 
-* Accessing :attr:`~codeobject.co_lnotab` on code objects was deprecated in
+* Accessing :attr:`!codeobject.co_lnotab` on code objects was deprecated in
   Python 3.10 via :pep:`626`,
   but it only got a proper :exc:`DeprecationWarning` in 3.12.
   May be removed in 3.15.

Doc/whatsnew/3.15.rst

@@ -184,6 +184,18 @@ function, class body, or ``try``/``except``/``finally`` block raises a
 (``lazy from module import *`` and ``lazy from __future__ import ...`` both
 raise :exc:`SyntaxError`).
 
+For code that cannot use the ``lazy`` keyword directly (for example, when
+supporting Python versions older than 3.15 while still using lazy
+imports on 3.15+), a module can define
+:attr:`~module.__lazy_modules__` as a container of fully qualified module
+name strings.  Regular ``import`` statements for those modules are then treated
+as lazy, with the same semantics as the ``lazy`` keyword::
+
+   __lazy_modules__ = ["json", "pathlib"]
+
+   import json     # lazy
+   import os       # still eager
+
 .. seealso:: :pep:`810` for the full specification and rationale.
 
 (Contributed by Pablo Galindo Salgado and Dino Viehland in :gh:`142349`.)
@@ -1646,6 +1658,14 @@ threading
   (Contributed by Bénédikt Tran in :gh:`134087`.)
 
 
+types
+-----
+
+* Removed deprecated in :pep:`626` since Python 3.12
+  :attr:`!codeobject.co_lnotab` from :class:`types.CodeType`.
+  (Contributed by Nikita Sobolev in :gh:`134690`.)
+
+
 typing
 ------
 

Doc/whatsnew/3.6.rst

@@ -2173,7 +2173,7 @@ Changes in the Python API
 * :c:func:`PyErr_SetImportError` now sets :exc:`TypeError` when its **msg**
   argument is not set. Previously only ``NULL`` was returned.
 
-* The format of the :attr:`~codeobject.co_lnotab` attribute of code objects
+* The format of the :attr:`!codeobject.co_lnotab` attribute of code objects
   changed to support
   a negative line number delta. By default, Python does not emit bytecode with
   a negative line number delta. Functions using :attr:`frame.f_lineno`,

InternalDocs/code_objects.md

@@ -70,14 +70,6 @@ The `co_linetable` bytes object of code objects contains a compact
 representation of the source code positions of instructions, which are
 returned by the `co_positions()` iterator.
 
-> [!NOTE]
-> `co_linetable` is not to be confused with `co_lnotab`.
-> For backwards compatibility, `co_lnotab` exposes the format
-> as it existed in Python 3.10 and lower: this older format
-> stores only the start line for each instruction.
-> It is lazily created from `co_linetable` when accessed.
-> See [`Objects/lnotab_notes.txt`](../Objects/lnotab_notes.txt) for more details.
-
 `co_linetable` consists of a sequence of location entries.
 Each entry starts with a byte with the most significant bit set, followed by
 zero or more bytes with the most significant bit unset.

Lib/asyncio/__main__.py

@@ -101,11 +101,15 @@ def run(self):
 
             if not sys.flags.isolated and (startup_path := os.getenv("PYTHONSTARTUP")):
                 sys.audit("cpython.run_startup", startup_path)
-
-                import tokenize
-                with tokenize.open(startup_path) as f:
-                    startup_code = compile(f.read(), startup_path, "exec")
+                try:
+                    import tokenize
+                    with tokenize.open(startup_path) as f:
+                        startup_code = compile(f.read(), startup_path, "exec")
                     exec(startup_code, console.locals)
+                except SystemExit:
+                    raise
+                except BaseException:
+                    console.showtraceback()
 
             ps1 = getattr(sys, "ps1", ">>> ")
             if CAN_USE_PYREPL:

Lib/dataclasses.py

@@ -1298,10 +1298,18 @@ def _update_func_cell_for__class__(f, oldcls, newcls):
         # This function doesn't reference __class__, so nothing to do.
         return False
     # Fix the cell to point to the new class, if it's already pointing
-    # at the old class.  I'm not convinced that the "is oldcls" test
-    # is needed, but other than performance can't hurt.
+    # at the old class.
     closure = f.__closure__[idx]
-    if closure.cell_contents is oldcls:
+
+    try:
+        contents = closure.cell_contents
+    except ValueError:
+        # Cell is empty
+        return False
+
+    # This check makes it so we avoid updating an incorrect cell if the
+    # class body contains a function that was defined in a different class.
+    if contents is oldcls:
         closure.cell_contents = newcls
         return True
     return False

Lib/inspect.py

@@ -416,7 +416,6 @@ def iscode(object):
         co_freevars         tuple of names of free variables
         co_posonlyargcount  number of positional only arguments
         co_kwonlyargcount   number of keyword only arguments (not including ** arg)
-        co_lnotab           encoded mapping of line numbers to bytecode indices
         co_name             name with which this code object was defined
         co_names            tuple of names other than arguments and function locals
         co_nlocals          number of local variables
@@ -1634,7 +1633,6 @@ def getframeinfo(frame, context=1):
 
 def getlineno(frame):
     """Get the line number from a frame object, allowing for optimization."""
-    # FrameType.f_lineno is now a descriptor that grovels co_lnotab
     return frame.f_lineno
 
 _FrameInfo = namedtuple('_FrameInfo', ('frame',) + Traceback._fields)

Lib/test/test_code.py

@@ -424,13 +424,6 @@ def func():
         new_code = code = func.__code__.replace(co_linetable=b'')
         self.assertEqual(list(new_code.co_lines()), [])
 
-    def test_co_lnotab_is_deprecated(self):  # TODO: remove in 3.14
-        def func():
-            pass
-
-        with self.assertWarns(DeprecationWarning):
-            func.__code__.co_lnotab
-
     @unittest.skipIf(_testinternalcapi is None, '_testinternalcapi is missing')
     def test_returns_only_none(self):
         value = True

Lib/test/test_dataclasses/__init__.py

@@ -5375,5 +5375,51 @@ def cls(self):
         # one will be keeping a reference to the underlying class A.
         self.assertIs(A().cls(), B)
 
+    def test_empty_class_cell(self):
+        # gh-148947: Make sure that we explicitly handle the empty class cell.
+        def maker():
+            if False:
+                __class__ = 42
+
+            def method(self):
+                return __class__
+            return method
+
+        from dataclasses import dataclass
+
+        @dataclass(slots=True)
+        class X:
+            a: int
+
+            meth = maker()
+
+        with self.assertRaisesRegex(NameError, '__class__'):
+            X(1).meth()
+
+    def test_class_cell_from_other_class(self):
+        # This test fails without the "is oldcls" check in
+        # _update_func_cell_for__class__.
+        class Base:
+            def meth(self):
+                return "Base"
+
+        class Child(Base):
+            def meth(self):
+                return super().meth() + " Child"
+
+        @dataclass(slots=True)
+        class DC(Child):
+            a: int
+
+            meth = Child.meth
+
+        closure = DC.meth.__closure__
+        self.assertEqual(len(closure), 1)
+        self.assertIs(closure[0].cell_contents, Child)
+
+        self.assertEqual(DC(1).meth(), "Base Child")
+
+
+
 if __name__ == '__main__':
     unittest.main()