* Update docs.

* bpo-40513: Per-interpreter signals pending (GH-19924)

Move signals_pending from _PyRuntime.ceval to
PyInterpreterState.ceval.

* bpo-40513: Per-interpreter gil_drop_request (GH-19927)

Move gil_drop_request member from _PyRuntimeState.ceval to
PyInterpreterState.ceval.

* bpo-40514: Add --with-experimental-isolated-subinterpreters (GH-19926)

Add --with-experimental-isolated-subinterpreters build option to
configure: better isolate subinterpreters, experimental build mode.

When used, force the usage of the libc malloc() memory allocator,
since pymalloc relies on the unique global interpreter lock (GIL).

* bpo-32117: Updated Simpsons names in docs (GH-19737)



`sally` is not a Simpsons character

Automerge-Triggered-By: @gvanrossum

* bpo-40513: Per-interpreter recursion_limit (GH-19929)

Move recursion_limit member from _PyRuntimeState.ceval to
PyInterpreterState.ceval.

* Py_SetRecursionLimit() now only sets _Py_CheckRecursionLimit
  of ceval.c if the current Python thread is part of the main
  interpreter.
* Inline _Py_MakeEndRecCheck() into _Py_LeaveRecursiveCall().
* Convert _Py_RecursionLimitLowerWaterMark() macro into a static
  inline function.

* bpo-29587: _PyErr_ChainExceptions() checks exception (GH-19902)

_PyErr_ChainExceptions() now ensures that the first parameter is an
exception type, as done by _PyErr_SetObject().

* The following function now check PyExceptionInstance_Check() in an
  assertion using a new _PyBaseExceptionObject_cast() helper
  function:

  * PyException_GetTraceback(), PyException_SetTraceback()
  * PyException_GetCause(), PyException_SetCause()
  * PyException_GetContext(), PyException_SetContext()

* PyExceptionClass_Name() now checks PyExceptionClass_Check() with an
  assertion.

* Remove XXX comment and add gi_exc_state variable to _gen_throw().

* Remove comment from test_generators

* bpo-40520: Remove redundant comment in pydebug.h (GH-19931)



Automerge-Triggered-By: @corona10

* Revert "bpo-40513: Per-interpreter signals pending (GH-19924)" (GH-19932)

This reverts commit 4e01946.

* bpo-40521: Disable Unicode caches in isolated subinterpreters (GH-19933)

When Python is built in the experimental isolated subinterpreters
mode, disable Unicode singletons and Unicode interned strings since
they are shared by all interpreters.

Temporary workaround until these caches are made per-interpreter.

* bpo-40458: Increase reserved stack space to prevent overflow crash on Windows (GH-19845)

* bpo-40521: Disable free lists in subinterpreters (GH-19937)

When Python is built with experimental isolated interpreters, disable
tuple, dict and free free lists.

Temporary workaround until these caches are made per-interpreter.

Add frame_alloc() and frame_get_builtins() subfunctions to simplify
_PyFrame_New_NoTrack().

* bpo-40522: _PyThreadState_Swap() sets autoTSSkey (GH-19939)

In the experimental isolated subinterpreters build mode,
_PyThreadState_GET() gets the autoTSSkey variable and
_PyThreadState_Swap() sets the autoTSSkey variable.

* Add _PyThreadState_GetTSS()
* _PyRuntimeState_GetThreadState() and _PyThreadState_GET()
  return _PyThreadState_GetTSS()
* PyEval_SaveThread() sets the autoTSSkey variable to current Python
  thread state rather than NULL.
* eval_frame_handle_pending() doesn't check that
  _PyThreadState_Swap() result is NULL.
* _PyThreadState_Swap() gets the current Python thread state with
  _PyThreadState_GetTSS() rather than
  _PyRuntimeGILState_GetThreadState().
* PyGILState_Ensure() no longer checks _PyEval_ThreadsInitialized()
  since it cannot access the current interpreter.

* bpo-40513: new_interpreter() init GIL earlier (GH-19942)

Fix also code to handle init_interp_main() failure.

* bpo-40513: Per-interpreter GIL (GH-19943)

In the experimental isolated subinterpreters build mode, the GIL is
now per-interpreter.

Move gil from _PyRuntimeState.ceval to PyInterpreterState.ceval.

new_interpreter() always get the config from the main interpreter.

* bpo-40513: _xxsubinterpreters.run_string() releases the GIL (GH-19944)

In the experimental isolated subinterpreters build mode,
_xxsubinterpreters.run_string() now releases the GIL.

* bpo-40355: Improve error messages in ast.literal_eval with malformed Dict nodes (GH-19868)

Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>

* bpo-40504: Allow weakrefs to lru_cache objects (GH-19938)

* bpo-40523: Add pass-throughs for hash() and reversed() to weakref.proxy objects (GH-19946)

* bpo-40480 "fnmatch" exponential execution time (GH-19908)

bpo-40480:  create different regexps in the presence of multiple `*`
patterns to prevent fnmatch() from taking exponential time.

* bpo-40517: Implement syntax highlighting support for ASDL (#19928)

* Revert "bpo-40517: Implement syntax highlighting support for ASDL (#19928)" (#19950)

This reverts commit d60040b.

* bpo-40527: Fix command line argument parsing (GH-19955)

* bpo-40528: Improve and clear several aspects of the ASDL definition code for the AST (GH-19952)

* bpo-40521: Disable method cache in subinterpreters (GH-19960)

When Python is built with experimental isolated interpreters, disable
the type method cache.

Temporary workaround until the cache is made per-interpreter.

* bpo-40533: Disable GC in subinterpreters (GH-19961)

When Python is built with experimental isolated interpreters, a
garbage collection now does nothing in an isolated interpreter.

Temporary workaround until subinterpreters stop sharing Python
objects.

* bpo-40521: Disable list free list in subinterpreters (GH-19959)

When Python is built with experimental isolated interpreters, disable
the list free list.

Temporary workaround until this cache is made per-interpreter.

* bpo-40334: Add type to the assignment rule in the grammar file (GH-19963)

* Fix typo in sqlite3 documentation (GH-19965)

*first* is repeated twice.

* bpo-40334: Allow trailing comma in parenthesised context managers (GH-19964)

* bpo-40334: Generate comments in the parser code to improve debugging (GH-19966)

* bpo-40397: Refactor typing._GenericAlias (GH-19719)

Make the design more object-oriented.
Split _GenericAlias on two almost independent classes: for special
generic aliases like List and for parametrized generic aliases like List[int].
Add specialized subclasses for Callable, Callable[...], Tuple and Union[...].

* bpo-1635741: Port errno module to multiphase initialization (GH-19923)

* bpo-40334: Fix error location upon parsing an invalid string literal (GH-19962)

When parsing a string with an invalid escape, the old parser used to
point to the beginning of the invalid string. This commit changes the new
parser to match that behaviour, since it's currently pointing to the
end of the string (or to be more precise, to the beginning of the next
token).

* bpo-40334: Error message for invalid default args in function call (GH-19973)

When parsing something like `f(g()=2)`, where the name of a default arg
is not a NAME, but an arbitrary expression, a specialised error message
is emitted.

* bpo-38787: C API for module state access from extension methods (PEP 573) (GH-19936)

Module C state is now accessible from C-defined heap type methods (PEP 573).
Patch by Marcel Plch and Petr Viktorin.

Co-authored-by: Marcel Plch <mplch@redhat.com>
Co-authored-by: Victor Stinner <vstinner@python.org>

* bpo-40545: Export _PyErr_GetTopmostException() function (GH-19978)

Declare _PyErr_GetTopmostException() with PyAPI_FUNC() to properly
export the function in the C API. The function remains private
("_Py") prefix.

Co-Authored-By: Julien Danjou <julien@danjou.info>

* bpo-32604: [_xxsubinterpreters] Propagate exceptions. (GH-19768)

(Note: PEP 554 is not accepted and the implementation in the code base is a private one for use in the test suite.)

If code running in a subinterpreter raises an uncaught exception then the "run" call in the calling interpreter fails. A RunFailedError is raised there that summarizes the original exception as a string. The actual exception type, __cause__, __context__, state, etc. are all discarded. This turned out to be functionally insufficient in practice. There is a more helpful solution (and PEP 554 has been updated appropriately).

This change adds the exception propagation behavior described in PEP 554 to the _xxsubinterpreters module. With this change a copy of the original exception is set to __cause__ on the RunFailedError. For now we are using "pickle", which preserves the exception's state. We also preserve the original __cause__, __context__, and __traceback__ (since "pickle" does not preserve those).

https://bugs.python.org/issue32604

* bpo-38787: Update structures.rst docs (PEP 573) (GH-19980)

* bpo-40548: Always run GitHub action, even on doc PRs (GH-19981)

Always run GitHub action jobs, even on documentation-only pull
requests. So it will be possible to make a GitHub action job, like
the Windows (64-bit) job, mandatory.

* bpo-40517: Implement syntax highlighting support for ASDL (GH-19967)

* bpo-40555: Check for p->error_indicator in loop rules after the main loop is done (GH-19986)

* bpo-40273: Reversible mappingproxy (FH-19513)

* bpo-40559: Add Py_DECREF to _asynciomodule.c:task_step_impl() (GH-19990)

This fixes a possible memory leak in the C implementation of
asyncio.Task.

* Make the first dataclass example more useful (GH-19994)

* bpo-40541: Add optional *counts* parameter to random.sample() (GH-19970)

* bpo-40502: Initialize n->n_col_offset (GH-19988)

* initialize n->n_col_offset

* 📜🤖 Added by blurb_it.

* Move initialization

Co-authored-by: nanjekyejoannah <joannah.nanjekye@ibm.com>
Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>

* bpo-39791: Add files() to importlib.resources (GH-19722)

* bpo-39791: Update importlib.resources to support files() API (importlib_resources 1.5).

* 📜🤖 Added by blurb_it.

* Add some documentation about the new objects added.

Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>

* bpo-40566: Apply PEP 573 to abc module (GH-20005)

* bpo-40570: Improve compatibility of uname_result with late-bound .platform (#20015)

* bpo-40570: Improve compatibility of uname_result with late-bound .platform.

* Add test capturing ability to cast uname to a tuple.

* bpo-40334: Avoid collisions between parser variables and grammar variables (GH-19987)

This is for the C generator:
- Disallow rule and variable names starting with `_`
- Rename most local variable names generated by the parser to start with `_`

Exceptions:
- Renaming `p` to `_p` will be a separate PR
- There are still some names that might clash, e.g.
  - anything starting with `Py`
  - C reserved words (`if` etc.)
  - Macros like `EXTRA` and `CHECK`

* Add link to Enum class (GH-19884)

* bpo-40397: Remove __args__ and __parameters__ from _SpecialGenericAlias (GH-19984)

* bpo-40549: Convert posixmodule.c to multiphase init (GH-19982)

Convert posixmodule.c ("posix" or "nt" module) to the multiphase
initialization (PEP 489).

* Create the module using PyModuleDef_Init().
* Create ScandirIteratorType and DirEntryType with the new
  PyType_FromModuleAndSpec() (PEP 573)
* Get the module state from ScandirIteratorType and DirEntryType with
  the new PyType_GetModule() (PEP 573)
* Pass module to functions which access the module state.
* convert_sched_param() gets a new module parameter. It is now called
  directly since Argument Clinic doesn't support passing the module
  to an argument converter callback.
* Remove _posixstate_global macro.

* bpo-37986: Improve perfomance of PyLong_FromDouble() (GH-15611)

* bpo-37986: Improve perfomance of PyLong_FromDouble()

* Use strict bound check for safety and symmetry

* Remove possibly outdated performance claims

Co-authored-by: Mark Dickinson <dickinsm@gmail.com>

* bpo-40397: Fix subscription of nested generic alias without parameters. (GH-20021)

* bpo-40257: Tweak docstrings for special generic aliases. (GH-20022)

* Add the terminating period.
* Omit module name for builtin types.

* Improve code clarity for the set lookup logic (GH-20028)

* bpo-40585: Normalize errors messages in codeop when comparing them (GH-20030)

With the new parser, the error message contains always the trailing
newlines, causing the comparison of the repr of the error messages
in codeop to fail. This commit makes the new parser mirror the old parser's
behaviour regarding trailing newlines.

* bpo-40575: Avoid unnecessary overhead in _PyDict_GetItemIdWithError() (GH-20018)

Avoid unnecessary overhead in _PyDict_GetItemIdWithError() by calling
_PyDict_GetItem_KnownHash() instead of the more generic PyDict_GetItemWithError(),
since we already know the hash of interned strings.

*