107 Commits
Author SHA1 Message Date
Jean-Marc Le Roux 3805038dec zlib: clear unconsumed_tail when a bounded decompress reaches stream end (#8908)
* zlib: clear unconsumed_tail when a bounded decompress reaches stream end

When a max_length-bounded Decompress.decompress() call reached the end
of the stream, the bytes after the stream went to unused_data, but
unconsumed_tail kept the previous call's tail, including input the call
had already consumed. A later flush() then moved those stale bytes into
unused_data.

Empty unconsumed_tail at end of stream, as CPython's
save_unconsumed_input() does since gh-158169. CPython releases before
that change report the bytes after the stream in unconsumed_tail, so
the snippet accepts either value when it runs under CPython.

Fixes #8906

Assisted-by: Claude Code:claude-opus-5-5

* zlib: bind the unconsumed input with an if expression

Choose between the empty slice and the rest of the input in one
expression instead of reassigning a mutable binding.

Assisted-by: Claude Code:claude-opus-5-5

* zlib: accept both valid tails in the snippet on every implementation

The snippet no longer branches on sys.implementation. RustPython and
CPython after gh-158169 give an empty tail; CPython before it gives the
bytes after the stream. The stale tail of gh-8906 fails either way.

Assisted-by: Claude Code:claude-opus-5-5
2026-09-30 22:15:40 +09:00
Jeong, YunWon bdc9246b37 Address builtin members by field offset (#8816)
* Address builtin members by field offset

`#[pymember]` now declares a field of the payload and generates a
PyMemberDef whose offset is the payload offset plus the field offset.
The getter/setter function form and `MemberAccess::Func` are removed;
builtin, slot, and C-API members share one get/set path. The macro
checks the field type against the member type.

Converted members: property fget/fset/fdel/__doc__, function
__globals__/__closure__/__builtins__/__doc__/__module__, staticmethod
and classmethod __func__/__wrapped__, complex real/imag (T_DOUBLE),
frame f_trace_lines (T_BOOL), defaultdict default_factory, getset and
member descriptor __name__/__objclass__, module __dict__.
frame.f_trace_opcodes is a getset.

Writable member fields are atomic pointer cells. The instance dict
pointer is an atomic cell at a fixed offset in front of the object,
and dict presence follows the type's HAS_DICT flag. The pickle
basicsize check no longer counts dict, weakref, and slot storage,
which live outside the payload.

Assisted-by: Grok:4.7
Assisted-by: Claude:claude-opus-5-5

* Address member review findings

- `#[pymember]` keeps leading `#[cfg]` attributes on the generated
  registration, and malformed `field`/`offset` values are compile
  errors.
- The `descriptor` module and the items the expansion names are public.
- Writable double members are an `AtomicU64` cell, loaded and stored
  with relaxed atomics. Readonly double members stay plain `f64` reads.
- `LOAD_ATTR_SLOT` is not specialized for `Py_AUDIT_READ` members.
- `defaultdict.__reduce__` passes no factory argument when
  `default_factory` is None.

Assisted-by: Grok:4.7
Assisted-by: Claude:claude-opus-5-5

* Declare members on payload fields

`#[pymember]` goes on a payload struct field, or on the struct with an
explicit `offset` when the storage is not a payload field. The struct
`#[pyclass]` builds `PyClassDef::MEMBERS`, a static `PyMemberSpec`
table, and `extend_class` registers one member descriptor per entry.
`path` addresses a subfield, one field may carry several members, and a
`#[cfg]` on the field gates its entry. The impl-side const form is
removed and now a compile error.

Assisted-by: Grok:4.7
Assisted-by: Claude:claude-opus-5-5

* Split nullable and non-null atomic cells

The nullable cell API (`new_empty`, `load_owned`, `store`,
`compare_exchange_empty`) moves from `PyAtomicRef<PyObject>` to
`PyAtomicRef<Option<PyObject>>`, and the typed `PyAtomicRef<Option<T>>`
shares it. The non-null `PyAtomicRef<PyObject>` gets `load_owned` and
`store` that return the object directly.

Slot cells, property fget/fset/fdel/__doc__, and defaultdict
default_factory are nullable cells. staticmethod and classmethod
callable are non-null cells and are read without `unwrap`. The
instance dict cell is `PyAtomicRef<Option<PyDict>>`, so reading it no
longer downcasts.

Assisted-by: Grok:4.7
Assisted-by: Claude:claude-opus-5-5

* Drop the unused cold trace_lines flag

`FrameColdData::trace_lines` had no writer after `f_trace_lines`
became a frame object member. A frame without a frame object traces
lines by default.

Assisted-by: Claude:claude-opus-5-5

* Compute payload offsets from the merged Py header

`PyInner` is now `Py`, so the payload offset and the dict member
offset are measured from `Py<T>`.

Assisted-by: Claude:claude-opus-5-5

* Expose descriptor names and owner types as members

method_descriptor, classmethod_descriptor, and wrapper_descriptor
expose `__objclass__` and `__name__` as readonly members, and
method-wrapper exposes `__self__` as a readonly member. The separate
`objclass` field of method and classmethod descriptors always equaled
`common.typ` and is removed.

Assisted-by: Grok:4.7
Assisted-by: Claude:claude-opus-5-5

* Expose remaining builtin tp_members as members

Attributes stored in a payload field become readonly or writable
member descriptors: bound method __func__/__self__, code
co_argcount/co_posonlyargcount/co_kwonlyargcount/co_stacksize (Py_T_UINT),
generic alias, coroutine and async generator members, interpolation and
template, range and slice start/stop/step, type __base__, union, and the
typing TypeVar, ParamSpec, TypeVarTuple, and TypeAliasType members.
`MemberKind` gains `Int` and `Uint` with the `PyMember_GetOne`/`SetOne`
range checks.

Attributes computed on access or kept behind a lock stay getsets.

Assisted-by: Grok:4.7
Assisted-by: Claude:claude-opus-5-5

* Spell a docless member as doc = false

`#[pymember(doc = false)]` stores no docstring, matching the
`doc = "..."` form, and replaces the separate `no_doc` flag.

Assisted-by: Claude:claude-opus-5-5

* Make pymember readonly by default

`#[pymember]` declares a readonly member unless `writable` is given.
The `readonly` option is removed and every declaration is converted.

Assisted-by: Claude:claude-opus-5-5

* Check the receiver of method descriptors

Binding or calling a method_descriptor with an object that is not an
instance of the owner type raises TypeError before the native function
runs. Static and class methods are exempt.

Assisted-by: Grok:4.7
Assisted-by: Claude:claude-opus-5-5

* Expose exception attributes as members

BaseException.__suppress_context__, StopIteration.value, SystemExit.code,
ImportError, NameError, AttributeError, OSError, SyntaxError,
BaseExceptionGroup and the UnicodeEncode/Decode/TranslateError attributes
are member descriptors backed by payload fields. ImportError, NameError,
AttributeError and SyntaxError gain payloads for their fields, and the
methods that read those attributes read the fields. Add the Py_ssize_t
member kind for UnicodeError start and end.

Assisted-by: Grok:4.7
Assisted-by: Claude:claude-opus-5-5

* Avoid same-type casts in unsigned member conversion

On targets where c_ulong is u32, casting through c_ulong was a no-op
cast that clippy rejects.

Assisted-by: Claude:claude-opus-5-5

* Prefer an explicit pymember doc over the doc table

doc = "text" is used as the docstring without consulting the stored
attribute documentation; only an omitted doc looks it up. Drop the member
doc strings that repeated the stored documentation.

Assisted-by: Grok:4.7
Assisted-by: Claude:claude-opus-5-5

* Infer pymember kinds from field types

MemberLayout gives the member kind of each accepted field type, and the
macro reads it from the field or path subfield, so type = "bool" and
the other numeric spellings are gone. type only selects object_ex.
Writable doubles use a new AtomicF64 cell instead of AtomicU64 bits.
MemberLayout and MemberCell replace the per-kind marker traits.

Assisted-by: Grok:4.7
Assisted-by: Claude:claude-opus-5-5

* Read nullable atomic cells only through load_owned

PyAtomicRef<Option<T>> and PyAtomicRef<Option<PyObject>> lose to_owned,
to_owned_ordering and try_to_owned; load_owned, which retries the
incref until it applies to the pointer still in the cell, is the one
owned read. Callers that kept a deref borrow across VM calls now take a
strong reference.

Assisted-by: Grok:4.7
Assisted-by: Claude:claude-opus-5-5

* Inherit static type slots from the whole MRO

extend_class copied slots only from the direct bases, and tp_init is
copied only from a base that defines it, so TabError missed the
SyntaxError init that IndentationError inherits. Walk the MRO the same
way init_slots does.

Assisted-by: Grok:4.7
Assisted-by: Claude:claude-opus-5-5

* Let Rust doc comments win over stored docstrings

A /// comment on a Python-exposed item is its docstring; the
rustpython-doc entry is used only when there is none. #[pymember] reads
the field's /// comment instead of doc = "...". Doc comments that were
shadowed by a stored docstring become // comments, so no docstring
changes. AGENTS.md describes the rule.

Assisted-by: Grok:4.7
Assisted-by: Claude:claude-opus-5-5

* Adapt members to upstream changes

_collections._tuplegetter.__doc__ is a writable nullable member on the
payload field. The impl-side const form no longer compiles.

Assisted-by: Grok:4.7

* Drop docstring text left as comments and inline downcast_cell

Comments that only repeated an item's docstring are removed; developer
notes stay as // comments. The typed cell methods call
downcast_unchecked directly, each with its own safety note.

Assisted-by: Grok:4.7
Assisted-by: Claude:claude-opus-5-5

* Read sqlite row factories through load_owned

The nullable cell no longer has to_owned; the sqlite module is built only
with the sqlite feature, so the default build did not catch it.

Assisted-by: Claude:claude-opus-5-5
2026-09-27 13:38:11 +09:00
Jeong, YunWon 155cea292f Store instance slots as atomic object pointers (#8804)
* Store instance slots as atomic object pointers

PyMemberDef now carries type, offset, and flags. Slot values are
atomic PyObject pointers with try-incref reads, so a concurrent
store cannot free the memory under a reader. Objects placed in a
slot stay published until QSBR reclaims them.

Assisted-by: Grok:4.7

* Collapse nested slot load condition

Assisted-by: Grok:4.7

* Reject over-long digit strings before parsing

A pure ASCII digit string longer than the int digit limit now fails
from a wide digit check. The denial-of-service test no longer spends
the failure path scanning and parsing the whole literal.

Assisted-by: Grok:4.7

* Collapse nested digit-limit condition

Assisted-by: Grok:4.7

* Restore MemberKind for member type codes

The VM stores the member type as an enum whose discriminants match
the C type codes. The C API still reads the integer and converts it
at the boundary. Flags stay integers.

Assisted-by: Grok:4.7

* Mark MemberKind::from_i32 as must_use

Assisted-by: Grok:4.7
2026-09-24 21:40:49 +09:00
Jeong, YunWonandLee Dogeon afad92bf1b Add OrderedDict, marshal, inspect, and chflags bitflagset (#8780)
* Implement _collections.OrderedDict

Extracted from #6799: native OrderedDict as a dict subclass,
iterator mutation tracking, and mapping-view set operations.

* Add OrderedDict, warnings source lines, and socket sendmsg

Implement _collections.OrderedDict as a dict subclass with a
linked list of insertion-order nodes.

Pack struct F/D as native float/double complex pairs, and report
unexpected __replace__ field names as a list repr.

Register encodings.latin_1 at startup. Reject NUL in input()
prompts. Copy non-exact type dicts in mapping order.

Fetch warning source lines through _bless_my_loader and unicode
splitlines. Keep the last warnings.filters list after deletion.

Snapshot sendmsg sequences before converting buffers, parse
ancillary ints with __index__, and dispatch AF_CAN by protocol.

Store sys.trace and sys.profile on each ThreadSlot so
_settraceallthreads/_setprofileallthreads are visible to
sys.gettrace/getprofile on other threads.

Use <frozen importlib._bootstrap> as frozen importlib
co_filename. Keep HEAPTYPE socket objects GC-tracked.

Assisted-by: Grok:grok-4.6

* Load marshal via readinto and dump sets in dumps order

marshal.load fills a scratch buffer with readinto on a
contiguous writable memoryview, and rejects a returned length
other than the requested size.

set and frozenset dumps write elements in sorted(v,
key=marshal.dumps) order.

Assisted-by: Grok:grok-4.6

* Add classmethod_descriptor and ABC IS_ABSTRACT flags

Give METH_CLASS methods a distinct classmethod_descriptor type.
Store Py_TPFLAGS_IS_ABSTRACT from __abstractmethods__ and look
up that attribute only in the type's own dict.

Expose defaultdict.default_factory as a member descriptor.
Inherit bool's unused number slots from int. Mark set and
frozenset __contains__ as METH_COEXIST.

Parse classmethod, staticmethod, object.__new__, and heap type
text signatures. Register interactive source in linecache.

Assisted-by: Grok:grok-4.6

* address review: odict reuse, descr call, new wrapper

Reuse odict node slots and walk the live list in next_after.
Require both | operands to be dicts. Drop the odict iterator
on GC clear. Bind classmethod descriptors through descr_get
and update IS_ABSTRACT under the type lock. Give odict keys
and items sq_contains. Walk tp_new_wrapper past new_wrapper
so HEAPTYPE socket subclasses can call socket.__new__.
Split FreeBSD Bluetooth protocol constants from Linux values.

Assisted-by: Grok:grok-4.6

* Represent chflags bits with bitflagset

Assisted-by: Grok:grok-4.6

* Represent access and mode bits with bitflagset

Assisted-by: Grok:grok-4.6

* Continue unfinished REPL suites as incomplete input

Assisted-by: Grok:grok-4.6

* Add pickle and os.stat inspect signatures

Give _pickle.Pickler the clinic constructor text signature and
accept fix_imports and buffer_callback as positional-or-keyword.
Allow #[pyfunction(text_signature)] and use it so os.stat reports
(path, *, dir_fd=None, follow_symlinks=True). Uncomment import
_pickle and drop the pickle inspect expectedFailures.

Assisted-by: Grok:grok-4.6

* Add Unpickler, dump/load, and lstat signatures

Give _pickle Unpickler, dump, dumps, load, and loads clinic
text signatures, and os.lstat (path, *, dir_fd=None).

Assisted-by: Grok:grok-4.6

* Complete OrderedDict with insertion-order links

Move the native OrderedDict into ordered_dict.rs and track order
with a linked list of nodes, keeping mapping-view set operations.

Assisted-by: Grok:grok-4.6

* address CI: stat casts, HCI_DATA_DIR, passing xfails

Compare stat permission bits as Mode so Linux clippy does not
flag a u32-to-u32 cast. Export HCI_DATA_DIR with the Bluetooth
socket option values. Drop expectedFailure from tests that now
pass.

Assisted-by: Grok:grok-4.6

* Fix wasm teardown deadlock and bluetooth constants

Assisted-by: Grok:grok-4.6

* Clear process-wide eval breaker bits in STW test

Assisted-by: Grok:grok-4.6

* Drop exclusive-held panic that tripped wasm clippy

Assisted-by: Grok:grok-4.6

* Fix OrderedDict contains and export Windows BDADDR

Assisted-by: Grok:grok-4.6

* Add cmp_to_key and hash-once LRU cache

_functools.cmp_to_key now returns KeyWrapper. LRU lookups store the
key hash on _lru_list_elem so __hash__ is not called again on hits
or eviction.

Assisted-by: Grok:grok-4.6

* Allow subclass keywords on list, tuple, and float

list.__init__ rejects keywords only when tp_new is still list's.
tuple/float.__new__ reject them only when tp_init is still the base's.

Assisted-by: Grok:grok-4.6

* Fix CI lint, test re-export, and structseq members

Drop the duplicate clear_eval_breaker_for_test re-export.
Format structseq imports. Expose struct sequence fields as
readonly members so assignment raises "readonly attribute".

Assisted-by: Grok:grok-4.6

* Allow subclass keywords on itertools and filter

Positional-only constructors ignore extra keywords when a subclass
has replaced tp_init, matching list/tuple/float.

Assisted-by: Grok:grok-4.6

* Remove text_signature derive parameter

Drop the string override on #[pyfunction] and #[pyclass]. Signatures
are generated from the Rust parameter list only. Restore inspect
expectedFailures that depended on the override.

Assisted-by: Grok:grok-4.6

* Rename set contains_method to __contains__

Keep a borrowed contains helper for slots and C-API. The coexist
pymethod is named __contains__.

Assisted-by: Grok:grok-4.6

* Use MonitoringEvent instead of EVENT_* aliases

Drop the unused MonitoringEvents bitflags and the EVENT_PY_START
style mask constants. Call sites use the enum and .mask().

Assisted-by: Grok:grok-4.6

* Store warnings filters as PyListRef

The list already serializes its elements. Drop the extra mutex around
the cached list pointer.

Assisted-by: Grok:grok-4.6

* Re-export clear_eval_breaker_for_test after rebase

Keep the STW test helper visible without bringing back stop_bit_set.

Assisted-by: Grok:grok-4.6

* Fix groupby reentrancy and islice arguments

Give _grouper its own tgtkey and take currvalue after the key
comparison. Accept __index__ on islice bounds, reject step 0, and
drain the source up to stop.

Assisted-by: Grok:grok-4.6

* SETREF warnings filters, onceregistry, and defaultaction

Keep the last list, dict, or str after the module attributes are
deleted by swapping the interpreter cache pointer. Do not store a
None fallback for _warnings_context.

Assisted-by: Grok:grok-4.6

* Iterate OrderedDict inner dict via next_entry

&PyDict is not an iterator after the borrowed-ref signature change.

Assisted-by: Grok:grok-4.6

* Remove expectedFailure from testBluetoothConstants

Linux now exports BTPROTO_HCI and the rest of the set.

Assisted-by: Grok:grok-4.6

* Borrow get_filter arguments as PyObject

Match the warn_explicit call site that passes borrowed
handles after the internal-helper borrow change.

Assisted-by: Grok:grok-4.6

* Fix bool slots and SemHandle safety docs

Leave unused bool number slots unset so inspect reports
__add__ on int. Document SemHandle::from_raw safety.

Assisted-by: Grok:grok-4.6

* Keep sendmsg errors and drop duplicate linecache

Replace sendmsg iterable TypeError only. Register REPL
source in linecache once per compiled input.

Assisted-by: Grok:grok-4.6

* Nest REPL parse or-patterns for clippy

Assisted-by: Grok:grok-4.6

* Mark pydoc os.stat signature test expectedFailure

Assisted-by: Grok:grok-4.6

---------

Co-authored-by: Lee Dogeon <dev.moreal@gmail.com>
2026-09-24 12:21:26 +09:00
Joshua Megnauth 86c7fa20c4 Fix missing workspace lints & fix lints (#8781)
Some of the workspace packages were missing the `[lints]` table. I
enabled the lints then fixed the resulting errors.
2026-09-24 07:49:50 +09:00
Jeong, YunWon 7b018871a3 host_env: export remaining stdlib constants (#8760)
* host_env: export winsound, spawn, and remaining SSL_OP flags

Assisted-by: Claude

* stdlib: take winsound, nt spawn, and SSL_OP names from host_env

Assisted-by: Claude

* host_env: export ssl alerts, sysexits, socket extras

Assisted-by: Claude

* stdlib: take remaining host_env and common constants

Assisted-by: Claude

* Remove unused workspace exitcode dependency

Assisted-by: Claude

* host_env: export PROTO, access, reparse, wait flags

Assisted-by: Claude

* stdlib: take PROTO, access, reparse, wait from host_env

Assisted-by: Claude
2026-09-21 19:37:16 +09:00
YujinBae 587880b9e1 Read decimal digit values from the bundled character database (#8748)
`char_to_decimal` carried its own sorted table of 590 decimal digit
characters, added in #5643 because `common` had no way to reach the
Unicode numeric data at the time: it lived in `stdlib`, which sits above
`common` in the dependency graph. The table's own comment said as much —
"this should probably live in a crate like unic or unicode-properties".

#8211 extracted that data into `rustpython-unicode`, below `common`, and
made `common` depend on it, so the table can now be dropped in favour of
`Ucd::decimal` — the same source `unicodedata.decimal` consults.

This fixes a CPython incompatibility. The table was last updated for
Unicode 10; the bundled UCD is Unicode 17, which has 180 more decimal
digits across 18 scripts (Hanifi Rohingya, Wancho, Tangsa, Ol Onal,
segmented digits and others). Those were rejected by `int()` and
`float()` even though `unicodedata.decimal` knew their value:

    >>> int('\u{10D33}')        # HANIFI ROHINGYA DIGIT THREE
    ValueError                  # CPython: 3
    >>> unicodedata.decimal('\u{10D33}')
    3

All 590 characters the table covered keep their previous value, so
nothing that already worked changes, and the two lookups can no longer
drift apart on a future Unicode update.

The lookup costs about 1.5ns more per non-ASCII character, since it reads
a property trie and a value table instead of binary-searching one 2.4KB
array: `int()` over a 4000-digit non-ASCII string goes from 12.2 to
13.6 ns/char. ASCII input never reaches it — the sole caller,
`transform_decimal_and_space_to_ascii`, returns early for ASCII strings —
so ordinary numeric parsing is unaffected.

Assisted-by: Claude Code:claude-opus-5
2026-09-20 17:48:22 +09:00
hyoinandout 4c7cc0a30c lzma: treat empty input as a no-op, not end of stream (#8752)
decompress_chunks reports whether the codec signalled LZMA_STREAM_END,
and it short-circuits when the chunker has nothing left to feed. That
early return answered "the stream ended" for the case where no input was
supplied at all, so LZMADecompressor.decompress(b"") claimed a finish the
decoder had never signalled.

The caller latches that answer with `self.eof |= stream_end`, which only
ever flips eof on. A single empty call therefore finished the object for
good: needs_input went false and every later call was rejected by the
`if self.eof` guard with EOFError, before a single compressed byte had
been seen. CPython leaves eof false and needs_input true, and accepts
compressed data handed over by a later call.

  d = lzma.LZMADecompressor()
  d.decompress(b"")   # d.eof was True, now False
  d.decompress(blob)  # was EOFError, now b'data'

The zlib engine returns false from the same short-circuit; lzma had
drifted away from it. bz2 was fixed incidentally by #8638 when its engine
moved into crates/common, so only lzma needed a code change.

Verified on macOS arm64 against CPython 3.14.7: the script from the issue
now prints the documented "False True" and b'data' for both
decompressors. test_decompressor_chunks_empty in Lib/test/test_lzma.py
covers exactly this and no longer needs its expectedFailure marker. The
added engine test is named after the zlib one that already existed and is
mirrored into bz2, so all three engines stay pinned to the same
behaviour. test_lzma, test_bz2, test_zlib, test_gzip, test_tarfile,
cargo test --workspace, cargo fmt --check and cargo clippy
-p rustpython-common --all-features --all-targets -D warnings are clean.

Fixes #8637

Assisted-by: Claude Code:claude-opus-5
2026-09-20 17:22:27 +09:00
Jeong, YunWon 7bc3ef6c0a ExceptionGroup fields, OSError use-init, and live f_lineno (#8738)
* Add ExceptionGroup fields and OSError use-init

BaseExceptionGroup stores msg, excs, and excs_str; args keep
the original sequence. OSError defers parse when a subclass
overrides only __init__. characters_written can be deleted.
Exception args/traceback/cause/context reject invalid
setattr/delattr. UnicodeError.object is a deletable field.
except* remainder projection copies traceback/context/cause.
SyntaxError.__init__ clears omitted location attributes.

Assisted-by: Grok:grok-4.6

* Fix OSError payload init and UnicodeError construction

new_payload_exception now runs slot_new so BlockingIOError
parses characters_written. new_exception falls back to
invoke_exception for extra-payload types. Mixed tab/space
UnexpectedIndentation is TabError. AttributeError pickle
omits obj.

Assisted-by: Grok:grok-4.6

* address review: classify TabError from error line

Assisted-by: Grok:grok-4.6

* Add new_simple_exception; fill SyntaxError and f_lineno

new_exception constructs extra-payload types; BaseException-sized
types use new_simple_exception. Non-UTF-8 SyntaxError sets location
and text. Codegen errors load text via ProgramText. Keep Missing
parentheses capitalization. f-string adjacent atoms report a missing
comma. f_lineno may be None; lasti is not restored on unwind.

Assisted-by: Grok:grok-4.6

* address review: skip f-string continuation keywords

Assisted-by: Grok:grok-4.6

* Fix clippy map_unwrap_or in Non-UTF-8 offset

Assisted-by: Grok:grok-4.6

* Rename encode error ctor and exception setters

new_unicode_encode_error_real is new_unicode_encode_error.
set___traceback__/__cause__/__context__ are pygetset setters;
Rust uses set_traceback/set_cause/set_context.

Assisted-by: Grok:grok-4.6

* Use set_context in native pickle

Assisted-by: Grok:grok-4.6

* Collapse nested if in asyncio traceback restore

Assisted-by: Grok:grok-4.6

* Use current instruction for f_lineno addr2line

lasti is stored as the next instruction index. addr2line of
that byte offset is past RETURN_VALUE, so f_lineno was None
and stdlib_threading_current_frames hung on leftover workers.

Assisted-by: Grok:grok-4.6

* Look up format args, dir class, and frame builtins

Consume printf args before rejecting unknown conversions.
object.__dir__ uses getattr of __class__/__dict__.
_PyEval_GetBuiltin looks up iter/__import__ on the frame.

Assisted-by: Grok:grok-4.6

* Fix builtin lookups after rebase and unxfail passing tests

Assisted-by: Grok:grok-4.6

* Restore RERAISE lasti and SyntaxError locations

RERAISE with oparg restores lasti from the exception table
before unwind, so leftover f_lineno matches the original raise.
Handler lookup still uses the raising instruction.

Indentation errors outrank print/exec missing-parentheses.
BOM-with-non-utf8, bytes literals, and global+nonlocal now
report the same offsets as the parser/symtable.

object.__dir__ keeps string keys; type.__type_params__ skips
the getset wrapper stored on builtin types.

Assisted-by: Grok:grok-4.6

* Unxfail syntax/import tests and bind jump locals

IMPORT_NAME passes fromlist None instead of an empty tuple.
Jumping f_lineno binds None into unbound localsplus slots.
str lstrip/rstrip copy subclasses to exact str when unchanged.

Assisted-by: Grok:grok-4.6

* Fix import_from callers and rename frame lineno

sqlite3.iterdump now passes fromlist as a PyObject.
FrameObject::lineno is the i32 helper; f_lineno is the getset.

Assisted-by: Grok:grok-4.6

* Pass sqlite fromlist without Into conversion

from_list.into() could not infer Into<PyObjectRef> at the
import_from call. The typed tuple already converts.

Assisted-by: Grok:grok-4.6
2026-09-20 14:22:58 +09:00
Jeong, YunWonandLee Dogeon d02d81e740 perf: VM and runtime hot paths from pyperformance (#8737)
* time: use CLOCK_UPTIME_RAW for monotonic/perf_counter on Apple

CLOCK_MONOTONIC keeps advancing during system sleep on macOS, unlike
CPython's mach_absolute_time()-backed perf_counter/monotonic. Benchmarks
that spanned a laptop sleep recorded thousands of seconds for a single
iteration (pyperformance float/fannkuch showed ~1000x slowdowns).
Use CLOCK_UPTIME_RAW (equivalent to mach_absolute_time) on Apple targets
and report it as such in time.get_clock_info().

Assisted-by: Claude Code:claude-fable-5-1

* vm: derive f_lineno lazily instead of tracking prev_line per instruction

The dispatch loop wrote prev_line (a locations lookup plus a Cell store)
on every instruction only so f_lineno could read it. f_lineno now derives
the line from lasti and code.locations, prev_line is only maintained on
the cold tracing path for 'line' event de-duplication, the two use_tracing
reads per instruction are merged into one, and the pre-dispatch lasti
reload is replaced by the value just stored.

When a trace function is installed on an already-running frame (bdb
stepping back into an untraced caller, frame.f_trace assignment, a local
trace returned from the 'call' event on a resumed generator) prev_line is
synced from lasti so no spurious 'line' event fires.

Assisted-by: Claude Code:claude-fable-5-1

* vm: coalesce per-call thread-locals into one FRAME_SLOT_CACHE

set_current_frame ran on every frame enter/exit and touched three separate
thread_local! statics (each a _tlv_get_addr call on macOS). Merge them into
a single thread-local struct so the hot path does one TLS access.

Assisted-by: Claude Code:claude-fable-5-1

* vm: fold stop/finalizing checks into EVAL_BREAKER

eval_breaker_tripped ran three checks per bytecode: the finalizing flag,
a thread-local stop_requested lookup, and the EVAL_BREAKER load. Add
STOP_BIT and FINALIZING_BIT so the per-instruction check is a single
relaxed atomic load; the slow path (check_signals) still re-derives the
exact per-thread answer. The bits are set alongside the per-thread flags
and cleared under the stop-the-world exclusion.

Assisted-by: Claude Code:claude-fable-5-1

* gc: set the TRACKED bit with a plain store for freshly allocated objects

gc_bits is zero for a fresh allocation (both the freelist reuse path and
PyInner::new zero it), so track_new_object can initialise the bit with a
relaxed store instead of a fetch_or. Re-tracking resurrected objects keeps
the read-modify-write variant.

Assisted-by: Claude Code:claude-fable-5-1

* vm: skip thread exception publish when pushing/popping a None exc slot

Generator/coroutine resume pushes and pops an exc_info slot on every
send. When that slot is None the value returned by topmost_exception
cannot change (it skips None entries), so the thread-local exception
publish in push_exception/pop_exception is unnecessary.

Assisted-by: Claude Code:claude-fable-5-1

* vm: allocation-free keyword-call fast path and super() MRO walk

Keyword calls to plain functions where every parameter is filled exactly
once are reordered in place into the fast-locals layout (no IndexMap, no
keyword name clones); any mismatch falls back to the existing slow path
so error messages are unchanged. super().attr now walks the type's MRO
by reference instead of cloning every class into two Vecs per lookup.

Assisted-by: Claude Code:claude-fable-5-1

* builtins: cheaper enumerate and zip iteration

enumerate kept its counter as a BigInt behind a write lock and did bignum
arithmetic on every item; use a machine integer that promotes to BigInt
only for huge/negative starts or on overflow. zip pre-sizes its per-item
Vec so the common two-iterable case allocates once.

Assisted-by: Claude Code:claude-fable-5-1

* _asyncio: cache module objects and use native set/dict operations

Task registration re-resolved _asyncio module attributes and re-imported
contextvars on every task; the eager path additionally went through generic
call_method for set add/discard. Cache the module objects per thread
(validated by identity), split the contextvars cache from the task
containers, and use PySet/PyDict methods directly.

Assisted-by: Claude Code:claude-fable-5-1

* perf: use mimalloc as global allocator for rustpython CLI

Adds mimalloc (0.1.52, default-features = false) as the #[global_allocator]
for the rustpython binary, gated behind a new `mimalloc` feature enabled
by default on non-wasm targets (dep declared under
target.'cfg(not(target_arch = "wasm32"))'.dependencies, so wasm builds
never pull it in regardless of default-features).

Profiling a `t = (a, b, c)` loop showed malloc/free at ~40% of samples on
macOS with the system allocator. Switching to mimalloc gives consistent
wins across small-object-heavy workloads, medians over 5-9 interleaved
A/B rounds (release build, this machine):

  tuple (5M `(a,b,c)`)         1.020s -> 0.863s  (1.18x)
  4-thread tuple (5M total)    1.643s -> 1.382s  (1.19x)
  class instances (2M)         0.874s -> 0.797s  (1.10x)
  dict-heavy (200k x 20)       2.196s -> 1.992s  (1.10x)
  string-heavy (join x 20)     0.662s -> 0.592s  (1.12x)
  nqueens (pyperformance)      0.327s -> 0.286s  (1.14x)
  chaos (pyperformance)        0.204s -> 0.191s  (1.06x)
  richards (pyperformance)     0.154s -> 0.151s  (1.02x)
  go (pyperformance)           0.411s -> 0.405s  (1.01x)
  listcomp / fib               ~neutral (<=1%)

Peak RSS (/usr/bin/time -l): instances workload roughly unchanged
(29.0MB -> 29.1MB); dict-heavy workload actually drops (155MB -> 106MB),
likely because mimalloc reclaims freed pages more aggressively than the
system allocator across repeated large-dict churn.

`cargo build` and `cargo build --release` are warning-free with the
default feature set, and `cargo build --release --no-default-features
--features stdlib,threading,importlib,stdio,host_env` (mimalloc
excluded) also builds cleanly. CI's wasm32-wasip1 and other
--no-default-features build matrices in .github/workflows already omit
`mimalloc` from their feature lists and target wasm via the
cfg(not(wasm32)) dependency gate, so no workflow changes needed.

`rustpython -m test -j4 test_gc test_weakref test_threading test_dict
test_list test_tuple test_str test_bytes test_memoryview test_ctypes
test_mmap test_array` passes identically (2541 tests, 241 skipped) on
both the baseline and mimalloc binaries.

Assisted-by: Claude Code:claude-fable-5-1

* vm: cap dict/set table shrink and compact holes on resize

asyncio's eager task path (and its per-task bookkeeping sets in general)
repeatedly adds and discards distinct task objects from a handful of
long-lived sets (_eager_tasks, _scheduled_tasks). Two dict_inner issues
turned that steady-state churn into the dominant cost of async_tree_eager:

1. resize() picked a target size of `used * 2` with no floor, so once a
   churny set settled around 1-2 live entries it shrank to a table that
   the very next insert would already overflow, forcing a resize on
   almost every single add. Clamping to the original minimum table size
   (8) restores the headroom dict/set start with.

2. `entries` only ever grows (holes from deletions are never reclaimed),
   so resize()'s rebuild pass scanned every entry ever inserted into the
   dict's lifetime, not just the live ones - a set with a stable working
   set size but heavy churn grew this scan, and the dict's memory, without
   bound. resize() now compacts holes out of `entries` first, matching
   CPython's compacting hash table and keeping the shape-stamp fast path
   (which already requires a hole-free layout) reachable more often.

Measured with a standalone async_tree micro-benchmark (6 levels x 6
branches, pyperformance's bm_async_tree "none"/"eager" shape) run inside
one process for 10 asyncio.run() iterations, comparing medians of
interleaved binary runs on an otherwise idle machine:

- eager: ~2.91s -> ~0.86s median (about 3.4x)
- none:  ~1.98s -> ~1.23s median (about 1.6x)

A single fresh-process run (no in-process accumulation) still improves
by roughly 15-20% for eager, since the resize-storm from point 1 hits
even a single run's worth of task churn.

test_asyncio (34 files, all passing), test_dict, test_set, test_weakref,
test_weakset, test_ordered_dict, test_gc, test_descr, test_class, and
`cargo test -p rustpython-vm -p rustpython-stdlib` all pass.

Assisted-by: Claude Code:claude-fable-5-1

* _functools: add native _lru_cache_wrapper

RustPython had no native _functools._lru_cache_wrapper, so
functools.lru_cache always fell back to the pure-Python implementation
in Lib/functools.py (RLock, linked-list bookkeeping, closures). That
fallback dominates typing.Protocol's __instancecheck__ path: it calls
inspect.getattr_static, whose _shadowed_dict is itself lru_cache'd, so
every isinstance() check against a runtime-checkable protocol paid for
several pure-Python cache-wrapper calls plus lock acquisitions.

Add a native pyclass mirroring CPython's C _lru_cache_wrapper: a
reentrant lock scoped only around the cache lookup/insert steps (not
held across the wrapped call, matching CPython's threading behavior),
LRU ordering piggybacked on the cache dict's own insertion order
(move-to-end via del+reinsert, oldest evicted from the front) so no
separate key-comparison structure is needed, and __copy__/__deepcopy__
returning self to match CPython since __reduce__ (used only for
pickling) requires __qualname__, which wrapped non-function callables
such as functools.partial don't have.

Measured with a standalone script reproducing pyperformance's
bm_typing_runtime_protocols isinstance() loop (300 loops, medians of
5 interleaved runs): 0.260s -> 0.182s, about 1.43x faster. In
isolation, a cache-hit through lru_cache went from ~0.31s to ~0.07s
for 200k calls, now faster than calling the underlying function
uncached (matching CPython's C accelerator).

Verified with test_typing, test_abc, test_inspect, test_functools,
test_weakref, test_isinstance, and test_descr (all pass, matching the
pre-existing baseline, including test_functools's already-present
TestLRUC suite which now actually exercises the native implementation).

Assisted-by: Claude Code:claude-fable-5-1

* sre_engine: ASCII fast path for \d \s \w unicode category checks

is_uni_digit/is_uni_space/is_uni_alnum went through icu_properties'
GeneralCategory table lookup for every character, even the common
ASCII case. Add a `ch < 0x80` fast path that resolves directly via
std's ascii predicates, falling back to the full table only for
non-ASCII code points (Latin-1 supplement chars like 'A-umlaut' still
route through the table since they are alphanumeric but not ASCII).

Measured on a tight `re.findall(r"\w+", ...)` / `re.sub` loop over
mostly-ASCII text (interleaved A/B, 4 rounds, medians):
  re.sub:    1.178s -> 1.134s  (~3.7% faster)
  re.findall: 1.110s -> 1.062s (~4.3% faster)

Assisted-by: Claude Code:claude-fable-5-1

* vm: skip VM attach for no-op generator/coroutine __del__

Generator, coroutine, and async-generator dealloc always went through
drop_slow_inner's call_slot_del, which unconditionally attaches to a VM
(with_vm -> begin_interpreter_section -> per-interpreter thread-slot
hashmap lookup) before running del(), even though del() itself is a
documented no-op once the object is already closed or running - the
common case for a generator/coroutine consumed to completion.

Add PyTypeSlots::del_needed, an optional VM-free fast predicate checked
before call_slot_del/with_vm; generator, coroutine, and async_generator
install a check mirroring their own del() no-op branches, letting
drop_slow_inner and try_call_finalizer skip the VM attach entirely for
finished objects.

Standalone microbenchmarks (median of 5 interleaved runs):
- create+drain a 3-yield generator, 2M times: 1.099s -> 0.997s (-9%)
- pyperformance bm_generators shape (yield-from tree traversal): -4%
- pyperformance bm_coroutines shape (recursive fibonacci coroutines): -13%

Assisted-by: Claude Code:claude-fable-5-1

* _asyncio: skip full __import__ dispatch on module-cache hot path

with_asyncio_cache/with_contextvars_cache called vm.import("_asyncio"/
"contextvars", 0) on every Task/Future registration just to validate
their module-identity cache, even on the (overwhelming) hit path. That
still pays the full __import__ builtin dispatch (attribute lookup on
builtins, FuncArgs construction, native slot_call, ImportArgs parsing,
import_module_level) instead of a cheap sys.modules lookup. Added
fast_import_cached(), which checks sys.modules directly and only falls
back to vm.import on a miss (module missing/reloaded).

Measured with a standalone asyncio_tree-style microbenchmark
(6 levels x 6 branches, several asyncio.run() iterations per process,
median of 5 interleaved A/B rounds):
  none:      1.045s -> 0.895s (~14% faster)
  eager:     0.716s -> 0.591s (~17% faster)
  eager_tg:  1.023s -> 0.849s (~17% faster)

test_asyncio (all files), test_contextvars (module absent from this
checkout, pre-existing), test_weakref, test_weakset all pass/unchanged.

Assisted-by: Claude Code:claude-fable-5-1

* vm: skip VM-attach section in with_vm when already on the current interpreter

Object teardown (drop_slow_inner -> call_slot_del, try_call_finalizer,
weakref callbacks) calls with_vm(), which unconditionally went through
set_current_vm -> begin_interpreter_section: an INTERP_THREAD_SLOTS
HashMap lookup plus an Arc clone, even in the overwhelmingly common
case where the dropping thread is already attached to the exact
interpreter that owns the object (a __del__ object or weakref target
going out of scope mid-bytecode).

with_vm now checks whether the object's owning interpreter is already
the one on top of VM_STACK. Only the top of VM_STACK is ever ATTACHED
on a thread (every push is preceded by an attach, every pop restores
the enclosing attach), so when it matches we call f(vm) directly and
skip begin_interpreter_section/set_current_vm entirely. The rare
not-attached/different-interpreter cases (nested subinterpreters,
thread outside any VM, shutdown) fall through to the original
attach/detach path unchanged.

Interleaved release-build measurements (5 rounds, medians), plain-Rust
micro-scripts, no pyperf:
- 2M create+drop of a __del__ object: ~0.55s -> ~0.46s (~16% faster)
- 2M create+drop with a weakref callback: ~1.14s -> ~1.06s (~7% faster)
- 2M io.StringIO() create+drop: ~0.734s -> ~0.697s (~5% faster)
- fib(30) and a 5M-iteration tuple-unpack loop: unchanged (noise-level)

`sample` profiles of the __del__ benchmark confirm
begin_interpreter_section/ensure_thread_slot frames disappear after
the change.

Verified: `cargo test -p rustpython-vm --release`, and
`-m test -j4 test_gc test_weakref test_finalization test_threading
test_thread test_concurrent_futures test_os test_signal test_generators
test_io test_atexit test_sys` (test_interpreters module absent in this
tree, pre-existing). Also a 4-thread stress script hammering __del__
object creation against a concurrent gc.collect() loop for 10s, and a
threading+queue handoff dropping a __del__ object after cross-thread
transfer, both pass.

Assisted-by: Claude Code:claude-fable-5-1

* vm: general sys.modules fast path for vm.import

VirtualMachine::import always resolved and called builtins.__import__
(FuncArgs construction, native slot_call, ImportArgs::from_args, then
import_module_level) even when the module was already cached in
sys.modules. ~63 Rust stdlib call sites hit this on hot paths
(copyreg, pickle's reduce_newobj, warnings, asyncio, etc).

Add VirtualMachine::try_import_cached: for a plain absolute import
(level 0, empty from-list), if builtins.__import__ is still the
original import function (compared by identity against vm.import_func)
and the module -- or, for a dotted name, its top-level package -- is
already present and fully initialized in sys.modules, return it
directly, skipping the __import__ dispatch and import_module_level
entirely. Falls through to the existing slow path whenever the module
is uncached, still initializing, or __import__ has been overridden by
user code, so test_import/test_importlib/test_builtin overrides still
work.

Exposed import::is_module_initializing (refactored out of
import_ensure_initialized) so the fast path can check
__spec__._initializing the same way the slow path does.

Removes _asyncio's local fast_import_cached workaround (added in
cb2064f0e) now that vm.import itself has the same fast path generally.

Measured (interleaved A/B, 5 rounds, pickle.dumps of a plain object,
which hits copyreg import via reduce_newobj): ~2% wall-clock
improvement per call (baseline ~4.75s / 100k dumps vs ~4.66s
candidate), consistent across all rounds. Verified: overridden
__import__ still invoked, a replaced sys.modules is read through the
same accessor, and a self-importing/initializing module is not handed
out early -- all match baseline behavior.

test suite (test_import test_importlib test_builtin test_pkg
test_pkgutil test_runpy test_zipimport test_site test_warnings
test_copy test_pickle test_asyncio.test_tasks test_threaded_import
test_sys): 13/14 files pass; test_threaded_import fails identically on
baseline (ModuleNotFoundError, pre-existing, unrelated to this change).

Assisted-by: Claude Code:claude-fable-5-1

* _asyncio: bypass generic context.run dispatch in task_eager_start

task_eager_start ran the first step via context.run(coro.send, None),
which builds a bound `send` method object and then re-enters the
generic Callable/FuncArgs dispatch just to invoke context.run's own
generic call. Since eager tasks in async_tree_eager complete almost
entirely synchronously (no event-loop scheduling needed), this
per-task dispatch overhead dominated. Enter/exit the native PyContext
directly and call coro.send via a single call_method instead,
falling back to the generic path for non-native Context subclasses.

async_tree_eager median: ~705ms -> ~697ms across 5 interleaved A/B
rounds (~1% eager-only win); async_tree (none) unaffected (noise-level
delta). test_asyncio (all files), test_weakref, test_weakset pass;
pre-existing test_contextvars module-not-found failure unchanged from
baseline.

Assisted-by: Claude Code:claude-fable-5-1

* vm: drop scopeguard::defer! from generator/coroutine resume hot path

resume_gen_frame restored owner/exc-slot/frame-chain state via a
scopeguard::defer! closure that ran on every exit (Ok, Err, or panic).
Since the closure's body is the function's only tail expression, a
plain captured result plus explicit cleanup (the same shape with_frame
already uses for the analogous call path) covers both normal exit
paths identically; only the recursion-depth decrement keeps a
scopeguard, matching with_frame's precedent that this codebase does
not otherwise guarantee generator/frame state consistency across a
Rust panic (panic=unwind is not used to implement any Python-level
control flow here).

Delegation-chain benchmark (chain.py, forwarding N values through a
yield-from chain) measures a small but consistent win: ~2-5% less
wall time per forwarded value at depths 1/4/16 across interleaved A/B
rounds. Single-generator create+finish cost is a wash.

Assisted-by: Claude Code:claude-fable-5-1

* vm: run generator bodies through the call trampoline

`Py<FrameObject>::resume` built its `ExecutingFrame` with
`tailcall_enabled: false`, because a `TailCall` result had nowhere to go:
the trampoline was reachable only from `run_frame_fast`, whose entry frame
lives on the data stack and can never yield. So every ordinary Python call
made from inside a generator or coroutine body re-entered `run_frame_fast`
recursively instead of being flattened.

Generalize the trampoline to drive a heap-resident entry frame whose
enter/exit bookkeeping belongs to its caller, and whose `Yield` is a valid
terminal result rather than a panic. `FrameKind` now says, per frame, what
the trampoline owes it: `Entry` (exit it, caller frees the storage),
`GenEntry` (`resume_gen_frame` linked it and will unlink it; a `Yield` is
the trampoline's result) or `Callee` (exit it and free its storage). The
three near-identical dispatch arms collapse into one `Step::Finished` /
`Step::Deliver` loop.

The suspended-frame stack moves onto the VM and is reused across
invocations: a generator body enters the trampoline once per resume, so a
`Vec::with_capacity(8)` there cost a malloc/free per yield (+27 ns/resume
when first measured). Invocations nest strictly LIFO, so each owns the
region above the length it finds on entry.

Neutral on its own — a generator body's first call was the only one not
already flattened, since the callee's own frame runs under the trampoline
either way. It is what lets SEND/FOR_ITER hand a generator frame to the
same loop. Measured (chain of `yield from`, 1-yield generator create+finish,
bm_generators, bm_coroutines, async_tree none/eager): within noise, except
generator create+finish 625 ns -> 603 ns.

Assisted-by: Claude Code:claude-fable-5-1

* vm: run a `yield from` chain in one eval loop

`SEND` on a suspended generator recursed: `Coro::send` -> `resume_gen_frame`
-> a fresh `ExecutingFrame::run` per level, and the value came back the same
way. Measured at ~55 ns per level of delegation, against CPython's ~5.8 ns.

Only about 5 ns of that is the resume bookkeeping itself (measured by
stubbing out the claim, the exception slot, the owner swap and the recursion
checks). The rest is what a delegating frame does per value: leave and
re-enter the eval loop, and dispatch `RESUME`, `JUMP_BACKWARD_NO_INTERRUPT`,
`SEND` and `YIELD_VALUE` — four instructions that, in the canonical
`yield from` / `await` shape, only hand a value along.

So the trampoline now runs the chain itself. `SendGen` parks its frame and
returns `ExecutionResult::GenResume`; the trampoline claims and links the
sub-generator (`coroutine::flat_resume_enter`, the first half of what
`Coro::send` does around a resume) and runs its frame in the same loop. On
the way down, every frame it finds already suspended at a `yield from` whose
delegate can be resumed is parked without being run at all
(`yield_from_delegate`); on the way back up, a yielded value is re-yielded
for each such frame by parking its `lasti` past the `YIELD_VALUE`
(`park_after_yield_from`) instead of running it. A whole chain therefore
costs one claim/link/unlink per level and no instruction dispatch at all,
with `Py<FrameObject>::resume` extending the same treatment to the outermost
level, which is where `next()` and asyncio's task step enter a chain.

Each level is still claimed, linked and unlinked exactly as a recursive
`Coro::send` would, so `gi_running`, `f_back`, `gi_frame`, `gi_yieldfrom`,
`sys._getframe`, tracebacks, `throw`, `close`, PEP 479 and the
`RecursionError` depth are unchanged; `resume_gen_frame` and the flat path
share `gen_frame_link`/`gen_frame_unlink` and the invariants are documented
on `FlatResume`. Everything else keeps the recursive path: tracing or
monitoring on (both would see the skipped instructions), `throw`/`close`,
async generators, subclasses, non-generator iterators, `FOR_ITER`, a `SEND`
that is not a `yield from`, and a delegate that has not started or is not
itself delegating — the last two because one lone level costs more to hand
to the trampoline than to send into from the eval loop the caller is in.

Measured (median of 5, ns/value or seconds):

    chain of `yield from`, depth 16   911   -> 479   -47%
    chain of `yield from`, depth 4    212   -> 158   -26%
    bm_generators                     0.272 -> 0.187 -31%
    richards                          0.772 -> 0.771    ~0
    bm_coroutines                     0.0129 -> 0.0130 +0.8%
    async_tree none                   ~neutral
    chain depth 1 (no delegation)     81.1  -> 83.6  +3.1%
    fib(24), calls through trampoline 0.0180 -> 0.0183 +1.7%

Per level of delegation: 55.3 ns -> 26.4 ns (CPython 3.14: 5.8 ns).

Assisted-by: Claude Code:claude-fable-5-1

* vm: reset the oparg prefix when a signal unwinds a frame

An `EXTENDED_ARG` leaves its prefix in `arg_state` for the instruction that
follows it. The signal path in the eval loop unwinds to a handler and
`continue`s straight back to the top, skipping the loop's own
`arg_state.reset()`, so the handler's first instruction was decoded with the
interrupted instruction's prefix still applied. Every other path that jumps
somewhere new — the `set_f_lineno` restart just above — resets first.

Reachable whenever a signal arrives on the instruction right after an
`EXTENDED_ARG` in a frame that has a handler: a `KeyboardInterrupt` into a
`yield from` chain panicked with `InvalidBytecode` in roughly half of the
runs of a 16-deep chain, and now does not in ten out of ten.

Assisted-by: Claude Code:claude-fable-5-1

* bytecode: fetch a code unit with one 16-bit acquire load

The dispatch loop read the opcode with an Acquire `AtomicU8` load and the
arg byte with a separate Relaxed one. The acquire load sits between the
two, so LLVM had to re-load `self.code` and `code.instructions` for the
second access: four extra instructions and two extra dependent loads on
the instruction-fetch path of every bytecode instruction.

`CodeUnits::read_unit` reads both bytes as a single aligned Acquire
`AtomicU16`, which pairs with `replace_op`'s Release store exactly as
`read_op` did. `CodeUnit` gains `align(2)` so the 16-bit access is
guaranteed aligned rather than relying on the allocator.

5.91 -> 5.76 ns/bytecode-instruction on a straight-line
LOAD_FAST/STORE_FAST loop (-2.5%); range loop -2%.

Assisted-by: Claude Code:claude-fable-5-1

* vm: compute the cache-entry count after dispatch, not before

`op.cache_entries()` is a byte-table lookup used only to skip inline
cache units after an instruction falls through. Computing it before the
handler kept it live across the whole (very large) inlined match, so
every bytecode instruction paid an address materialization, the table
load, a stack spill and a reload of the count.

Moving it next to its only use lets it be computed on the fall-through
path with the value in a register.

Measured together with the following commit (the eval-breaker outline):
5.76 -> 5.55 ns/bytecode-instruction on a straight-line
LOAD_FAST/STORE_FAST loop, range loop -1.5%, fib(27) -2.5%.

Assisted-by: Claude Code:claude-fable-5-1

* vm: move the eval-breaker body out of the dispatch loop

The eval-breaker check itself stays inline on the per-instruction path
(moving it off regresses badly), but everything it guards -- the
finalizing/main-thread check, stop-the-world suspend, the QSBR
checkpoint, signal delivery and the scheduled GC -- was inlined into the
loop body too. That code is never executed on the hot path yet its
address materializations and live values competed for registers with
every opcode handler, so the loop head spilled more than it needed to.

`eval_breaker_work` is `#[cold] #[inline(never)]`, leaving a single
`ldrb`/`cbz` pair inline for the common "nothing pending" case.

Measured with the preceding commit: 5.76 -> 5.55 ns/bytecode-instruction
on a straight-line LOAD_FAST/STORE_FAST loop.

Assisted-by: Claude Code:claude-fable-5-1

* vm: always inline the eval stack push/pop primitives

`pop_value`, `pop_value_opt`, `top_value` and friends are a handful of
instructions each, but `ExecutingFrame::run` is ~50 KB of inlined opcode
handlers, so LLVM's inline budget refused them and emitted real calls:
STORE_FAST and POP_TOP each began with `bl ...pop_value`, which also
forced spills around the call. `#[inline(always)]` puts the four or five
instructions they actually are back into the handlers.

5.55 -> 5.29 ns/bytecode-instruction on a straight-line
LOAD_FAST/STORE_FAST loop (-4.8%); nbody -3.5%, fib(27) -3.5%,
`s += i` loop -3.5%, `for _ in range(n)` -4%.

Assisted-by: Claude Code:claude-fable-5-1

* vm: carry the instruction fetch state in loop locals

Instruction fetch went through memory three times per bytecode
instruction: `self.lasti` (a pointer field) was re-loaded, the program
counter was stored to it and read back at the top of the next iteration,
and `self.code` -> `code.instructions` was re-loaded to address the code
unit. LLVM cannot keep any of them in registers because the handlers
write through `&mut self`, so the fetch chain started with a
store-to-load round trip followed by two dependent pointer loads.

`lasti_cell` and `instructions` are now copied into locals once (both are
plain shared references with the frame's lifetime), and the program
counter is carried in `idx`: after a handler that did not jump the next
index is already known from `lasti_before` plus the cache count. The
frame's `lasti` is still stored before every instruction, so tracebacks,
`f_lineno`, signals and `sys._getframe` see exactly what they did; only
the read-back is gone. The paths that unwind (signal, exception handler,
`set_f_lineno`) re-read it, since they jump to a new position.

Also collapses the eval-breaker `if`, which clippy flagged after the
previous commit moved its body out of line.

range loop -3.3%, richards -3.1%, nbody -2.9%, `s += i` loop -2.2%,
go -1.7%, raytrace -1.2%; mean -1.1% over the 13-benchmark set. The
straight-line LOAD_FAST/STORE_FAST micro is unchanged at 5.28
ns/bytecode-instruction (it has no cache entries and never jumps, so it
was already the best case for the old code).

Assisted-by: Claude Code:claude-fable-5-1

* bytecode: hoist the instruction array base out of the dispatch loop

Addressing a code unit still went `self.code` -> `code.instructions` ->
the `Box<[CodeUnit]>` data pointer on every instruction, two dependent
loads before the acquire load that fetches the unit itself, because the
handlers write through `&mut self` and LLVM has to assume the fields
could change.

The instruction array is allocated once when the code object is built
and never reallocated -- specialization rewrites units in place -- so
`CodeUnits::units_ptr` may be read once before the loop and reused.
`read_unit_from` is the same 16-bit acquire load taken from that base;
`read_unit` now delegates to it, and the index is unchecked exactly as
it was before.

nqueens -1.9%, raytrace -1.6%, range loop -1.3%, deltablue -1.1%,
nbody -0.8%, dispatch micro -0.7%; mean -0.7% over the 13-benchmark set.

Assisted-by: Claude Code:claude-fable-5-1

* common: an immortal bit in the refcount word

Atomic reference counting is about a third of what a bytecode costs now
that the dispatch loop is trimmed: built `--no-default-features`, where
`PyAtomic` is a `Cell`, the straight-line dispatch micro runs at
3.5 ns/instruction against 5.4. Every `TO_BOOL`/`POP_JUMP_IF_*` pair and
every `None` or small-int push pays a relaxed `ldadd` and a `Release`
`ldaddl` on an object that can never die.

PEP 683's answer is to say so in the word. A fourth flag bit, `IMMORTAL`,
takes a bit from the strong count (leaving 60 on a 64-bit target, 28 on a
32-bit one, both far past what a program reaches); `make_immortal` sets it
and parks the count at CPython's `_Py_IMMORTAL_REFCNT`, and `inc`,
`inc_by`, `dec` and `safe_inc` read the bit and return without touching
the counter. The parked count is what keeps the rest of the tree honest
without a special case: it is far too large for a `strong_count() == 1`
in-place-mutation fast path to fire on, and `start_gc_refs` already reads
a count that large as `GC_REACHABLE`, so an immortal object is a permanent
root that keeps its referents alive.

Two details pay for the branch the mortal path now runs, which cost 4% on
object-heavy benchmarks before they went in:

* `leak` sets `IMMORTAL` alongside `LEAKED`. An interned object could
  already never reach zero, so `dec` no longer needs the test it made on
  the result of the decrement: the immortal test at the top decides both.
* `inc`'s three exceptional cases — a destructed word, a count at the
  ceiling, a count at zero — fold into one comparison against the masked
  word, with the handling moved to a cold helper.

What is left is one instruction on `dec` and roughly nothing on `inc`, and
the mortal path measures at parity.

Assisted-by: Claude Code:claude-fable-5-1

* vm: make the singletons, small ints, interned strings and static types immortal

Everything the `Context` builds once and keeps — `None`, `True`, `False`,
`Ellipsis`, `NotImplemented`, the empty tuple, frozenset, bytes and str,
the -5..256 int cache and the interned one-character strings — is now
marked immortal, as is every static type object, which its `static_cell`
holds for the life of the process. So is every entry of the string pool:
`mark_intern` already stopped those refcounts from reaching zero, so
immortality frees no memory that would otherwise have been freed; it only
takes the atomic read-modify-write off every incref and decref of an
attribute name, a dict key or a docstring.

Straight-line dispatch micro (200 LOAD_FAST/STORE_FAST pairs over cached
ints, median of 5 interleaved runs): 5.39 -> 4.01 ns/instruction, -26%.
A four-thread `if flag:` loop, where the contention on the shared bool was
real: 2.36 s -> 2.14 s, -10%.

pyperformance bench functions run standalone, medians of 5 interleaved
rounds against a matched build: fannkuch -7.8%, nqueens -3.8%, chaos
-3.0%, raytrace +1.0%, go +1.2%, richards +4.2%, nine of them together
-2.9%. Per-benchmark deltas under about 4% sit inside this tree's
build-to-build ThinLTO layout noise, which reaches that size between two
builds of identical source.

Observable: `sys.getrefcount` of an immortal object reports 4294967295,
CPython's `_Py_IMMORTAL_REFCNT`, and stops moving — what
`test_sys.test_refcount` expects of `None`. `is_interned`, and the dict
pointer-equality key fast path behind it, keep answering from the separate
`LEAKED` bit.

Assisted-by: Claude Code:claude-fable-5-1

* codecs: fast-path utf-8 decode, skipping the codec registry round trip

bytes.decode('utf-8') / str(bytes, 'utf-8', ...) always went through the
generic codec registry: a per-call attribute lookup for
_is_text_encoding, then a full call into the pure-Python
encodings.utf_8.decode wrapper, which called back into the native
utf_8_decode and unpacked a 2-tuple result.

CPython's PyUnicode_Decode special-cases a handful of built-in encoding
names (utf-8 among them) and decodes them directly, bypassing the codec
registry entirely -- a codecs.register() override does not affect
str(b"...", "utf-8") there either. This adds the same fast path here:
recognized utf-8 aliases go straight to the native decoder.

Measured with a pure-Python `str(bytes, 'utf-8', 'surrogatepass')` loop:
~723ns -> ~401ns per call (1.8x). On the pyperformance unpickle
benchmark (which decodes short strings this way for every
SHORT_BINUNICODE opcode): ~14.4ms -> ~13.2ms per loop, an ~8.3% win.

Assisted-by: Claude Code:claude-fable-5-1

* codecs: fast-path utf-8/ascii/latin-1 encode and ascii/latin-1 decode

Extend the utf-8 decode fast path from 3fe684629 to the symmetric encode
direction (str.encode()/bytes(s, enc)), and add the same registry-skipping
fast path for ascii and latin-1 encode/decode, all of which are simple
native codecs.rs functions already. For utf-8 encode with no surrogates in
the string (the common case), encoding is just a copy of the string's
existing UTF-8 bytes, so that's the fastest path; strings containing
surrogates and non-strict error handlers still go through the native
encoder + ErrorsHandler, matching custom codecs.register_error handlers.

Measured (median of interleaved runs vs baseline, 2M iterations):
  str.encode("utf-8"):   351ns -> 195ns  (-44%)
  str.encode():          449ns -> 291ns  (-35%)
  bytes(s, "utf-8"):     542ns -> 382ns  (-30%)
  str.encode("ascii"):   436ns -> 302ns  (-31%)
  str.encode("latin-1"): 487ns -> 333ns  (-32%)
  bytes.decode("ascii"): 519ns -> 359ns  (-31%)
  bytes.decode("latin-1"):590ns -> 417ns (-29%)
  bytes.decode("utf-8")/str(b,"utf-8"): unchanged (already fast-pathed)

Assisted-by: Claude Code:claude-fable-5-1

* vm: make the runtime safe for borrowed stack entries

`PyStackRef` has carried a borrow tag since the stack was unified with the
fastlocals, but only `LOAD_SMALL_INT` -- which borrows immortal `Context`
objects -- ever set it, so nothing in the runtime had to be right about
borrowed entries. Turning `LOAD_FAST_BORROW` into a real borrow makes three
places load-bearing, and this fixes them ahead of the switch.

`Traverse for PyStackRef` handed every entry to the tracer, borrowed ones
included. The cycle collector subtracts one from an object's `gc_refs` per
edge it is shown, so a borrowed entry -- which owns no strong count -- would
have pushed a live object's count to zero and freed it out from under the
frame. Borrowed entries are now skipped; nothing becomes unreachable, because
the fastlocals slot the entry borrows from is on the same traversal.

`park_after_yield_from` stands in for a `YIELD_VALUE` that never runs, so the
`promote_stack()` in that handler never ran either; it now promotes there too,
and the debug assertion after it stops being vacuous.

`STORE_FAST`, `DELETE_FAST` and the fused stores now call
`LocalsPlus::debug_audit_local_release`, which in debug builds panics if the
slot is about to drop the last count of an object a borrowed entry still
points at -- the one shape codegen's `optimize_load_fast` exists to prevent,
and the one that would be a use-after-free if the analysis or a modelled stack
effect were wrong.

`BORROW_LOCAL_LOADS` (off) is the switch for the borrow itself, and
`LOAD_FAST_BORROW`/`LOAD_FAST_BORROW_LOAD_FAST_BORROW` now go through
`push_local`, which is a plain clone while it is off. The invariant the switch
depends on is written out where `PyStackRef` is defined.

No measurable change: with the switch off the only behavioral difference is
the traversal fix, which no current bytecode can reach.

Assisted-by: Claude Code:claude-fable-5-1

* vm: read consumed stack entries in place instead of owning them

`pop_value()` turns whatever is on the stack into an owned `PyObjectRef`, so
an instruction that only reads its operand still pays a reference count round
trip -- and, once `LOAD_FAST_BORROW` starts pushing borrows, would pay an
atomic increment to promote a borrow it is about to throw away. This moves
every consumer that never needs ownership onto `pop_stackref()`, which hands
back the tagged entry and costs nothing for a borrow.

Discarding pops (62 of them, across the `LOAD_ATTR`, `TO_BOOL`, `BINARY_OP`,
`COMPARE_OP`, `CONTAINS_OP` and `CALL` specializations, which read their
operands through `top_value()`/`nth_value()` and then drop them) become
`pop_stackref()`. So do the read-only operands of `POP_TOP`, `POP_JUMP_IF_*`,
`TO_BOOL`, `BINARY_OP`, `COMPARE_OP`, `CONTAINS_OP`, `IS_OP`, `STORE_ATTR`,
`DELETE_ATTR`, `STORE_SUBSCR`, `DELETE_SUBSCR` and `UNPACK_SEQUENCE`.

Two protocol entry points had to move from an owned receiver to `&PyObject` to
make that reachable: `try_to_bool`, which never used the ownership it took,
and `rich_compare`, which forwards to the `&self` `_cmp` anyway. Both keep
working unchanged for `PyObjectRef` callers through deref.

`LOAD_ATTR`'s method specializations popped the receiver and pushed it
straight back below the bound function; they now move the entry across with
its tag intact, which is how CPython keeps a method call's receiver borrowed
from `LOAD_ATTR` all the way through `CALL`. The plain attribute read reads
through the receiver rather than owning it.

Neutral while `BORROW_LOCAL_LOADS` is off -- for an owned entry
`pop_stackref()` and `pop_value()` compile to the same thing.

Assisted-by: Claude Code:claude-fable-5-1

* vm: turn LOAD_FAST_BORROW into an actual borrow

`LOAD_FAST_BORROW` accounts for 21.5% of executed instructions on
nbody+richards+nqueens, and until now it did exactly what `LOAD_FAST` does:
an atomic increment on the way onto the stack and, from the instruction that
consumed it, an atomic release decrement on the way off. Neither is needed.
The fastlocals slot holds a count for as long as the entry is on the stack --
codegen's `optimize_load_fast` only rewrites a `LOAD_FAST` when it can prove
the entry is consumed before anything can release that slot -- so the entry
can be a borrow that owns nothing, which is what CPython 3.14 does with a
tagged `_PyStackRef`.

Flipping `BORROW_LOCAL_LOADS` on is the whole change; the two preceding
commits are what make it safe (cycle-collector traversal, yield-point
promotion, a debug audit of the invariant) and what make it pay (consumers
that read through the entry rather than promoting it back to owned).

Medians of 7 interleaved rounds, this machine, against the pre-series binary:

  straight-line while loop   6.32 -> 6.01 ns/instruction  (-5.0%)
  x = a + b loop             -6.3%      if flag: loop     -3.8%
  attribute-read loop        -5.2%      method-call loop  -3.3%
  subscript loop             -6.7%      fib(27)           -0.8%

  nbody   -2.6%   fannkuch -1.7%   nqueens  +1.3%   richards -3.0%
  deltablue -2.3% go       -3.0%   raytrace -1.7%   float    -3.2%
  chaos   -2.6%   spectral_norm -2.5%      mean     -2.1%

About half of that is the consumer rewrite alone (mean -1.0% with the switch
still off) and the rest is the borrow. nqueens is the one benchmark that goes
the other way, by less than the roughly 4% of build-to-build layout noise this
tree has, and it moves with the consumer rewrite rather than the switch.

Full suite green (418 files, 42,110 tests). A build with debug assertions on
runs the suite with no audit failure, and trips the audit exactly when
`LOAD_FAST` is forced to borrow in a shape codegen refuses to convert
(`f(x, (x := None))`). Adversarial scripts -- swap loops and reassignment
under `__del__` tracking, argument evaluation that deletes its sibling,
`a[a.pop()]`, closures over a rebound cell, generators dropped while
suspended, tracebacks whose `f_locals` are read after unwinding, `settrace`
writing `f_locals` mid-expression, a method receiver whose local is cleared
while the call is being built, `__add__`/`__lt__`/`__bool__` that clear the
local their operand came from, threads sharing objects through locals, and
`gc.collect()` from a finalizer -- all agree with CPython 3.13 under
`gc.set_threshold(1, 1, 1)`, in both builds.

Assisted-by: Claude Code:claude-fable-5-1

* vm: exact-dict fast path for DICT_MERGE and CALL_FUNCTION_EX kwargs

`g(**d)` on an exact dict compiled to BUILD_MAP+DICT_MERGE+CALL_FUNCTION_EX
and paid for two Python-level `keys()`/`__getitem__` round trips per key at
both the DICT_MERGE handler and collect_ex_args' iterate_mapping_keys, even
though the source is a plain dict. Add an exact-dict (downcast + type
check, so subclasses still go through the mapping protocol) fast path to
both sites that iterates entries natively via PyDict::items_vec, matching
CPython's PyDict_Check fast paths in PyDict_Merge / CALL_FUNCTION_EX.

Measured (1M calls, release build): g(**d) 1320ns -> 665ns, f(**d)
1470ns -> 900ns, c.m(**d) 1690ns -> 1135ns, f(x=1,**d) 1600ns -> 1035ns,
f(**d1,**d2) 1700ns -> 1013ns. bm_django_template ~7% faster,
bm_argparse (subparsers) ~7% faster.

Assisted-by: Claude Code:claude-fable-5-1

* vm: skip the recursion guard hashing exact ints inside a tuple

tuple.__hash__ hashed every element through PyObject::hash, which wraps
each call in with_recursion's native-stack-depth check. That guard exists
for elements whose hash can recurse into arbitrary Python code, but
int.__hash__ is a leaf computation - it can neither recurse nor call back
into Python - so the check is pure overhead for the overwhelmingly common
case of tuples of plain ints (e.g. namedtuple-shaped dict keys).

pyperformance's mdp benchmark builds huge tables keyed by tuples of deeply
nested namedtuples whose leaves are ints; profiling with `sample` showed
PyObject::hash/with_recursion/tuple's slot_hash dominating the CPU time.
Hashing exact-int elements directly via hash::hash_bigint cuts mdp's
wall time from ~6.79s to ~4.81s (median of 5 interleaved runs), about 29%
faster, with no change to hash values or recursion-guard behavior for any
other element type.

Assisted-by: Claude Code:claude-fable-5-1

* vm: wire slot descriptors from __slots__ into C-level type slots

Classes that put a dunder name (e.g. "__setitem__") into __slots__ get
a per-instance member descriptor for it, which is a legitimate way to
override a special method per-instance (chameleon's tal.RepeatDict does
exactly this). PyType::new_verbose ran init_slots() to compute
mp_ass_subscript/mp_subscript/etc. before these member descriptors were
added to the type's attribute namespace, so the slot lookup never saw
them and __setitem__/__getitem__ silently fell back to "does not
support item assignment".

Fix by calling update_slot for each dunder-shaped __slots__ member
right after it is installed on the type, mirroring what
type.__setattr__ already does for regular attribute updates.

Assisted-by: Claude Code:claude-fable-5-1

* frame: stop allocating cold data to close a generator

`clear_locals_and_stack`, which runs whenever a generator or coroutine
comes to an end, reached for the frame's lazily-allocated `FrameColdData`
through `cold()`. That allocates it on first access, so every finishing
generator paid a `Box<FrameColdData>` malloc and free just to find
`f_extra_locals`, `f_locals_cache` and `f_overwritten_fast_locals` all
empty -- cold data is only ever populated by tracing and frame
introspection. Ask for it with `cold_opt()` instead and skip the three
reads when it was never allocated.

Medians of interleaved A/B runs, ns per generator create+finish over a
plain call: `for _ in g(): pass` 265 -> 231 (-13%), a coroutine that
completes synchronously 642 -> 617 (-4%), `sum(x for x in range(3))`
1033 -> 997 (-3.5%).

Assisted-by: Claude Code:claude-fable-5-1

* function: bind exact args straight into a generator's frame

Calling a generator, coroutine or async generator function took the
general argument-binding path even when the call site was the simplest
possible one. `invoke_exact_args_slots` and the vectorcall fast path both
recognised the shape -- every parameter positional, filled exactly once
-- and then handed generator-like code back to `invoke()`, which built a
`FuncArgs` (a `Vec` plus an `IndexMap`) only for
`fill_locals_from_args_inner` to walk varargs packing, keyword matching
and defaults that this shape cannot reach.

Add `make_generator_exact_args`, the counterpart of
`prepare_exact_args_frame` for the one call shape it refuses: it builds
the heap frame the generator will own, moves the arguments straight into
its fastlocals and returns the generator. Both fast paths now use it. The
vectorcall one matters on its own for generator expressions, whose fresh
`MAKE_FUNCTION` on every evaluation keeps them out of the call-site
specialization that would otherwise catch them.

Medians of interleaved A/B runs, ns per create+finish over a plain call:
`for _ in g(): pass` 231 -> 218 (-6%), a synchronously-completing
coroutine 616 -> 598 (-3%), `sum(x for x in range(3))` 1007 -> 967 (-4%).

Assisted-by: Claude Code:claude-fable-5-1

* frame: drain a dead frame in place instead of moving it out

Three allocations and a large move on the path a finishing generator
takes to release its frame.

`Traverse::clear` opened with `self.iframe.get_mut().take()`, moving the
whole `InterpreterFrame` -- a couple of hundred bytes -- out of its slot
and onto the stack, only to drop it there. Drain it through `as_mut()`
and empty the slot afterwards.

`LocalsPlus::clear_into` collected the evaluation stack into a `Vec` that
existed only to be extended into the caller's; push into that one
directly. And `clear_stack_and_cells` built (and dropped) a `Vec` for a
stack it had not looked at -- a frame that reached its `return`, which is
every generator that simply finished, left nothing there. Look first.

Medians of 5 interleaved rounds, ns per create+finish: `for _ in g():
pass` 307 -> 297 (-3.4%), a synchronously-completing coroutine 600 -> 585
(-2.5%), `list(g())` 565 -> 558; a plain call is unchanged.

Assisted-by: Claude Code:claude-fable-5-1

* vm: don't raise a TypeError to ask an iterator for its length

`length_hint_opt` opened with `iter.length()`, whose whole job on a type
with no length slot is to build the `TypeError` that says so -- which
this caller then catches, recognises and discards. Every iterator and
every generator takes that path, and `list()` calls it on whatever it is
handed, so a `list(gen)` paid for an exception object per call.
`length_opt` answers the same question with `None`. CPython's
`PyObject_LengthHint` gates the call on the slots for the same reason.

Median of 5 interleaved rounds: `list(g())` x200k for a 1-yield
generator 556 -> 407 ns (-27%). pyperformance generators, coroutines,
comprehensions and async_tree are unchanged, as are nqueens, richards
and chaos.

Assisted-by: Claude Code:claude-fable-5-1

* gc: track a generator and its frame in one pass

Making a generator tracks two objects that are born together and die
together -- the generator and the frame it owns -- and each one took the
gen0 list lock and a thread-local read of the running interpreter for
itself. Give the pair one entry point: `PyGenerator`, `PyCoroutine` and
`PyAsyncGen` opt out of tracking at allocation, the way frames already
do, and `make_generator_or_coro` links both into gen0 under a single
lock, with one owner read and one collection check.

Medians of 5 interleaved rounds: pyperformance coroutines -2.5%,
generators -0.9%; `for _ in g(): pass` over a plain call 205 -> 200 ns.

Assisted-by: Claude Code:claude-fable-5-1

* dict_inner: fast-path exact-int equality in key_eq

Mirrors CPython's lookdict: two exact `int` keys now compare by BigInt
value directly instead of going through the generic rich-compare
dispatch (identical_or_equal -> bool_eq -> rich_compare_bool -> __eq__
slot lookup). Falls back to bool_eq whenever either side isn't exactly
`int` (subclasses may override __eq__), so behavior is unchanged there.

Measured (min-of-6 rounds, 2M-iteration micros, this tree's build has
~4% layout noise so min is used as the noise floor):
- dict_int_lookup (`d[i]`, int keys): 70.9ns -> 62.0ns (-12.5%)
- dict_str_lookup / dict_tuple_lookup / set_str_contains: unchanged
  (within noise), confirming no regression on non-int keys.

pyperformance sanity checks (single round each, base vs candidate):
bm_mdp median ~5027ms/loop vs ~5003ms/loop (no regression, hashing
isn't the dominant cost there); bm_nqueens, bm_go, bm_deltablue,
bm_hexiom, bm_chaos all within ~1% (noise).

Hash/equality values cross-checked bit-identical against CPython 3.14
for 0, 1, -1, True, False, 2**61-1, 2**61, -(2**63), 2**100, -(2**100),
and int/float/bool/Decimal/Fraction(1) hash-equality invariants.

Also tried an exact-type fast dispatch in PyObject::hash (skipping the
slots.hash vtable call + with_recursion for exact int/str) - it only
moved hash_small_int/hash_large_int by ~2%, under the 3% bar, so it was
not committed.

Tests: `rustpython -m test -j4 test_hash test_int test_long test_tuple
test_dict test_set test_dictviews test_ordered_dict test_collections
test_fractions test_numeric_tower test_float test_bool test_str
test_userdict test_weakref` all pass (1796 run, 72 skipped). `cargo
test -p rustpython-vm --release -p rustpython-common` passes. clippy
clean on the touched lines.

Assisted-by: Claude Code:claude-fable-5-1

* vm: let the modulus type handle a three-argument pow

CPython's ternary dispatch offers the operation to the third operand's type
whenever its slot differs from the two already tried, including the case where
neither operand had one. The port required both of those slots to exist, so
`pow(10, 2, Decimal(7))` never reached `Decimal` and raised TypeError.

Assisted-by: Claude Code:claude-fable-5-1

* vm: add a feature-gated opcode-pair histogram

Counts `(prev_op, op)` in the dispatch loop and dumps the nonzero pairs at
exit, so superinstruction and specialization candidates can be ranked from
what pyperformance-shaped code actually dispatches rather than guessed at.

Entirely behind the non-default `opcode-histogram` feature: the module is
`#[cfg]`-ed out and the loop's two-line hook with it, so a default build is
byte-identical to one without the patch.

Assisted-by: Claude Code:claude-fable-5-1

* vm: let boolean producers run the branch that follows them

`TO_BOOL*`, `COMPARE_OP*`, `CONTAINS_OP*` and `IS_OP` materialised a bool
only for the `POP_JUMP_IF_*` one dispatch later to pop and test it, and the
compiler's `NOT_TAKEN` marker cost a third dispatch on the fall-through edge.
Generalise the `COMPARE_OP_INT`-only jump fusion so every boolean producer
resolves the jump itself, and step over `NOT_TAKEN` from there and from the
plain `POP_JUMP_IF_*` handlers. Both back off to ordinary dispatch when the
successor is an instrumented opcode or while tracing, so `sys.monitoring`
branch events and `sys.settrace` opcode events are unaffected.

Dispatches over 13 standalone pyperformance benchmarks: -5.0% total
(richards -11.7%, unpickle_pure_python -8.9%, sympy -8.4%, hexiom -8.1%,
django_template -7.1%, go -6.1%; nbody unchanged). Times, best of 7
interleaved rounds: deltablue -4.0%, hexiom -3.5%, go -3.4%,
unpickle_pure_python -3.3%, richards -3.2%, raytrace -3.0%, nqueens -1.9%,
geomean -1.0%; a branch-heavy microbenchmark -4.7% against a straight-line
control at 0%.

Assisted-by: Claude Code:claude-fable-5-1

* Adapt yield-from resume to optional generator frames

Coro.frame is now PyAtomicRef<Option<FrameObject>>, so the flattened
resume path uses frame_opt/clear_except_code instead of a direct frame.

Assisted-by: Grok:4.6

* Fix clippy and cr_origin after try_to_bool/f_lineno changes

try_to_bool now takes &self, so drop the leftover clones. Derive
cr_origin lines from lasti instead of prev_line, and satisfy
-Dwarnings on the immortal-refcount and del_needed types.

Assisted-by: Grok:4.6

* Convert fd filenames without the os ToPyObject impl

host_env-free builds (sandbox check, wasm) do not compile os.rs, so
OsPathOrFd::filename cannot use Borrowed's ToPyObject. Use as_raw()
instead, which is the same conversion.

Assisted-by: Grok:4.6

* Gate fd path helpers on the host_env feature

WASM clippy builds rustpython-vm without host_env, so OsPathOrFd and
the fspath/fd helpers are unused and fail -Dwarnings.

Assisted-by: Grok:4.6

* Drop redundant pickle try_to_bool clones after rebase

Assisted-by: Grok:4.6

* Document why enumerate keeps a Counter beside BigInt

Assisted-by: Grok:4.6

* Move fd path helpers into ospath_fd under host_env

Assisted-by: Grok:4.6

* Group threading eval-breaker bits in one module

Assisted-by: Grok:4.6

* Make InterpreterFrame construction unsafe

run_iframe stays safe: a live frame already has valid identity pointers.

Assisted-by: Grok:4.6

* Move OsPathOrFd re-export to the top of ospath.rs

Assisted-by: Grok:4.6

---------

Co-authored-by: Lee Dogeon <dev.moreal@gmail.com>
2026-09-20 00:32:26 +09:00
Jeong, YunWon 66a3d9daa7 common: implement remaining builtin text codecs (#8687)
* common: implement remaining builtin text codecs

Move utf-16/32/7, unicode-escape, raw-unicode-escape and the
bytes escape transform into rustpython-common and call them from
_codecs instead of _pycodecs.

Assisted-by: Claude:grok-4.6

* host_env: share locale grouping, uuid and pipe state

Add localeconv_numeric so grouping keeps a CHAR_MAX terminator,
UuidCreateSequential for _uuid, and GetNamedPipeHandleStateW.

Assisted-by: Claude:grok-4.6

* Fix utf-7 clippy and the utf-16-be snippet length

Assisted-by: Claude:grok-4.6

* codecs: treat escape decode as final and accept str

unicode_escape_decode and raw_unicode_escape_decode default final to
true and accept a str as UTF-8. Fix clippy on wide_order, escape
encode, and encode closures. Remove expectedFailure markers that now
pass.

Assisted-by: Grok:grok-4.6
2026-09-12 15:51:28 +09:00
Roshan Ramani b701e5cbe9 Report which format string mistake was made (#8659)
* fix(vm): report which format string mistake was made

`ToPyException for FormatParseError` mapped two variants and sent the rest to
"Unexpected error parsing format string", so most format-string mistakes gave
no hint about the mistake. Against CPython 3.14.0:

| expression | before | CPython |
| --- | --- | --- |
| `"a}b".format()` | Unexpected error… | Single `}` encountered in format string |
| `"{0.}".format(1)` | Unexpected error… | Empty attribute in format string |
| `"{0[]}".format([1])` | Unexpected error… | Empty attribute in format string |
| `"{0[1}".format([1,2])` | Unexpected error… | expected `}` before end of string |
| `"{0[0]x}".format([1])` | Unexpected error… | Only `.` or `[` may follow `]` in format field specifier |
| `"{:{{}}".format(1)` | Unexpected error… | unmatched `{` in format spec |

The match is now exhaustive, so a new variant cannot silently inherit the
generic message.

Two cases are deliberately left generic, with the reason in a comment beside
each. `UnknownConversion` is raised both for a multi-character conversion
(`{0!xy}`, where CPython says "expected ':' after conversion specifier") and
for an empty one (`{0!}`, "unmatched '{' in format spec"), so one message
cannot serve both without the parser saying which it hit. And a trailing lone
`{` reaches `UnmatchedBracket` rather than
`UnescapedStartBracketInLiteral`, so `"{".format()` still differs from CPython;
that needs a parser change, not a message.

Expectations in the new snippet are CPython 3.14.0's output and pass under both
interpreters. Reverting only format.rs fails the snippet's first assertion.

Assisted-by: Claude Code:claude-opus-5

* fix(common): separate a stray `{` from an unclosed field

`parse_literal` already reports `UnescapedStartBracketInLiteral` for a brace
that was not doubled, but `from_str` discards it with `or_else` and retries as a
field, so `"{".format()` surfaced `UnmatchedBracket` and read as
"expected '}' before end of string". CPython separates the two by whether
anything follows the brace:

    "{"   "a{"    Single '{' encountered in format string
    "{s"  "a{b"   expected '}' before end of string
    "{0"          expected '}' before end of string

`parse_spec` now returns the literal error when the text is the brace alone,
which is also what makes `UnescapedStartBracketInLiteral` reachable — the
previous commit could map it but not trigger it.

`format_parse_lone_start_bracket` pins both directions at the parser level, and
the snippet covers the four messages under CPython 3.14.0 as well. The existing
`format_parse_fail` assertion for `"{s"` is unchanged.

Assisted-by: Claude Code:claude-opus-5
2026-09-08 17:52:57 +09:00
Jeong, YunWon ae7bc5b619 lzma: build the xz-core engine on wasm32 (#8664)
Expose `_lzma` on wasm32 and Android by compiling the xz-core
engine on those targets instead of gating it out.

Assisted-by: Claude
2026-09-07 10:19:03 +09:00
Jeong, YunWon 699913d8cd Align codec, call, exception, and Unix module behavior with CPython (#8647)
* Collect consecutive charmap encoding failures

Pass one contiguous run of unmappable characters to the codec error handler, and use the full run when a text replacement is itself unmappable.

Assisted-by: Codex:gpt-5

* Leave conversions out of standalone format specs

A conversion belongs to a replacement field rather than the format specification consumed by format(), so stop accepting and storing it in FormatSpec.

Assisted-by: Codex:gpt-5

* Decode empty byte strings without looking up a codec

Match PyUnicode_FromEncodedObject by returning the shared empty string before resolving the requested encoding for empty bytes and bytearray inputs.

Assisted-by: Codex:gpt-5

* Validate call shape before converting builtin arguments

Reject unknown keywords and excess arguments before conversions can raise a different error. Align Python-function positional-only handling, use declared list arguments in heapq, keep delegated codecs positional-only, and preserve CPython parameter names and validation order.

Assisted-by: Codex:gpt-5

* Align attribute and exception initialization errors

Give __dict__ and type __qualname__ their CPython diagnostics, preserve OSError filename fields correctly, accept seven-item SyntaxError details, and report Unicode error constructor arity before converting values.

Assisted-by: Codex:gpt-5

* Expose missing Unix and Darwin module APIs

Add the platform constants exported by fcntl, mmap, select, socket, syslog, termios, stat, errno, time, and _sre. Implement posix.killpg and resource.getpagesize, and expose resource.error as OSError.

Assisted-by: Codex:gpt-5

* Honor the configured Python CPU count

Parse -X cpu_count and PYTHON_CPU_COUNT, expose the stored value through sys._get_cpu_count_config, and let os.cpu_count prefer it over the host count. Also publish getsizeof with its CPython parameter name.

Assisted-by: Codex:gpt-5

* Fix CPU count and WASI CI coverage

Remove the obsolete expected-failure marker now that CPU count overrides pass, and avoid exporting FASYNC where WASI libc has no O_ASYNC constant.

Assisted-by: Codex:gpt-5

* self review
2026-09-05 11:34:43 +09:00
Jeong, YunWon 6e6792ee5c common: share the hashlib engine, and publish blake2b/blake2s as types (#8643)
The digest, HMAC, PBKDF2 and scrypt state moves out of the `_hashlib`
module into a feature-gated `rustpython_common::hashlib` that owns each
state behind a `Mutex` and reports plain Rust results; `_hashlib` and
`_blake2` keep the object glue.

The engine writes its state through a raw pointer into a caller-owned
buffer, so the buffer is boxed and only the pointer travels with the
Python object, and it carries the alignment the engine asserts.  The
wrapper is built only after a successful init, so a rejected digest name
leaves nothing to drop over storage the engine never wrote.

blake2 moves from `blake2` to `blake2b_simd` / `blake2s_simd`, whose
`Params` carry the whole parameter block.  `_blake2.blake2b` and
`blake2s` become immutable types with `SALT_SIZE`, `PERSON_SIZE`,
`MAX_KEY_SIZE` and `MAX_DIGEST_SIZE` as class attributes, and their
instances are instances of those types.  They accept `key`, `salt`,
`person`, `fanout`, `depth`, `leaf_size`, `node_offset`, `node_depth`,
`inner_size` and `last_node`.  `_hashlib.scrypt` is published on the
same engine.

Six `test_hashlib` expectedFailure markers drop with it.  `blake2`,
`digest`, `dyn-clone`, `hmac` and `pbkdf2` lose their last consumer.

Assisted-by: Grok
Assisted-by: Claude
2026-09-03 22:50:41 +09:00
Jeong, YunWon aa59f1ee53 common: share the bzip2 stream engine (#8638)
Move the VM-independent bzip2 stream owner into a `bz2`-gated
`rustpython-common` module beside the zlib and lzma engines, and keep
`rustpython-stdlib` as the Python object and exception adapter.  The adapter no
longer names the `bzip2` crate; the `bz2` feature carries it.

`_bz2` was the last user of the generic `DecompressState` / `DecompressStatus` /
`Decompressor` machinery in `stdlib/src/compression.rs`, so that goes with it;
`DecompressArgs` stays for zlib and lzma.  The decompressor feeds the stream
through the existing `Chunker`, so buffered and freshly supplied input are no
longer joined into a new allocation first.

`test_decompress_after_data_error` passes on the ported engine, so its
`expectedFailure` marker goes.

Assisted-by: Grok
2026-09-02 20:26:14 +09:00
Jeong, YunWon c716a7d070 common: share the zlib stream engine (#8631)
* common: share the zlib stream engine

Move the VM-independent zlib-rs stream owner and state machine into a feature-gated rustpython-common module. Make rustpython-stdlib adapt that engine instead of carrying its own flate2 implementation, including native stream copy/deepcopy, Z_BLOCK flushes, and wbits=0 decompression.

Assisted-by: Codex:GPT-5

* common: share the lzma stream engine

Move the VM-independent liblzma stream owner, filter properties, and compression state into a target-gated rustpython-common module. Keep rustpython-stdlib as the Python object and exception adapter, and remove its direct xz dependencies and lzma-only generic compressor machinery.

Assisted-by: Codex:GPT-5

* common: address compression engine reviews
2026-09-01 15:29:56 +09:00
Jeong, YunWon 306f104847 codecs: address post-merge review findings (#8623)
Assisted-by: Codex:GPT-5
2026-08-31 18:52:34 +09:00
Jeong, YunWon 322f294a21 common: add VM-independent codec and text engines (#8622)
* common: add PyPy CJK codec engines

Assisted-by: Codex:GPT-5

* common: mark CJK mapping tables generated

Assisted-by: Codex:GPT-5

* common: add reusable byte and text engines

Assisted-by: Codex:GPT-5

* common: record opt-in engine dependencies

Assisted-by: Codex:GPT-5

* stdlib: add `_multibytecodec` and the six `_codecs_*` modules

Wire the CJK codec engines in `rustpython-common` up to the VM. `_multibytecodec`
holds `MultibyteCodec`, `MultibyteIncrementalEncoder`, `MultibyteIncrementalDecoder`,
`MultibyteStreamReader` and `MultibyteStreamWriter`, the encode/decode drivers and
the error-handler protocol; each `_codecs_*` module exposes `getcodec` for the
encodings of its region.

`rustpython-stdlib` now enables the `cjk-codecs` feature of `rustpython-common`.

Add `cjk::decode_reset`, which the decoder `reset()` methods need. It differs from
building a fresh decoder state: ISO 2022 keeps its G1..G3 designations and the
escape-throughout flag, and resets only G0 and the shifted flag.

Drop the markers from the CJK codec tests and from the `test_codecs`, `test_io`,
`test_email`, `test_zipfile` and `test_traceback` cases that needed a CJK codec.
`test_codecs.BasicUnicodeTest.{test_basics,test_decoder_state}` stay expected
failures for an unrelated reason: `codecs.charmap_encode` rejects a `None` mapping.

Assisted-by: Claude Code:claude-opus-5

* stdlib: use the byte and text engines from `rustpython-common`

`binascii`, `_json` and `_socket`'s address converters now call the engines in
`rustpython-common` instead of carrying their own copies, and `rustpython-stdlib`
enables the `binascii`, `inet` and `json` features for them. That leaves
`base64` and `crc32fast` with no caller in `rustpython-stdlib`, and
`crates/stdlib/src/json/machinery.rs`, the last of the json_in_type-derived code,
goes away with its last caller.

The address converters change behaviour. `inet_aton` reads the lenient forms
(`127.1`, `16909060`, `0x7f.1`, `0177.0.0.1`), `inet_pton` rejects an octet with a
redundant leading zero and a group of five hex digits, `inet_ntop` writes the
IPv4-compatible form as `::c000:201`, and an address family with no converter
raises `EAFNOSUPPORT` instead of a bare `OSError`.

Give the JSON engine the closing-quote scan and the allocation-free `\uXXXX`
escape it needs to carry `_json`'s workload. Against the code it replaces,
`json.dumps` runs 2.3x faster with `ensure_ascii=True` and 1.7x without it, and
`json.loads` 1.2x.

`binascii.a2b_base64` now reports the messages `binascii.c` does: no
`error decoding base64: ` prefix, and the data-character count in parentheses.

Assisted-by: Claude Code:claude-opus-5

* test: enable the Windows cp932 codec case

The shared CJK engine now satisfies the Windows code-page adapter, so keeping this test marked as an expected failure turns its success into a CI failure.

Assisted-by: Codex:GPT-5
2026-08-31 15:44:55 +09:00
Jeong, YunWon f9b177719b Fix formatting, numeric, unicode, codec, complex and marshal mismatches found by differential testing (#8600)
* Fix %-formatting of bytes precision, width and %c errors

`format_bytes` subtracted the byte length from the field width without
saturating, so `b'%1s' % (b'abcde',)` aborted with a capacity overflow.
A precision written as a bare dot now truncates to nothing, and `%r`/`%a`
on bytes now honour the precision and width like the other conversions.

`%c` with a bytes, bytearray or str argument that is not one unit long
now names the argument by its length instead of by its type.

Assisted-by: Claude Code:claude-opus-5

* Fix format spec handling of grouping, bool, 'c' and complex

A grouping option next to an unrecognised presentation type now reports
"Cannot specify ',' with 'a'." instead of falling through to the type
check. `format(True, spec)` now validates the spec the way an int does.

The 'c' type now pads and aligns its character, and an integer outside
the C long range raises OverflowError rather than reporting a code point
out of range.

A complex formatted with the 'n'/'g' types or with a precision and no
type now goes through the general format without forcing a fraction.

Assisted-by: Claude Code:claude-opus-5

* Round floats at a negative ndigits from the exact decimal digits

Dividing by a power of ten rounded twice: once when the quotient was
stored and again at the tie, so e.g. `round(2.5e2, -2)` came out as 300.0.
The digits now come from the exact decimal expansion of the value.

Assisted-by: Claude Code:claude-opus-5

* Report the requested base in int literal errors and reject a bare sign

An invalid literal parsed with base 0 named the base that the prefix
turned out to mean rather than 0. A string of nothing but a sign was
taken for the old octal form and returned 0 instead of raising.

Assisted-by: Claude Code:claude-opus-5

* Split, strip and expand tabs over the Py_UNICODE_ISSPACE set

`str.split`, `rsplit`, `strip`, `lstrip` and `rstrip` with no separator
used Rust's whitespace predicate, which differs from the 29 code points
`Py_UNICODE_ISSPACE` names: U+001C-U+001F and U+0085 were skipped and
U+200B was treated as a separator.

`expandtabs` went through `str`, so it dropped the lone surrogates of a
WTF-8 string; it now works on `Wtf8` throughout.

Indexing a str out of range now says "string index out of range".

Assisted-by: Claude Code:claude-opus-5

* Read Unicode numeric values as exact rationals

`DerivedNumericValues.txt` field 1 carries a rounded decimal, so
`unicodedata.numeric('⅐')` and its neighbours came back short of the
value CPython reports. The generator now reads the rational in field 3,
and takes the 3.2 values from field 8 of `UnicodeData-3.2.0.txt`.

Assisted-by: Claude Code:claude-opus-5

* Return a mappingproxy from Pattern.groupindex

`pattern_groupindex` wraps the group index in a dict proxy, and hands
back a plain dict only when the pattern has no named group.

Assisted-by: Claude Code:claude-opus-5

* Fix the utf-16/32/7 codecs' error handling

The utf-32 decoder dropped a code point above U+10FFFF instead of calling
the error handler, and both the utf-16 and utf-32 handlers were told the
encoding was "utf-16"/"utf-32" whichever byte order the data was in.

The encoders now take a bytes replacement from the handler as it stands,
rejecting one that does not fill whole code units, rather than iterating
over it as text; a str replacement from the utf-16 encoder now splits an
astral code point into a surrogate pair.

The utf-7 decoder names its encoding "utf7", as its codec does.

Assisted-by: Claude Code:claude-opus-5

* Rework complex multiplication, division and power

Division now divides by whichever part of the divisor is larger, the way
`_Py_c_quot` does, and both it and multiplication recover the infinities
that the plain formulas turn into nan, following C11 Annex G. An operand
that is a real number is now multiplied and divided component-wise, which
keeps the sign of a zero and the other part of an infinity; a real
numerator has its own quotient so that its zero keeps a sign too.

An integer exponent no greater than 100 in magnitude is now reached by
repeated multiplication rather than through the polar form, so e.g.
`(1+2j) ** 2` is exact. A zero exponent gives 1, and an exponent with no
imaginary part no longer reaches for a logarithm that turns an infinite
magnitude into a nan. A result that came out infinite raises
OverflowError.

`complex() arg is a malformed string` is replaced by `could not convert
string to complex: ...` when the string carries a misplaced underscore,
`complex division by zero` by `division by zero`, and the message for
zero raised to a negative or complex power no longer names the base.

Assisted-by: Claude Code:claude-opus-5

* Intern the string constants that read as names

A code object's string constants were interned by length, so a short
string that is not a name was interned and a long name was not. They are
now picked out the way `all_name_chars` does. The one-character latin-1
strings are interned as well, so that every route to one of them lands on
the same object.

Assisted-by: Claude Code:claude-opus-5

* Honour the marshal version and separate its EOF errors

Versions below 2 now write a float or complex as its digits under
TYPE_FLOAT/TYPE_COMPLEX, versions from 4 on write a tuple of fewer than
256 items under TYPE_SMALL_TUPLE and a long ascii string under
TYPE_ASCII, and a string is marked interned only when it is.

`marshal.loads` now tells apart the three ways its data can run out:
"EOF read where object expected" where an object was to start, "EOF read
where not expected" where a single byte was, and "marshal data too short"
where a run of bytes was cut short.

Assisted-by: Claude Code:claude-opus-5
2026-08-29 22:43:11 +09:00
Jeong, YunWon 17deb6af5b lock: add an opt-in rwlock that detaches before it blocks (#8556)
* lock: add an opt-in rwlock that detaches before it blocks

A thread blocked acquiring a lock reaches no safepoint, so stop-the-world
cannot stop it, and the lock it waits for is routinely one a thread the
requester already suspended is holding. `RawDetachingRwLock` wraps the raw
rwlock and hands the wait for a contended acquire to a hook that leaves the
interpreter first; an acquire that takes the lock on its first try does not
reach the hook. The vm installs the hook during interpreter init and
implements it with `allow_threads`.

The wait ends with the lock acquired while detached, so re-attaching can park
the thread holding it. That is only safe where nothing reachable from a
stop-the-world section takes the same lock, so it is opt-in per lock:
`PyDetachingRwLock` is a separate type from `PyRwLock`, and `Traverse` is not
implemented for it, so a payload holding one cannot derive `Traverse`.

`PyByteArray::inner` takes it. `BorrowedValue`/`BorrowedValueMut` gain the
matching mapped-guard variants.

`a_thread_blocked_on_a_lock_does_not_stall_stop_the_world` blocks an
interpreter thread on a `PyDetachingRwLock` and asserts stop-the-world still
completes, running the stop on its own thread with a timeout so a stop that
never completes fails rather than hangs. Without the hook installed it fails
on the 10 s timeout; with it, it passes in 0.07 s.

Assisted-by: Claude

* lock: stop detaching where the lock may already be held

`upgrade` runs with the upgradable lock held, and `lock_shared_recursive` may
be the re-entrant take of a lock the calling thread holds; detaching there
parks a thread holding the lock, which is what this type documents it must not
do. They forward to the wrapped lock instead. `lock_upgradable` starts from
holding nothing, but nothing takes an upgradable read of one of these, so it
forwards too. `lock_shared` and `lock_exclusive` still detach.

Also narrow two claims the comments overstated. Not implementing `Traverse`
enforces the opt-in rule only against collections, not against the other things
that stop the world. And the requester exemption the hook relies on is wider
than `_PyEval_StopTheWorld` gives, so it is a local invariant.

Assisted-by: Claude

* os.readinto: read aside when the fd can wait

`readinto` held the destination's write lock for the whole call, including the
`read(2)` inside `allow_threads`. On a pipe, socket or terminal that read
returns only when the other end writes, so a thread reaching the same object
waited on a lock for an unbounded time, reaching no safepoint while it did.

Take the fd that answers without waiting directly, as before, and otherwise
read into scratch and take the lock only for the copy. This is what
`FileIO.readinto`, `socket.recv_into` and `socket.recvfrom_into` already do;
`os.readinto` was the site left over.

The EINTR retry moves to `read_into_slice`, unchanged.

Assisted-by: Claude

* fcntl: detach around the calls that wait

Every call in this module ran with the thread attached, so a thread inside one
reached no safepoint until it returned. `flock(LOCK_EX)` and `lockf(F_LOCK)`
return when whoever holds the lock gives it up, which may be never, and an
ioctl on a terminal or socket answers when the device is ready to; the world
could not be stopped for that long. `fcntl_fcntl_impl`, `fcntl_ioctl_impl`,
`fcntl_flock_impl` and `fcntl_lockf_impl` all release around the call.

`ioctl` with `mutate_flag` additionally held the target's write lock for the
whole call, so a thread reaching the same object waited on a lock for as long
as the device took. Its bytes now go in and come back through a buffer of our
own, as `fcntl_ioctl_impl` copies through one of its own for anything up to
IOCTL_BUFSZ. The export the argument holds is what keeps the length from
changing in between.

test_fcntl and test_ioctl pass.

Assisted-by: Claude

* openssl: read aside instead of holding the caller's buffer locked

`SSLSocket.read` wrote straight into the destination buffer, holding the lock
that reaching its bytes takes for the whole call. That read returns when the
peer writes, which may be never, so a thread touching the same object waited on
that lock for as long as the peer took, reaching no safepoint while it did.

Read into a buffer of our own and take the destination's lock only for the
copy. The rustls backend already reads this way, and `_ssl__SSLSocket_read_impl`
works from a `Py_buffer` whose critical section ended before the read.

`test_ssl` on this backend fails the same 16 tests before and after.

Assisted-by: Claude

* vm: add the inverse of allow_threads for callbacks

A call that detaches hands the thread to stop-the-world, which counts it as
parked. A callback that reaches Python from inside such a call would then run
on a thread the requester believes is stopped, and nothing in the vm could
stop it: `attach_thread` and `detach_thread` are private to `thread.rs`, and
`allow_threads` only goes the one way.

`attach_for_callback` attaches for the duration of the closure and returns the
thread to where it was, the way `PyGILState_Ensure` and `PyGILState_Release`
bracket `_servername_callback`. It tests for "not ATTACHED" rather than for
DETACHED, so a thread a stop-the-world has already moved to SUSPENDED routes
through `attach_thread` and parks there until the world starts again.

`a_callback_inside_a_detached_call_waits_for_the_world` stops the world with a
thread detached, then turns that thread loose at a callback and asserts it does
not run until the world starts. With the transition disabled it fails.

Assisted-by: Claude

* openssl: attach around the callbacks that run Python

`_servername_callback` and `_msg_callback` reach the interpreter from inside an
SSL call -- they take a reference to the Python callback, build arguments and
call it. That call is about to detach, and running Python from a detached
thread runs it on a thread a stop-the-world requester counts as parked.
`_servername_callback` opens with `PyGILState_Ensure()` for the same reason.

Both now rejoin the interpreter for the duration of the callback and give the
thread back afterwards. The reference to the callback moves inside that
section, since taking it is itself an interpreter operation; the check for
whether a callback is set at all stays outside, so a socket with none set never
reaches the interpreter.

No behavior change yet: nothing detaches around these calls, so
`attach_for_callback` finds the thread already attached and just runs.

Assisted-by: Claude

* openssl: detach around the SSL calls that wait

On a socket with a timeout the wait lands in `select` -> `sock_wait`, which
already detaches. On a blocking socket there is no such return: `SSL_read`
blocks in `recv(2)` through `impl Read for &PySocket`, with the thread attached
and the connection's write lock held, so the world could not be stopped for as
long as the peer stayed silent. `SSL_do_handshake`, `SSL_read_ex`,
`SSL_write_ex` and `SSL_shutdown` all run between `Py_BEGIN_ALLOW_THREADS` and
`Py_END_ALLOW_THREADS`; these now do too, in both socket and BIO mode as there.

The connection lock stays held across the call and so becomes a detaching lock:
a thread reaching the same socket gives up its interpreter rather than wait for
it attached. `connection` is `#[pytraverse(skip)]`, so a collection does not
walk into it and never takes that lock -- which is the rule for opting in,
though the skip is what supplies it here rather than the missing `Traverse`.

A server that completes a handshake and then says nothing used to deadlock the
whole process: the collector suspended the main thread at a safepoint and then
waited forever for the reader, so even the test's own timeout could not fire.
It now collects in 3 ms. Verified separately that a Python `_msg_callback`
still runs from inside the handshake -- 920 invocations across 40 handshakes
with a collector looping, five runs clean.

test_ssl on this backend fails the same 8 tests before and after, by name, and
openssl.rs draws no clippy warning it did not draw before.

Assisted-by: Claude

* lock: assert the opt-in rule against every stop-the-world section

Not implementing `Traverse` for `PyDetachingRwLock` states the rule to a
collection: a payload holding one cannot derive `Traverse`, so a collection
cannot walk into it. It says nothing to the other sections that stop the world
-- fork, traceback dumps, frame enumeration -- and `#[pytraverse(skip)]` steps
around it besides, which is how `_SSLSocket.connection` holds one. For those
the rule was a comment.

`set_world_stopped` records, on the one thread still running inside a stopped
world, that it is that thread; `lock_shared` and `lock_exclusive` assert it is
not set. A section that took one of these could block on a lock a parked thread
holds and only that section can release, which is the deadlock the rule exists
to prevent. Debug builds only; release builds track nothing.

Nothing in the tree trips it: 180 rounds of collect, `sys._current_frames`,
`faulthandler.dump_traceback` and 18 forks with four threads churning
bytearrays, plus test_gc/test_bytes/test_threading/test_memoryview/test_buffer
on a debug build, all clean.

`taking_one_while_stopping_the_world_is_caught` takes one with the flag set and
asserts the panic, so the guard is not dead code.

Assisted-by: Claude

* clippy: drop std_instead_of_core suppressions

1.98 no longer reports `std::io` items for the lint, so the six `expect`
attributes for it are unfulfilled. Also drops `from_iter_instead_of_collect`
from the workspace lint table, which 1.98 removed.

Assisted-by: Claude

* lock: spell out why the detaching rwlock exists

States the motivation as the three-thread cycle it avoids: how a stop reaches
a DETACHED thread but not an ATTACHED one, why a thread blocked on a lock
reaches no safepoint, and why the waiter rather than the holder gives way.

Puts it on `RawDetachingRwLock`, which is public and so rendered; the module
doc is private and keeps only the hook description.

Assisted-by: Claude

* fcntl: raise the error the call returned

The six detached calls discarded the `io::Error` and read `errno` again after
`allow_threads`, which re-attaches in between and can park on the way. `lockf`
already converts the returned error; these now do too.

Assisted-by: Claude

* openssl: allocate the read buffer through the vm

Without a `buffer` argument `read_len` is whatever non-negative size the caller
passed, so `vec![0u8; read_len]` aborts on allocation failure.
`new_zeroed_bytes` raises `MemoryError` instead, as the two other reads in this
file already do.

Assisted-by: Claude

* lock: leave no attached blocking acquire on a detaching lock

`lock_upgradable` starts from holding nothing, so it detaches like
`lock_shared`. A recursive read cannot: it may be the re-entrant take of a lock
this thread holds, so detaching there parks a thread holding it, and staying
attached stalls stop-the-world. `RawRwLockRecursive` is no longer implemented,
which removes `read_recursive` from these locks; nothing took one.

The assertion test no longer replaces the panic hook, which is process-wide and
was suppressing panic output from whatever else ran beside it.

Assisted-by: Claude

* vm: wait for the actual block in the stop-the-world test

The worker signalled before `read()` and the test slept 50ms, so a stop could
complete with nothing blocked on the lock and the test would pass having
checked nothing. It now publishes its thread id from inside the interpreter and
the test waits for that slot to reach DETACHED, bounded so an acquire that
never detaches fails rather than hangs.

Assisted-by: Claude
2026-08-28 16:20:39 +09:00
Andrej730 e2f7529f32 str.format: reject non-existing !b format conversion (#8597) 2026-08-26 15:42:53 +09:00
Shahar Naveh 50b60dc85c Remove #[repr(C)] from LinkedList (#8575)
* fix doc

* drop `repr(C)]`

* remove needless generics from LinkedList

* clippy
2026-08-22 20:54:18 +09:00
Jeong, YunWonandJean-Marc Le Roux 4ea9e84a3a Give the strong count the bits an unused weak field held (#8574)
* Give the strong count the bits an unused weak field held

RefCount packs its state into one usize and splits the non-flag bits evenly
between a strong and a weak count, so a 32-bit target left the strong count
15 bits. An object reaching 32 767 references then called refcount_overflow,
which aborts the process; on wasm that surfaces as an unreachable trap with
no Python-level error. Two ordinary module imports pass that total.

The weak half is never read and never written. WEAK_COUNT appears once
outside its own definition, in RefCount::new, and nothing in the repository
observes those bits: weak references live in the object's WeakRefList, which
Py::weak_count walks. The strong count now takes every bit the three flags
leave, which is 29 on a 32-bit target and 61 on a 64-bit one.

The tests run on wasm32-wasip2, where the old layout traps and the new one
passes. A 64-bit host passes either way, since 31 bits already covered them.

Fixes #8469

Assisted-by: Claude Code:claude-opus-5

* Return the strong count as usize so a 64-bit target cannot truncate it

The count is 61 bits wide on a 64-bit target once it takes the bits the weak
field held, so a u32 return truncates above 4 294 967 295 references: inc
would read a wrapped 0 and re-increment, and dec would read a wrapped 1 and
free a live object. A 32-bit target is unaffected, where 29 bits fit u32.

Assisted-by: Claude Code:claude-opus-5

* Cover the refcount ceiling through inc and dec

inc_by writes its own overflow check, so a test built on it leaves inc and
dec unexercised. The reported aborts came through inc, one reference at a
time.

Assisted-by: Claude Code:claude-opus-5

---------

Co-authored-by: Jean-Marc Le Roux <jeanmarc@lx.industries>
2026-08-22 16:42:12 +09:00
Luan Taraschi e17555459f Reject the string format flags CPython refuses (#8571)
A sign, a space or an alternate form parsed fine on a string spec and
then had no effect:

    >>> format('ab', '+')
    'ab'
    >>> f"{'ab':#5}"
    'ab   '

CPython raises ValueError for all three. format_string already refused z
and an explicit '=' alignment with the same family of messages, so the
three checks go next to those, in the order CPython reports them: sign,
then z, then the alternate form, then the alignment.

Assisted-by: Claude Code:claude-opus-5
2026-08-22 12:43:38 +09:00
Luan Taraschi d86ec309b1 Apply the format spec to a bool instead of dropping it (#8566)
format_bool answered "True" or "False" for every spec that carries no
presentation type, so width, fill, alignment and sign were all discarded:

    >>> f"{True:>5}"
    'True'

CPython has no bool.__format__ of its own. It uses int's, where an empty
spec on a subclass gives str(self) and everything else formats the integer.
The empty spec keeps the spelled out answer, the rest now goes to
format_int, which also brings back the errors an integer spec raises.

Assisted-by: Claude Code:claude-opus-5
2026-08-22 12:42:10 +09:00
Luan Taraschi cdb8a8dd83 Fix str.expandtabs aborting on a tab size of zero (#8562)
`"a\tb".expandtabs(0)` panicked with a capacity overflow. CPython returns
`'ab'`: with no width to advance to, the tabs come out and nothing else
moves. `expandtabs(-1)` is the same call, since `ExpandTabsArgs::tabsize`
sends every negative value to 0.

`expandtabs` keeps the tab stop in `tab_size` and the current column in
`col_count`, and on a tab it does `tab_size - col_count`. With a tab size of
zero both start at 0, the first character makes `col_count` 1 while
`tab_size` stays 0, and the subtraction underflows. The run of spaces asked
for next is `usize::MAX`, and the allocation aborts the process. A tab has to
follow something on the line to reach it: `"\ta".expandtabs(0)` subtracts 0
from 0 and comes out right by accident.

`BytesInner::expandtabs` already returns early for this and filters the tabs
out. The string version now does the same.

Assisted-by: Claude Code:claude-opus-5
2026-08-21 20:29:22 +09:00
1f2f7ff012 Fix int unicode decimal digits (#8521)
* Accept Unicode decimal digits in int(), Decimal() and complex()

CPython runs a string argument through
_PyUnicode_TransformDecimalAndSpaceToASCII before parsing it, so decimal
digits from any script are accepted:

    int('١٢٣')          # 123
    int('0x١f', 16)     # 31
    Decimal('١٢٣')      # Decimal('123')
    complex('1+2j')    # (1+2j)

RustPython only did this for float(), which had the transform inlined.
int() handed the raw UTF-8 bytes to bytes_to_int(), whose digit check is
is_ascii_alphanumeric(), so every non-ASCII digit was rejected — even
though float() accepted the same string.

Lift the inlined transform out of float_from_string() into
common::str::transform_decimal_and_space_to_ascii() and apply it to the
str paths of int() and complex() too. The result is always ASCII: as in
CPython, a character that is neither ASCII, whitespace nor a decimal
digit becomes '?' and truncates the string, which no parser accepts at
any base, leaving the caller to raise the error from the original string.

Bytes-like input keeps going straight to the parser, matching CPython's
split between PyLong_FromUnicodeObject and PyLong_FromString.

This unmarks two expectedFailure tests: test_int.test_unicode and
test_decimal.test_unicode_digits.

* Share one PyStr-to-numeric-literal step across int, float and complex

All three constructors need the same thing from a str argument: trim it,
fold Unicode decimal digits and whitespace to ASCII, and give up on a
string holding surrogates. Each expressed that last part differently —
float matched PyKindStr and returned b"", complex leaned on to_str()
returning None, int returned an empty Cow — so the rule lived in three
places at once.

Move it into protocol::numeric_literal_from_str() and have all three call
it. CPython repeats this per type because its wrapper is three lines over
a single PyUnicode representation; ours has to match over Ascii/Utf8/Wtf8,
which is worth writing once.

Only the shared step moves. int keeps its base handling, int and float
keep accepting bytes-like input, complex keeps rejecting it, and each
keeps raising its own error, because none of that is shared.

No behavior change: the CPython differential suite is byte-identical
before and after.

* Drop the now-empty test_unicode_digits override in test_decimal

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>
Co-authored-by: Jeong, YunWon <69878+youknowone@users.noreply.github.com>
2026-08-18 22:24:02 +09:00
Jeong, YunWon fd41418bd2 common: distinguish printf width and precision overflow (#8549)
Assisted-by: Codex:gpt-5.6-sol
2026-08-18 22:22:13 +09:00
Jeong, YunWon a78d0eb577 Fix crashes found hunting the last open fuzzing record (#8524)
* specialize: check the member descriptor's type before caching its slot offset

The LOAD_ATTR/STORE_ATTR specializations cached the slot offset of any member
descriptor found on the owner's type and then guarded the specialized
instruction on the type version alone, while descr_get()/descr_set() check on
every access that the instance belongs to the type the descriptor was defined
for. A descriptor taken from a wider class and bound to a narrower one read
past the instance's slot array once the cache warmed up:

    class Big:
        __slots__ = ("a0", "a1", "a2", "a3", "a4", "a5", "a6", "a7")
    class Narrow:
        __slots__ = ("z",)
    Narrow.x = Big.__dict__["a7"]
    o = Narrow()
    for _ in range(1000):
        try: o.x
        except TypeError: pass
    # index out of bounds: the len is 1 but the index is 7 (object/core.rs)

A class with no slots at all reached the ext_ref().unwrap() on the same line.

Assisted-by: Claude

* socket: reserve recv()'s buffer fallibly

recv() and recvfrom() handed the caller's bufsize straight to
Vec::with_capacity, so an unreachable size aborted the process through
handle_alloc_error before any syscall was made:

    socket.socket().recv(2**62)
    # memory allocation of 4611686018427387904 bytes failed -> SIGABRT

try_reserve_exact reports MemoryError instead, which is what CPython raises.

Assisted-by: Claude

* types: count the __call__ and __get__ slot dispatches as recursion

Both wrappers re-enter Python without pushing a frame, so nothing counted the
nesting when the special method named the object it was looked up on:

    class C: pass
    c = C(); C.__call__ = c
    c()                                    # native stack overflow, SIGSEGV

    class D: pass
    d = D(); D.__get__ = d; D.x = d
    d.x                                    # the same, through descr_get

with_recursion around the two dispatches raises RecursionError instead, the
way Py_EnterRecursiveCall bounds a tp_call dispatch. It costs about 5% on a
__call__ dispatch and 3% on a __get__ dispatch through these wrappers.

Assisted-by: Claude

* typevar: show a ParamSpecArgs origin by its repr

ParamSpecArgs and ParamSpecKwargs fell back to a Rust `{:?}` of __origin__ when
it had no __name__. That walks the object graph natively through Debug for
PyInner, where no recursion guard sits, so a single repr() of a deeply nested
chain overflowed the native stack:

    a = object()
    for _ in range(30000):
        a = typing.ParamSpecArgs(a)
    repr(a)                                # SIGSEGV

The origin is formatted with its repr now, which is guarded, and a ParamSpec
origin is recognized by its type rather than by carrying a __name__.

Assisted-by: Claude

* Do not hold a lock across a call back into Python

Three places kept a lock while running code that can reach the same object, so
a callback that touched it wedged the process:

    _asyncio.future_add_to_awaited_by(fut, waiter)   # waiter.__hash__ adds again
    select.select(elements, [], [], 0)               # fileno() clears `elements`
    select.poll().poll(1000)                         # SIGALRM handler registers

The future's awaited-by field is read and written under its lock but the set is
built outside it, the list extraction re-reads the list on each step the way
map_iterable_object() does, and poll() waits on a copy of its descriptors. All
three ran forever before and now finish the way they do on CPython.

Assisted-by: Claude

* Validate memoryview.cast() arguments and export negative strides correctly

cast() accepted any struct format and any shape element. A zero-size
format ('0s') and a 0 in the shape both reached a division by zero;
cast() now takes only a native single character format, optionally
'@'-prefixed, and shape elements that are ints greater than zero.

A view with a negative stride starts at its last item, so the bytes it
exported began there and its own offsets walked off the front of them.
Such a view now exports the whole underlying buffer with `start` folded
into the descriptor's offsets, and zip_eq() hands over a whole run only
when both sides are contiguous in the last dimension.

Assisted-by: Claude
Assisted-by: Codex:GPT-5

* Charge native recursion to the stack, not to the frame limit

with_recursion() checked the limit sys.setrecursionlimit() sets and
incremented the same counter that pushing a frame does, so a guard on a
native dispatch spent what Python code had left to call with, and did so
where sys._getframe() cannot see it: test.support.get_recursion_available()
reported frames that were no longer there. Py_EnterRecursiveCall bounds
the native stack instead, which is a separate budget, and the C stack
check with_recursion already performs is that bound.

The snippets pinning the guarded paths nest deep enough to reach the
stack rather than the frame limit.

Assisted-by: Claude

* Report a size that cannot be allocated instead of aborting on it

A size taken from Python went straight into an infallible allocation in
several places, so the process aborted through handle_alloc_error before
any exception could be raised:

- str/bytes/bytearray center(), ljust(), rjust() and zfill() reserved
  the padded result for the caller's width
- expandtabs() built its runs of spaces from a tabsize of any width;
  the argument is a C int, and a wider one does not fit
- Buffered{Reader,Writer,Random} allocated buffer_size, and read(),
  read1() and FileIO.read() their read size
- bytes(n) and bytearray(n) allocated n
- pbkdf2_hmac() allocated the derived key length, which is a C int

Each of these now reports MemoryError, or OverflowError where the
argument does not fit the type it is declared with.

new_zeroed_bytes() leaves the zeroing to the allocator, so a large
request costs the pages that are written to rather than all of them.

Assisted-by: Claude

* marshal: answer allow_code where a code object is written or read

allow_code was answered by walking the whole result a second time, with
no depth counter and no record of what it had already seen, so a value
that referred back to itself or nested deeply enough ran off the native
stack. w_object() and r_object() answer it where the code object is,
inside the walk that already bounds its depth and resolves references.

A container length is read the way r_long() reads one: it is signed, so
a length with the top bit set is out of range rather than four billion
items to reserve room for.

load() no longer holds a borrow of the buffer read() returned across the
seek() it makes afterwards.

Assisted-by: Claude

* Do not lock an object while running code that can reach it

Several places held a lock or a borrow of an object across a call back
into Python, so a callback that touched the same object waited on a lock
its own caller was holding:

- memoryview slice assignment read a source overlapping the destination,
  and __setitem__ converted the value while holding the write borrow
- BytesIO.readinto() read into a buffer viewing the same BytesIO
- array.__setitem__ converted the value under the array's write lock,
  and mmap.write() read a source viewing the same map
- bytearray.join() and bytearray.__mod__ drove Python with the
  bytearray borrowed
- array and bytearray answered "is this resizable" after taking the
  write lock, though an export is exactly a borrow someone else holds

A TextIOWrapper cookie now has to name a position inside what was
decoded in characters as well as in bytes; only the byte offset was
checked, and the character count is what read() and tell() index with.

Assisted-by: Claude
Assisted-by: Codex:GPT-5

* Stop asserting a pbkdf2 message that depends on the width of a C long

The snippet asserted "key length is too great.", which pbkdf2_hmac()
only reaches once the length has been converted; where a C long is
narrower than the length asked for, the conversion fails first and says
so instead. Both are OverflowError, which is what the case is about.

test_support.test_get_recursion_depth passes now that a native recursion
guard no longer spends frames get_recursion_depth() cannot see.

Assisted-by: Claude

* Publish and read the same pointer for a thread's top frame

set_current_frame() casts the `Py<FrameObject>` it publishes straight to
`*mut FrameObject`, so ThreadSlot::top_frame holds the object's base.
sys._current_frames() read it back through Py::from_payload_ptr(), which
subtracts the payload offset from what it is given. The reference it took
therefore incremented, and later decremented, a word 48 bytes ahead of
the frame -- inside the object allocated before it, whose OnceLock state
word sits exactly there for two frames adjacent in the size class. The
neighbour then read an initialized-looking cold pointer that had never
been written and locked whatever the uninitialized word addressed, so
the thread that owned it crashed rather than the one that read.

The slot now holds `*mut Py<FrameObject>`, which is what both sides mean.

A thread parked in a call has no FrameObject for its topmost frame, so
top_frame is null there and the reader takes the materialize path
instead: test_sys.test_current_frames never reaches the branch. The
snippet takes _current_frames() against threads that are running.

Assisted-by: Claude
Assisted-by: Codex:GPT-5

* Decide stop-the-world parking under the thread registry lock

do_suspend() published SUSPENDED first and only then re-read `requested`,
restoring itself to ATTACHED if the stop had ended in the meantime. That
made a thread the second writer able to leave SUSPENDED, so a stop whose
completion check had already observed the thread parked could be undone
behind the requester's back:

  worker    CAS ATTACHED -> SUSPENDED
  requester all_non_requester_suspended() -> true, world_stopped = true
  requester start_the_world(): requested = false, then walks the registry
  worker    reads requested == false, stores ATTACHED

With the store landing inside that walk the debug assertion in
start_the_world fires; with the walk already past the slot, a following
stop force-parks the thread DETACHED -> SUSPENDED, counts it as stopped,
and the store then puts it back to ATTACHED with the world declared
stopped and the thread running bytecode.

`requested` is set in init_thread_countdown() and cleared in
start_the_world() with the registry held, and start_the_world() keeps
holding it while releasing every SUSPENDED thread. Taking the registry
around the check and the transition therefore makes the two orders the
only ones possible: park before that release pass and be woken by it, or
find the request already withdrawn and stay ATTACHED. The requester is
left as the only writer that takes a thread out of SUSPENDED, and the
self-restore is gone.

suspend_if_needed() takes the VirtualMachine to reach the registry.

Assisted-by: Claude
Assisted-by: Codex:GPT-5

* Keep an atexit callback alive while it is being compared

atexit.unregister() releases the callback list around each __eq__ call and
identified the entry it had compared by the address of its Box. __eq__ can
call atexit._clear(), which drops that Box, and atexit.register(), whose
new Box lands on the freed allocation; the identity search then matched
the freshly registered callback and removed it.

  atexit.register(a); atexit.register(b); atexit.register(c)
  # __eq__ runs _clear() then register(d), returns True
  atexit.unregister(probe)

left no callbacks registered where CPython leaves d.

Entries are Arc-shared now, so unregister() holds the one it is comparing
and matches it with Arc::ptr_eq: an address cannot be reused while the
comparison that named it is still running.

Assisted-by: Claude

* Hold atexit entries in PyRc rather than Arc

PyObjectRef is Send and Sync only under the threading feature, so an Arc
over a callback entry trips clippy::arc_with_non_send_sync in builds
without it, such as the wasm package. PyRc is Arc there and Rc otherwise.

Assisted-by: Claude

* Do not hold a buffer's storage while waiting for a peer

FileIO.readinto() and socket.recv_into()/recvfrom_into() took the target
buffer's write borrow and kept it for the whole call, including the wait
for data a pipe, socket or terminal may never deliver. What CPython holds
across that wait is the export, which only forbids resizing; the borrow is
a lock every other thread touching the same object waits on, so

    threading.Thread(target=lambda: sock.recv_into(buf)).start()
    len(buf)

did not answer until the peer sent. A thread parked on that lock is
ATTACHED and never reaches a safepoint, so gc.collect() in a third thread
waited for the peer as well: one incidental read of the buffer stopped the
world from being stopped at all.

The wait now runs against storage of its own and the bytes are copied over
once they arrive, with the export held throughout so the target still
cannot be resized meanwhile. A seekable file answers from itself rather
than from a peer, so FileIO.readinto() writes into the target directly
there and the buffered read path is unchanged.

Assisted-by: Claude

* Do not hold a buffer's storage while waiting to hand it over

socket.send()/sendall()/sendto()/sendmsg() and FileIO.write() kept the
source buffer's read borrow for the whole call, including the wait for a
peer that may never make room. That borrow is a lock every other thread
writing to the same object waits on, so

    threading.Thread(target=lambda: sock.sendall(buf)).start()
    buf[0] = 1

did not return until the peer read; and a thread parked there is ATTACHED
and never reaches a safepoint, so gc.collect() in a third thread waited
for the peer too -- the same wedge readinto() had on the receiving side.

ArgBytesLike::borrow_buf_unlocked() answers with bytes that survive the
borrow being dropped. An immutable object hands out a plain reference and
locks nothing, so those are sent where they lie and bytes and memoryviews
over them cost nothing; only bytes reached through a lock are copied out
first. The export is held throughout either way, so the source still
cannot be resized while it is being sent.

The regression snippet covers both directions now and is renamed for it.

Assisted-by: Claude
Assisted-by: Codex:GPT-5

* Check select()'s descriptor limit while the sequence is walked

seq2set() collected the whole sequence and compared the result's length
against FD_SETSIZE afterwards. Selectable::try_from_object() calls
fileno(), which runs Python and can append to the list being walked, and
the walk re-reads the list on every step, so the collection had no end to
reach and the comparison was never made. seq2set in Modules/selectmodule.c
checks the count per element instead.

stdlib_select.py gains a fileno() that appends to its own list, and
releases its sockets with close() rather than by dropping the name.

Assisted-by: Claude

* Bound native recursion where the C stack cannot be measured

check_c_stack_overflow() answers no unconditionally under miri and on
musl, where the stack pointer is not read. Since 9c9905aff that check is
all with_recursion() does, so every guard placed on native recursion --
__call__ and __get__ dispatch among them -- was a no-op on those targets
and the nesting ran until the stack ran out.

with_recursion() now counts its own depth on those targets and refuses
past NATIVE_RECURSION_LIMIT_UNMEASURED. The count is separate from the
frame limit sys.setrecursionlimit() sets, and compiles away where the
stack pointer can be read.

Assisted-by: Claude

* Report the failure to allocate pbkdf2's key and Take.readinto's scratch

Both buffers are sized from an argument -- pbkdf2_hmac's dklen accepts up
to i32::MAX, and readinto's from the length of the destination -- and were
built with vec![0u8; n], which aborts the process on allocation failure.
new_zeroed_bytes() raises MemoryError instead.

Assisted-by: Claude

* Read the frozen-code tuple length as a signed length

The '(' branches in read_marshal_str_vec() and read_marshal_const_tuple()
took the length with read_u32() as usize, so a value with the top bit set
read as four billion items rather than as out of range. read_len() is what
every other length in this file goes through, and it reinterprets as i32.

Both readers serve deserialize_code(), which reads only the frozen modules
baked in at build time, so this changes no reachable behavior;
marshal.loads() already went through read_len().

Assisted-by: Claude

* Make the snippets from the fuzzer sweep assert what they check

builtin_str.py expanded a tab to 2**31-1 columns, allocating 2 GiB to
observe that the width is accepted; a string with no tab observes the same
acceptance without laying anything out.

stdlib_array.py caught the refusal of frombytes() on its own exported
buffer and passed silently when nothing was raised. stdlib_hashlib.py
used a bare `assert False` as its failure branch. Both now say so through
the same shapes the other snippets use.

stdlib_socket.py also accepts OverflowError from recv() with a size that
does not fit the platform's C int.

stdlib_threading_current_frames.py indexed the frame chain for "f123"
without first asserting it is there.

Assisted-by: Claude

* Ask for a marshal container's room instead of assuming it

A flagged tuple or list is published in the reference table before its
children are read, and the placeholder was built with vec![none; len].
The length is the input's to choose and read_len() lets it reach
i32::MAX, so marshal.loads(b"\xa8\xff\xff\xff\x7f") -- five bytes -- asks
for 17 GB of element slots and aborts the process where the allocator
cannot serve it. r_object() allocates the container up front too, but
PyTuple_New() reports what it cannot get.

The elements are now reserved with try_reserve_exact() and a refusal is
raised as MemoryError through the decoder's pending-error channel.
PyTuple::new_marshal_placeholder() held nothing but that allocation and
is gone; the caller builds the elements and uses new_ref().

Assisted-by: Claude

* Compare the blocking-buffer snippet against something

measure() asserted len(buf) == len(buf), which holds whatever the length
is; it now takes the length the caller expects. The pipe case compared
the drained total against the whole source, while an unbuffered write()
reports only what it transferred and a signal can cut that short; it now
compares against what write() returned.

Assisted-by: Claude

* Refuse array.frombytes() a source whose items are not bytes

frombytes() reads its argument as bytes, but accepted any contiguous
buffer, so array("i").frombytes(memoryview(array("d", [1.0]))) appended a
double's bytes read as ints instead of raising. array_array_frombytes_impl
requires an itemsize of 1; ArgBytesLike now reports the itemsize so the
same check can be made here.

The BufferError that a resize meets while the array is exported also names
the array rather than repeating bytearray's wording.

stdlib_array.py's frombytes-of-itself case used typecode "i", where the
new check answers before the resize guard is reached; it uses "b" so the
guard is what refuses, and asserts the wider case separately.

Assisted-by: Claude

* Tell apart the ways marshal data can be bad

A type byte no reader knows, a back reference that names nothing, and
TYPE_NULL all came out as a bare "bad marshal data" ValueError. r_object()
answers the first two with "bad marshal data (unknown type code)" and
"bad marshal data (invalid reference)", and read_object() answers the
third with a TypeError, "NULL object in marshal data for object", since
TYPE_NULL stands for no object rather than for a value.

MarshalError gains the three cases and deserialize_value() maps them.
The container-specific wording r_object() uses for a NULL read inside a
tuple or list is not reproduced; the exception type is.

Assisted-by: Claude

* Hash the collector's tables by address rather than by SipHash

A collection keys three sets and two maps by object address, and it visits
every tracked object and every edge between them, so the hashing is a
per-edge cost. Those tables used the default RandomState, whose SipHash
buys resistance against a caller choosing colliding keys -- and nothing
chooses these keys: they are addresses this process handed out into tables
that live and die inside one collection. A profile of gc.collect() over a
423k-object heap spent 45% of its samples in SipHash.

They now hash with a splitmix64 finalizer. The shifts matter: a table
picks its bucket from the low bits and an address arrives with those bits
zeroed by alignment, so a plain multiply leaves every object in a handful
of buckets and is slower than SipHash was.

The reachability walk also copied each object's referent vector out of the
map it was cached in, a second pass over every edge; it reads them in
place, and reference subtraction hands its vector to the map instead of
cloning it.

Measured over 423k live objects: 0.93s to 0.15s. Over 843k dead ones:
3.00s to 0.79s. extra_tests/snippets/stdlib_threading_gc_import.py, whose
collector thread calls gc.collect() in a loop, ran anywhere from 2.7s to
28s and now runs in 3.1-3.5s: a collection that takes longer leaves more
garbage for the next one to walk, so the cost fed back on itself.

Assisted-by: Claude
Assisted-by: Codex:GPT-5

* Keep the collection's candidates and their counts in one table

A collection built a set of candidates and, beside it, a map from the same
addresses to their reference counts. Both were probed for every edge in
the heap -- membership from the set, the count from the map -- so each
edge paid to hash the same address twice, and each candidate paid to be
inserted twice. The map alone answers both questions.

The candidates also keep a walkable order now, which the reference
subtraction pass needs since it writes the counts while reading the
candidates, and which the unreachable set is built from instead of a
set difference.

Over the 423k-object heap measured in the previous commit: 0.15s to
0.13s live, and 0.79s to 0.49s dead.

Assisted-by: Claude
Assisted-by: Codex:GPT-5

* gc: collect referents into one buffer instead of a vector per object

Step 3 allocated a `Vec` for every tracked object to hold its referents
and kept them all in a map until step 4 read them back. The referents now
go into a single growing buffer, with the map holding each object's range
into it.

Adds `PyObject::gc_extend_referent_ptrs`, which appends to a caller's
buffer; `gc_get_referent_ptrs` calls it with a fresh one.

Assisted-by: Claude

* memoryview and struct: match the checks and errors of the reference

memoryview:
- `cast()` accepted a source and destination that are both item types,
  which reinterprets the items rather than re-dividing the bytes; one side
  now has to be a byte format.
- A cast to `shape=()` returned without checking that the buffer holds
  exactly the one item that shape describes.
- `hash()` hashes the bytes, so it now raises ValueError for a view whose
  items are not bytes, rather than returning a hash that disagrees with the
  value the view compares equal to.
- `tobytes()` takes the `order` argument, with 'F' walking a
  multidimensional view down its columns; `BufferDescriptor` gained
  `for_each_segment_fortran` for that walk.

struct:
- A value the format has no room for reported "argument out of range"
  instead of naming the format and its range. The format character is now
  passed to the packing functions to report it.
- `Struct.__new__` no longer reads the format; `__init__` does, so
  `__init__` can be called again and a subclass can pass the format up.
  Methods raise RuntimeError until it has run, and `Struct` is a base type.

Removes the expectedFailure from test_Struct_reinitialization and
test_struct_subclass_instantiation.

Assisted-by: Claude
Assisted-by: Codex:GPT-5

* io: decide the readinto path by file type, not by seekability

FileIO.readinto wrote straight into the caller's buffer, holding its write
borrow, when the fd was seekable; otherwise it read aside into scratch and
copied. Seekability stood in for "this read answers without waiting on a
peer", which a pipe on Windows breaks: lseek on one succeeds, so the pipe
took the borrow-holding path and every other thread touching that bytearray
waited for the peer.

host_io::reads_without_waiting answers it directly -- seekability elsewhere,
GetFileType() == FILE_TYPE_DISK on Windows.

The regression snippet times each operation separately, so a failure names
the one that waited; it asserts the transfer is still in flight before
checking the export; and the socket case fills the connection until it
refuses rather than assuming a size that outruns it, which SO_SNDBUF on an
already-connected pair does not settle.

Assisted-by: Claude
2026-08-17 00:33:27 +09:00
Jeong, YunWon a97e8f0746 str: take search bounds through the character index (#8530)
* str: count an empty needle in characters

str.count with an empty needle ran find_iter over the range's bytes, which
reports one position per encoded byte boundary rather than one per
character: '가나다'.count('') answered 10 instead of 4. Count the range's
code points instead; bytes.count keeps the byte-position answer.

Assisted-by: Claude

* str: take search bounds through the character index

find, rfind, index, rindex, count, startswith and endswith resolved their
start/stop bounds with AnyStr::get_chars, which walks the payload to both
bounds, and find reported its hit by counting the code points in front of
it -- so a sweep over a subject's own indices walked it once per call.
Resolve the bounds with StrData::char_range_to_bytes instead, which is the
converter the subscript and slice paths already use, and map the hit back
with Wtf8Index::char_index_at_byte, added here as the table's inverse: a
bracketed search over the groups, then at most an entry's worth of steps.

The payload alone does not say whether it is ASCII, so get_chars walked
there too; that path is now off it as well.

n=8000, sweeping the bound over the subject, best of 3, interleaved:

                     '가나다라'*n/4            'abcd'*n/4
    find          18.00ms ->  0.15ms      3.48ms -> 0.14ms
    startswith    16.75ms ->  0.12ms
    count         22.78ms ->  4.02ms

count stays linear in the range it is given, as it is in CPython.

Assisted-by: Claude
2026-08-15 17:23:37 +09:00
Jeong, YunWon 9616b28d3d str: resolve subscripts and slices through the code point index (#8526)
`nth_char` and the four `SliceableSequenceOp` methods each walked the buffer
to reach a character index, so `s[i]` and `s[a:b]` on a non-ASCII string were
O(i) and O(b), and a loop over either was quadratic. They now resolve through
`char_index_to_byte`, which is what the index table was added for: a plain
slice becomes a byte reslice, and a stepped slice one lookup per collected
character.

An index within four code points of an end is still walked to, and so is a
slice that reaches within four of both. PyPy draws the same line with
`MAX_UNROLL_NEXT_CODEPOINT_POS`, in a guard that also asks the JIT whether the
index is a constant; there is no JIT here, but the reason to skip the build
survives it -- `s[0]` on a long string should not pay for a table.

The stepped slices took their character count from `(range.len() / step) + 1`,
which overshoots whenever the last step lands short: `"aéc"[::3]` reported a
length of 2 for a one-character string, and `reversed()` on it read past the
end of the buffer and panicked. The count is now the index iterator's own
length, so it cannot drift from the characters actually collected.

Assisted-by: Claude
2026-08-15 01:03:09 +09:00
Jeong, YunWon 4a8c613b04 _sre: drive a non-ASCII str subject through a character index on the string (#8522)
* common: index a WTF-8 buffer's code points for random access

`Wtf8`'s iterators are sequential, so resolving a code point index through
them is O(n) and code that indexes the same string repeatedly walks it once
per index. `Wtf8Index` is a side table -- one 24-byte group per 64 code
points, 0.375 bytes per code point -- that answers the same question in
constant time; the layout is PyPy's `UTF8_INDEX_STORAGE`.

`StrData` builds one on the first call to the new `char_index_to_byte`, in a
slot published by compare-exchange, and drops it with the string. ASCII
strings answer from the index itself and never build a table. A clone gets an
empty slot, since it indexes its own copy of the buffer.

Assisted-by: Claude

* _sre: drive a non-ASCII str subject through the string's character index

The `&Wtf8` drive answers `count` and `create_cursor` by decoding from the
start of the subject, so a scan that restarts at successive positions walks
the subject once per position, and `slice` walks it again per extracted
group. `Utf8Str` holds the `PyStr` and asks it instead: `count` is the cached
character length, and `create_cursor` and `slice` resolve their positions
through `char_index_to_byte`. Stepping is the `&Wtf8` drive's, unchanged.

The table lives on the string, so a `Match` that outlives the scan shares it
-- `group` has no cursor of its own to move relative to.

`SreStr for &Wtf8` has no callers left; the `StrDrive` impl stays, since
`Utf8Str` steps through it. The three subject helpers now share one downcast.

Assisted-by: Claude
2026-08-14 23:33:58 +09:00
Seonghun An 33d98d122e Implement negative zero coercion format option (#8475)
Assisted-by: Codex:gpt-5
2026-08-09 14:58:07 +09:00
Seonghun An c258bad623 Fix complex zero-padding error priority (#8453)
Assisted-by: Codex:gpt-5
2026-08-05 02:13:43 +09:00
Joshua Megnauth 33eb99af44 Fix some clippy lints for 1.99 (#8412) 2026-07-30 22:11:31 +09:00
Seonghun An 7c6e7dc29e Fix zero padding for string format specs (#8407)
* Fix zero padding for string format specs

Assisted-by: Codex:gpt-5

* Add string alignment format regression test

Assisted-by: Codex:gpt-5
2026-07-29 20:27:59 +09:00
OkJaandClaude Opus 5 6b554d96c7 Implement fractional grouping in format specs (#8373)
Support the CPython 3.13+ format spec syntax that puts a grouping option
after the precision, so `format(1234.56789, '.6,f')` gives
'1234.567,890'. The integer and fractional parts group independently and
may use different separators (`,.6_f` -> '1,234.567_890'), so the spec
carries a separate `frac_grouping_option`.

`parse_precision` now consumes the separator that follows the precision
digits and rejects a `,`/`_` mix. A repeated separator is deliberately
left in the spec so the trailing-text check reports it, which is how
CPython arrives at a different message there. A dot followed by neither
digits nor a separator now raises "Format specifier missing precision"
rather than an unrelated error.

Fraction digits group away from the decimal point, so the last group may
be short, and any exponent or percent tail is left intact. The
separators count toward the field width, so zero padding of the integer
part reserves room for them.

'n' takes its separators from the locale and so cannot carry one. The
complex locale path rewrites 'n' to 'g' before delegating, so it has to
validate first; that also makes `format(1+2j, ',n')` fail as it does in
CPython, which it previously did not.

Reference (CPython 3.14), Python/formatter_unicode.c:
- parsing: https://github.com/python/cpython/blob/3.14/Python/formatter_unicode.c#L257-L299
- 'n' rejection: https://github.com/python/cpython/blob/3.14/Python/formatter_unicode.c#L361-L367
- number split: https://github.com/python/cpython/blob/3.14/Python/formatter_unicode.c#L488-L516
- zero-pad width: https://github.com/python/cpython/blob/3.14/Python/formatter_unicode.c#L604-L606

Remove `@unittest.expectedFailure` from tests that now pass
(2 in test_format, 1 in test_float).

Assisted-by: Claude:claude-opus-5

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>
2026-07-26 14:31:34 +09:00
Jeong, YunWon 210ccc889c Thread-safe type operations: type lock, QSBR type-cache reclamation, GC stop-the-world, and interpreter optimizations (#7416)
* type lock

* Drop old PyObjectRef outside type lock to prevent deadlock

Dropping values inside with_type_lock can trigger weakref callbacks,
which may access attributes (LOAD_ATTR specialization) and re-acquire
the non-reentrant type mutex, causing deadlock.

Return old values from lock closures so they drop after lock release.

* Align type lock behavior with CPython

* Add PUBLISHED flag bit to RefCount state word

Assisted-by: Claude

* Add QSBR module for deferred memory reclamation

Assisted-by: Claude

* Defer memory free of cache-published objects via QSBR

Assisted-by: Claude

* Wire QSBR checkpoints into thread lifecycle and eval breaker

Assisted-by: Claude

* Publish type-cache values to QSBR and bypass cache without a VM

Mark cached type-method values as QSBR-published before storing their
pointer in TYPE_CACHE, so racing readers never try-incref freed memory.
Debug-assert that the current thread is ATTACHED whenever a lock-free
cache read happens.

Delete find_name_in_mro_without_vm and its unsound direct SeqLock read
outside any VM/thread registration; find_name_in_mro now falls back to
the locked, uncached MRO walk when no VM is current. This also removes
assign_version_tag()'s last caller, so its unlocked fallback is deleted
along with it (version_for_specialization keeps the locked path).

VirtualMachine::initialize() runs Python bytecode (e.g. importing
codecs/encodings) before any enter_vm scope exists, which left the
bootstrap thread not ATTACHED for cache reads during startup. Add
thread::VmBootstrapGuard, an RAII counterpart to enter_vm usable across
statements that need &mut VirtualMachine, and wrap initialize() with it.

Assisted-by: Claude

* Use try-incref reads and QSBR-backed swaps in specialization cache

Assisted-by: Claude

* Reset QSBR thread registry after fork in the child

Add Qsbr::reset_after_fork, which clears the registered thread slots
before draining the retire queue. Call it in py_os_after_fork_child,
right after type_cache_after_fork() and before
_thread::after_fork_child() re-registers the surviving thread.

Dead parent threads' Arc<QsbrSlot> handles live on in the child's
copied memory with no destructor ever running, so without this the
registry keeps them 'online' forever and future grace periods never
complete.

Assisted-by: Claude

* Add threaded stress test for type cache mutation races

Assisted-by: Claude

* Restrict qsbr internals to pub(crate) and fix clippy lints

Downgrade pub items in the private qsbr::threading module (QsbrSlot,
Qsbr, QSBR, and its methods) to pub(crate), since they were never
reachable outside the crate. Downgrade ThreadSlot::qsbr accordingly to
avoid a private-interfaces warning. Import Arc/Weak from alloc instead
of std to match clippy::std_instead_of_alloc. Rewrite the process()
comment: goals are not strictly ordered by push order since advance()
and the queue push aren't atomic together, so concurrent free_delayed
calls can interleave; the drained prefix stays sound because each item
individually passed poll, with reordering only affecting reclamation
latency.

Assisted-by: Claude

* Gate per-instruction QSBR check behind a global pending flag

eval_breaker_tripped() and check_signals() called
thread::qsbr_break_requested() on every bytecode instruction, which
does a thread-local lookup, RefCell borrow, and atomic load even when
no QSBR retirement is pending. This caused a measured 10-18% slowdown
on tight interpreter loops.

Add Qsbr::pending, a global AtomicBool set under the queue lock while
free_delayed() holds a retired allocation, and cleared under the same
lock by process()/drain_all() once the queue empties. The hot path now
checks Qsbr::break_pending() (a single relaxed static load) before
touching thread-local state, and only pays the TLS cost while a
retirement is actually in flight.

Assisted-by: Claude

* Merge signal and QSBR eval-breaker flags into one atomic word

Replace the separate ANY_TRIGGERED AtomicBool and QSBR pending
AtomicBool checks in the per-instruction eval-breaker path with a
single AtomicU8 (EVAL_BREAKER) holding a bit per source. The global
QSBR instance mirrors its pending state into the QSBR bit under the
same queue-lock critical sections that already toggle pending, while
local QSBR instances used by unit tests are left untouched.

eval_breaker_tripped() and check_signals() now read/act on the merged
word (eval_breaker_pending(), qsbr_bit_set()) instead of issuing two
separate atomic loads per instruction. set_triggered() switches from
store to fetch_or so a signal handler never clobbers the QSBR bit.

Removed the now-unreferenced is_triggered() helper; break_pending()
is kept for unit tests only and marked allow(dead_code) outside test
builds.

Assisted-by: Claude

* Skip freelist reuse for published objects in default_dealloc

Freelist-eligible payloads (tuple, int, list, dict, float, ...) were
routed to T::freelist_push before ever reaching PyInner::dealloc, so a
published object (e.g. a tuple cached as a type attribute) bypassed the
is_published -> free_delayed QSBR hook entirely. That let PyRef::new_ref
reuse the slot and rewrite the refcount word with a non-atomic
core::ptr::write racing a reader's atomic try-incref, and let
FreeList::drop call alloc::dealloc directly while a reader could still
be mid-read.

Gate the freelist branch in default_dealloc on
RefCount::is_published(), checked before any teardown. A published
object now always falls through to PyInner::dealloc, whose existing
hook defers the memory free via QSBR.

Document the non-unix (e.g. Windows) reclamation-latency limitation in
the QSBR design doc's Lifecycle integration section (previously only
noted in a code comment in vm/thread.rs).

Extend the type-cache stress test so the mutator also churns a
freelist-eligible published tuple class attribute (C.shape), read by
readers each inner loop and deleted on the same cadence as C.m, to
exercise the fixed bypass.

Assisted-by: Claude

* Use itoa for PyInt::to_str_radix_10 i64 fast path

Format small integers with itoa::Buffer instead of i64::to_string()
in PyInt::to_str_radix_10(), which backs both str(int)/repr(int) for
exact int and PyObject::str()'s exact-int fast path. Adds the itoa
crate as a workspace dependency.

Assisted-by: Claude

* Make object attribute dunders wrapper descriptors

Remove the __getattribute__, __setattr__ and __delattr__ #[pymethod]s
from PyBaseObject so add_operators installs PyWrapper slot wrappers for
them from the #[pyslot] functions instead of method descriptors.

lookup_slot_in_mro now classifies these entries as NativeSlot, so heap
types without Python-level overrides keep the native getattro/setattro
slot functions, which lets LOAD_ATTR/STORE_ATTR specialization apply to
instances of Python-defined classes.

Since __setattr__ and __delattr__ share the setattro slot, resolve both
names together in update_one_slot: overriding only one of them no longer
lets the other name's native resolution overwrite the dispatching
wrapper.

Assisted-by: Claude

* Resolve TpSetattro pair on attribute deletion, not just addition

update_one_slot's TpSetattro branch only ran the combined
__setattr__/__delattr__ resolution (added in the previous commit) when
ADD was true. On deletion (e.g. del C.__setattr__), it fell back to
inherit_from_mro, which copies the base class's slot and discards the
class's own remaining Python-level override of the other name.

lookup_slot_in_mro reads the current attribute dicts, so the same
resolution is correct for both addition and deletion; the ADD-only
guard is removed and the logic now always runs.

Assisted-by: Claude

* Generate Opcode::cache_entries/deopt as table lookups

generate_rs_opcode_metadata.py now emits a 256-entry const array for
each function instead of a chained match over opcode names.
Opcode::deopt() indexes an [Option<Opcode>; 256] table built from the
existing specialization-to-base mapping, and Opcode::cache_entries()
indexes a [u8; 256] table that bakes in the same deopt/to_base
composition deoptimize() previously performed before its own match.
Regenerated opcode_metadata.rs from the updated script; PseudoOpcode's
bodies are unchanged since it has no cache/deopt entries to table.

Added an exhaustive test in instruction.rs that checks every valid u8
opcode against a frozen copy of the old chained-match bodies.

Assisted-by: Claude

* Make Opcode/Instruction numeric conversions O(1)

Opcode::as_numeric, Opcode::as_instruction and Instruction::as_opcode
were each a per-variant match over ~230 arms in the define_opcodes!
macro. Opcode now carries the same explicit $op_id discriminants and
#[repr($typ)] as Instruction, which makes the conversions sound as:

- Opcode::as_numeric: a plain `self as $typ` identity cast.
- Opcode::as_instruction / Instruction::as_opcode: a mem::transmute,
  relying on both enums sharing one-$typ-wide layout (Instruction's
  payload fields are all the zero-sized Arg<T> marker, checked by a
  new per-instantiation size_of assertion).

try_from_numeric is left as a match: $op_id values have gaps
(specialized/instrumented opcode ranges), so a range check can't
replace it.

Adds #[inline] to the rewritten conversions plus deoptimize, and to
the small generated wrapper/table-lookup functions from the previous
opcode-metadata change (as_u8/as_u16, cache_entries, deopt, to_base)
via generate_rs_opcode_metadata.py, then regenerates
opcode_metadata.rs.

Extends the instruction.rs equivalence-test pattern with two
exhaustive tests (u8 and u16 instantiations) checking the new
identity-cast/transmute conversions against the untouched
try_from_numeric/TryFrom paths.

Assisted-by: Claude

* Pop CallIsinstance arguments directly instead of collecting into Vecs

The specialized handler built two heap-allocated Vecs per call
(pop_multiple().collect() plus a with_capacity(2) buffer) before
invoking is_instance. Pop the class and instance straight off the
stack for the effective two-argument case, removing the per-call
allocations.

Assisted-by: Claude

* Inherit tp_new instead of always installing new_wrapper

update_one_slot's TpNew branch stored new_wrapper for every ADD, so all
heap types had slots.new == new_wrapper and the CallAllocAndEnterInit
specialization never fired. Now __new__ is resolved through the MRO
dicts: an own or Python-level definition installs new_wrapper, while a
builtin __new__ entry (or none) inherits slots.new from the solid base.

The now-reachable CallAllocAndEnterInit path gains the missing guards:
the specializer requires co_argcount == oparg + 1 (via
can_specialize_call) and rejects generator-like __init__, and the
handler re-checks the argcount against the class-level init cache.
Without the argcount check, __init__ defaults broke re._parser
(UnboundLocalError in SubPattern.__init__). Remove the now-unused
is_simple_for_call_specialization.

Assisted-by: Claude

* Skip locals dict allocation for the init-cleanup shim frame

Mark the shim code object NEWLOCALS and create the shim frame with no
locals mapping so FrameLocals::lazy() is used. The shim only executes
ExitInitCheck/ReturnValue and never touches locals, so this removes one
dict allocation per specialized instantiation.

Assisted-by: Claude

* Guard CALL_ALLOC_AND_ENTER_INIT with cached function version

The init specialization cache stored only the type version, so swapping
__init__.__code__ (which zeroes func_version) did not deopt the warmed
call site and stale code assumptions (argcount shape, no varargs/kwonly,
not a generator) were applied to the new code object.

Store get_version_for_current_state() in the specialization cache when
caching __init__ and re-check func_version() in the handler before using
the cached function, deopting to the generic call path on mismatch, the
same way the getitem specialization cache does.

Assisted-by: Claude

* Apply rustfmt and ruff-format fixes to files from earlier commits

Assisted-by: Claude

* Add frame object freelist

Frame.iframe becomes FrameUnsafeCell<Option<InterpreterFrame>> so a dead
frame can be left as an empty husk. Traverse::clear extracts all owned
child references (including localsplus values via LocalsPlus::clear_into)
and empties the cell. Dead frame allocations are cached in a thread-local
FreeList<Frame> (up to 200 entries) and reused by PyRef::new_ref.

clear_generator returns early when the frame was already cleared by cycle
collection; generator drops can run after tp_clear of their frame.

gc: skip tp_clear for objects saved to gc.garbage by DEBUG_SAVEALL, since
they remain reachable from Python.

Assisted-by: Claude

* Drop frame children directly in tp_clear instead of extracting

Pushing the frame's ~10 child references into the clear buffer grew a
Vec on every frame deallocation. Take the interpreter frame out of the
cell and drop it in place; LocalsPlus::clear_into is removed.

Assisted-by: Claude

* Untrack objects before tp_clear and guard cross-thread f_locals

The cycle collector called tp_clear on unreachable objects while they
were still linked into the GC generation lists, so another thread could
obtain a strong reference to an already-cleared object (e.g. a frame
husk with iframe == None) via gc.get_objects() and access the cleared
payload. Untrack the dead set before the clear phase, mirroring the
untrack-then-clear ordering of the refcount dealloc path.

Objects that gained an external reference before untracking are found
by comparing each object's strong count against the references coming
from within the dead set; such late-resurrected objects and everything
reachable from them are re-tracked and skipped, letting a later
collection retry once the external references are released.

Also reject f_locals access for a frame currently executing on another
thread. Reading fastlocals of such a frame races with the executing
thread overwriting the slots (torn reads of dropped values). Access
from the executing thread itself (locals(), trace callbacks) is still
allowed via the current-frame chain check.

Assisted-by: Claude

* Skip localsplus heap copy for uniquely referenced dying frames

release_datastack_frame now checks the frame's strong count after
untracking it from the GC generation lists. When the caller holds the
only reference, localsplus values are dropped in place and the data
stack storage is released without the heap copy; escaped frames
(traceback, sys._getframe, trace callbacks) keep the copy path.
The three inline materialize+pop call sites in function.rs are routed
through release_datastack_frame.

Assisted-by: Claude

* Stage exact-args call arguments in stack slot buffers

CallPyExactArgs, CallBoundMethodExactArgs and CallAllocAndEnterInit no
longer collect popped arguments into a per-call Vec (plus a second Vec
for self-prepending). Arguments are popped into a fixed-size
Option<PyObjectRef> slot buffer (CallArgBuffer, 8 inline slots, heap
fallback for larger arities) and moved into fastlocals via the new
invoke_exact_args_slots / a take() iterator.

- prepare_exact_args_frame now accepts an ExactSizeIterator of args
- specialization_run_init_cleanup_shim takes the slot buffer and fills
  slot 0 with new_obj, dropping one redundant clone
- LoadAttrGetattributeOverridden, LoadAttrProperty and
  BinaryOpSubscrGetitem pass inline slot arrays instead of vec![]

Assisted-by: Claude

* Reduce allocations in generic call paths

- FuncArgs::prepend_arg: use reserve instead of reserve_exact so
  exact-capacity vectors do not realloc on every prepend.
- IntoFuncArgs::into_method_args: build the final args vec once with
  capacity len + 1 instead of prepending into a full vector.
- PyType::call: skip cloning FuncArgs when no init slot can run after
  slot_new (no init slot, not `type`, and slot_new is not new_wrapper).

Assisted-by: Claude

* Skip redundant exc_info restore on frame exit

with_frame_impl saves the current exc_info slot value and restores it
when the frame exits. When the slot still holds the same value, the
restore rewrites the slot and recomputes the thread-exception mirror
for no effect. Add restore_exception, which compares the slot against
the saved value by pointer identity and skips the store when they
match. The saved value is a strong reference held for the whole frame
scope, so the pointed-to object cannot be freed and its address reused
while the frame runs, making the pointer comparison free of ABA.

Assisted-by: Claude

* Apply rustfmt to gc_state.rs

Assisted-by: Claude

* Avoid empty FuncArgs clone in PyType::call

Cloning args for the init call clones the kwargs map even when args is
empty, which shows up in no-argument instantiation profiles. Prepare
the init-call args before slot_new: a default FuncArgs when args is
empty (indistinguishable from a clone of empty args), the existing
clone otherwise. The empty check also keeps the init-slot load of the
clone-elision path off the no-argument call path.

Assisted-by: Claude

* Push freelist husks only after tp_clear and child drops

default_dealloc pushed the object onto the thread-local freelist before
running clear_fn. Payloads that drop children inside clear (Frame) can
run __del__ there, and a reentrant allocation could pop the husk and
overwrite its payload while clear_fn still held a &mut borrow of it.
Tuples had the same window through the extracted-edges drop, which ran
after the push.

Reorder default_dealloc to clear, drop the extracted children, and only
then attempt the freelist push, so the husk becomes reusable only when
no borrows into the payload remain.

The tuple freelist bucketed husks by element count, which required
reading the payload during push; after this reordering the elements are
already cleared. PyInner<PyTuple> is a fixed-size allocation (the
elements box is dropped and replaced on reuse), so replace the per-size
buckets with the shared single-list FreeList. Remove the now-unused
pyinner_layout helper.

Assisted-by: Claude

* Resolve __set__ and __delete__ together for the descr_set slot

The descr_set slot serves both __set__ and __delete__, but the
TpDescrSet accessor resolved only the single modified name and fell
back to MRO inheritance on delete. Deleting one of the pair could
disable the surviving operation: after `del D.__set__`, an instance
delete stopped calling the remaining __delete__.

Resolve both names together like the TpSetattro accessor does: any
Python-level definition selects the dispatching wrapper, matching
native functions are stored directly, a single native function with
the other name absent is stored directly, and the slot is inherited
from the MRO only when neither name resolves.

Assisted-by: Claude

* Update type base on __bases__ assignment

set_bases replaced bases and mro but never updated the stored base, so
__base__ kept reporting the old value after reassignment and slot
resolution (tp_new inheritance, set_new/set_alloc during init_slots)
read the stale solid base.

Change the base field to PyAtomicRef<Option<PyType>> so it can be
swapped under the type lock while remaining lock-free for readers, and
recompute it in set_bases with the same best_base validation type
creation uses (BASETYPE flag, instance layout conflict among bases).
The swapped-out base is parked in the frame's temporary refs; other
references released inside the critical section are dropped after the
lock is released.

Also in set_bases:
- remove this class from the old bases' subclass lists (pruning dead
  entries), so repeated assignment no longer accumulates duplicates
- roll back bases, base, and all updated mros when the recursive mro
  update fails, instead of leaving the type half-reparented
- fix the misformatted empty-tuple error message

Remove the expectedFailure marker from test_unsubclassable_types,
which now passes.

Assisted-by: Claude

* Fix rollback order, dead weakrefs, and lock-held drops in set_bases

- Restore recorded mros in reverse on rollback so a class visited
  multiple times through diamond inheritance ends with its original
  mro instead of an intermediate one.
- Skip dead weakrefs in the subclass list during the recursive mro
  update instead of panicking on upgrade.
- Retire the replaced mros on the success path instead of dropping
  them while the type lock is held.

Assisted-by: Claude

* Reify number sub-slot wrapper once in update_one_slot

The update_sub_slot! macro expanded the Python-method wrapper closure at
both the own and inherited store sites. Each expansion is a distinct fn
item, so a base and a non-overriding subclass stored wrappers with
distinct addresses in unmerged debug builds. binary_op1 compares slot fn
addresses to detect whether a subclass overrides the operator, so the
inherited slot was misread as an override and C() // E() dispatched to
__rfloordiv__ instead of __floordiv__.

Bind the wrapper store in a single closure and call it from both branches
so the fn item is reified once and the slot value stays identical across
a base and its subclasses. Document the conservative-on-mismatch nature
of the new_wrapper address guard in call_wrapped.

Assisted-by: Claude

* Restrict type_cache_after_fork visibility and guard type-cache reads

type_cache_after_fork is only called from within the crate, so mark it
pub(crate) to resolve the unreachable-pub warning.

Add debug_assert_current_thread_attached at the has_name_in_mro lock-free
type-cache read site, matching lookup_ref_and_version_interned, and gate
the function on debug_assertions so it is not compiled unused in release
builds where the call sites are elided.

Assisted-by: Claude

* Guard BinaryOpSubscrGetitem with the cached type version

The specialized BINARY_OP_SUBSCR_GETITEM handler used the cached
__getitem__ after checking only the function version, unlike the sibling
specialized handlers which revalidate the type version tag first.

Store the type version in the inline cache at specialization time and
revalidate owner.class().tp_version_tag against it before using the cached
function, deopting to the generic subscript path on mismatch.

Assisted-by: Claude

* Call __abstractmethods__ __len__ once in object.__new__

The abstract-method check invoked the user-visible __len__ twice: once via
length_opt for the count and again while materializing the method names.
Derive the count from the materialized list instead, so __len__ runs once.

Assisted-by: Claude

* Use i64 fast paths for specialized int add/sub/mul

Rewrite execute_binary_op_int to box results through new_int via i64
checked arithmetic instead of raw BigInt ops with new_bigint. Add an
int_mul helper and a shared int_fast_op that computes the i64 result and
falls back to the BigInt operation on to_i64 or checked-op failure.

Wire int_mul into both the specialized BinaryOpMultiplyInt handler and
the generic execute_bin_op Multiply/InplaceMultiply path, gated on exact
int operands so subclasses keep dispatching through _mul/_imul.

Assisted-by: Claude

* Use i64 fast paths for exact int floordiv and remainder

Add floordiv_i64/mod_i64 computing i64 floor-division and divisor-signed
remainder, guarding zero divisor and i64::MIN overflow by returning None.
Wire them through int_floordiv/int_mod (shared int_div_fast_op boxes via
new_int) into the generic execute_bin_op FloorDivide/Remainder and their
Inplace variants, gated on exact int operands so subclasses and zero
divisors fall through to the existing _floordiv/_mod/_ifloordiv/_imod
slow path.

Assisted-by: Claude

* Skip trashcan and untrack for non-GC-tracked objects in dealloc

default_dealloc read is_gc_tracked() only to decide untracking, and
entered the trashcan recursion guard unconditionally. Non-GC objects
(int, float, str, ...) own no child references that recurse during
deallocation, so they need neither the trashcan nor untracking. Read
is_gc_tracked() once and gate both trashcan begin/end and untrack on it,
removing three thread-local accesses per non-GC object deallocation.

Assisted-by: Claude

* Merge trashcan depth and defer queue into one thread-local struct

trashcan::end accessed two separate thread-locals (DEALLOC_DEPTH and
DEALLOC_QUEUE) at the outermost deallocation. Combine both into a single
`Trashcan` thread-local holding Cell-based depth and queue fields, so
begin and end each reach their state through one thread-local access.
The queue is set back before each deferred dealloc call so reentrant
begin/end during draining never holds an outstanding borrow.

Assisted-by: Claude

* Check object layout compatibility on __bases__ and __class__ assignment

Add a shared compatible_for_assignment helper that walks each type to the
base that fixes its instance layout and rejects the assignment when the old
and new layouts differ (basicsize, itemsize, member count, __dict__,
__weakref__, and __slots__ names). Wire it into set_bases, which previously
performed no layout check, and replace the inline check in __class__
assignment, which compared the two types directly and over-rejected a
subclass that adds no layout.

Enable test_descr.test_builtin_bases, which the new set_bases check passes.

Assisted-by: Claude

* Stop the world around GC pointer-reading phases

The cycle collector reads each tracked object's interpreter state during
reference subtraction, the reachability walk and the strong-reference
snapshot, including the localsplus of frames other threads are executing.
Those slots are written without synchronization, so the reads are a data
race under threading.

collect_inner now stops the world before taking the generation read locks
and restarts it after the strong-reference snapshot, before the
finalizer/weakref/tp_clear phases. A debug assertion checks that no frame
on any thread's call stack was classified unreachable.

Automatic collections from maybe_collect are deferred to the next bytecode
safepoint via a new eval-breaker GC bit instead of running synchronously:
a synchronous collection can hold an internal lock (e.g. the lazy frame
locals cell) that another thread is blocked on with no way to reach a
safepoint, deadlocking the stop.

Hardens the stop-the-world machinery for these frequent, concurrent GC
stops: attach_thread now honors a pending stop after re-attaching so a
thread doing rapid allow_threads calls cannot run past the requester;
stop_the_world completion is level-triggered on all-threads-suspended
rather than an edge-triggered countdown; and the thread-start started/ready
handshakes detach while waiting so the waiter is parkable.

Updates the Frame and PyRwLock/PyMutex traversal SAFETY comments to state
the actual invariant.

Assisted-by: Claude

* Add threaded GC vs executing-frame stress snippet

Workers churn frame state (recursion, generators, frame cycles) while a
collector loops gc.collect() and an introspector walks live frame objects.
Exercises the stop-the-world barrier around GC traversal.

Assisted-by: Claude

* Serialize fork and GC stop-the-world requesters

fork() (posix before/after-fork) and the cycle collector both drive the
single StopTheWorldState. With no mutual exclusion their requester word and
suspension countdown could interleave and be clobbered, so the completion
check never converged and a requester waited on itself forever (reproducible
parent-side hang when forking with GC enabled).

Add one exclusion held for the whole stop->start span of either requester:
stop_the_world acquires it before any stop bookkeeping and
start_the_world/reset_after_fork release it. The acquire is park-friendly
(poll try-lock and honor a pending suspend between tries) so a requester
blocked behind an active stop can still be force-parked instead of deadlocking
the active requester. The acquirer holds no other lock while spinning.

Also correct the PyRwLock traverse SAFETY note: a failed try_read may mean a
force-parked thread holds the write lock; skipping is safe because
under-traversal only over-approximates liveness. Document the residual
gc.collect()-under-a-non-generation-lock exposure at the collect_inner barrier.

Assisted-by: Claude

* Add fork under concurrent GC stop-the-world snippet

Worker threads allocate cyclic garbage with GC enabled while the main thread
forks repeatedly and each child collects. Exercises the fork/GC
stop-the-world exclusion; the allocation rate is throttled so a collection
stays cheap in unoptimized builds.

Assisted-by: Claude

* Detach while acquiring the import lock

The global import lock is held across bytecode by the importlib bootstrap,
so its holder can be parked at a safepoint mid-hold. Acquiring it while
attached let another thread block attached on the lock, so a stop-the-world
requester could wait forever for that attached thread to suspend while the
holder stayed parked.

Wrap IMP_LOCK acquisition in allow_threads in both _imp.acquire_lock and the
pre-fork acquire_imp_lock_for_fork so the wait honors stop-the-world requests.
Correct the acquire_exclusion comment: a spinning requester may hold IMP_LOCK
(fork) or the collecting mutex (GC); safety relies on those never being
acquired attached-blocking by another thread.

Assisted-by: Claude

* Add concurrent-import vs GC deadlock snippet

Two threads re-import modules (contending the import lock) while a third
storms the cycle collector and a fourth allocates cyclic garbage. Regressed
as a hang before the import lock acquisition was made park-friendly.

Assisted-by: Claude

* Create call frames untracked and track generators explicitly

Add PyPayload::NEW_REF_UNTRACKED (default false, true for Frame) so
PyRef::new_ref skips auto-tracking ordinary call frames in the GC.
Generator/coroutine/async-generator frames are tracked explicitly in
invoke_with_locals before their generator back-reference is installed.
run_frame debug-asserts that a datastack frame is untracked on entry.

Assisted-by: Claude

* Track escaped call frames lazily at datastack release

Rewrite release_datastack_frame around the invariant that a datastack
frame is never GC-tracked while it runs: strong_count() == 1 means the
frame never escaped, so drop localsplus in place without touching the
GC; strong_count() > 1 means it escaped, so materialize localsplus onto
the heap and then track the frame. This removes the untrack and the
untrack-recheck dance from the common non-escaping path.

Assisted-by: Claude

* Guard the tracked-frame localsplus invariant

Document at Frame::traverse that references to a frame are always
recorded as graph edges, so the collector reads a frame's localsplus
only when the frame is itself a tracked candidate. Add debug assertions
at both frame track sites (escaped datastack frames and generator
frames) that a frame is heap-backed before it is tracked, so a collector
never reads data-stack-resident, still-mutating storage.

Assisted-by: Claude

* Reword frame/dealloc invariant comments and drop needless borrow

- frame.rs: replace the task codename in the tracked-frame localsplus
  invariant comment with a description of the collector-vs-executing-frame
  behavior.
- object.rs: remove needless borrow on current_cls in the __class__
  assignment compatibility check.
- core.rs: rewrite the default_dealloc trashcan/untrack-skip comment to
  state the actual invariant, which now covers untracked non-escaped
  frames releasing at interpreter depth with bounded recursion.

Assisted-by: Claude

* Move type SetAttr slot rewrite inside the type lock and tighten cache reads

Run update_slot inside the same with_type_lock transaction as
modified_inner and the attributes dict mutation, so the version
invalidation, dict change, and slot-table rewrite are published together.

Load init_version and getitem_version with Acquire in the specialization
cache readers to pair with the Release stores in the writers.

Assisted-by: Claude

* Capture the type version before reading mutable slots in specializers

specialize_load_attr, specialize_store_attr, specialize_to_bool, and the
CallAllocAndEnterInit path of specialize_call read the version tag with
version_for_specialization before inspecting getattro, setattro, the
bool/len slots, and tp_new/tp_alloc, so a concurrent install of the
corresponding dunder invalidates the version the specialization is cached
against.

In the BinaryOpSubscr __getitem__ path, check the HEAPTYPE and
eval-frame gates before lookup_ref_and_version_interned, which takes the
global type lock and may allocate a version tag.

Assisted-by: Claude

* Use _get_method_dict for the test_type check in the test runner

Replace the direct __func__.__dict__ access with the _get_method_dict
helper so plain functions without __func__ do not raise AttributeError.

Assisted-by: Claude

* Fix lint hooks: cspell dictionary entries, spelling fix, formatting

Add qsbr to the rustpython dictionary and reborrows/reparenting to
the top-level word list. Rename oldto/newto locals to old_to/new_to.
Fix Stabilise -> Stabilize typo in a frame.rs comment.
Apply cargo fmt to object.rs, type.rs, and frame.rs, and ruff
format/check fixes to two extra_tests snippet files.

Assisted-by: Claude

* Rebuild all slots for type and descendants on __bases__ reassignment

Add PyType::update_all_slots, which invalidates version tags and iterates
the full SLOT_DEFS name table calling update_slot::<true> for each distinct
name. Unlike init_slots, which is additive and driven only by dunder names
present in the current MRO, this resets a slot whose method left the MRO
instead of leaving a stale dispatcher pointer.

Call it from set_bases in place of the previous modified_inner + init_slots
pair, so reassigning __bases__ rebuilds slots for the type and every
descendant.

Add extra_tests/snippets/type_bases_slot_rebuild.py covering removed-method
resets on zelf and deep descendants, the wrong-target switch, __getattr__,
the added-method mirror, and a swap-away-and-back round trip.

Assisted-by: Claude

* Derive the thread-local frame stack from the frame chain

Remove the per-VM `frames` Vec. current_frame, sys._getframe,
sys._getframemodulename, frame.f_back, sys.monitoring re-instrumentation,
gc.get_referrers, faulthandler stack dumps and the post-fork slot rebuild
now walk the signal-safe CURRENT_FRAME/`previous` chain instead. Add
`Py::from_payload_ptr` to recover a frame object from a chain pointer.

The cross-thread `ThreadSlot::frames` registry (sys._current_frames,
cross-thread f_back, GC stop-the-world assertion) is unchanged.

Assisted-by: Claude

* Inherit sub-slot fallback into the field being resolved

update_one_slot's number/sequence/mapping fallback inherited via the
accessor's default field. Left and right binary ops (add/right_add)
share one accessor but occupy distinct fields, so resolving an absent
right op or deleting it reset the left op's field, dropping a
still-defined __add__ dispatcher. Inherit the exact field under
resolution instead.

Assisted-by: Claude

* Gate type_cache_after_fork to its fork caller and use Self in downcast

type_cache_after_fork is only called from the unix fork path, so gate it
with all(feature = "host_env", unix) to match the caller and avoid a
dead-code error on non-unix targets. Replace the explicit PyType with Self
in the modified_inner downcast.

Assisted-by: Claude

* Unmark test_attr and test_method_call_error in test_monitoring

Both TestLoadSuperAttr tests now pass; remove their expectedFailure markers.

Assisted-by: Claude

* Run tp_new specialization __init__ without a trampoline frame

CallAllocAndEnterInit ran __init__ inside a synthetic init-cleanup shim
frame whose code carried the __init__ name. Since the thread frame stack
is derived from the frame chain, that shim frame was visible to
sys._getframe, f_back walks, traceback construction and inspect.stack /
inspect.trace. Its code object has empty co_positions, so a stack walk
that reached it raised StopIteration inside inspect._get_code_position,
cascading into unrelated failures (test_inspect trace/stack/frame,
asyncio source traceback).

Call __init__ directly via run_frame, enforce the __init__() should
return None contract inline, and drop the shim: the init-cleanup code
object, its builder, with_frame_untraced, monitoring_disabled_for_code,
and the extra-frame datastack/recursion budget. Removing the second
frame per construction also cuts the specialization's per-call cost.

Assisted-by: Claude

* Replace per-call thread-frame mutex with an atomic top-of-stack (unix)

On unix threading builds, publish each thread's top Python frame in a
single relaxed AtomicPtr store from set_current_frame instead of pushing
onto a parking_lot::Mutex<Vec<FramePtr>> per call. Cross-thread readers
(sys._current_frames, cross-thread f_back, faulthandler.dump_traceback,
the GC unreachable debug-assert) run under stop-the-world and walk the
published top frame down the Frame::previous chain; the owning thread is
then parked at a safepoint, so the pointer and the frames it reaches are
quiescent and alive. The faulthandler watchdog is a plain OS thread that
cannot stop-the-world, so it walks the chain lock-free and best-effort.

Non-unix threading builds have no stop-the-world and keep the existing
mutex-guarded frame stack unchanged.

Assisted-by: Claude

* Skip exc_info save/restore for callees that never touch the slot

with_frame saves and restores the shared exc_info slot around every
Python call to contain frames that leave it unbalanced. Cache a
has_exc_handling bit on PyCode at creation, set when the bytecode
contains any opcode that calls vm.set_exception (PushExcInfo, PopExcept,
CheckEgMatch, EndAsyncFor, InstrumentedEndAsyncFor). A callee whose code
has none of these cannot mutate the slot, so the save and restore are
skipped for it. Generators go through resume_gen_frame and are
unaffected.

Assisted-by: Claude

* Return a write-through FrameLocalsProxy from frame.f_locals

Optimized (function) frames now expose `f_locals` as a `FrameLocalsProxy`
implementing PEP 667 semantics instead of a cached snapshot dict:

- reads go live through the fast-local slots; each access mints a fresh
  proxy; keys that do not name a fast local are stored in a per-frame
  `f_extra_locals` side dict and folded into `locals()`.
- writes to a fast-local key store into the slot (or its cell) in place;
  deleting a fast local raises ValueError; extra keys delete normally.
- full mapping protocol: keys/values/items (lists), get/pop/setdefault,
  update (dict or FrameLocalsProxy only), __or__/__ior__/__ror__ (dict
  result), copy (plain dict), __reduce__ blocks pickling/copy, repr with
  recursion guard, mapping-pattern and Mapping ABC support.

Class/module/exec frames keep returning their namespace mapping directly.
Cross-thread access to a frame running on another thread still raises
RuntimeError.

A closed generator now keeps its frame locals when a durable frame
reference escaped (f_locals proxy, sys._getframe, f_back), matching
take_ownership; the escape is tracked with a per-frame flag. The
snapshot-then-fold locals_to_fast/locals_dirty write-back is retired
since proxy writes reach the slots directly.

Assisted-by: Claude

* Retain the caller frame so f_back resolves after it returns

When a frame escapes its execution (referenced through a traceback,
`sys._getframe`, `f_locals`, ...), capture a strong reference to its
caller at release time. `f_back` consults it once the caller has left
the live frame chain, so the Python-visible frame chain survives return.
The retained reference is a GC-traversed edge and is cleared by
`frame.clear()`, so ancestor chains stay collectable.

Assisted-by: Claude

* Fix debug-build native stack overflow on deep recursion

Make check_c_stack_overflow one-sided (trip whenever the stack pointer
is below the soft limit) so a single native frame larger than the margin
cannot step past the danger band undetected.

Raise the debug STACK_MARGIN_BYTES from 4096 to 16384 words so the margin
exceeds a single debug interpreter frame, leaving headroom to raise
RecursionError. Release margin unchanged.

Clamp the soft-limit margin to half the stack so small explicit thread
stacks do not get a soft limit above their stack top.

Assisted-by: Claude

* Allocate exception instance __dict__ lazily

Exception construction went through into_ref_with_type, which eagerly
allocated an empty instance dict for every HAS_DICT type. Add
into_ref_with_type_lazy_dict, which builds the instance with an
unallocated dict slot, and route the four exception construction sites
(PyBaseException, PyOSError, OSErrorBuilder, PyBaseExceptionGroup)
through it. The dict now materializes on first attribute write or
__dict__ access via the existing get_or_insert path.

add_note and PyImportError::slot_init now obtain the dict through
object_get_dict so they materialize it instead of assuming it exists.

A freshly constructed exception no longer reports an empty dict in
gc.get_referents, matching the reference interpreter.

Assisted-by: Claude

* Allocate exception __dict__ lazily in vm.new_exception

Route vm.new_exception() through into_ref_with_type_lazy_dict so
internally raised exceptions (new_type_error, new_value_error, etc.)
start without an instance dict, matching the slot_new path. The dict
is materialized on the first attribute write or __dict__ access.

Assisted-by: Claude

* Validate FrameLocalsProxy.update() arguments

Reject keyword arguments and require exactly one positional argument,
raising TypeError with the "takes no keyword arguments" and "takes
exactly one argument (N given)" messages.

Assisted-by: Claude

* Address review nits in frame and faulthandler

- Drop stale vm.frames reference from the release_datastack_frame
  uniqueness argument.
- Assert has_exc_handling when unwinding an Except-typed stack slot,
  documenting the invariant that guards the shared exc_info write.
- Truncate the specialized __init__ return-type name to 200 chars,
  matching the unspecialized wrapper.
- Reword two comments to describe behavior without prose references
  to CPython.

Assisted-by: Claude

* Use scopeguard for start_the_world in faulthandler dump_all_threads

Wrap the unix stop-the-world registry walk in a scope with
scopeguard::defer! so start_the_world runs on panic, matching the
f_back and get_all_current_frames sites. Add scopeguard to the stdlib
dependencies. Also correct the restore_exception doc comment to name
with_frame after the rename.

Assisted-by: Claude

* Gitignore docs/superpowers

Assisted-by: Claude

* Rename type_bases_slot_rebuild.py to builtin_type_bases.py

Match the builtin_* naming convention of extra_tests/snippets.

Assisted-by: Claude

* Apply rustfmt, ruff, and cspell lint fixes

Reformat with rustfmt, fix import spacing in builtin_type_bases.py with
ruff, and add "pointee" to the cspell word list.

Assisted-by: Claude

* Gate unix-only QSBR methods to their call sites

`online`, `drain_all`, and `reset_after_fork` are called only from unix
code (thread attach/detach, post-fork reset), and `offline` from unix
code plus a unit test. Gate them with matching cfg so `-D dead_code`
does not fire on non-unix targets.

Assisted-by: Claude

* Visit the function closure tuple as a GC edge

PyFunction::traverse visited the cells inside the closure tuple instead
of the tuple object itself, so the tuple's reference from the function
was never subtracted during cycle collection. A closure tuple that
reached back to its function (or, through a frame retained by f_back,
to a Thread) was stranded as a false GC root and never collected,
leaking the whole cycle. Visit the tuple itself, matching clear().

Assisted-by: Claude

* Apply formatting hook fix to builtin_type_bases.py

Assisted-by: Claude

* Unmark asyncgen finalization-by-gc tests in test_base_events

test_asyncgen_finalization_by_gc and
test_asyncgen_finalization_by_gc_in_other_thread now pass; GC finalizes
the async generators.

Assisted-by: Claude

* Unmark test_sni_callback_refcycle in test_ssl

The servername-callback reference cycle is now collected by GC.

Assisted-by: Claude

* Widen GC stop-the-world gates from unix-only to all threading builds

Change `cfg(all(unix, feature = "threading"))` to `cfg(feature = "threading")`
on the stop-the-world machinery so it also compiles and runs on non-unix
threading builds:

- StopTheWorldState, its stats, stw_trace, and the stop_the_world field
- ThreadSlot state/stop_requested/thread fields and their initializers
- wait_while_suspended/attach_thread/detach_thread/suspend_if_needed/do_suspend,
  allow_threads, stop_requested_for_current_thread, and the enter_vm /
  VmBootstrapGuard / attach_current_thread / release_current_thread / cleanup
  attach-state wiring
- eval_breaker_tripped, check_signals, run_scheduled_gc, signal GC_BIT /
  schedule_gc / take_gc_scheduled, and the frame.rs safepoint call
- CollectStopTheWorld and its use in collect_inner
- QSBR::online/offline, now called from attach/detach on all threading builds
- debug_assert_current_thread_attached and its type-cache call sites

maybe_collect defers auto-collection to the bytecode safepoint on every
threading build instead of only unix; non-threading builds keep the inline
collect. stw_trace writes to std stderr on non-unix.

top_frame publishing (CURRENT_TOP_FRAME_SLOT, set_current_frame), the
frame-walk debug assert in collect_inner, and the fork reinit helpers remain
unix-only; non-unix keeps ThreadSlot::frames for introspection.

Assisted-by: Claude

* Detach current thread around blocking _winapi/_overlapped waits

Wrap the blocking Windows wait calls in `vm.allow_threads` so the calling
thread transitions ATTACHED -> DETACHED for the duration of the wait:

- _winapi: WaitForSingleObject, WaitForMultipleObjects,
  BatchedWaitForMultipleObjects, ConnectNamedPipe, ReadFile,
  Overlapped.GetOverlappedResult
- _overlapped: Overlapped.getresult

These previously blocked while ATTACHED, so a stop-the-world requester
could never suspend the thread and spun in its wait loop indefinitely.

* Format WaitForMultipleObjects allow_threads closure

* Treat concurrent sni_callback removal as no-op in invoke_sni_callback

* Assert capi refcount on a fresh mortal list instead of the int type object

The refcount test asserted exact incref/decref deltas on PyInt's shared
type object. That object's reference count is perturbed by the other capi
tests running in parallel, and is immortal under some interpreter
configurations, so the deltas were not reliably +1/-1. Assert them on a
freshly created, uniquely owned list whose reference count is private to
the test and mortal.

Assisted-by: Claude

* Traverse and GC-track PyOSError instances

The `#[pyexception]` struct macro now forwards a `traverse` option to the
generated `#[pyclass]`, and `ExceptionItemMeta` accepts the `traverse`
key. `PyOSError` is marked `traverse = "manual"`, so `HAS_TRAVERSE` is
true and OSError-family instances are tracked at creation and traversed
by the collector.

`PyOSError::traverse` now visits the underlying `PyBaseException`
(traceback, cause, context, args) instead of `PyException::try_traverse`,
which was a no-op because `PyException` has `HAS_TRAVERSE = false`.

* Unmark test_blockingioerror in test_io

The BlockingIOError reference cycle is now collected by GC.

Assisted-by: Claude
2026-07-08 15:21:41 +09:00
Jeong, YunWon d77b80daed Implement round-half-even float.fromhex in common float_ops (#8234)
* Add round-half-even hex float parser to common float_ops

Add float_ops::from_hex returning Result<f64, HexFloatError>, which parses
the coefficient and exponent, rounds round-half-even over the full exponent
range, and detects overflow. Route float.fromhex through it: raise
OverflowError for values too large to represent and ValueError for invalid
input. Remove the expectedFailure on test_from_hex.

Assisted-by: Claude

* Address review: Option-returning byte helpers, const fns, drop test_ prefix

Assisted-by: Claude

* Whitelist fdigits and inity in cspell

Assisted-by: Claude

* Home is_py_ascii_whitespace in rustpython-wtf8; share with common and sre_engine

Assisted-by: Claude

* Use shared wtf8 is_py_ascii_whitespace in bytes_inner

Remove the private copy of is_py_ascii_whitespace in bytes_inner.rs and
import the shared rustpython_common::wtf8::is_py_ascii_whitespace.

Assisted-by: Claude
2026-07-08 10:03:29 +09:00
Jeong, YunWon 58ae87c00a Fix decompose_float subnormals, float format grouping/empty type; add HashSecret::from_keys (#8232)
* common: fix decompose_float for subnormal inputs

Subnormals carry a biased exponent of 0 and no implicit leading mantissa
bit, so the bit-twiddling frexp misread them: hash(5e-324) returned
8404992 instead of CPython's 16777216. Scale subnormals into the normal
range by 2**54 (exact) before decomposing and fold the shift back into
the returned exponent. Adds a frexp-contract unit test over normals,
subnormals, and boundary values.

Assisted-by: Claude

* common: add HashSecret::from_keys

HashSecret's fields are private and the only constructor derives k0/k1
from a u32 seed, so an embedder cannot reproduce a fixed keying (e.g. a
deterministic PYTHONHASHSEED=0-style run). Add a const constructor
taking explicit SipHash keys; the seeded path is unchanged.

Assisted-by: Claude

* common: fix float format grouping and empty presentation type

Thousands grouping split the magnitude only on '.', so exponent and
percent tails received separators (format(1e20, ',e') gave
'1e+,20'-class corruption). Group only the leading integer digits for
interval-3 output; hex/octal/binary keep whole-magnitude grouping.

Empty presentation type: with a precision, clamp it to at least 1 and
restore a trailing '.0' on integer-looking results (Py_DTSF_ADD_DOT_0);
without one, alternate form now inserts the forced decimal point before
an exponent instead of appending it.

Verified byte-identical to CPython 3.14 over a hash/format differential
battery; test_format, test_float, test_fstring, test_hash pass.

Assisted-by: Claude

* common: satisfy rustfmt and clippy in new hash/float tests

- float_ops: use core::f64::consts::PI in the frexp-contract battery
  (clippy::approx_constant)
- hash: rewrite the keyed_hash test via BuildHasher::hash_one
  (clippy::manual_hash_one)
- rustfmt the new float_ops/hash/format test modules

Assisted-by: Claude

* common: add DTSF to format.rs spell-checker ignores

Assisted-by: Claude
2026-07-07 15:29:52 +09:00
Jeong, YunWon 55c012cffd unicode crate (#8211)
* Extract unicodedata core into rustpython-unicode crate

Move the vm-free Unicode character database access — the generated UCD 3.2.0 /
latest tables, their build-time generation, and the icu4x/unicode_names2 lookups
for category/bidirectional/combining/east_asian_width/mirrored/decomposition/
normalize/is_normalized/digit/decimal/numeric/name/lookup — into a new leaf crate
over char/CodePoint/&Wtf8. stdlib/unicodedata.rs keeps the UCD pyclass binding: it
extracts the code point, boxes results, and maps errors. The unicode data files,
build.rs table generation, and the icu_properties/icu_normalizer/unicode_names2
dependencies move out of stdlib.

Assisted-by: Claude

* Route str predicates, casefold, and printable through rustpython-unicode

Add classify/case/identifier modules to the shared crate over char/&str/&Wtf8:
isalpha/isalnum/isdecimal/isdigit/isnumeric/isspace/isprintable classification,
XID identifier predicates, and full-mapping casefold. vm/builtins/str.rs and
literal/char.rs now call these instead of icu_properties/icu_casemap directly.
String-level iteration with final-sigma handling (lower/upper/title/capitalize,
islower/isupper) stays in the runtime.

Assisted-by: Claude

* Route sre_engine char classes through rustpython-unicode

Add the regex module with the SRE character-class and case predicates
(is_word/is_space/is_digit, is_uni_* Unicode variants, ascii/locale/unicode case
folding). sre_engine/string.rs now forwards to it, keeping its public API and
behavior identical — including the ASCII-only is_uni_digit and the hardcoded
is_uni_space table.

Assisted-by: Claude

* Route \N{} name lookups through rustpython-unicode

codegen/string_parser.rs (\N{...} escapes) and common/encodings.rs (the
namereplace error handler) now resolve character names via rustpython-unicode
instead of depending on unicode_names2 directly, leaving the crate as the sole
owner of the name database.

Assisted-by: Claude

* Add differential Unicode sweep and shared-crate snippet test

tests/differential.rs sweeps the full 0..0x110000 range and compares each str
classification predicate against a committed CPython 3.14 reference dataset
(tests/data/cpython3.14_predicates.txt, produced by generate_reference.py). Code
points that differ only because the Rust std / icu4x build ships a later Unicode
release than CPython 3.14's 16.0.0 are recorded in
tests/data/version_skew_cpython3.14.txt, regenerable via
RUSTPYTHON_UNICODE_REGEN_SKEW=1; the regen refuses to record any
cpython=true/crate=false divergence, so only newly-assigned code points are
allowed. Any other divergence fails. Both data files use a run-length
`predicate start:end,...` encoding.

extra_tests/snippets/stdlib_unicode_shared.py exercises the routed surface end to
end (str predicates, casefold, identifiers, unicodedata, normalize, \N{}, and re
character classes) and passes identically on CPython 3.14 and RustPython.

Assisted-by: Claude

* Match regex \d to Unicode decimal digits

is_uni_digit previously matched only ASCII 0-9, so re's \d in Unicode mode
missed decimal digits like ٥ and ५. SRE_UNI_IS_DIGIT matches Py_UNICODE_ISDECIMAL
(category Nd), so route it through classify::is_decimal. Unmasks test_bug_6561 in
test_re and extends the shared-crate snippet with the Nd/Nl/No cases.

Assisted-by: Claude

* Replace shallow Unicode wrappers with re-exports

Address review feedback on the extraction.

Functions that only forwarded to the shared crate become `use ... as`
re-exports rather than hand-written wrappers:

- literal: is_printable is dropped; escape.rs calls
  rustpython_unicode::classify::is_repr_printable directly.
- unicode::identifier::is_continue re-exports is_xid_continue.
- unicode::data::lookup_character re-exports unicode_names2::character.
- Drop the unused repr(u8) on DecompositionType.

The SRE character-class and case predicates move back into
sre_engine::string (their pre-extraction home) instead of living in a
unicode::regex module that only sre_engine and the vm _sre binding used;
is_uni_digit/is_uni_alnum still delegate to rustpython_unicode::classify.
engine.rs and _sre consume them from sre_engine::string again.

The unicode crate's tests move from a single root tests module in lib.rs
into per-module test submodules (case, classify, data, identifier,
normalize).

Assisted-by: Claude

* no-std

* Address review feedback: test module, dead variant, WTF-8 normalization

- differential.rs: move the sweep tests into a `mod tests` block and drop
  the file-level allow of clippy::tests_outside_test_module and
  std_instead_of_alloc; the test uses alloc collections instead.
- data.rs: remove the never-constructed DecompositionType::Canonical variant
  and its allow(unused); compatibility decomposition never produces it and
  canonical decomposition is handled through icu4x.
- normalize.rs: is_normalized now takes &Wtf8 and checks each UTF-8 run,
  skipping lone surrogates, matching normalize's run-wise behavior.
- unicodedata.rs: pass as_wtf8() to is_normalized.

Assisted-by: Claude
2026-07-07 09:19:25 +09:00
Jeong, YunWon c6907f3228 Move tuple/frozenset hash algorithms into common::hash (#8213)
* Move tuple/frozenset hash algorithms into common::hash

Move the pure tuplehash fold (xxHash-based) into `hash::hash_tuple`, taking
a fallible iterator of element hashes, and the frozenset XOR-fold into a
`hash::FrozenSetHash` streaming accumulator. `builtins::tuple` and
`builtins::set` keep only the element-hash loop and delegate the arithmetic.

Assisted-by: Claude

* common/hash: rename acc_pyhash to acc_py_hash

Drop the now-unused `// cspell:ignore pyhash` from tuple.rs left behind
by the tuple hash move; the only remaining occurrence was the
acc_pyhash local. Renaming it lets cspell pass without an ignore.

Assisted-by: Claude
2026-07-06 23:05:56 +09:00
Shahar Naveh 85ba1df3b1 Add more clippy rules (#8183)
* clippy `assigning_clones`

* string_lit_as_bytes

* tuple_array_conversions

* while_float

* manual_assert

* Revert "string_lit_as_bytes"

This reverts commit f40f756440.
2026-06-30 23:40:29 +09:00
Shahar Naveh 9f2c4e14a9 More clippy rules (#8127)
* clippy `elidable_lifetime_names`

* large_types_passed_by_value

* trivially_copy_pass_by_ref

* type_repetition_in_bounds

* copy_iterator

* collection_is_never_read

* same_functions_in_if_condition

* unnecessary_struct_initialization

* clippy on windows

* ssl windows
2026-06-22 16:30:51 +09:00
Shahar Naveh 11da0b42c3 clippy enum_glob_use (#8121) 2026-06-17 13:24:36 +09:00
Shahar Naveh 72052484ca clippy significant_drop_in_scrutinee & explicit_deref_methods (#8104) 2026-06-15 11:21:13 +09:00
Shahar Naveh dc81e050c6 more clippy rules (#8050)
* `checked_conversions`

* duration_suboptimal_units

* inefficient_to_string

* iter_on_single_items

* needless_collect

* needless_for_each

* ptr_offset_by_literal

* return_self_not_must_use
2026-06-10 11:13:42 +09:00
Shahar Naveh 9a0291188c Clippy rules (test related) (#7968) 2026-05-25 22:03:18 +09:00
Shahar Naveh acf12468c4 Clippy nursery lints (#7875) 2026-05-15 10:38:36 +00:00