[pull] main from python:main

.github/workflows/build.yml

@@ -706,6 +706,7 @@ jobs:
       uses: re-actors/alls-green@05ac9388f0aebcb5727afa17fcccfecd6f8ec5fe
       with:
         allowed-failures: >-
+          build-ios,
           build-windows-msi,
           build-ubuntu-ssltests-awslc,
           build-ubuntu-ssltests-openssl,

Doc/c-api/gcsupport.rst

@@ -232,6 +232,10 @@ The :c:member:`~PyTypeObject.tp_traverse` handler must have the following type:
    object argument.  If *visit* returns a non-zero value that value should be
    returned immediately.
 
+   The traversal function must not have any side effects.  Implementations
+   may not modify the reference counts of any Python objects nor create or
+   destroy any Python objects.
+
 To simplify writing :c:member:`~PyTypeObject.tp_traverse` handlers, a :c:func:`Py_VISIT` macro is
 provided.  In order to use this macro, the :c:member:`~PyTypeObject.tp_traverse` implementation
 must name its arguments exactly *visit* and *arg*:

Doc/c-api/typeobj.rst

@@ -1569,6 +1569,11 @@ and :c:data:`PyType_Type` effectively act as defaults.)
        but the instance has no strong reference to the elements inside it, as they
        are allowed to be removed even if the instance is still alive).
 
+   .. warning::
+      The traversal function must not have any side effects.  It must not
+      modify the reference counts of any Python objects nor create or destroy
+      any Python objects.
+
    Note that :c:func:`Py_VISIT` requires the *visit* and *arg* parameters to
    :c:func:`!local_traverse` to have these specific names; don't name them just
    anything.

Doc/whatsnew/3.15.rst

@@ -1236,6 +1236,12 @@ Build changes
   modules that are missing or packaged separately.
   (Contributed by Stan Ulbrych and Petr Viktorin in :gh:`139707`.)
 
+* Annotating anonymous mmap usage is now supported if Linux kernel supports
+  :manpage:`PR_SET_VMA_ANON_NAME <PR_SET_VMA(2const)>` (Linux 5.17 or newer).
+  Annotations are visible in ``/proc/<pid>/maps`` if the kernel supports the feature
+  and :option:`-X dev <-X>` is passed to the Python or Python is built in :ref:`debug mode <debug-build>`.
+  (Contributed by Donghee Na in :gh:`141770`)
+
 
 Porting to Python 3.15
 ======================

Include/internal/pycore_mmap.h

@@ -0,0 +1,45 @@
+#ifndef Py_INTERNAL_MMAP_H
+#define Py_INTERNAL_MMAP_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifndef Py_BUILD_CORE
+#  error "this header requires Py_BUILD_CORE define"
+#endif
+
+#include "pycore_pystate.h"
+
+#if defined(HAVE_PR_SET_VMA_ANON_NAME) && defined(__linux__)
+#  include <linux/prctl.h>
+#  include <sys/prctl.h>
+#endif
+
+#if defined(HAVE_PR_SET_VMA_ANON_NAME) && defined(__linux__)
+static inline void
+_PyAnnotateMemoryMap(void *addr, size_t size, const char *name)
+{
+#ifndef Py_DEBUG
+    if (!_Py_GetConfig()->dev_mode) {
+        return;
+    }
+#endif
+    assert(strlen(name) < 80);
+    int old_errno = errno;
+    prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, (unsigned long)addr, size, name);
+    /* Ignore errno from prctl */
+    /* See: https://bugzilla.redhat.com/show_bug.cgi?id=2302746 */
+    errno = old_errno;
+}
+#else
+static inline void
+_PyAnnotateMemoryMap(void *Py_UNUSED(addr), size_t Py_UNUSED(size), const char *Py_UNUSED(name))
+{
+}
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+#endif  // !Py_INTERNAL_MMAP_H

Include/internal/pycore_stackref.h

@@ -479,13 +479,6 @@ PyStackRef_AsPyObjectBorrow(_PyStackRef stackref)
 
 #define PyStackRef_IsDeferred(ref) (((ref).bits & Py_TAG_BITS) == Py_TAG_DEFERRED)
 
-static inline PyObject *
-PyStackRef_NotDeferred_AsPyObject(_PyStackRef stackref)
-{
-    assert(!PyStackRef_IsDeferred(stackref));
-    return (PyObject *)stackref.bits;
-}
-
 static inline PyObject *
 PyStackRef_AsPyObjectSteal(_PyStackRef stackref)
 {

InternalDocs/README.md

@@ -36,6 +36,8 @@ Program Execution
 
 - [The Bytecode Interpreter](interpreter.md)
 
+- [Stack references (_PyStackRef)](stackrefs.md)
+
 - [The JIT](jit.md)
 
 - [Garbage Collector Design](garbage_collector.md)

InternalDocs/stackrefs.md

@@ -0,0 +1,80 @@
+# Stack references (`_PyStackRef`)
+
+Stack references are the interpreter's tagged representation of values on the evaluation stack.
+They carry metadata to track ownership and support optimizations such as tagged small ints.
+
+## Shape and tagging
+
+- A `_PyStackRef` is a tagged pointer-sized value (see `Include/internal/pycore_stackref.h`).
+- Tag bits distinguish three cases:
+  - `Py_TAG_REFCNT` unset - reference count lives on the pointed-to object.
+  - `Py_TAG_REFCNT` set - ownership is "borrowed" (no refcount to drop on close) or the object is immortal.
+  - `Py_INT_TAG` set - tagged small integer stored directly in the stackref (no heap allocation).
+- Special constants: `PyStackRef_NULL`, `PyStackRef_ERROR`, and embedded `None`/`True`/`False`.
+
+In GIL builds, most objects carry their refcount; tagged borrowed refs skip decref on close. In free
+threading builds, the tag is also used to mark deferred refcounted objects so the GC can see them and
+to avoid refcount contention on commonly shared objects.
+
+## Converting to and from PyObject*
+
+Three conversions control ownership:
+
+- `PyStackRef_FromPyObjectNew(obj)` - create a new reference (INCREF if mortal).
+- `PyStackRef_FromPyObjectSteal(obj)` - take over ownership without changing the count unless the
+  object is immortal.
+- `PyStackRef_FromPyObjectBorrow(obj)` - create a borrowed stackref (never decref on close).
+
+The `obj` argument must not be `NULL`.
+
+Going back to `PyObject*` mirrors this:
+
+- `PyStackRef_AsPyObjectBorrow(ref)` - borrow the underlying pointer
+- `PyStackRef_AsPyObjectSteal(ref)` - transfer ownership from the stackref; if ref is borrowed or
+   deferred, this creates a new owning `PyObject*` reference.
+- `PyStackRef_AsPyObjectNew(ref)` - create a new owning reference
+
+Only `PyStackRef_AsPyObjectBorrow` allows ref to be `PyStackRef_NULL`.
+
+## Operations on stackrefs
+
+The interpreter treats `_PyStackRef` as the unit of stack storage. Ownership must be managed with
+the stackref primitives:
+
+- `PyStackRef_DUP` - like `Py_NewRef` for stackrefs; preserves the original.
+- `PyStackRef_Borrow` - create a borrowed stackref from another stackref.
+- `PyStackRef_CLOSE` / `PyStackRef_XCLOSE` - like `Py_DECREF`; invalidates the stackref.
+- `PyStackRef_CLEAR` - like `Py_CLEAR`; closes and sets the stackref to `PyStackRef_NULL`
+- `PyStackRef_MakeHeapSafe` - converts borrowed reference to owning reference
+
+Borrow tracking (for debug builds with `Py_STACKREF_DEBUG`) records who you borrowed from and reports
+double-close, leaked borrows, or use-after-close via fatal errors.
+
+## Borrow-friendly opcodes
+
+The interpreter can push borrowed references directly. For example, `LOAD_FAST_BORROW` loads a local
+variable as a borrowed `_PyStackRef`, avoiding both INCREF and DECREF for the temporary lifetime on
+the evaluation stack.
+
+## Tagged integers on the stack
+
+Small ints can be stored inline with `Py_INT_TAG`, so no heap object is involved. Helpers like
+`PyStackRef_TagInt`, `PyStackRef_UntagInt`, and `PyStackRef_IncrementTaggedIntNoOverflow` operate on
+these values. Type checks use `PyStackRef_IsTaggedInt` and `PyStackRef_LongCheck`.
+
+## Free threading considerations
+
+With `Py_GIL_DISABLED`, `Py_TAG_DEFERRED` is an alias for `Py_TAG_REFCNT`.
+Objects that support deferred reference counting can be pushed to the evaluation
+stack and stored in local variables without directly incrementing the reference
+count because they are only freed during cyclic garbage collection. This avoids
+reference count contention on commonly shared objects such as methods and types. The GC
+scans each thread's locals and evaluation stack to keep objects that use
+deferred reference counting alive.
+
+## Debugging support
+
+`Py_STACKREF_DEBUG` builds replace the inline tags with table-backed IDs so the runtime can track
+creation sites, borrows, closes, and leaks. Enabling `Py_STACKREF_CLOSE_DEBUG` additionally records
+double closes. The tables live on `PyInterpreterState` and are initialized in `pystate.c`; helper
+routines reside in `Python/stackrefs.c`.

Lib/_py_warnings.py

@@ -563,7 +563,6 @@ def warn_explicit(message, category, filename, lineno,
     else:
         text = message
         message = category(message)
-    modules = None
     key = (text, category, lineno)
     with _wm._lock:
         if registry is None:

Lib/_threading_local.py

@@ -57,7 +57,7 @@ def thread_deleted(_, idt=idt):
             # as soon as the OS-level thread ends instead.
             local = wrlocal()
             if local is not None:
-                dct = local.dicts.pop(idt)
+                local.dicts.pop(idt)
         wrlocal = ref(self, local_deleted)
         wrthread = ref(thread, thread_deleted)
         thread.__dict__[key] = wrlocal

Lib/asyncio/base_events.py

@@ -949,7 +949,7 @@ async def sock_sendfile(self, sock, file, offset=0, count=None,
         try:
             return await self._sock_sendfile_native(sock, file,
                                                     offset, count)
-        except exceptions.SendfileNotAvailableError as exc:
+        except exceptions.SendfileNotAvailableError:
             if not fallback:
                 raise
         return await self._sock_sendfile_fallback(sock, file,
@@ -1270,7 +1270,7 @@ async def sendfile(self, transport, file, offset=0, count=None,
             try:
                 return await self._sendfile_native(transport, file,
                                                    offset, count)
-            except exceptions.SendfileNotAvailableError as exc:
+            except exceptions.SendfileNotAvailableError:
                 if not fallback:
                     raise
 

Lib/asyncio/proactor_events.py

@@ -733,7 +733,7 @@ async def sock_accept(self, sock):
     async def _sock_sendfile_native(self, sock, file, offset, count):
         try:
             fileno = file.fileno()
-        except (AttributeError, io.UnsupportedOperation) as err:
+        except (AttributeError, io.UnsupportedOperation):
             raise exceptions.SendfileNotAvailableError("not a regular file")
         try:
             fsize = os.fstat(fileno).st_size

Lib/asyncio/tools.py

@@ -244,7 +244,7 @@ def _get_awaited_by_tasks(pid: int) -> list:
             e = e.__context__
         print(f"Error retrieving tasks: {e}")
         sys.exit(1)
-    except PermissionError as e:
+    except PermissionError:
         exit_with_permission_help_text()
 
 

Lib/asyncio/unix_events.py

@@ -359,7 +359,7 @@ async def _sock_sendfile_native(self, sock, file, offset, count):
                 "os.sendfile() is not available")
         try:
             fileno = file.fileno()
-        except (AttributeError, io.UnsupportedOperation) as err:
+        except (AttributeError, io.UnsupportedOperation):
             raise exceptions.SendfileNotAvailableError("not a regular file")
         try:
             fsize = os.fstat(fileno).st_size

Lib/codeop.py

@@ -66,9 +66,9 @@ def _maybe_compile(compiler, source, filename, symbol, flags):
             try:
                 compiler(source + "\n", filename, symbol, flags=flags)
                 return None
-            except _IncompleteInputError as e:
+            except _IncompleteInputError:
                 return None
-            except SyntaxError as e:
+            except SyntaxError:
                 pass
                 # fallthrough
 

Lib/compileall.py

@@ -223,7 +223,7 @@ def compile_file(fullname, ddir=None, force=False, rx=None, quiet=0,
                     cfile = importlib.util.cache_from_source(fullname)
                     opt_cfiles[opt_level] = cfile
 
-        head, tail = name[:-3], name[-3:]
+        tail = name[-3:]
         if tail == '.py':
             if not force:
                 try:

Lib/concurrent/interpreters/_queues.py

@@ -223,7 +223,7 @@ def put(self, obj, block=True, timeout=None, *,
         while True:
             try:
                 _queues.put(self._id, obj, unboundop)
-            except QueueFull as exc:
+            except QueueFull:
                 if timeout is not None and time.time() >= end:
                     raise  # re-raise
                 time.sleep(_delay)
@@ -258,7 +258,7 @@ def get(self, block=True, timeout=None, *,
         while True:
             try:
                 obj, unboundop = _queues.get(self._id)
-            except QueueEmpty as exc:
+            except QueueEmpty:
                 if timeout is not None and time.time() >= end:
                     raise  # re-raise
                 time.sleep(_delay)
@@ -277,7 +277,7 @@ def get_nowait(self):
         """
         try:
             obj, unboundop = _queues.get(self._id)
-        except QueueEmpty as exc:
+        except QueueEmpty:
             raise  # re-raise
         if unboundop is not None:
             assert obj is None, repr(obj)

Lib/dis.py

@@ -530,7 +530,6 @@ def print_instruction_line(self, instr, mark_as_current):
         fields.append(instr.opname.ljust(_OPNAME_WIDTH))
         # Column: Opcode argument
         if instr.arg is not None:
-            arg = repr(instr.arg)
             # If opname is longer than _OPNAME_WIDTH, we allow it to overflow into
             # the space reserved for oparg. This results in fewer misaligned opargs
             # in the disassembly output.

Lib/encodings/uu_codec.py

@@ -56,7 +56,7 @@ def uu_decode(input, errors='strict'):
             break
         try:
             data = binascii.a2b_uu(s)
-        except binascii.Error as v:
+        except binascii.Error:
             # Workaround for broken uuencoders by /Fredrik Lundh
             nbytes = (((s[0]-32) & 63) * 4 + 5) // 3
             data = binascii.a2b_uu(s[:nbytes])

Lib/ftplib.py

@@ -314,9 +314,9 @@ def makeport(self):
         port = sock.getsockname()[1] # Get proper port
         host = self.sock.getsockname()[0] # Get proper host
         if self.af == socket.AF_INET:
-            resp = self.sendport(host, port)
+            self.sendport(host, port)
         else:
-            resp = self.sendeprt(host, port)
+            self.sendeprt(host, port)
         if self.timeout is not _GLOBAL_DEFAULT_TIMEOUT:
             sock.settimeout(self.timeout)
         return sock
@@ -455,7 +455,7 @@ def retrlines(self, cmd, callback = None):
         """
         if callback is None:
             callback = print_line
-        resp = self.sendcmd('TYPE A')
+        self.sendcmd('TYPE A')
         with self.transfercmd(cmd) as conn, \
                  conn.makefile('r', encoding=self.encoding) as fp:
             while 1:
@@ -951,7 +951,7 @@ def test():
         elif file[:2] == '-d':
             cmd = 'CWD'
             if file[2:]: cmd = cmd + ' ' + file[2:]
-            resp = ftp.sendcmd(cmd)
+            ftp.sendcmd(cmd)
         elif file == '-p':
             ftp.set_pasv(not ftp.passiveserver)
         else:

Lib/functools.py

@@ -687,7 +687,7 @@ def wrapper(*args, **kwds):
                     # still adjusting the links.
                     root = oldroot[NEXT]
                     oldkey = root[KEY]
-                    oldresult = root[RESULT]
+                    oldresult = root[RESULT]  # noqa: F841
                     root[KEY] = root[RESULT] = None
 
                     # Now update the cache dictionary.

Lib/idlelib/pyshell.py

@@ -498,7 +498,6 @@ def restart_subprocess(self, with_cwd=False, filename=''):
         self.rpcclt.close()
         self.terminate_subprocess()
         console = self.tkconsole
-        was_executing = console.executing
         console.executing = False
         self.spawn_subprocess()
         try:

Lib/idlelib/textview.py

@@ -129,8 +129,8 @@ def __init__(self, parent, title, contents, modal=True, wrap=WORD,
         self.title(title)
         self.viewframe = ViewFrame(self, contents, wrap=wrap)
         self.protocol("WM_DELETE_WINDOW", self.ok)
-        self.button_ok = button_ok = Button(self, text='Close',
-                                            command=self.ok, takefocus=False)
+        self.button_ok = Button(self, text='Close',
+                                command=self.ok, takefocus=False)
         self.viewframe.pack(side='top', expand=True, fill='both')
 
         self.is_modal = modal