Merge remote-tracking branch 'upstream/main'

Doc/library/contextlib.rst

@@ -314,7 +314,9 @@ Functions and classes provided:
 
    If the code within the :keyword:`!with` block raises a
    :exc:`BaseExceptionGroup`, suppressed exceptions are removed from the
-   group.  If any exceptions in the group are not suppressed, a group containing them is re-raised.
+   group.  Any exceptions of the group which are not suppressed are re-raised in
+   a new group which is created using the original group's :meth:`~BaseExceptionGroup.derive`
+   method.
 
    .. versionadded:: 3.4
 

Doc/library/exceptions.rst

@@ -989,7 +989,8 @@ their subgroups based on the types of the contained exceptions.
       Returns an exception group with the same :attr:`message`, but which
       wraps the exceptions in ``excs``.
 
-      This method is used by :meth:`subgroup` and :meth:`split`. A
+      This method is used by :meth:`subgroup` and :meth:`split`, which
+      are used in various contexts to break up an exception group. A
       subclass needs to override it in order to make :meth:`subgroup`
       and :meth:`split` return instances of the subclass rather
       than :exc:`ExceptionGroup`.

Doc/library/ipaddress.rst

@@ -990,7 +990,7 @@ The module also provides the following module level functions:
 .. function:: collapse_addresses(addresses)
 
    Return an iterator of the collapsed :class:`IPv4Network` or
-   :class:`IPv6Network` objects.  *addresses* is an iterator of
+   :class:`IPv6Network` objects.  *addresses* is an :term:`iterable` of
    :class:`IPv4Network` or :class:`IPv6Network` objects.  A :exc:`TypeError` is
    raised if *addresses* contains mixed version objects.
 

InternalDocs/exception_handling.md

@@ -67,14 +67,18 @@ handler located at label `L1`.
 Handling Exceptions
 -------------------
 
-At runtime, when an exception occurs, the interpreter looks up
-the offset of the current instruction in the exception table. If
-it finds a handler, control flow transfers to it. Otherwise, the
+At runtime, when an exception occurs, the interpreter calls
+``get_exception_handler()`` in
+[Python/ceval.c](https://github.com/python/cpython/blob/main/Python/ceval.c)
+to look up the offset of the current instruction in the exception
+table. If it finds a handler, control flow transfers to it. Otherwise, the
 exception bubbles up to the caller, and the caller's frame is
 checked for a handler covering the `CALL` instruction. This
 repeats until a handler is found or the topmost frame is reached.
 If no handler is found, the program terminates. During unwinding,
-the traceback is constructed as each frame is added to it.
+the traceback is constructed as each frame is added to it by
+``PyTraceBack_Here()``, which is in
+[Python/traceback.c](https://github.com/python/cpython/blob/main/Python/traceback.c).
 
 Along with the location of an exception handler, each entry of the
 exception table also contains the stack depth of the `try` instruction
@@ -169,33 +173,12 @@ which is then encoded as:
 
 for a total of five bytes.
 
+The code to construct the exception table is in ``assemble_exception_table()``
+in [Python/assemble.c](https://github.com/python/cpython/blob/main/Python/assemble.c).
 
-Script to parse the exception table
------------------------------------
-
-```
-def parse_varint(iterator):
-    b = next(iterator)
-    val = b & 63
-    while b&64:
-        val <<= 6
-        b = next(iterator)
-        val |= b&63
-    return val
-```
-```
-def parse_exception_table(code):
-    iterator = iter(code.co_exceptiontable)
-    try:
-        while True:
-            start = parse_varint(iterator)*2
-            length = parse_varint(iterator)*2
-            end = start + length - 2 # Present as inclusive, not exclusive
-            target = parse_varint(iterator)*2
-            dl = parse_varint(iterator)
-            depth = dl >> 1
-            lasti = bool(dl&1)
-            yield start, end, target, depth, lasti
-    except StopIteration:
-        return
-```
+The interpreter's function to lookup the table by instruction offset is
+``get_exception_handler()`` in
+[Python/ceval.c](https://github.com/python/cpython/blob/main/Python/ceval.c).
+The Python function ``_parse_exception_table()`` in
+[Lib/dis.py](https://github.com/python/cpython/blob/main/Lib/dis.py)
+returns the exception table content as a list of namedtuple instances.

Lib/ipaddress.py

@@ -310,7 +310,7 @@ def collapse_addresses(addresses):
                            [IPv4Network('192.0.2.0/24')]
 
     Args:
-        addresses: An iterator of IPv4Network or IPv6Network objects.
+        addresses: An iterable of IPv4Network or IPv6Network objects.
 
     Returns:
         An iterator of the collapsed IPv(4|6)Network objects.

Lib/pathlib/_abc.py

@@ -12,8 +12,8 @@
 """
 
 import functools
+import posixpath
 from glob import _Globber, _no_recurse_symlinks
-from errno import ENOTDIR, ELOOP
 from stat import S_ISDIR, S_ISLNK, S_ISREG, S_ISSOCK, S_ISBLK, S_ISCHR, S_ISFIFO
 
 
@@ -696,65 +696,34 @@ def resolve(self, strict=False):
         """
         if self._resolving:
             return self
-        path_root, parts = self._stack
-        path = self.with_segments(path_root)
-        try:
-            path = path.absolute()
-        except UnsupportedOperation:
-            path_tail = []
-        else:
-            path_root, path_tail = path._stack
-            path_tail.reverse()
-
-        # If the user has *not* overridden the `readlink()` method, then symlinks are unsupported
-        # and (in non-strict mode) we can improve performance by not calling `stat()`.
-        querying = strict or getattr(self.readlink, '_supported', True)
-        link_count = 0
-        while parts:
-            part = parts.pop()
-            if not part or part == '.':
-                continue
-            if part == '..':
-                if not path_tail:
-                    if path_root:
-                        # Delete '..' segment immediately following root
-                        continue
-                elif path_tail[-1] != '..':
-                    # Delete '..' segment and its predecessor
-                    path_tail.pop()
-                    continue
-            path_tail.append(part)
-            if querying and part != '..':
-                path = self.with_segments(path_root + self.parser.sep.join(path_tail))
+
+        def getcwd():
+            return str(self.with_segments().absolute())
+
+        if strict or getattr(self.readlink, '_supported', True):
+            def lstat(path_str):
+                path = self.with_segments(path_str)
                 path._resolving = True
-                try:
-                    st = path.stat(follow_symlinks=False)
-                    if S_ISLNK(st.st_mode):
-                        # Like Linux and macOS, raise OSError(errno.ELOOP) if too many symlinks are
-                        # encountered during resolution.
-                        link_count += 1
-                        if link_count >= self._max_symlinks:
-                            raise OSError(ELOOP, "Too many symbolic links in path", self._raw_path)
-                        target_root, target_parts = path.readlink()._stack
-                        # If the symlink target is absolute (like '/etc/hosts'), set the current
-                        # path to its uppermost parent (like '/').
-                        if target_root:
-                            path_root = target_root
-                            path_tail.clear()
-                        else:
-                            path_tail.pop()
-                        # Add the symlink target's reversed tail parts (like ['hosts', 'etc']) to
-                        # the stack of unresolved path parts.
-                        parts.extend(target_parts)
-                        continue
-                    elif parts and not S_ISDIR(st.st_mode):
-                        raise NotADirectoryError(ENOTDIR, "Not a directory", self._raw_path)
-                except OSError:
-                    if strict:
-                        raise
-                    else:
-                        querying = False
-        return self.with_segments(path_root + self.parser.sep.join(path_tail))
+                return path.lstat()
+
+            def readlink(path_str):
+                path = self.with_segments(path_str)
+                path._resolving = True
+                return str(path.readlink())
+        else:
+            # If the user has *not* overridden the `readlink()` method, then
+            # symlinks are unsupported and (in non-strict mode) we can improve
+            # performance by not calling `path.lstat()`.
+            def skip(path_str):
+                # This exception will be internally consumed by `_realpath()`.
+                raise OSError("Operation skipped.")
+
+            lstat = readlink = skip
+
+        return self.with_segments(posixpath._realpath(
+            str(self), strict, self.parser.sep,
+            getcwd=getcwd, lstat=lstat, readlink=readlink,
+            maxlinks=self._max_symlinks))
 
     def symlink_to(self, target, target_is_directory=False):
         """

Lib/posixpath.py

@@ -22,6 +22,7 @@
 altsep = None
 devnull = '/dev/null'
 
+import errno
 import os
 import sys
 import stat
@@ -401,7 +402,10 @@ def realpath(filename, *, strict=False):
         curdir = '.'
         pardir = '..'
         getcwd = os.getcwd
+    return _realpath(filename, strict, sep, curdir, pardir, getcwd)
 
+def _realpath(filename, strict=False, sep=sep, curdir=curdir, pardir=pardir,
+              getcwd=os.getcwd, lstat=os.lstat, readlink=os.readlink, maxlinks=None):
     # The stack of unresolved path parts. When popped, a special value of None
     # indicates that a symlink target has been resolved, and that the original
     # symlink path can be retrieved by popping again. The [::-1] slice is a
@@ -418,6 +422,10 @@ def realpath(filename, *, strict=False):
     # the same links.
     seen = {}
 
+    # Number of symlinks traversed. When the number of traversals is limited
+    # by *maxlinks*, this is used instead of *seen* to detect symlink loops.
+    link_count = 0
+
     while rest:
         name = rest.pop()
         if name is None:
@@ -436,38 +444,48 @@ def realpath(filename, *, strict=False):
         else:
             newpath = path + sep + name
         try:
-            st = os.lstat(newpath)
+            st = lstat(newpath)
             if not stat.S_ISLNK(st.st_mode):
                 path = newpath
                 continue
-            if newpath in seen:
+            elif maxlinks is not None:
+                link_count += 1
+                if link_count > maxlinks:
+                    if strict:
+                        raise OSError(errno.ELOOP, os.strerror(errno.ELOOP),
+                                      newpath)
+                    path = newpath
+                    continue
+            elif newpath in seen:
                 # Already seen this path
                 path = seen[newpath]
                 if path is not None:
                     # use cached value
                     continue
                 # The symlink is not resolved, so we must have a symlink loop.
                 if strict:
-                    # Raise OSError(errno.ELOOP)
-                    os.stat(newpath)
+                    raise OSError(errno.ELOOP, os.strerror(errno.ELOOP),
+                                  newpath)
                 path = newpath
                 continue
-            target = os.readlink(newpath)
+            target = readlink(newpath)
         except OSError:
             if strict:
                 raise
             path = newpath
             continue
         # Resolve the symbolic link
-        seen[newpath] = None # not resolved symlink
         if target.startswith(sep):
             # Symlink target is absolute; reset resolved path.
             path = sep
-        # Push the symlink path onto the stack, and signal its specialness by
-        # also pushing None. When these entries are popped, we'll record the
-        # fully-resolved symlink target in the 'seen' mapping.
-        rest.append(newpath)
-        rest.append(None)
+        if maxlinks is None:
+            # Mark this symlink as seen but not fully resolved.
+            seen[newpath] = None
+            # Push the symlink path onto the stack, and signal its specialness
+            # by also pushing None. When these entries are popped, we'll
+            # record the fully-resolved symlink target in the 'seen' mapping.
+            rest.append(newpath)
+            rest.append(None)
         # Push the unresolved symlink target parts onto the stack.
         rest.extend(target.split(sep)[::-1])
 

Lib/test/datetimetester.py

@@ -4412,6 +4412,8 @@ def test_fromisoformat_fails(self):
             '12:30:45.123456-',         # Extra at end of microsecond time
             '12:30:45.123456+',         # Extra at end of microsecond time
             '12:30:45.123456+12:00:30a',    # Extra at end of full time
+            '12.5',                     # Decimal mark at end of hour
+            '12:30,5',                  # Decimal mark at end of minute
         ]
 
         for bad_str in bad_strs:

Lib/test/test_weakref.py

@@ -82,7 +82,7 @@ def callback(self, ref):
 
 
 @contextlib.contextmanager
-def collect_in_thread(period=0.0001):
+def collect_in_thread(period=0.005):
     """
     Ensure GC collections happen in a different thread, at a high frequency.
     """

Misc/ACKS

@@ -315,6 +315,7 @@ Greg Chapman
 Mitch Chapman
 Matt Chaput
 William Chargin
+Ben Chatterton
 Yogesh Chaudhari
 Gautam Chaudhuri
 David Chaum

Misc/NEWS.d/next/Library/2024-05-21-19-10-30.gh-issue-115225.eRmfJH.rst

@@ -0,0 +1 @@
+Raise error on certain technically valid but pathological ISO 8601 strings passed to :meth:`datetime.time.fromisoformat` that were previously parsed incorrectly.

Modules/_datetimemodule.c

@@ -1020,6 +1020,9 @@ parse_hh_mm_ss_ff(const char *tstr, const char *tstr_end, int *hour,
             continue;
         }
         else if (c == '.' || c == ',') {
+            if (i < 2) {
+                return -3; // Decimal mark on hour or minute
+            }
             break;
         } else if (!has_separator) {
             --p;