gh-103921: Document PEP 695

Doc/library/ast.rst

@@ -43,12 +43,12 @@
 
 .. class:: AST
 
    This is the base of all AST node classes.  The actual node classes are
    derived from the :file:`Parser/Python.asdl` file, which is reproduced
    :ref:`above <abstract-grammar>`.  They are defined in the :mod:`_ast` C
    module and re-exported in :mod:`ast`.
 
    There is one class defined for each left-hand side symbol in the abstract
    grammar (for example, :class:`ast.stmt` or :class:`ast.expr`).  In addition,
    there is one class defined for each constructor on the right-hand side; these
    classes inherit from the classes for the left-hand side trees.  For example,
@@ -64,7 +64,7 @@
       Each concrete class has an attribute :attr:`_fields` which gives the names
       of all child nodes.
 
       Each instance of a concrete class has one attribute for each child node,
       of the type as defined in the grammar.  For example, :class:`ast.BinOp`
       instances have an attribute :attr:`left` of type :class:`ast.expr`.
 
@@ -79,7 +79,7 @@
                   end_lineno
                   end_col_offset
 
       Instances of :class:`ast.expr` and :class:`ast.stmt` subclasses have
       :attr:`lineno`, :attr:`col_offset`, :attr:`end_lineno`, and
       :attr:`end_col_offset` attributes.  The :attr:`lineno` and :attr:`end_lineno`
       are the first and last line numbers of source text span (1-indexed so the
@@ -93,9 +93,9 @@
       one can get the source segment of a one-line expression node using
       ``source_line[node.col_offset : node.end_col_offset]``.
 
    The constructor of a class :class:`ast.T` parses its arguments as follows:
 
    * If there are positional arguments, there must be as many as there are items
      in :attr:`T._fields`; they will be assigned as attributes of these names.
    * If there are keyword arguments, they will set the attributes of the same
      names to the given values.
@@ -917,6 +917,25 @@
             type_ignores=[])
 
 
+.. class:: TypeAlias(name, type_params, value)
+
+   A :ref:`type alias <type-aliases>` created through the :keyword:`type`
+   statement. ``name`` is the name of the alias, ``type_params`` is a list of
+   :ref:`type parameters <ast-type-params>`, and ``value`` is the value of the
+   type alias.
+
+   .. doctest::
+
+        >>> print(ast.dump(ast.parse('type Alias = int'), indent=4))
+        Module(
+            body=[
+                TypeAlias(
+                    name=Name(id='Alias', ctx=Store()),
+                    type_params=[],
+                    value=Name(id='int', ctx=Load()))],
+            type_ignores=[])
+
+
 Other statements which are only applicable inside functions or loops are
 described in other sections.
 
@@ -1644,15 +1663,93 @@
                                     value=Constant(value=Ellipsis))])])],
             type_ignores=[])
 
+.. _ast-type-params:
+
+Type parameters
+^^^^^^^^^^^^^^^
+
+:ref:`Type parameters <type-params>` can exist on classes, functions, and type
+aliases.
+
+.. class:: TypeVar(name, bound)
+
+   A :class:`typing.TypeVar`. ``name`` is the name of the type variable.
+   ``bound`` is the bound or constraints, if any. If ``bound`` is a :class:`Tuple`,
+   it represents constraints; otherwise it represents the bound.
+
+   .. doctest::
+
+        >>> print(ast.dump(ast.parse("type Alias[T: int] = list[T]"), indent=4))
+        Module(
+            body=[
+                TypeAlias(
+                    name=Name(id='Alias', ctx=Store()),
+                    type_params=[
+                        TypeVar(
+                            name='T',
+                            bound=Name(id='int', ctx=Load()))],
+                    value=Subscript(
+                        value=Name(id='list', ctx=Load()),
+                        slice=Name(id='T', ctx=Load()),
+                        ctx=Load()))],
+            type_ignores=[])
+
+.. class:: ParamSpec(name)
+
+   A :class:`typing.ParamSpec`. ``name`` is the name of the parameter specification.
+
+   .. doctest::
+
+        >>> print(ast.dump(ast.parse("type Alias[**P] = Callable[P, int]"), indent=4))
+        Module(
+            body=[
+                TypeAlias(
+                    name=Name(id='Alias', ctx=Store()),
+                    type_params=[
+                        ParamSpec(name='P')],
+                    value=Subscript(
+                        value=Name(id='Callable', ctx=Load()),
+                        slice=Tuple(
+                            elts=[
+                                Name(id='P', ctx=Load()),
+                                Name(id='int', ctx=Load())],
+                            ctx=Load()),
+                        ctx=Load()))],
+            type_ignores=[])
+
+.. class:: TypeVarTuple(name)
+
+   A :class:`typing.TypeVarTuple`. ``name`` is the name of the type variable tuple.
+
+   .. doctest::
+
+        >>> print(ast.dump(ast.parse("type Alias[*Ts] = tuple[*Ts]"), indent=4))
+        Module(
+            body=[
+                TypeAlias(
+                    name=Name(id='Alias', ctx=Store()),
+                    type_params=[
+                        TypeVarTuple(name='Ts')],
+                    value=Subscript(
+                        value=Name(id='tuple', ctx=Load()),
+                        slice=Tuple(
+                            elts=[
+                                Starred(
+                                    value=Name(id='Ts', ctx=Load()),
+                                    ctx=Load())],
+                            ctx=Load()),
+                        ctx=Load()))],
+            type_ignores=[])
 
 Function and class definitions
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-.. class:: FunctionDef(name, args, body, decorator_list, returns, type_comment)
+.. class:: FunctionDef(name, type_params, args, body, decorator_list, returns, type_comment)
 
    A function definition.
 
    * ``name`` is a raw string of the function name.
+   * ``type_params`` is a list of :ref:`type parameters <ast-type-params>`.
    * ``args`` is an :class:`arguments` node.
    * ``body`` is the list of nodes inside the function.
    * ``decorator_list`` is the list of decorators to be applied, stored outermost
@@ -1820,11 +1917,12 @@
             type_ignores=[])
 
 
-.. class:: ClassDef(name, bases, keywords, starargs, kwargs, body, decorator_list)
+.. class:: ClassDef(name, type_params, bases, keywords, starargs, kwargs, body, decorator_list)
 
    A class definition.
 
    * ``name`` is a raw string for the class name
+   * ``type_params`` is a list of :ref:`type parameters <ast-type-params>`.
    * ``bases`` is a list of nodes for explicitly specified base classes.
    * ``keywords`` is a list of :class:`keyword` nodes, principally for 'metaclass'.
      Other keywords will be passed to the metaclass, as per `PEP-3115

Doc/library/dis.rst

@@ -188,9 +188,9 @@ operation is being performed, so the intermediate analysis object isn't useful:
    For a module, it disassembles all functions. For a class, it disassembles
    all methods (including class and static methods). For a code object or
    sequence of raw bytecode, it prints one line per bytecode instruction.
-   It also recursively disassembles nested code objects (the code of
-   comprehensions, generator expressions and nested functions, and the code
-   used for building nested classes).
+   It also recursively disassembles nested code objects. These can include
+   generator expressions, nested functions, the bodies of nested classes,
+   and the code objects used for :ref:`annotation scopes <annotation-scopes>`.
    Strings are first compiled to code objects with the :func:`compile`
    built-in function before being disassembled.  If no object is provided, this
    function disassembles the last traceback.
@@ -926,6 +926,27 @@ iterations of the loop.
 .. opcode:: LOAD_NAME (namei)
 
    Pushes the value associated with ``co_names[namei]`` onto the stack.
+   The name is looked up within the locals, then the globals, then the builtins.
+
+
+.. opcode:: LOAD_LOCALS
+
+   Pushes a reference to the locals dictionary onto the stack.  This is used
+   to prepare namespace dictionaries for :opcode:`LOAD_FROM_DICT_OR_DEREF`
+   and :opcode:`LOAD_FROM_DICT_OR_GLOBALS`.
+
+   .. versionadded:: 3.12
+
+
+.. opcode:: LOAD_FROM_DICT_OR_GLOBALS (i)
+
+   Pops a mapping off the stack and looks up the value for ``co_names[namei]``.
+   If the name is not found there, looks it up in the globals and then the builtins,
+   similar to :opcode:`LOAD_GLOBAL`.
+   This is used for loading global variables in
+   :ref:`annotation scopes <annotation-scopes>` within class bodies.
+
+   .. versionadded:: 3.12
 
 
 .. opcode:: BUILD_TUPLE (count)
@@ -1243,16 +1264,17 @@ iterations of the loop.
       ``i`` is no longer offset by the length of ``co_varnames``.
 
 
-.. opcode:: LOAD_CLASSDEREF (i)
+.. opcode:: LOAD_FROM_DICT_OR_DEREF (i)
 
-   Much like :opcode:`LOAD_DEREF` but first checks the locals dictionary before
-   consulting the cell.  This is used for loading free variables in class
-   bodies.
-
-   .. versionadded:: 3.4
+   Pops a mapping off the stack and looks up the name associated with
+   slot ``i`` of the "fast locals" storage in this mapping.
+   If the name is not found there, loads it from the cell contained in
+   slot ``i``, similar to :opcode:`LOAD_DEREF`. This is used for loading
+   free variables in class bodies (which previously used
+   :opcode:`!LOAD_CLASSDEREF`) and in
+   :ref:`annotation scopes <annotation-scopes>` within class bodies.
 
-   .. versionchanged:: 3.11
-      ``i`` is no longer offset by the length of ``co_varnames``.
+   .. versionadded:: 3.12
 
 
 .. opcode:: STORE_DEREF (i)
@@ -1504,13 +1526,45 @@ iterations of the loop.
 
    The operand determines which intrinsic function is called:
 
-   * ``0`` Not valid
-   * ``1`` Prints the argument to standard out. Used in the REPL.
-   * ``2`` Performs ``import *`` for the named module.
-   * ``3`` Extracts the return value from a ``StopIteration`` exception.
-   * ``4`` Wraps an aync generator value
-   * ``5`` Performs the unary ``+`` operation
-   * ``6`` Converts a list to a tuple
+   +-----------------------------------+-----------------------------------+
+   | Operand                           | Description                       |
+   +===================================+===================================+
+   | ``INTRINSIC_1_INVALID``           | Not valid                         |
+   +-----------------------------------+-----------------------------------+
+   | ``INTRINSIC_PRINT``               | Prints the argument to standard   |
+   |                                   | out. Used in the REPL.            |
+   +-----------------------------------+-----------------------------------+
+   | ``INTRINSIC_IMPORT_STAR``         | Performs ``import *`` for the     |
+   |                                   | named module.                     |
+   +-----------------------------------+-----------------------------------+
+   | ``INTRINSIC_STOPITERATION_ERROR`` | Extracts the return value from a  |
+   |                                   | ``StopIteration`` exception.      |
+   +-----------------------------------+-----------------------------------+
+   | ``INTRINSIC_ASYNC_GEN_WRAP``      | Wraps an aync generator value     |
+   +-----------------------------------+-----------------------------------+
+   | ``INTRINSIC_UNARY_POSITIVE``      | Performs the unary ``+``          |
+   |                                   | operation                         |
+   +-----------------------------------+-----------------------------------+
+   | ``INTRINSIC_LIST_TO_TUPLE``       | Converts a list to a tuple        |
+   +-----------------------------------+-----------------------------------+
+   | ``INTRINSIC_TYPEVAR``             | Creates a :class:`typing.TypeVar` |
+   +-----------------------------------+-----------------------------------+
+   | ``INTRINSIC_PARAMSPEC``           | Creates a                         |
+   |                                   | :class:`typing.ParamSpec`         |
+   +-----------------------------------+-----------------------------------+
+   | ``INTRINSIC_TYPEVARTUPLE``        | Creates a                         |
+   |                                   | :class:`typing.TypeVarTuple`      |
+   +-----------------------------------+-----------------------------------+
+   | ``INTRINSIC_SUBSCRIPT_GENERIC``   | Returns :class:`typing.Generic`   |
+   |                                   | subscripted with the argument     |
+   +-----------------------------------+-----------------------------------+
+   | ``INTRINSIC_TYPEALIAS``           | Creates a                         |
+   |                                   | :class:`typing.TypeAliasType`;    |
+   |                                   | used in the :keyword:`type`       |
+   |                                   | statement. The argument is a tuple|
+   |                                   | of the type alias's name,         |
+   |                                   | type parameters, and value.       |
+   +-----------------------------------+-----------------------------------+
 
    .. versionadded:: 3.12
 
@@ -1522,8 +1576,25 @@ iterations of the loop.
 
    The operand determines which intrinsic function is called:
 
-   * ``0`` Not valid
-   * ``1`` Calculates the :exc:`ExceptionGroup` to raise from a ``try-except*``.
+   +----------------------------------------+-----------------------------------+
+   | Operand                                | Description                       |
+   +========================================+===================================+
+   | ``INTRINSIC_2_INVALID``                | Not valid                         |
+   +----------------------------------------+-----------------------------------+
+   | ``INTRINSIC_PREP_RERAISE_STAR``        | Calculates the                    |
+   |                                        | :exc:`ExceptionGroup` to raise    |
+   |                                        | from a ``try-except*``.           |
+   +----------------------------------------+-----------------------------------+
+   | ``INTRINSIC_TYPEVAR_WITH_BOUND``       | Creates a :class:`typing.TypeVar` |
+   |                                        | with a bound.                     |
+   +----------------------------------------+-----------------------------------+
+   | ``INTRINSIC_TYPEVAR_WITH_CONSTRAINTS`` | Creates a                         |
+   |                                        | :class:`typing.TypeVar` with      |
+   |                                        | constraints.                      |
+   +----------------------------------------+-----------------------------------+
+   | ``INTRINSIC_SET_FUNCTION_TYPE_PARAMS`` | Sets the ``__type_params__``      |
+   |                                        | attribute of a function.          |
+   +----------------------------------------+-----------------------------------+
 
    .. versionadded:: 3.12
 

Doc/library/stdtypes.rst

@@ -5476,6 +5476,14 @@ types, where they are relevant.  Some of these are not reported by the
    .. versionadded:: 3.3
 
 
+.. attribute:: definition.__type_params__
+
+   The :ref:`type parameters <type-params>` of generic classes, functions,
+   and :ref:`type aliases <type-aliases>`.
+
+   .. versionadded:: 3.12
+
+
 .. attribute:: class.__mro__
 
    This attribute is a tuple of classes that are considered when looking for