Add support for PEP 695 syntax

CHANGES.md

@@ -32,6 +32,8 @@
 
 <!-- Changes to the parser or to version autodetection -->
 
+- Add support for the new PEP 695 syntax in Python 3.12 (#3703)
+
 ### Performance
 
 <!-- Changes that improve Black's performance. -->

pyproject.toml

@@ -214,4 +214,6 @@ filterwarnings = [
     # aiohttp is using deprecated cgi modules - Safe to remove when fixed:
     # https://github.com/aio-libs/aiohttp/issues/6905
     '''ignore:'cgi' is deprecated and slated for removal in Python 3.13:DeprecationWarning''',
+    # Work around https://github.com/pytest-dev/pytest/issues/10977 for Python 3.12
+    '''ignore:(Attribute s|Attribute n|ast.Str|ast.Bytes|ast.NameConstant|ast.Num) is deprecated and will be removed in Python 3.14:DeprecationWarning'''
 ]

src/black/__init__.py

@@ -1275,6 +1275,9 @@ def get_features_used(  # noqa: C901
         ):
             features.add(Feature.VARIADIC_GENERICS)
 
+        elif n.type in (syms.type_stmt, syms.typeparams):
+            features.add(Feature.TYPE_PARAMS)
+
     return features
 
 

src/black/linegen.py

@@ -215,6 +215,18 @@ def visit_stmt(
 
             yield from self.visit(child)
 
+    def visit_typeparams(self, node: Node) -> Iterator[Line]:
+        yield from self.visit_default(node)
+        node.children[0].prefix = ""
+
+    def visit_typevartuple(self, node: Node) -> Iterator[Line]:
+        yield from self.visit_default(node)
+        node.children[1].prefix = ""
+
+    def visit_paramspec(self, node: Node) -> Iterator[Line]:
+        yield from self.visit_default(node)
+        node.children[1].prefix = ""
+
     def visit_dictsetmaker(self, node: Node) -> Iterator[Line]:
         if Preview.wrap_long_dict_values_in_parens in self.mode:
             for i, child in enumerate(node.children):

src/black/mode.py

@@ -30,6 +30,7 @@ class TargetVersion(Enum):
     PY39 = 9
     PY310 = 10
     PY311 = 11
+    PY312 = 12
 
 
 class Feature(Enum):
@@ -51,6 +52,7 @@ class Feature(Enum):
     VARIADIC_GENERICS = 15
     DEBUG_F_STRINGS = 16
     PARENTHESIZED_CONTEXT_MANAGERS = 17
+    TYPE_PARAMS = 18
     FORCE_OPTIONAL_PARENTHESES = 50
 
     # __future__ flags
@@ -143,6 +145,25 @@ class Feature(Enum):
         Feature.EXCEPT_STAR,
         Feature.VARIADIC_GENERICS,
     },
+    TargetVersion.PY312: {
+        Feature.F_STRINGS,
+        Feature.DEBUG_F_STRINGS,
+        Feature.NUMERIC_UNDERSCORES,
+        Feature.TRAILING_COMMA_IN_CALL,
+        Feature.TRAILING_COMMA_IN_DEF,
+        Feature.ASYNC_KEYWORDS,
+        Feature.FUTURE_ANNOTATIONS,
+        Feature.ASSIGNMENT_EXPRESSIONS,
+        Feature.RELAXED_DECORATORS,
+        Feature.POS_ONLY_ARGUMENTS,
+        Feature.UNPACKING_ON_FLOW,
+        Feature.ANN_ASSIGN_EXTENDED_RHS,
+        Feature.PARENTHESIZED_CONTEXT_MANAGERS,
+        Feature.PATTERN_MATCHING,
+        Feature.EXCEPT_STAR,
+        Feature.VARIADIC_GENERICS,
+        Feature.TYPE_PARAMS,
+    },
 }
 
 

src/blib2to3/Grammar.txt

@@ -12,11 +12,17 @@ file_input: (NEWLINE | stmt)* ENDMARKER
 single_input: NEWLINE | simple_stmt | compound_stmt NEWLINE
 eval_input: testlist NEWLINE* ENDMARKER
 
+typevar: NAME [':' expr]
+paramspec: '**' NAME
+typevartuple: '*' NAME
+typeparam: typevar | paramspec | typevartuple
+typeparams: '[' typeparam (',' typeparam)* [','] ']'
+
 decorator: '@' namedexpr_test NEWLINE
 decorators: decorator+
 decorated: decorators (classdef | funcdef | async_funcdef)
 async_funcdef: ASYNC funcdef
-funcdef: 'def' NAME parameters ['->' test] ':' suite
+funcdef: 'def' NAME [typeparams] parameters ['->' test] ':' suite
 parameters: '(' [typedargslist] ')'
 
 # The following definition for typedarglist is equivalent to this set of rules:
@@ -74,7 +80,7 @@ vfplist: vfpdef (',' vfpdef)* [',']
 
 stmt: simple_stmt | compound_stmt
 simple_stmt: small_stmt (';' small_stmt)* [';'] NEWLINE
-small_stmt: (expr_stmt | print_stmt  | del_stmt | pass_stmt | flow_stmt |
+small_stmt: (type_stmt | expr_stmt | print_stmt  | del_stmt | pass_stmt | flow_stmt |
              import_stmt | global_stmt | exec_stmt | assert_stmt)
 expr_stmt: testlist_star_expr (annassign | augassign (yield_expr|testlist) |
                      ('=' (yield_expr|testlist_star_expr))*)
@@ -105,6 +111,7 @@ dotted_name: NAME ('.' NAME)*
 global_stmt: ('global' | 'nonlocal') NAME (',' NAME)*
 exec_stmt: 'exec' expr ['in' test [',' test]]
 assert_stmt: 'assert' test [',' test]
+type_stmt: "type" NAME [typeparams] '=' expr
 
 compound_stmt: if_stmt | while_stmt | for_stmt | try_stmt | with_stmt | funcdef | classdef | decorated | async_stmt | match_stmt
 async_stmt: ASYNC (funcdef | with_stmt | for_stmt)
@@ -174,7 +181,7 @@ dictsetmaker: ( ((test ':' asexpr_test | '**' expr)
                 ((test [':=' test] | star_expr)
 		 (comp_for | (',' (test [':=' test] | star_expr))* [','])) )
 
-classdef: 'class' NAME ['(' [arglist] ')'] ':' suite
+classdef: 'class' NAME [typeparams] ['(' [arglist] ')'] ':' suite
 
 arglist: argument (',' argument)* [',']
 

src/blib2to3/pygram.py

@@ -95,6 +95,7 @@ class _python_symbols(Symbols):
     old_test: int
     or_test: int
     parameters: int
+    paramspec: int
     pass_stmt: int
     pattern: int
     patterns: int
@@ -126,7 +127,12 @@ class _python_symbols(Symbols):
     tname_star: int
     trailer: int
     try_stmt: int
+    type_stmt: int
     typedargslist: int
+    typeparam: int
+    typeparams: int
+    typevar: int
+    typevartuple: int
     varargslist: int
     vfpdef: int
     vfplist: int

tests/data/py_312/type_aliases.py

@@ -0,0 +1,13 @@
+type A=int
+type Gen[T]=list[T]
+
+type = aliased
+print(type(42))
+
+# output
+
+type A = int
+type Gen[T] = list[T]
+
+type = aliased
+print(type(42))

tests/data/py_312/type_params.py

@@ -0,0 +1,57 @@
+def func  [T ](): pass
+async def func [ T ] (): pass
+class C[ T ] : pass
+
+def all_in[T   :   int,U : (bytes, str),*   Ts,**P](): pass
+
+def really_long[WhatIsTheLongestTypeVarNameYouCanThinkOfEnoughToMakeBlackSplitThisLine](): pass
+
+def even_longer[WhatIsTheLongestTypeVarNameYouCanThinkOfEnoughToMakeBlackSplitThisLine: WhatIfItHadABound](): pass
+
+def it_gets_worse[WhatIsTheLongestTypeVarNameYouCanThinkOfEnoughToMakeBlackSplitThisLine, ItCouldBeGenericOverMultipleTypeVars](): pass
+
+def magic[Trailing, Comma,](): pass
+
+# output
+
+
+def func[T]():
+    pass
+
+
+async def func[T]():
+    pass
+
+
+class C[T]:
+    pass
+
+
+def all_in[T: int, U: (bytes, str), *Ts, **P]():
+    pass
+
+
+def really_long[
+    WhatIsTheLongestTypeVarNameYouCanThinkOfEnoughToMakeBlackSplitThisLine
+]():
+    pass
+
+
+def even_longer[
+    WhatIsTheLongestTypeVarNameYouCanThinkOfEnoughToMakeBlackSplitThisLine: WhatIfItHadABound
+]():
+    pass
+
+
+def it_gets_worse[
+    WhatIsTheLongestTypeVarNameYouCanThinkOfEnoughToMakeBlackSplitThisLine,
+    ItCouldBeGenericOverMultipleTypeVars,
+]():
+    pass
+
+
+def magic[
+    Trailing,
+    Comma,
+]():
+    pass

tests/test_black.py

@@ -271,6 +271,15 @@ def test_pep_572_version_detection(self) -> None:
         versions = black.detect_target_versions(root)
         self.assertIn(black.TargetVersion.PY38, versions)
 
+    def test_pep_695_version_detection(self) -> None:
+        for file in ("type_aliases", "type_params"):
+            source, _ = read_data("py_312", file)
+            root = black.lib2to3_parse(source)
+            features = black.get_features_used(root)
+            self.assertIn(black.Feature.TYPE_PARAMS, features)
+            versions = black.detect_target_versions(root)
+            self.assertIn(black.TargetVersion.PY312, versions)
+
     def test_expression_ff(self) -> None:
         source, expected = read_data("simple_cases", "expression.py")
         tmp_file = Path(black.dump_to_file(source))
@@ -1533,14 +1542,25 @@ def test_infer_target_version(self) -> None:
         for version, expected in [
             ("3.6", [TargetVersion.PY36]),
             ("3.11.0rc1", [TargetVersion.PY311]),
-            (">=3.10", [TargetVersion.PY310, TargetVersion.PY311]),
-            (">=3.10.6", [TargetVersion.PY310, TargetVersion.PY311]),
+            (">=3.10", [TargetVersion.PY310, TargetVersion.PY311, TargetVersion.PY312]),
+            (
+                ">=3.10.6",
+                [TargetVersion.PY310, TargetVersion.PY311, TargetVersion.PY312],
+            ),
             ("<3.6", [TargetVersion.PY33, TargetVersion.PY34, TargetVersion.PY35]),
             (">3.7,<3.10", [TargetVersion.PY38, TargetVersion.PY39]),
-            (">3.7,!=3.8,!=3.9", [TargetVersion.PY310, TargetVersion.PY311]),
+            (
+                ">3.7,!=3.8,!=3.9",
+                [TargetVersion.PY310, TargetVersion.PY311, TargetVersion.PY312],
+            ),
             (
                 "> 3.9.4, != 3.10.3",
-                [TargetVersion.PY39, TargetVersion.PY310, TargetVersion.PY311],
+                [
+                    TargetVersion.PY39,
+                    TargetVersion.PY310,
+                    TargetVersion.PY311,
+                    TargetVersion.PY312,
+                ],
             ),
             (
                 "!=3.3,!=3.4",
@@ -1552,6 +1572,7 @@ def test_infer_target_version(self) -> None:
                     TargetVersion.PY39,
                     TargetVersion.PY310,
                     TargetVersion.PY311,
+                    TargetVersion.PY312,
                 ],
             ),
             (
@@ -1566,6 +1587,7 @@ def test_infer_target_version(self) -> None:
                     TargetVersion.PY39,
                     TargetVersion.PY310,
                     TargetVersion.PY311,
+                    TargetVersion.PY312,
                 ],
             ),
             ("==3.8.*", [TargetVersion.PY38]),

tests/test_format.py

@@ -134,6 +134,13 @@ def test_python_311(filename: str) -> None:
     assert_format(source, expected, mode, minimum_version=(3, 11))
 
 
+@pytest.mark.parametrize("filename", all_data_cases("py_312"))
+def test_python_312(filename: str) -> None:
+    source, expected = read_data("py_312", filename)
+    mode = black.Mode(target_versions={black.TargetVersion.PY312})
+    assert_format(source, expected, mode, minimum_version=(3, 12))
+
+
 @pytest.mark.parametrize("filename", all_data_cases("fast"))
 def test_fast_cases(filename: str) -> None:
     source, expected = read_data("fast", filename)