Add unsupported version checks for major 3.11 and 3.12 features (#9792)

* Bump DEFAULT_PYTHON checks.yaml to 3.12

.github/workflows/checks.yaml

@@ -11,9 +11,9 @@ on:
       - "maintenance/**"
 
 env:
-  CACHE_VERSION: 1
+  CACHE_VERSION: 2
   KEY_PREFIX: base-venv
-  DEFAULT_PYTHON: "3.11"
+  DEFAULT_PYTHON: "3.12"
   PRE_COMMIT_CACHE: ~/.cache/pre-commit
 
 concurrency:

doc/data/messages/a/anomalous-backslash-in-string/bad.py

@@ -1 +1 @@
-string = "\z"  # [anomalous-backslash-in-string]
+string = "\z"  # [syntax-error]

doc/data/messages/a/anomalous-backslash-in-string/details.rst

@@ -1,2 +1,6 @@
 ``\z`` is same as ``\\z`` because there's no escape sequence for ``z``. But it is not clear
 for the reader of the code.
+
+The only reason this is demonstrated to raise ``syntax-error`` is because
+pylint's CI now runs on Python 3.12, where this truly raises a ``SyntaxError``.
+We hope to address this discrepancy in the documentation in the future.

doc/data/messages/a/anomalous-unicode-escape-in-string/bad.py

@@ -1 +1 @@
-print(b"\u%b" % b"0394")  # [anomalous-unicode-escape-in-string]
+print(b"\u%b" % b"0394")  # [syntax-error]

doc/data/messages/u/using-exception-groups-in-unsupported-version/bad.py

@@ -0,0 +1,12 @@
+def f():
+    excs = [OSError("error 1"), SystemError("error 2")]
+    # +1: [using-exception-groups-in-unsupported-version]
+    raise ExceptionGroup("there were problems", excs)
+
+
+try:  # [using-exception-groups-in-unsupported-version]
+    f()
+except* OSError as e:
+    print("There were OSErrors")
+except* SystemError as e:
+    print("There were SystemErrors")

doc/data/messages/u/using-exception-groups-in-unsupported-version/details.rst

@@ -0,0 +1 @@
+Exception groups were introduced in Python 3.11; to use it, please use a more recent version of Python.

doc/data/messages/u/using-exception-groups-in-unsupported-version/good.py

@@ -0,0 +1,10 @@
+def f():
+    raise OSError("error 1")
+
+
+try:
+    f()
+except OSError as e:
+    print("There were OSErrors")
+except SystemError as e:
+    print("There were SystemErrors")

doc/data/messages/u/using-exception-groups-in-unsupported-version/pylintrc

@@ -0,0 +1,2 @@
+[main]
+py-version=3.10

doc/data/messages/u/using-generic-type-syntax-in-unsupported-version/bad.py

@@ -0,0 +1 @@
+type Vector = list[float]  # [using-generic-type-syntax-in-unsupported-version]

doc/data/messages/u/using-generic-type-syntax-in-unsupported-version/details.rst

@@ -0,0 +1 @@
+Generic type syntax was introduced in Python 3.12; to use it, please use a more recent version of Python.

doc/data/messages/u/using-generic-type-syntax-in-unsupported-version/good.py

@@ -0,0 +1,3 @@
+from typing import TypeAlias
+
+Vector: TypeAlias = list[float]

doc/data/messages/u/using-generic-type-syntax-in-unsupported-version/pylintrc

@@ -0,0 +1,2 @@
+[main]
+py-version=3.11

doc/user_guide/checkers/features.rst

@@ -1351,9 +1351,15 @@ Verbatim name of the checker is ``unsupported_version``.
 
 Unsupported Version checker Messages
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+:using-exception-groups-in-unsupported-version (W2603): *Exception groups are not supported by all versions included in the py-version setting*
+  Used when the py-version set by the user is lower than 3.11 and pylint
+  encounters ``except*`` or `ExceptionGroup``.
 :using-f-string-in-unsupported-version (W2601): *F-strings are not supported by all versions included in the py-version setting*
   Used when the py-version set by the user is lower than 3.6 and pylint
   encounters an f-string.
+:using-generic-type-syntax-in-unsupported-version (W2604): *Generic type syntax (PEP 695) is not supported by all versions included in the py-version setting*
+  Used when the py-version set by the user is lower than 3.12 and pylint
+  encounters generic type syntax.
 :using-final-decorator-in-unsupported-version (W2602): *typing.final is not supported by all versions included in the py-version setting*
   Used when the py-version set by the user is lower than 3.8 and pylint
   encounters a ``typing.final`` decorator.

doc/user_guide/messages/messages_overview.rst

@@ -349,8 +349,10 @@ All messages in the warning category:
    warning/useless-type-doc
    warning/useless-with-lock
    warning/using-constant-test
+   warning/using-exception-groups-in-unsupported-version
    warning/using-f-string-in-unsupported-version
    warning/using-final-decorator-in-unsupported-version
+   warning/using-generic-type-syntax-in-unsupported-version
    warning/while-used
    warning/wildcard-import
    warning/wrong-exception-operation

doc/whatsnew/fragments/9791.new_check

@@ -0,0 +1,5 @@
+Add `using-exception-group-in-unsupported-version` and
+`using-generic-type-syntax-in-unsupported-version` for uses of Python 3.11+ or
+3.12+ features on lower supported versions provided with `--py-version`.
+
+Closes #9791

pylint/checkers/unsupported_version.py

@@ -42,13 +42,27 @@ class UnsupportedVersionChecker(BaseChecker):
             "Used when the py-version set by the user is lower than 3.8 and pylint encounters "
             "a ``typing.final`` decorator.",
         ),
+        "W2603": (
+            "Exception groups are not supported by all versions included in the py-version setting",
+            "using-exception-groups-in-unsupported-version",
+            "Used when the py-version set by the user is lower than 3.11 and pylint encounters "
+            "``except*`` or `ExceptionGroup``.",
+        ),
+        "W2604": (
+            "Generic type syntax (PEP 695) is not supported by all versions included in the py-version setting",
+            "using-generic-type-syntax-in-unsupported-version",
+            "Used when the py-version set by the user is lower than 3.12 and pylint encounters "
+            "generic type syntax.",
+        ),
     }
 
     def open(self) -> None:
         """Initialize visit variables and statistics."""
         py_version = self.linter.config.py_version
         self._py36_plus = py_version >= (3, 6)
         self._py38_plus = py_version >= (3, 8)
+        self._py311_plus = py_version >= (3, 11)
+        self._py312_plus = py_version >= (3, 12)
 
     @only_required_for_messages("using-f-string-in-unsupported-version")
     def visit_joinedstr(self, node: nodes.JoinedStr) -> None:
@@ -79,6 +93,51 @@ def _check_typing_final(self, node: nodes.Decorators) -> None:
                 "using-final-decorator-in-unsupported-version", node=decorator
             )
 
+    @only_required_for_messages("using-exception-groups-in-unsupported-version")
+    def visit_trystar(self, node: nodes.TryStar) -> None:
+        if not self._py311_plus:
+            self.add_message("using-exception-groups-in-unsupported-version", node=node)
+
+    @only_required_for_messages("using-exception-groups-in-unsupported-version")
+    def visit_excepthandler(self, node: nodes.ExceptHandler) -> None:
+        if (
+            not self._py311_plus
+            and isinstance(node.type, nodes.Name)
+            and node.type.name == "ExceptionGroup"
+        ):
+            self.add_message("using-exception-groups-in-unsupported-version", node=node)
+
+    @only_required_for_messages("using-exception-groups-in-unsupported-version")
+    def visit_raise(self, node: nodes.Raise) -> None:
+        if (
+            not self._py311_plus
+            and isinstance(node.exc, nodes.Call)
+            and isinstance(node.exc.func, nodes.Name)
+            and node.exc.func.name == "ExceptionGroup"
+        ):
+            self.add_message("using-exception-groups-in-unsupported-version", node=node)
+
+    @only_required_for_messages("using-generic-type-syntax-in-unsupported-version")
+    def visit_typealias(self, node: nodes.TypeAlias) -> None:
+        if not self._py312_plus:
+            self.add_message(
+                "using-generic-type-syntax-in-unsupported-version", node=node
+            )
+
+    @only_required_for_messages("using-generic-type-syntax-in-unsupported-version")
+    def visit_typevar(self, node: nodes.TypeVar) -> None:
+        if not self._py312_plus:
+            self.add_message(
+                "using-generic-type-syntax-in-unsupported-version", node=node
+            )
+
+    @only_required_for_messages("using-generic-type-syntax-in-unsupported-version")
+    def visit_typevartuple(self, node: nodes.TypeVarTuple) -> None:
+        if not self._py312_plus:
+            self.add_message(
+                "using-generic-type-syntax-in-unsupported-version", node=node
+            )
+
 
 def register(linter: PyLinter) -> None:
     linter.register_checker(UnsupportedVersionChecker(linter))

tests/functional/u/unsupported/unsupported_version_for_exception_group.py

@@ -0,0 +1,21 @@
+# pylint: disable=missing-function-docstring, missing-module-docstring
+def f():
+    excs = [OSError("error 1"), SystemError("error 2")]
+    # +1: [using-exception-groups-in-unsupported-version]
+    raise ExceptionGroup("there were problems", excs)
+
+
+try:  # [using-exception-groups-in-unsupported-version]
+    f()
+except* OSError as e:
+    print("There were OSErrors")
+except* SystemError as e:
+    print("There were SystemErrors")
+
+
+try:
+    f()
+except ExceptionGroup as group:  # [using-exception-groups-in-unsupported-version]
+    # https://github.com/pylint-dev/pylint/issues/8985
+    for exc in group.exceptions:  # pylint: disable=not-an-iterable
+        print("ERROR: ", exc)

tests/functional/u/unsupported/unsupported_version_for_exception_group.rc

@@ -0,0 +1,5 @@
+[main]
+py-version=3.10
+
+[testoptions]
+min_pyver=3.11

tests/functional/u/unsupported/unsupported_version_for_exception_group.txt

@@ -0,0 +1,3 @@
+using-exception-groups-in-unsupported-version:5:4:5:53:f:Exception groups are not supported by all versions included in the py-version setting:UNDEFINED
+using-exception-groups-in-unsupported-version:8:0:13:36::Exception groups are not supported by all versions included in the py-version setting:UNDEFINED
+using-exception-groups-in-unsupported-version:18:0:21:29::Exception groups are not supported by all versions included in the py-version setting:UNDEFINED

tests/functional/u/unsupported/unsupported_version_for_generic_type_syntax.py

@@ -0,0 +1,5 @@
+# pylint: disable=missing-function-docstring, missing-module-docstring, line-too-long
+# +1: [using-generic-type-syntax-in-unsupported-version, using-generic-type-syntax-in-unsupported-version]
+type Point[T] = tuple[float, float]
+# +1: [using-generic-type-syntax-in-unsupported-version, using-generic-type-syntax-in-unsupported-version]
+type Alias[*Ts] = tuple[*Ts]

tests/functional/u/unsupported/unsupported_version_for_generic_type_syntax.rc

@@ -0,0 +1,5 @@
+[main]
+py-version=3.11
+
+[testoptions]
+min_pyver=3.12

tests/functional/u/unsupported/unsupported_version_for_generic_type_syntax.txt

@@ -0,0 +1,4 @@
+using-generic-type-syntax-in-unsupported-version:3:0:3:35::Generic type syntax (PEP 695) is not supported by all versions included in the py-version setting:UNDEFINED
+using-generic-type-syntax-in-unsupported-version:3:11:3:12::Generic type syntax (PEP 695) is not supported by all versions included in the py-version setting:UNDEFINED
+using-generic-type-syntax-in-unsupported-version:5:0:5:28::Generic type syntax (PEP 695) is not supported by all versions included in the py-version setting:UNDEFINED
+using-generic-type-syntax-in-unsupported-version:5:11:5:14::Generic type syntax (PEP 695) is not supported by all versions included in the py-version setting:UNDEFINED