[ruff] Added cls.__dict__.get('__annotations__') check (RUF063) (#18233)

Added `cls.__dict__.get('__annotations__')` check for Python 3.10+ and
Python < 3.10 with `typing-extensions` enabled.

Closes #17853 

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## Summary

Added `cls.__dict__.get('__annotations__')` check for Python 3.10+ and
Python < 3.10 with `typing-extensions` enabled.

## Test Plan

`cargo test`

---------

Co-authored-by: Brent Westbrook <36778786+ntBre@users.noreply.github.com>
Co-authored-by: Micha Reiser <micha@reiser.io>

crates/ruff_linter/resources/test/fixtures/ruff/RUF063.py

@@ -0,0 +1,18 @@
+# RUF063
+# Cases that should trigger the violation
+
+foo.__dict__.get("__annotations__")  # RUF063
+foo.__dict__.get("__annotations__", None)  # RUF063
+foo.__dict__.get("__annotations__", {})  # RUF063
+foo.__dict__["__annotations__"]  # RUF063
+
+# Cases that should NOT trigger the violation
+
+foo.__dict__.get("not__annotations__")
+foo.__dict__.get("not__annotations__", None)
+foo.__dict__.get("not__annotations__", {})
+foo.__dict__["not__annotations__"]
+foo.__annotations__
+foo.get("__annotations__")
+foo.get("__annotations__", None)
+foo.get("__annotations__", {})

crates/ruff_linter/src/checkers/ast/analyze/expression.rs

@@ -179,6 +179,9 @@ pub(crate) fn expression(expr: &Expr, checker: &Checker) {
             if checker.enabled(Rule::MissingMaxsplitArg) {
                 pylint::rules::missing_maxsplit_arg(checker, value, slice, expr);
             }
+            if checker.enabled(Rule::AccessAnnotationsFromClassDict) {
+                ruff::rules::access_annotations_from_class_dict_by_key(checker, subscript);
+            }
             pandas_vet::rules::subscript(checker, value, expr);
         }
         Expr::Tuple(ast::ExprTuple {
@@ -1196,6 +1199,9 @@ pub(crate) fn expression(expr: &Expr, checker: &Checker) {
             if checker.enabled(Rule::StarmapZip) {
                 ruff::rules::starmap_zip(checker, call);
             }
+            if checker.enabled(Rule::AccessAnnotationsFromClassDict) {
+                ruff::rules::access_annotations_from_class_dict_with_get(checker, call);
+            }
             if checker.enabled(Rule::LogExceptionOutsideExceptHandler) {
                 flake8_logging::rules::log_exception_outside_except_handler(checker, call);
             }

crates/ruff_linter/src/codes.rs

@@ -1028,6 +1028,7 @@ pub fn code_to_rule(linter: Linter, code: &str) -> Option<(RuleGroup, Rule)> {
         (Ruff, "059") => (RuleGroup::Preview, rules::ruff::rules::UnusedUnpackedVariable),
         (Ruff, "060") => (RuleGroup::Preview, rules::ruff::rules::InEmptyCollection),
         (Ruff, "061") => (RuleGroup::Preview, rules::ruff::rules::LegacyFormPytestRaises),
+        (Ruff, "063") => (RuleGroup::Preview, rules::ruff::rules::AccessAnnotationsFromClassDict),
         (Ruff, "064") => (RuleGroup::Preview, rules::ruff::rules::NonOctalPermissions),
         (Ruff, "100") => (RuleGroup::Stable, rules::ruff::rules::UnusedNOQA),
         (Ruff, "101") => (RuleGroup::Stable, rules::ruff::rules::RedirectedNOQA),

crates/ruff_linter/src/rules/ruff/mod.rs

@@ -171,6 +171,60 @@ mod tests {
         Ok(())
     }
 
+    #[test]
+    fn access_annotations_from_class_dict_py39_no_typing_extensions() -> Result<()> {
+        let diagnostics = test_path(
+            Path::new("ruff/RUF063.py"),
+            &LinterSettings {
+                typing_extensions: false,
+                unresolved_target_version: PythonVersion::PY39.into(),
+                ..LinterSettings::for_rule(Rule::AccessAnnotationsFromClassDict)
+            },
+        )?;
+        assert_diagnostics!(diagnostics);
+        Ok(())
+    }
+
+    #[test]
+    fn access_annotations_from_class_dict_py39_with_typing_extensions() -> Result<()> {
+        let diagnostics = test_path(
+            Path::new("ruff/RUF063.py"),
+            &LinterSettings {
+                typing_extensions: true,
+                unresolved_target_version: PythonVersion::PY39.into(),
+                ..LinterSettings::for_rule(Rule::AccessAnnotationsFromClassDict)
+            },
+        )?;
+        assert_diagnostics!(diagnostics);
+        Ok(())
+    }
+
+    #[test]
+    fn access_annotations_from_class_dict_py310() -> Result<()> {
+        let diagnostics = test_path(
+            Path::new("ruff/RUF063.py"),
+            &LinterSettings {
+                unresolved_target_version: PythonVersion::PY310.into(),
+                ..LinterSettings::for_rule(Rule::AccessAnnotationsFromClassDict)
+            },
+        )?;
+        assert_diagnostics!(diagnostics);
+        Ok(())
+    }
+
+    #[test]
+    fn access_annotations_from_class_dict_py314() -> Result<()> {
+        let diagnostics = test_path(
+            Path::new("ruff/RUF063.py"),
+            &LinterSettings {
+                unresolved_target_version: PythonVersion::PY314.into(),
+                ..LinterSettings::for_rule(Rule::AccessAnnotationsFromClassDict)
+            },
+        )?;
+        assert_diagnostics!(diagnostics);
+        Ok(())
+    }
+
     #[test]
     fn confusables() -> Result<()> {
         let diagnostics = test_path(

crates/ruff_linter/src/rules/ruff/rules/access_annotations_from_class_dict.rs

@@ -0,0 +1,185 @@
+use crate::checkers::ast::Checker;
+use crate::{FixAvailability, Violation};
+use ruff_macros::{ViolationMetadata, derive_message_formats};
+use ruff_python_ast::{Expr, ExprCall, ExprSubscript, PythonVersion};
+use ruff_text_size::Ranged;
+
+/// ## What it does
+/// Checks for uses of `foo.__dict__.get("__annotations__")` or
+/// `foo.__dict__["__annotations__"]` on Python 3.10+ and Python < 3.10 when
+/// [typing-extensions](https://docs.astral.sh/ruff/settings/#lint_typing-extensions)
+/// is enabled.
+///
+/// ## Why is this bad?
+/// Starting with Python 3.14, directly accessing `__annotations__` via
+/// `foo.__dict__.get("__annotations__")` or `foo.__dict__["__annotations__"]`
+/// will only return annotations if the class is defined under
+/// `from __future__ import annotations`.
+///
+/// Therefore, it is better to use dedicated library functions like
+/// `annotationlib.get_annotations` (Python 3.14+), `inspect.get_annotations`
+/// (Python 3.10+), or `typing_extensions.get_annotations` (for Python < 3.10 if
+/// [typing-extensions](https://pypi.org/project/typing-extensions/) is
+/// available).
+///
+/// The benefits of using these functions include:
+/// 1.  **Avoiding Undocumented Internals:** They provide a stable, public API,
+///     unlike direct `__dict__` access which relies on implementation details.
+/// 2.  **Forward-Compatibility:** They are designed to handle changes in
+///     Python's annotation system across versions, ensuring your code remains
+///     robust (e.g., correctly handling the Python 3.14 behavior mentioned
+///     above).
+///
+/// See [Python Annotations Best Practices](https://docs.python.org/3.14/howto/annotations.html)
+/// for alternatives.
+///
+/// ## Example
+///
+/// ```python
+/// foo.__dict__.get("__annotations__", {})
+/// # or
+/// foo.__dict__["__annotations__"]
+/// ```
+///
+/// On Python 3.14+, use instead:
+/// ```python
+/// import annotationlib
+///
+/// annotationlib.get_annotations(foo)
+/// ```
+///
+/// On Python 3.10+, use instead:
+/// ```python
+/// import inspect
+///
+/// inspect.get_annotations(foo)
+/// ```
+///
+/// On Python < 3.10 with [typing-extensions](https://pypi.org/project/typing-extensions/)
+/// installed, use instead:
+/// ```python
+/// import typing_extensions
+///
+/// typing_extensions.get_annotations(foo)
+/// ```
+///
+/// ## Fix safety
+///
+/// No autofix is currently provided for this rule.
+///
+/// ## Fix availability
+///
+/// No autofix is currently provided for this rule.
+///
+/// ## References
+/// - [Python Annotations Best Practices](https://docs.python.org/3.14/howto/annotations.html)
+#[derive(ViolationMetadata)]
+pub(crate) struct AccessAnnotationsFromClassDict {
+    python_version: PythonVersion,
+}
+
+impl Violation for AccessAnnotationsFromClassDict {
+    const FIX_AVAILABILITY: FixAvailability = FixAvailability::None;
+
+    #[derive_message_formats]
+    fn message(&self) -> String {
+        let suggestion = if self.python_version >= PythonVersion::PY314 {
+            "annotationlib.get_annotations"
+        } else if self.python_version >= PythonVersion::PY310 {
+            "inspect.get_annotations"
+        } else {
+            "typing_extensions.get_annotations"
+        };
+        format!("Use `{suggestion}` instead of `__dict__` access")
+    }
+}
+
+/// RUF063
+pub(crate) fn access_annotations_from_class_dict_with_get(checker: &Checker, call: &ExprCall) {
+    let python_version = checker.target_version();
+    let typing_extensions = checker.settings.typing_extensions;
+
+    // Only apply this rule for Python 3.10 and newer unless `typing-extensions` is enabled.
+    if python_version < PythonVersion::PY310 && !typing_extensions {
+        return;
+    }
+
+    // Expected pattern: foo.__dict__.get("__annotations__" [, <default>])
+    // Here, `call` is the `.get(...)` part.
+
+    // 1. Check that the `call.func` is `get`
+    let get_attribute = match call.func.as_ref() {
+        Expr::Attribute(attr) if attr.attr.as_str() == "get" => attr,
+        _ => return,
+    };
+
+    // 2. Check that the `get_attribute.value` is `__dict__`
+    match get_attribute.value.as_ref() {
+        Expr::Attribute(attr) if attr.attr.as_str() == "__dict__" => {}
+        _ => return,
+    }
+
+    // At this point, we have `foo.__dict__.get`.
+
+    // 3. Check arguments to `.get()`:
+    //    - No keyword arguments.
+    //    - One or two positional arguments.
+    //    - First positional argument must be the string literal "__annotations__".
+    //    - The value of the second positional argument (if present) does not affect the match.
+    if !call.arguments.keywords.is_empty() || call.arguments.len() > 2 {
+        return;
+    }
+
+    let Some(first_arg) = &call.arguments.find_positional(0) else {
+        return;
+    };
+
+    let is_first_arg_correct = first_arg
+        .as_string_literal_expr()
+        .is_some_and(|s| s.value.to_str() == "__annotations__");
+
+    if is_first_arg_correct {
+        checker.report_diagnostic(
+            AccessAnnotationsFromClassDict { python_version },
+            call.range(),
+        );
+    }
+}
+
+/// RUF063
+pub(crate) fn access_annotations_from_class_dict_by_key(
+    checker: &Checker,
+    subscript: &ExprSubscript,
+) {
+    let python_version = checker.target_version();
+    let typing_extensions = checker.settings.typing_extensions;
+
+    // Only apply this rule for Python 3.10 and newer unless `typing-extensions` is enabled.
+    if python_version < PythonVersion::PY310 && !typing_extensions {
+        return;
+    }
+
+    // Expected pattern: foo.__dict__["__annotations__"]
+
+    // 1. Check that the slice is a string literal "__annotations__"
+    if subscript
+        .slice
+        .as_string_literal_expr()
+        .is_none_or(|s| s.value.to_str() != "__annotations__")
+    {
+        return;
+    }
+
+    // 2. Check that the `subscript.value` is `__dict__`
+    let is_value_correct = subscript
+        .value
+        .as_attribute_expr()
+        .is_some_and(|attr| attr.attr.as_str() == "__dict__");
+
+    if is_value_correct {
+        checker.report_diagnostic(
+            AccessAnnotationsFromClassDict { python_version },
+            subscript.range(),
+        );
+    }
+}

crates/ruff_linter/src/rules/ruff/rules/mod.rs

@@ -1,3 +1,4 @@
+pub(crate) use access_annotations_from_class_dict::*;
 pub(crate) use ambiguous_unicode_character::*;
 pub(crate) use assert_with_print_message::*;
 pub(crate) use assignment_in_assert::*;
@@ -59,6 +60,7 @@ pub(crate) use used_dummy_variable::*;
 pub(crate) use useless_if_else::*;
 pub(crate) use zip_instead_of_pairwise::*;
 
+mod access_annotations_from_class_dict;
 mod ambiguous_unicode_character;
 mod assert_with_print_message;
 mod assignment_in_assert;

crates/ruff_linter/src/rules/ruff/snapshots/ruff_linter__rules__ruff__tests__access_annotations_from_class_dict_py310.snap

@@ -0,0 +1,40 @@
+---
+source: crates/ruff_linter/src/rules/ruff/mod.rs
+---
+RUF063.py:4:1: RUF063 Use `inspect.get_annotations` instead of `__dict__` access
+  |
+2 | # Cases that should trigger the violation
+3 |
+4 | foo.__dict__.get("__annotations__")  # RUF063
+  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ RUF063
+5 | foo.__dict__.get("__annotations__", None)  # RUF063
+6 | foo.__dict__.get("__annotations__", {})  # RUF063
+  |
+
+RUF063.py:5:1: RUF063 Use `inspect.get_annotations` instead of `__dict__` access
+  |
+4 | foo.__dict__.get("__annotations__")  # RUF063
+5 | foo.__dict__.get("__annotations__", None)  # RUF063
+  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ RUF063
+6 | foo.__dict__.get("__annotations__", {})  # RUF063
+7 | foo.__dict__["__annotations__"]  # RUF063
+  |
+
+RUF063.py:6:1: RUF063 Use `inspect.get_annotations` instead of `__dict__` access
+  |
+4 | foo.__dict__.get("__annotations__")  # RUF063
+5 | foo.__dict__.get("__annotations__", None)  # RUF063
+6 | foo.__dict__.get("__annotations__", {})  # RUF063
+  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ RUF063
+7 | foo.__dict__["__annotations__"]  # RUF063
+  |
+
+RUF063.py:7:1: RUF063 Use `inspect.get_annotations` instead of `__dict__` access
+  |
+5 | foo.__dict__.get("__annotations__", None)  # RUF063
+6 | foo.__dict__.get("__annotations__", {})  # RUF063
+7 | foo.__dict__["__annotations__"]  # RUF063
+  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ RUF063
+8 |
+9 | # Cases that should NOT trigger the violation
+  |

crates/ruff_linter/src/rules/ruff/snapshots/ruff_linter__rules__ruff__tests__access_annotations_from_class_dict_py314.snap

@@ -0,0 +1,40 @@
+---
+source: crates/ruff_linter/src/rules/ruff/mod.rs
+---
+RUF063.py:4:1: RUF063 Use `annotationlib.get_annotations` instead of `__dict__` access
+  |
+2 | # Cases that should trigger the violation
+3 |
+4 | foo.__dict__.get("__annotations__")  # RUF063
+  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ RUF063
+5 | foo.__dict__.get("__annotations__", None)  # RUF063
+6 | foo.__dict__.get("__annotations__", {})  # RUF063
+  |
+
+RUF063.py:5:1: RUF063 Use `annotationlib.get_annotations` instead of `__dict__` access
+  |
+4 | foo.__dict__.get("__annotations__")  # RUF063
+5 | foo.__dict__.get("__annotations__", None)  # RUF063
+  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ RUF063
+6 | foo.__dict__.get("__annotations__", {})  # RUF063
+7 | foo.__dict__["__annotations__"]  # RUF063
+  |
+
+RUF063.py:6:1: RUF063 Use `annotationlib.get_annotations` instead of `__dict__` access
+  |
+4 | foo.__dict__.get("__annotations__")  # RUF063
+5 | foo.__dict__.get("__annotations__", None)  # RUF063
+6 | foo.__dict__.get("__annotations__", {})  # RUF063
+  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ RUF063
+7 | foo.__dict__["__annotations__"]  # RUF063
+  |
+
+RUF063.py:7:1: RUF063 Use `annotationlib.get_annotations` instead of `__dict__` access
+  |
+5 | foo.__dict__.get("__annotations__", None)  # RUF063
+6 | foo.__dict__.get("__annotations__", {})  # RUF063
+7 | foo.__dict__["__annotations__"]  # RUF063
+  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ RUF063
+8 |
+9 | # Cases that should NOT trigger the violation
+  |

crates/ruff_linter/src/rules/ruff/snapshots/ruff_linter__rules__ruff__tests__access_annotations_from_class_dict_py39_no_typing_extensions.snap

@@ -0,0 +1,4 @@
+---
+source: crates/ruff_linter/src/rules/ruff/mod.rs
+---
+

crates/ruff_linter/src/rules/ruff/snapshots/ruff_linter__rules__ruff__tests__access_annotations_from_class_dict_py39_with_typing_extensions.snap

@@ -0,0 +1,40 @@
+---
+source: crates/ruff_linter/src/rules/ruff/mod.rs
+---
+RUF063.py:4:1: RUF063 Use `typing_extensions.get_annotations` instead of `__dict__` access
+  |
+2 | # Cases that should trigger the violation
+3 |
+4 | foo.__dict__.get("__annotations__")  # RUF063
+  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ RUF063
+5 | foo.__dict__.get("__annotations__", None)  # RUF063
+6 | foo.__dict__.get("__annotations__", {})  # RUF063
+  |
+
+RUF063.py:5:1: RUF063 Use `typing_extensions.get_annotations` instead of `__dict__` access
+  |
+4 | foo.__dict__.get("__annotations__")  # RUF063
+5 | foo.__dict__.get("__annotations__", None)  # RUF063
+  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ RUF063
+6 | foo.__dict__.get("__annotations__", {})  # RUF063
+7 | foo.__dict__["__annotations__"]  # RUF063
+  |
+
+RUF063.py:6:1: RUF063 Use `typing_extensions.get_annotations` instead of `__dict__` access
+  |
+4 | foo.__dict__.get("__annotations__")  # RUF063
+5 | foo.__dict__.get("__annotations__", None)  # RUF063
+6 | foo.__dict__.get("__annotations__", {})  # RUF063
+  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ RUF063
+7 | foo.__dict__["__annotations__"]  # RUF063
+  |
+
+RUF063.py:7:1: RUF063 Use `typing_extensions.get_annotations` instead of `__dict__` access
+  |
+5 | foo.__dict__.get("__annotations__", None)  # RUF063
+6 | foo.__dict__.get("__annotations__", {})  # RUF063
+7 | foo.__dict__["__annotations__"]  # RUF063
+  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ RUF063
+8 |
+9 | # Cases that should NOT trigger the violation
+  |

ruff.schema.json

@@ -4040,6 +4040,7 @@
         "RUF06",
         "RUF060",
         "RUF061",
+        "RUF063",
         "RUF064",
         "RUF1",
         "RUF10",