Add flake-pyi PYI033 "Do not use type comments in stubs"

I think this is also a case where people like want this for .py files, too, at least on 3.7+ (https://docs.python.org/3/whatsnew/3.7.html#pep-563-postponed-evaluation-of-annotations)

On that note, does none of the tools upgrade all type comments to type annotations automatically? I looked in pyupgrade and googled but couldn't find anything

crates/ruff/resources/test/fixtures/flake8_pyi/PYI033.py

@@ -0,0 +1,7 @@
+# OK
+x = 1 # type: int
+
+
+# OK
+def reverse(x):  # type:(str) -> str
+    ...

crates/ruff/resources/test/fixtures/flake8_pyi/PYI033.pyi

@@ -0,0 +1,7 @@
+# ERROR: PYI033 Don't use type comments in stub file
+x = 1 # type: int
+
+
+# ERROR: PYI033 Don't use type comments in stub file
+def reverse(x):  # type:(str) -> str
+  ...

crates/ruff/src/checkers/tokens.rs

@@ -7,8 +7,8 @@ use crate::lex::docstring_detection::StateMachine;
 use crate::registry::{Diagnostic, Rule};
 use crate::rules::ruff::rules::Context;
 use crate::rules::{
-    eradicate, flake8_commas, flake8_implicit_str_concat, flake8_quotes, pycodestyle, pyupgrade,
-    ruff,
+    eradicate, flake8_commas, flake8_implicit_str_concat, flake8_pyi, flake8_quotes, pycodestyle,
+    pyupgrade, ruff,
 };
 use crate::settings::{flags, Settings};
 use crate::source_code::Locator;
@@ -18,6 +18,7 @@ pub fn check_tokens(
     tokens: &[LexResult],
     settings: &Settings,
     autofix: flags::Autofix,
+    is_interface_definition: bool,
 ) -> Vec<Diagnostic> {
     let mut diagnostics: Vec<Diagnostic> = vec![];
 
@@ -55,6 +56,7 @@ pub fn check_tokens(
             .enabled(&Rule::TrailingCommaOnBareTupleProhibited)
         || settings.rules.enabled(&Rule::TrailingCommaProhibited);
     let enforce_extraneous_parenthesis = settings.rules.enabled(&Rule::ExtraneousParentheses);
+    let enforce_type_comment_in_stub = settings.rules.enabled(&Rule::TypeCommentInStub);
 
     // RUF001, RUF002, RUF003
     if enforce_ambiguous_unicode_character {
@@ -161,5 +163,10 @@ pub fn check_tokens(
         );
     }
 
+    // PYI033
+    if enforce_type_comment_in_stub && is_interface_definition {
+        diagnostics.extend(flake8_pyi::rules::type_comment_in_stub(tokens));
+    }
+
     diagnostics
 }

crates/ruff/src/codes.rs

@@ -500,6 +500,7 @@ pub fn code_to_rule(linter: Linter, code: &str) -> Option<Rule> {
         (Flake8Pyi, "011") => Rule::TypedArgumentSimpleDefaults,
         (Flake8Pyi, "014") => Rule::ArgumentSimpleDefaults,
         (Flake8Pyi, "021") => Rule::DocstringInStub,
+        (Flake8Pyi, "033") => Rule::TypeCommentInStub,
 
         // flake8-pytest-style
         (Flake8PytestStyle, "001") => Rule::IncorrectFixtureParenthesesStyle,

crates/ruff/src/linter.rs

@@ -21,6 +21,7 @@ use crate::doc_lines::{doc_lines_from_ast, doc_lines_from_tokens};
 use crate::message::{Message, Source};
 use crate::noqa::{add_noqa, rule_is_ignored};
 use crate::registry::{Diagnostic, Rule};
+use crate::resolver::is_interface_definition_path;
 use crate::rules::pycodestyle;
 use crate::settings::{flags, Settings};
 use crate::source_code::{Indexer, Locator, Stylist};
@@ -83,7 +84,14 @@ pub fn check_path(
         .iter_enabled()
         .any(|rule_code| rule_code.lint_source().is_tokens())
     {
-        diagnostics.extend(check_tokens(locator, &tokens, settings, autofix));
+        let is_interface_definition = is_interface_definition_path(path);
+        diagnostics.extend(check_tokens(
+            locator,
+            &tokens,
+            settings,
+            autofix,
+            is_interface_definition,
+        ));
     }
 
     // Run the filesystem-based rules.

crates/ruff/src/registry.rs

@@ -474,6 +474,7 @@ ruff_macros::register_rules!(
     rules::flake8_pyi::rules::DocstringInStub,
     rules::flake8_pyi::rules::TypedArgumentSimpleDefaults,
     rules::flake8_pyi::rules::ArgumentSimpleDefaults,
+    rules::flake8_pyi::rules::TypeCommentInStub,
     // flake8-pytest-style
     rules::flake8_pytest_style::rules::IncorrectFixtureParenthesesStyle,
     rules::flake8_pytest_style::rules::FixturePositionalArgs,
@@ -827,7 +828,8 @@ impl Rule {
             | Rule::MultipleStatementsOnOneLineColon
             | Rule::UselessSemicolon
             | Rule::MultipleStatementsOnOneLineSemicolon
-            | Rule::TrailingCommaProhibited => &LintSource::Tokens,
+            | Rule::TrailingCommaProhibited
+            | Rule::TypeCommentInStub => &LintSource::Tokens,
             Rule::IOError => &LintSource::Io,
             Rule::UnsortedImports | Rule::MissingRequiredImport => &LintSource::Imports,
             Rule::ImplicitNamespacePackage | Rule::InvalidModuleName => &LintSource::Filesystem,

crates/ruff/src/rules/flake8_pyi/mod.rs

@@ -31,6 +31,8 @@ mod tests {
     #[test_case(Rule::ArgumentSimpleDefaults, Path::new("PYI014.pyi"))]
     #[test_case(Rule::DocstringInStub, Path::new("PYI021.py"))]
     #[test_case(Rule::DocstringInStub, Path::new("PYI021.pyi"))]
+    #[test_case(Rule::TypeCommentInStub, Path::new("PYI033.py"))]
+    #[test_case(Rule::TypeCommentInStub, Path::new("PYI033.pyi"))]
     fn rules(rule_code: Rule, path: &Path) -> Result<()> {
         let snapshot = format!("{}_{}", rule_code.noqa_code(), path.to_string_lossy());
         let diagnostics = test_path(

crates/ruff/src/rules/flake8_pyi/rules/mod.rs

@@ -7,6 +7,7 @@ pub use simple_defaults::{
     argument_simple_defaults, typed_argument_simple_defaults, ArgumentSimpleDefaults,
     TypedArgumentSimpleDefaults,
 };
+pub use type_comment_in_stub::{type_comment_in_stub, TypeCommentInStub};
 pub use unrecognized_platform::{
     unrecognized_platform, UnrecognizedPlatformCheck, UnrecognizedPlatformName,
 };
@@ -17,4 +18,5 @@ mod non_empty_stub_body;
 mod pass_statement_stub_body;
 mod prefix_type_params;
 mod simple_defaults;
+mod type_comment_in_stub;
 mod unrecognized_platform;

crates/ruff/src/rules/flake8_pyi/rules/type_comment_in_stub.rs

@@ -0,0 +1,59 @@
+use rustpython_parser::lexer::LexResult;
+use rustpython_parser::Tok;
+
+use ruff_macros::{define_violation, derive_message_formats};
+
+use crate::registry::Diagnostic;
+use crate::violation::Violation;
+use crate::Range;
+
+define_violation!(
+    /// ## What it does
+    /// Do not use type comments (e.g. `x = 1 # type: int`) in stubs, even if
+    /// the stub supports Python 2. Always use annotations instead (e.g.
+    /// `x: int = 1`).
+    ///
+    /// ## Why is this bad?
+    /// You should use type annotation directly in pyi files.
+    ///
+    /// ## Example
+    /// ```python
+    /// x = 1 # type: int
+    /// ```
+    ///
+    /// Use instead:
+    /// ```python
+    /// x: int = 1
+    /// ```
+    pub struct TypeCommentInStub;
+);
+impl Violation for TypeCommentInStub {
+    #[derive_message_formats]
+    fn message(&self) -> String {
+        format!("Don't use type comments in stub file")
+    }
+}
+
+/// PYI033
+pub fn type_comment_in_stub(tokens: &[LexResult]) -> Vec<Diagnostic> {
+    let mut diagnostics = vec![];
+
+    for token in tokens.iter().flatten() {
+        if let (location, Tok::Comment(comment), end_location) = token {
+            // I couldn't find any PEP on the exact syntax (the closest being
+            // https://peps.python.org/pep-0484/#type-comments), but every case I saw used
+            // `# type:` verbatim so this seems to be the right thing to pick
+            if comment.starts_with("# type:") {
+                diagnostics.push(Diagnostic::new(
+                    TypeCommentInStub,
+                    Range {
+                        location: *location,
+                        end_location: *end_location,
+                    },
+                ));
+            }
+        }
+    }
+
+    diagnostics
+}

crates/ruff/src/rules/flake8_pyi/snapshots/ruff__rules__flake8_pyi__tests__PYI033_PYI033.py.snap

@@ -0,0 +1,6 @@
+---
+source: crates/ruff/src/rules/flake8_pyi/mod.rs
+expression: diagnostics
+---
+[]
+

crates/ruff/src/rules/flake8_pyi/snapshots/ruff__rules__flake8_pyi__tests__PYI033_PYI033.pyi.snap

@@ -0,0 +1,25 @@
+---
+source: crates/ruff/src/rules/flake8_pyi/mod.rs
+expression: diagnostics
+---
+- kind:
+    TypeCommentInStub: ~
+  location:
+    row: 2
+    column: 6
+  end_location:
+    row: 2
+    column: 17
+  fix: ~
+  parent: ~
+- kind:
+    TypeCommentInStub: ~
+  location:
+    row: 6
+    column: 17
+  end_location:
+    row: 6
+    column: 36
+  fix: ~
+  parent: ~
+

docs/configuration.md

@@ -206,6 +206,8 @@ Options:
           Run in watch mode by re-running whenever files change
       --fix-only
           Fix any fixable lint violations, but don't report on leftover violations. Implies `--fix`
+      --ignore-noqa
+          Ignore any `# noqa` comments
       --format <FORMAT>
           Output serialization format for violations [env: RUFF_FORMAT=] [possible values: text, json, junit, grouped, github, gitlab, pylint]
       --target-version <TARGET_VERSION>