[ruff] Add non-empty-init-module (RUF067)

crates/ruff/tests/cli/snapshots/cli__lint__requires_python_extend_from_shared_config.snap

@@ -261,6 +261,7 @@ linter.pylint.max_locals = 15
 linter.pylint.max_nested_blocks = 5
 linter.pyupgrade.keep_runtime_typing = false
 linter.ruff.parenthesize_tuple_in_subscript = false
+linter.ruff.strictly_empty_init_modules = false
 
 # Formatter Settings
 formatter.exclude = []

crates/ruff/tests/cli/snapshots/cli__lint__requires_python_no_tool.snap

@@ -263,6 +263,7 @@ linter.pylint.max_locals = 15
 linter.pylint.max_nested_blocks = 5
 linter.pyupgrade.keep_runtime_typing = false
 linter.ruff.parenthesize_tuple_in_subscript = false
+linter.ruff.strictly_empty_init_modules = false
 
 # Formatter Settings
 formatter.exclude = []

crates/ruff/tests/cli/snapshots/cli__lint__requires_python_no_tool_preview_enabled.snap

@@ -265,6 +265,7 @@ linter.pylint.max_locals = 15
 linter.pylint.max_nested_blocks = 5
 linter.pyupgrade.keep_runtime_typing = false
 linter.ruff.parenthesize_tuple_in_subscript = false
+linter.ruff.strictly_empty_init_modules = false
 
 # Formatter Settings
 formatter.exclude = []

crates/ruff/tests/cli/snapshots/cli__lint__requires_python_no_tool_target_version_override.snap

@@ -265,6 +265,7 @@ linter.pylint.max_locals = 15
 linter.pylint.max_nested_blocks = 5
 linter.pyupgrade.keep_runtime_typing = false
 linter.ruff.parenthesize_tuple_in_subscript = false
+linter.ruff.strictly_empty_init_modules = false
 
 # Formatter Settings
 formatter.exclude = []

crates/ruff/tests/cli/snapshots/cli__lint__requires_python_pyproject_toml_above.snap

@@ -262,6 +262,7 @@ linter.pylint.max_locals = 15
 linter.pylint.max_nested_blocks = 5
 linter.pyupgrade.keep_runtime_typing = false
 linter.ruff.parenthesize_tuple_in_subscript = false
+linter.ruff.strictly_empty_init_modules = false
 
 # Formatter Settings
 formatter.exclude = []

crates/ruff/tests/cli/snapshots/cli__lint__requires_python_pyproject_toml_above_with_tool.snap

@@ -262,6 +262,7 @@ linter.pylint.max_locals = 15
 linter.pylint.max_nested_blocks = 5
 linter.pyupgrade.keep_runtime_typing = false
 linter.ruff.parenthesize_tuple_in_subscript = false
+linter.ruff.strictly_empty_init_modules = false
 
 # Formatter Settings
 formatter.exclude = []

crates/ruff/tests/cli/snapshots/cli__lint__requires_python_ruff_toml_above-2.snap

@@ -261,6 +261,7 @@ linter.pylint.max_locals = 15
 linter.pylint.max_nested_blocks = 5
 linter.pyupgrade.keep_runtime_typing = false
 linter.ruff.parenthesize_tuple_in_subscript = false
+linter.ruff.strictly_empty_init_modules = false
 
 # Formatter Settings
 formatter.exclude = []

crates/ruff/tests/cli/snapshots/cli__lint__requires_python_ruff_toml_above.snap

@@ -261,6 +261,7 @@ linter.pylint.max_locals = 15
 linter.pylint.max_nested_blocks = 5
 linter.pyupgrade.keep_runtime_typing = false
 linter.ruff.parenthesize_tuple_in_subscript = false
+linter.ruff.strictly_empty_init_modules = false
 
 # Formatter Settings
 formatter.exclude = []

crates/ruff/tests/cli/snapshots/cli__lint__requires_python_ruff_toml_no_target_fallback.snap

@@ -261,6 +261,7 @@ linter.pylint.max_locals = 15
 linter.pylint.max_nested_blocks = 5
 linter.pyupgrade.keep_runtime_typing = false
 linter.ruff.parenthesize_tuple_in_subscript = false
+linter.ruff.strictly_empty_init_modules = false
 
 # Formatter Settings
 formatter.exclude = []

crates/ruff/tests/snapshots/show_settings__display_default_settings.snap

@@ -374,6 +374,7 @@ linter.pylint.max_locals = 15
 linter.pylint.max_nested_blocks = 5
 linter.pyupgrade.keep_runtime_typing = false
 linter.ruff.parenthesize_tuple_in_subscript = false
+linter.ruff.strictly_empty_init_modules = false
 
 # Formatter Settings
 formatter.exclude = []

crates/ruff_linter/resources/test/fixtures/ruff/RUF067/modules/__init__.py

@@ -0,0 +1,51 @@
+"""This is the module docstring."""
+
+# convenience imports:
+import os
+from pathlib import Path
+
+__all__ = ["MY_CONSTANT"]
+__all__ += ["foo"]
+__all__: list[str] = __all__
+__all__ = __all__ = __all__
+
+MY_CONSTANT = 5
+"""This is an important constant."""
+
+os.environ["FOO"] = 1
+
+
+def foo():
+    return Path("foo.py")
+
+def __getattr__(name):  # ok
+    return name
+
+__path__ = __import__('pkgutil').extend_path(__path__, __name__)  # ok
+
+if os.environ["FOO"] != "1":  # RUF067
+    MY_CONSTANT = 4  # ok, don't flag nested statements
+
+if TYPE_CHECKING:  # ok
+    MY_CONSTANT = 3
+
+import typing
+
+if typing.TYPE_CHECKING: # ok
+    MY_CONSTANT = 2
+
+__version__ = "1.2.3"  # ok
+
+def __dir__():  # ok
+    return ["foo"]
+
+import pkgutil
+
+__path__ = pkgutil.extend_path(__path__, __name__)  # ok
+__path__ = unknown.extend_path(__path__, __name__)  # also ok
+
+# non-`extend_path` assignments are not allowed
+__path__ = 5  # RUF067
+
+# also allow `__author__`
+__author__ = "The Author"  # ok

crates/ruff_linter/resources/test/fixtures/ruff/RUF067/modules/okay.py

@@ -0,0 +1,54 @@
+"""
+The code here is not in an `__init__.py` file and should not trigger the
+lint.
+"""
+
+# convenience imports:
+import os
+from pathlib import Path
+
+__all__ = ["MY_CONSTANT"]
+__all__ += ["foo"]
+__all__: list[str] = __all__
+__all__ = __all__ = __all__
+
+MY_CONSTANT = 5
+"""This is an important constant."""
+
+os.environ["FOO"] = 1
+
+
+def foo():
+    return Path("foo.py")
+
+def __getattr__(name):  # ok
+    return name
+
+__path__ = __import__('pkgutil').extend_path(__path__, __name__)  # ok
+
+if os.environ["FOO"] != "1":  # RUF067
+    MY_CONSTANT = 4  # ok, don't flag nested statements
+
+if TYPE_CHECKING:  # ok
+    MY_CONSTANT = 3
+
+import typing
+
+if typing.TYPE_CHECKING: # ok
+    MY_CONSTANT = 2
+
+__version__ = "1.2.3"  # ok
+
+def __dir__():  # ok
+    return ["foo"]
+
+import pkgutil
+
+__path__ = pkgutil.extend_path(__path__, __name__)  # ok
+__path__ = unknown.extend_path(__path__, __name__)  # also ok
+
+# non-`extend_path` assignments are not allowed
+__path__ = 5  # RUF067
+
+# also allow `__author__`
+__author__ = "The Author"  # ok

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

@@ -1630,4 +1630,7 @@ pub(crate) fn statement(stmt: &Stmt, checker: &mut Checker) {
         }
         _ => {}
     }
+    if checker.is_rule_enabled(Rule::NonEmptyInitModule) {
+        ruff::rules::non_empty_init_module(checker, stmt);
+    }
 }

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

@@ -33,7 +33,7 @@ pub(crate) fn unresolved_references(checker: &Checker) {
                 }
 
                 // Allow __path__.
-                if checker.path.ends_with("__init__.py") {
+                if checker.in_init_module() {
                     if reference.name(checker.source()) == "__path__" {
                         continue;
                     }

crates/ruff_linter/src/checkers/ast/mod.rs

@@ -21,7 +21,7 @@
 //! represents the lint-rule analysis phase. In the future, these steps may be separated into
 //! distinct passes over the AST.
 
-use std::cell::RefCell;
+use std::cell::{OnceCell, RefCell};
 use std::path::Path;
 
 use itertools::Itertools;
@@ -198,6 +198,8 @@ pub(crate) struct Checker<'a> {
     parsed_type_annotation: Option<&'a ParsedAnnotation>,
     /// The [`Path`] to the file under analysis.
     path: &'a Path,
+    /// Whether `path` points to an `__init__.py` file.
+    in_init_module: OnceCell<bool>,
     /// The [`Path`] to the package containing the current file.
     package: Option<PackageRoot<'a>>,
     /// The module representation of the current file (e.g., `foo.bar`).
@@ -274,6 +276,7 @@ impl<'a> Checker<'a> {
             noqa_line_for,
             noqa,
             path,
+            in_init_module: OnceCell::new(),
             package,
             module,
             source_type,
@@ -482,9 +485,11 @@ impl<'a> Checker<'a> {
         self.context.settings
     }
 
-    /// The [`Path`] to the file under analysis.
-    pub(crate) const fn path(&self) -> &'a Path {
-        self.path
+    /// Returns whether the file under analysis is an `__init__.py` file.
+    pub(crate) fn in_init_module(&self) -> bool {
+        *self
+            .in_init_module
+            .get_or_init(|| self.path.ends_with("__init__.py"))
     }
 
     /// The [`Path`] to the package containing the current file.
@@ -3171,7 +3176,7 @@ impl<'a> Checker<'a> {
                         // F822
                         if self.is_rule_enabled(Rule::UndefinedExport) {
                             if is_undefined_export_in_dunder_init_enabled(self.settings())
-                                || !self.path.ends_with("__init__.py")
+                                || !self.in_init_module()
                             {
                                 self.report_diagnostic(
                                     pyflakes::rules::UndefinedExport {

crates/ruff_linter/src/codes.rs

@@ -1060,6 +1060,7 @@ pub fn code_to_rule(linter: Linter, code: &str) -> Option<(RuleGroup, Rule)> {
         (Ruff, "064") => rules::ruff::rules::NonOctalPermissions,
         (Ruff, "065") => rules::ruff::rules::LoggingEagerConversion,
         (Ruff, "066") => rules::ruff::rules::PropertyWithoutReturn,
+        (Ruff, "067") => rules::ruff::rules::NonEmptyInitModule,
 
         (Ruff, "100") => rules::ruff::rules::UnusedNOQA,
         (Ruff, "101") => rules::ruff::rules::RedirectedNOQA,

crates/ruff_linter/src/rules/pyflakes/rules/unused_import.rs

@@ -389,7 +389,7 @@ pub(crate) fn unused_import(checker: &Checker, scope: &Scope) {
         }
     }
 
-    let in_init = checker.path().ends_with("__init__.py");
+    let in_init = checker.in_init_module();
     let fix_init = !checker.settings().ignore_init_module_imports;
     let preview_mode = is_dunder_init_fix_unused_import_enabled(checker.settings());
     let dunder_all_exprs = find_dunder_all_exprs(checker.semantic());

crates/ruff_linter/src/rules/pylint/rules/useless_import_alias.rs

@@ -77,7 +77,7 @@ pub(crate) fn useless_import_alias(checker: &Checker, alias: &Alias) {
     }
 
     // A re-export in __init__.py is probably intentional.
-    if checker.path().ends_with("__init__.py") {
+    if checker.in_init_module() {
         return;
     }
 
@@ -116,7 +116,7 @@ pub(crate) fn useless_import_from_alias(
     }
 
     // A re-export in __init__.py is probably intentional.
-    if checker.path().ends_with("__init__.py") {
+    if checker.in_init_module() {
         return;
     }
 

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

@@ -119,6 +119,8 @@ mod tests {
     #[test_case(Rule::RedirectedNOQA, Path::new("RUF101_0.py"))]
     #[test_case(Rule::RedirectedNOQA, Path::new("RUF101_1.py"))]
     #[test_case(Rule::InvalidRuleCode, Path::new("RUF102.py"))]
+    #[test_case(Rule::NonEmptyInitModule, Path::new("RUF067/modules/__init__.py"))]
+    #[test_case(Rule::NonEmptyInitModule, Path::new("RUF067/modules/okay.py"))]
     fn rules(rule_code: Rule, path: &Path) -> Result<()> {
         let snapshot = format!("{}_{}", rule_code.noqa_code(), path.to_string_lossy());
         let diagnostics = test_path(
@@ -136,6 +138,7 @@ mod tests {
             &LinterSettings {
                 ruff: super::settings::Settings {
                     parenthesize_tuple_in_subscript: true,
+                    ..super::settings::Settings::default()
                 },
                 ..LinterSettings::for_rule(Rule::IncorrectlyParenthesizedTupleInSubscript)
             },
@@ -151,6 +154,7 @@ mod tests {
             &LinterSettings {
                 ruff: super::settings::Settings {
                     parenthesize_tuple_in_subscript: false,
+                    ..super::settings::Settings::default()
                 },
                 unresolved_target_version: PythonVersion::PY310.into(),
                 ..LinterSettings::for_rule(Rule::IncorrectlyParenthesizedTupleInSubscript)
@@ -714,4 +718,26 @@ mod tests {
         assert_diagnostics!(snapshot, diagnostics);
         Ok(())
     }
+
+    #[test]
+    fn strictly_empty_init_modules_ruf067() -> Result<()> {
+        assert_diagnostics_diff!(
+            Path::new("ruff/RUF067/modules/__init__.py"),
+            &LinterSettings {
+                ruff: super::settings::Settings {
+                    strictly_empty_init_modules: false,
+                    ..super::settings::Settings::default()
+                },
+                ..LinterSettings::for_rule(Rule::NonEmptyInitModule)
+            },
+            &LinterSettings {
+                ruff: super::settings::Settings {
+                    strictly_empty_init_modules: true,
+                    ..super::settings::Settings::default()
+                },
+                ..LinterSettings::for_rule(Rule::NonEmptyInitModule)
+            },
+        );
+        Ok(())
+    }
 }

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

@@ -32,6 +32,7 @@ pub(crate) use mutable_dataclass_default::*;
 pub(crate) use mutable_fromkeys_value::*;
 pub(crate) use needless_else::*;
 pub(crate) use never_union::*;
+pub(crate) use non_empty_init_module::*;
 pub(crate) use non_octal_permissions::*;
 pub(crate) use none_not_at_end_of_union::*;
 pub(crate) use parenthesize_chained_operators::*;
@@ -99,6 +100,7 @@ mod mutable_dataclass_default;
 mod mutable_fromkeys_value;
 mod needless_else;
 mod never_union;
+mod non_empty_init_module;
 mod non_octal_permissions;
 mod none_not_at_end_of_union;
 mod parenthesize_chained_operators;