When checking module visibility, don't check entire ancestry (#3835)

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

@@ -60,6 +60,9 @@ mod tests {
     #[test_case(Rule::UndocumentedPublicMethod, Path::new("D.py"); "D102_0")]
     #[test_case(Rule::UndocumentedPublicMethod, Path::new("setter.py"); "D102_1")]
     #[test_case(Rule::UndocumentedPublicModule, Path::new("D.py"); "D100")]
+    #[test_case(Rule::UndocumentedPublicModule, Path::new("_unrelated/pkg/D100_pub.py"); "D100_ignore_unrelated_pub")]
+    #[test_case(Rule::UndocumentedPublicModule, Path::new("_unrelated/pkg/_priv/no_D100_priv.py"); "no_d100_priv")]
+    #[test_case(Rule::UndocumentedPublicModule, Path::new("_unrelated/_no_pkg_priv.py"); "no_d100_priv_script")]
     #[test_case(Rule::UndocumentedPublicNestedClass, Path::new("D.py"); "D106")]
     #[test_case(Rule::UndocumentedPublicPackage, Path::new("D.py"); "D104_0")]
     #[test_case(Rule::UndocumentedPublicPackage, Path::new("D104/__init__.py"); "D104_1")]

crates/ruff/src/rules/pydocstyle/snapshots/ruff__rules__pydocstyle__tests__D100__unrelated___no_pkg_priv.py.snap

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

crates/ruff/src/rules/pydocstyle/snapshots/ruff__rules__pydocstyle__tests__D100__unrelated__pkg__D100_pub.py.snap

@@ -0,0 +1,19 @@
+---
+source: crates/ruff/src/rules/pydocstyle/mod.rs
+expression: diagnostics
+---
+- kind:
+    name: UndocumentedPublicModule
+    body: Missing docstring in public module
+    suggestion: ~
+    fixable: false
+  location:
+    row: 1
+    column: 0
+  end_location:
+    row: 1
+    column: 0
+  fix:
+    edits: []
+  parent: ~
+

crates/ruff/src/rules/pydocstyle/snapshots/ruff__rules__pydocstyle__tests__D100__unrelated__pkg___priv__no_D100_priv.py.snap

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

crates/ruff_python_ast/src/context.rs

@@ -63,6 +63,7 @@ impl<'a> Context<'a> {
         path: &'a Path,
         module_path: Option<Vec<String>>,
     ) -> Self {
+        let visibility = module_visibility(module_path.as_deref(), path);
         Self {
             typing_modules,
             module_path,
@@ -79,7 +80,7 @@ impl<'a> Context<'a> {
             body_index: 0,
             visible_scope: VisibleScope {
                 modifier: Modifier::Module,
-                visibility: module_visibility(path),
+                visibility,
             },
             in_annotation: false,
             in_type_definition: false,

crates/ruff_python_ast/src/visibility.rs

@@ -131,28 +131,24 @@ fn stem(path: &str) -> &str {
 }
 
 /// Return the `Visibility` of the Python file at `Path` based on its name.
-pub fn module_visibility(path: &Path) -> Visibility {
-    let mut components = path.iter().rev();
-
-    // Is the module itself private?
-    // Ex) `_foo.py` (but not `__init__.py`)
-    if let Some(filename) = components.next() {
-        let module_name = filename.to_string_lossy();
-        let module_name = stem(&module_name);
-        if is_private_module(module_name) {
+pub fn module_visibility(module_path: Option<&[String]>, path: &Path) -> Visibility {
+    if let Some(module_path) = module_path {
+        if module_path.iter().any(|m| is_private_module(m)) {
             return Visibility::Private;
         }
-    }
-
-    // Is the module in a private parent?
-    // Ex) `_foo/bar.py`
-    for component in components {
-        let module_name = component.to_string_lossy();
-        if is_private_module(&module_name) {
-            return Visibility::Private;
+    } else {
+        // When module_path is None, path is a script outside a package, so just
+        // check to see if the module name itself is private.
+        // Ex) `_foo.py` (but not `__init__.py`)
+        let mut components = path.iter().rev();
+        if let Some(filename) = components.next() {
+            let module_name = filename.to_string_lossy();
+            let module_name = stem(&module_name);
+            if is_private_module(module_name) {
+                return Visibility::Private;
+            }
         }
     }
-
     Visibility::Public
 }