Don't walk past project root when figuring out exclusion (#2471)

resources/test/package/pyproject.toml

@@ -1,2 +1,7 @@
 [tool.ruff]
 src = ["."]
+
+# This will make sure that `exclude` paths are rooted
+# to where the configuration file was found; this file exists
+# in a `resources/test` hierarchy.
+exclude = ["resources"]

resources/test/package/resources/ignored.py

@@ -0,0 +1,4 @@
+# This file should be ignored, but it would otherwise trigger
+# an unused import error:
+
+import math

src/resolver.rs

@@ -411,6 +411,11 @@ fn is_file_excluded(
                 return true;
             }
         }
+        if path == settings.project_root {
+            // Bail out; we'd end up past the project root on the next iteration
+            // (excludes etc. are thus "rooted" to the project).
+            break;
+        }
     }
     false
 }
@@ -424,8 +429,13 @@ mod tests {
     use path_absolutize::Absolutize;
 
     use crate::fs;
-    use crate::resolver::{is_python_path, match_exclusion};
+    use crate::resolver::{
+        is_file_excluded, is_python_path, match_exclusion, resolve_settings_with_processor,
+        NoOpProcessor, PyprojectDiscovery, Relativity, Resolver,
+    };
+    use crate::settings::pyproject::find_settings_toml;
     use crate::settings::types::FilePattern;
+    use crate::test::test_resource_path;
 
     #[test]
     fn inclusions() {
@@ -567,4 +577,30 @@ mod tests {
 
         Ok(())
     }
+
+    #[test]
+    fn rooted_exclusion() -> Result<()> {
+        let package_root = test_resource_path("package");
+        let resolver = Resolver::default();
+        let ppd = PyprojectDiscovery::Hierarchical(resolve_settings_with_processor(
+            &find_settings_toml(&package_root)?.unwrap(),
+            &Relativity::Parent,
+            &NoOpProcessor,
+        )?);
+        // src/app.py should not be excluded even if it lives in a hierarchy that should be
+        // excluded by virtue of the pyproject.toml having `resources/*` in it.
+        assert!(!is_file_excluded(
+            &package_root.join("src/app.py"),
+            &resolver,
+            &ppd,
+        ));
+        // However, resources/ignored.py should be ignored, since that `resources` is beneath
+        // the package root.
+        assert!(is_file_excluded(
+            &package_root.join("resources/ignored.py"),
+            &resolver,
+            &ppd,
+        ));
+        Ok(())
+    }
 }

src/settings/defaults.rs

@@ -71,6 +71,7 @@ impl Default for Settings {
             respect_gitignore: true,
             show_source: false,
             src: vec![path_dedot::CWD.clone()],
+            project_root: path_dedot::CWD.clone(),
             target_version: TARGET_VERSION,
             task_tags: TASK_TAGS.iter().map(ToString::to_string).collect(),
             typing_modules: vec![],

src/settings/mod.rs

@@ -90,6 +90,7 @@ pub struct Settings {
     pub extend_exclude: HashableGlobSet,
     pub force_exclude: bool,
     pub respect_gitignore: bool,
+    pub project_root: PathBuf,
 
     // Rule-specific settings
     pub allowed_confusables: HashableHashSet<char>,
@@ -167,6 +168,7 @@ impl Settings {
             src: config
                 .src
                 .unwrap_or_else(|| vec![project_root.to_path_buf()]),
+            project_root: project_root.to_path_buf(),
             target_version: config.target_version.unwrap_or(defaults::TARGET_VERSION),
             task_tags: config.task_tags.unwrap_or_else(|| {
                 defaults::TASK_TAGS