Output GitLab paths relative to CI_PROJECT_DIR (#3475)

Cargo.lock

@@ -1503,6 +1503,12 @@ dependencies = [
  "once_cell",
 ]
 
+[[package]]
+name = "pathdiff"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8835116a5c179084a830efb3adc117ab007512b535bc1a21c991d3b32a6b44dd"
+
 [[package]]
 name = "peg"
 version = "0.8.1"
@@ -1979,6 +1985,7 @@ dependencies = [
  "num-traits",
  "once_cell",
  "path-absolutize",
+ "pathdiff",
  "regex",
  "result-like",
  "ruff_cache",

crates/ruff/Cargo.toml

@@ -46,6 +46,7 @@ path-absolutize = { workspace = true, features = [
   "once_cell_cache",
   "use_unix_paths_on_wasm",
 ] }
+pathdiff = { version = "0.2.1" }
 regex = { workspace = true }
 result-like = { version = "0.4.6" }
 rustc-hash = { workspace = true }

crates/ruff/src/fs.rs

@@ -74,10 +74,20 @@ pub fn normalize_path_to<P: AsRef<Path>, R: AsRef<Path>>(path: P, project_root:
 }
 
 /// Convert an absolute path to be relative to the current working directory.
-pub fn relativize_path(path: impl AsRef<Path>) -> String {
+pub fn relativize_path<P: AsRef<Path>>(path: P) -> String {
     let path = path.as_ref();
     if let Ok(path) = path.strip_prefix(&*path_dedot::CWD) {
         return format!("{}", path.display());
     }
     format!("{}", path.display())
 }
+
+/// Convert an absolute path to be relative to the specified project root.
+pub fn relativize_path_to<P: AsRef<Path>, R: AsRef<Path>>(path: P, project_root: R) -> String {
+    format!(
+        "{}",
+        pathdiff::diff_paths(&path, project_root)
+            .expect("Could not diff paths")
+            .display()
+    )
+}

crates/ruff_cli/src/printer.rs

@@ -3,9 +3,9 @@ use std::collections::hash_map::DefaultHasher;
 use std::collections::BTreeMap;
 use std::fmt::Display;
 use std::hash::{Hash, Hasher};
-use std::io;
 use std::io::{BufWriter, Write};
 use std::path::Path;
+use std::{env, io};
 
 use annotate_snippets::display_list::{DisplayList, FormatOptions};
 use annotate_snippets::snippet::{Annotation, AnnotationType, Slice, Snippet, SourceAnnotation};
@@ -18,7 +18,7 @@ use rustc_hash::FxHashMap;
 use serde::Serialize;
 use serde_json::json;
 
-use ruff::fs::relativize_path;
+use ruff::fs::{relativize_path, relativize_path_to};
 use ruff::linter::FixTable;
 use ruff::logging::LogLevel;
 use ruff::message::{Location, Message};
@@ -341,7 +341,8 @@ impl Printer {
             }
             SerializationFormat::Gitlab => {
                 // Generate JSON with violations in GitLab CI format
-                // https://docs.gitlab.com/ee/ci/testing/code_quality.html#implementing-a-custom-tool
+                // https://docs.gitlab.com/ee/ci/testing/code_quality.html#implement-a-custom-tool
+                let project_dir = env::var("CI_PROJECT_DIR").ok();
                 writeln!(stdout,
                     "{}",
                     serde_json::to_string_pretty(
@@ -354,7 +355,10 @@ impl Printer {
                                     "severity": "major",
                                     "fingerprint": fingerprint(message),
                                     "location": {
-                                        "path": message.filename,
+                                        "path": project_dir.as_ref().map_or_else(
+                                            || relativize_path(Path::new(&message.filename)),
+                                            |project_dir| relativize_path_to(&message.filename, project_dir),
+                                        ),
                                         "lines": {
                                             "begin": message.location.row(),
                                             "end": message.end_location.row()