feat: add .pnp.cjs to file dependencies on PnP load (#193)

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: stormslowly

src/lib.rs

@@ -115,7 +115,7 @@ pub struct ResolverGeneric<Fs> {
   options: ResolveOptions,
   cache: Arc<Cache<Fs>>,
   #[cfg(feature = "yarn_pnp")]
-  pnp_manifest: Arc<arc_swap::ArcSwapOption<pnp::Manifest>>,
+  pnp_manifest: Arc<arc_swap::ArcSwapOption<(PathBuf, pnp::Manifest)>>,
   /// Paths that have been searched and confirmed to have no `.pnp.cjs` reachable by filesystem walk.
   #[cfg(feature = "yarn_pnp")]
   pnp_no_manifest_cache: Arc<DashSet<CachedPath>>,
@@ -957,7 +957,7 @@ impl<Fs: FileSystem + Send + Sync> ResolverGeneric<Fs> {
 
   #[cfg(feature = "yarn_pnp")]
   #[cfg_attr(feature = "enable_instrument", tracing::instrument(level=tracing::Level::DEBUG, skip_all, fields(path = %cached_path.path().to_string_lossy())))]
-  fn find_pnp_manifest(&self, cached_path: &CachedPath) -> Option<Arc<pnp::Manifest>> {
+  fn find_pnp_manifest(&self, cached_path: &CachedPath) -> Option<Arc<(PathBuf, pnp::Manifest)>> {
     // 1. Already have a manifest → return it (covers global cache paths too)
     if let Some(manifest) = self.pnp_manifest.load_full() {
       return Some(manifest);
@@ -986,7 +986,7 @@ impl<Fs: FileSystem + Send + Sync> ResolverGeneric<Fs> {
     tracing::debug!("use manifest path: {:?}", manifest_path);
 
     let manifest = pnp::load_pnp_manifest(&manifest_path).ok()?;
-    let manifest = Arc::new(manifest);
+    let manifest = Arc::new((manifest_path, manifest));
 
     let previous = self
       .pnp_manifest
@@ -1007,13 +1007,15 @@ impl<Fs: FileSystem + Send + Sync> ResolverGeneric<Fs> {
     specifier: &str,
     ctx: &mut Ctx,
   ) -> Result<Option<CachedPath>, ResolveError> {
-    let Some(manifest) = self.find_pnp_manifest(cached_path) else {
+    let Some(pnp_data) = self.find_pnp_manifest(cached_path) else {
       return Ok(None);
     };
+    let (manifest_path, manifest) = pnp_data.as_ref();
+    ctx.add_file_dependency(manifest_path);
 
     let mut path = cached_path.to_path_buf();
     path.push("");
-    let resolution = pnp::resolve_to_unqualified_via_manifest(&manifest, specifier, &path);
+    let resolution = pnp::resolve_to_unqualified_via_manifest(manifest, specifier, &path);
 
     tracing::debug!("pnp resolve unqualified as: {:?}", resolution);
 

src/tests/pnp.rs

@@ -3,7 +3,7 @@
 //! enhanced_resolve's test <https://github.com/webpack/enhanced-resolve/blob/main/test/pnp.test.js>
 //! cannot be ported over because it uses mocks on `pnpApi` provided by the runtime.
 
-use crate::{path::PathUtil, ResolveError::NotFound, ResolveOptions, Resolver};
+use crate::{path::PathUtil, ResolveContext, ResolveError::NotFound, ResolveOptions, Resolver};
 
 #[tokio::test]
 async fn pnp1() {
@@ -78,6 +78,28 @@ async fn pnp1() {
     );
 }
 
+#[tokio::test]
+async fn pnp_file_dependencies() {
+  let fixture = super::fixture_root().join("pnp");
+
+  let resolver = Resolver::new(ResolveOptions {
+    extensions: vec![".js".into()],
+    condition_names: vec!["import".into()],
+    ..ResolveOptions::default()
+  });
+
+  let mut ctx = ResolveContext::default();
+  let result = resolver
+    .resolve_with_context(&fixture, "is-even", &mut ctx)
+    .await;
+  assert!(result.is_ok());
+  assert!(
+    ctx.file_dependencies.contains(&fixture.join(".pnp.cjs")),
+    ".pnp.cjs should be in file_dependencies, got: {:?}",
+    ctx.file_dependencies
+  );
+}
+
 // https://github.com/webpack/enhanced-resolve/blob/main/lib/PnpPlugin.js#L118
 // `fullySpecified` should be disabled for bare specifiers without subpath,
 // so that the `main` field value (e.g. "index" without extension) can be resolved.