fix: align package exports fallback array resolution with Node.js spec

README.md

@@ -167,12 +167,12 @@ The options are aligned with [enhanced-resolve](https://github.com/webpack/enhan
 
 ### Other Options
 
-| Field               | Default | Description                                                                                                                                                                                                                                                                                                                                                                                                |
-| ------------------- | ------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
-| tsconfig            | None    | TypeScript related config for resolver                                                                                                                                                                                                                                                                                                                                                                     |
-| tsconfig.configFile |         | A relative path to the tsconfig file based on `cwd`, or an absolute path of tsconfig file.                                                                                                                                                                                                                                                                                                                 |
-| tsconfig.references | `[]`    | - 'auto': inherits from TypeScript config <br/> - `string []`: relative path (based on directory of the referencing tsconfig file) or absolute path of referenced project's tsconfig                                                                                                                                                                                                                       |
-| enablePnp           | false   | Enable Yarn Plug'n'Play support                                                                                                                                                                                                                                                                                                                                                                            |
+| Field               | Default | Description                                                                                                                                                                          |
+| ------------------- | ------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
+| tsconfig            | None    | TypeScript related config for resolver                                                                                                                                               |
+| tsconfig.configFile |         | A relative path to the tsconfig file based on `cwd`, or an absolute path of tsconfig file.                                                                                           |
+| tsconfig.references | `[]`    | - 'auto': inherits from TypeScript config <br/> - `string []`: relative path (based on directory of the referencing tsconfig file) or absolute path of referenced project's tsconfig |
+| enablePnp           | false   | Enable Yarn Plug'n'Play support                                                                                                                                                      |
 
 In the context of `@rspack/resolver`, the `tsconfig.references` option helps isolate the `paths` configurations of different TypeScript projects.
 This ensures that path aliases defined in one TypeScript project do not unintentionally affect the resolving behavior of another.

src/cache.rs

@@ -106,7 +106,7 @@ impl<Fs: Send + Sync + FileSystem> Cache<Fs> {
   }
 }
 
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 pub struct CachedPath(Arc<CachedPathImpl>);
 
 impl Hash for CachedPath {
@@ -158,6 +158,12 @@ pub struct CachedPathImpl {
   package_json: OnceLock<Option<Arc<PackageJson>>>,
 }
 
+impl std::fmt::Debug for CachedPathImpl {
+  fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+    self.path.fmt(f)
+  }
+}
+
 impl CachedPathImpl {
   fn new(hash: u64, path: Box<Path>, parent: Option<CachedPath>) -> Self {
     Self {

src/lib.rs

@@ -1948,7 +1948,8 @@ impl<Fs: FileSystem + Send + Sync> ResolverGeneric<Fs> {
             ));
           }
           // 2. For each item targetValue in target, do
-          for (i, target_value) in targets.iter().enumerate() {
+          let mut last_error = None;
+          for target_value in targets.iter() {
             // 1. Let resolved be the result of PACKAGE_TARGET_RESOLVE( packageURL, targetValue, patternMatch, isImports, conditions), continuing the loop on any Invalid Package Target error.
             let resolved = self
               .package_target_resolve(
@@ -1962,18 +1963,24 @@ impl<Fs: FileSystem + Send + Sync> ResolverGeneric<Fs> {
               )
               .await;
 
-            if resolved.is_err() && i == targets.len() {
-              return resolved;
-            }
-
-            // 2. If resolved is undefined, continue the loop.
-            if let Ok(Some(path)) = resolved {
+            match resolved {
+              // Only track InvalidPackageTarget for re-throwing after the loop.
+              Err(e @ ResolveError::InvalidPackageTarget(..)) => {
+                last_error = Some(e);
+              }
+              Err(_) => {}
+              // 2. If resolved is undefined, continue the loop.
+              Ok(None) => {
+                last_error = None;
+              }
               // 3. Return resolved.
-              return Ok(Some(path));
+              Ok(Some(path)) => return Ok(Some(path)),
             }
           }
           // 3. Return or throw the last fallback resolution null return or error.
-          // Note: see `resolved.is_err() && i == targets.len()`
+          if let Some(e) = last_error {
+            return Err(e);
+          }
         }
         JSONValue::Static(_) => {}
       }

src/tests/exports_field.rs

@@ -2634,3 +2634,26 @@ async fn test_cases() {
     }
   }
 }
+
+/// When all targets in a fallback array are invalid, `package_target_resolve` should
+/// propagate `InvalidPackageTarget` instead of swallowing it and returning `Ok(None)`.
+/// Bug: `resolved.is_err() && i == targets.len()` is always false (off-by-one),
+/// causing errors to be silently dropped.
+#[tokio::test]
+async fn array_fallback_all_invalid_targets_should_return_invalid_package_target() {
+  let resolved = Resolver::new(ResolveOptions::default())
+    .package_exports_resolve(
+      Path::new(""),
+      ".",
+      &exports_field(json!({
+        ".": ["invalid_target_1", "invalid_target_2"]
+      })),
+      &mut Ctx::default(),
+    )
+    .await;
+
+  assert!(
+    matches!(resolved, Err(ResolveError::InvalidPackageTarget(..))),
+    "expected InvalidPackageTarget, got {resolved:?}"
+  );
+}