fix: resolve "browser" field when "exports" is present

closes #58

Failed to resolve `path` in browser mode for `postcss` when

```
"exports": {
  ...
}

"browser": {
    "./lib/terminal-highlight": false,
    "source-map-js": false,
    "path": false,
    "url": false,
    "fs": false
  },
```

Are both present

There are no such test cases for this type of combination in enhanced_resolve.

fixtures/enhanced_resolve/test/fixtures/browser-module/package.json

@@ -1,4 +1,6 @@
 {
+  "exports": {
+  },
   "browser": {
     "./lib/ignore.js": false,
     "./lib/replaced.js": "./lib/browser",

fixtures/pnpm8/package.json

@@ -8,6 +8,7 @@
   "packageManager": "pnpm@8.10.5",
   "devDependencies": {
     "axios": "1.6.2",
-    "styled-components": "6.1.1"
+    "styled-components": "6.1.1",
+    "postcss": "8.4.33"
   }
 }

napi/Cargo.toml

@@ -9,7 +9,7 @@ test       = false
 doctest    = false
 
 [dependencies]
-oxc_resolver = { path = "../../oxc_resolver" }
+oxc_resolver = { path = ".." }
 napi         = { version = "2", default-features = false, features = ["napi3", "serde-json"] }
 napi-derive  = { version = "2" }
 

src/lib.rs

@@ -722,36 +722,34 @@ impl<Fs: FileSystem + Default> ResolverGeneric<Fs> {
             return Ok(None);
         };
         // 3. If the SCOPE/package.json "exports" is null or undefined, return.
-        if package_json.exports.is_empty() {
-            return self.load_browser_field(cached_path, Some(specifier), &package_json, ctx);
-        }
-        // 4. If the SCOPE/package.json "name" is not the first segment of X, return.
-        let Some(subpath) = package_json
-            .name
-            .as_ref()
-            .and_then(|package_name| Self::strip_package_name(specifier, package_name))
-        else {
-            return Ok(None);
-        };
-        // 5. let MATCH = PACKAGE_EXPORTS_RESOLVE(pathToFileURL(SCOPE),
-        // "." + X.slice("name".length), `package.json` "exports", ["node", "require"])
-        // defined in the ESM resolver.
-        let package_url = package_json.directory();
-        // Note: The subpath is not prepended with a dot on purpose
-        // because `package_exports_resolve` matches subpath without the leading dot.
-        for exports in &package_json.exports {
-            if let Some(cached_path) = self.package_exports_resolve(
-                package_url,
-                subpath,
-                exports,
-                &self.options.condition_names,
-                ctx,
-            )? {
-                // 6. RESOLVE_ESM_MATCH(MATCH)
-                return self.resolve_esm_match(specifier, &cached_path, &package_json, ctx);
+        if !package_json.exports.is_empty() {
+            // 4. If the SCOPE/package.json "name" is not the first segment of X, return.
+            if let Some(subpath) = package_json
+                .name
+                .as_ref()
+                .and_then(|package_name| Self::strip_package_name(specifier, package_name))
+            {
+                // 5. let MATCH = PACKAGE_EXPORTS_RESOLVE(pathToFileURL(SCOPE),
+                // "." + X.slice("name".length), `package.json` "exports", ["node", "require"])
+                // defined in the ESM resolver.
+                let package_url = package_json.directory();
+                // Note: The subpath is not prepended with a dot on purpose
+                // because `package_exports_resolve` matches subpath without the leading dot.
+                for exports in &package_json.exports {
+                    if let Some(cached_path) = self.package_exports_resolve(
+                        package_url,
+                        subpath,
+                        exports,
+                        &self.options.condition_names,
+                        ctx,
+                    )? {
+                        // 6. RESOLVE_ESM_MATCH(MATCH)
+                        return self.resolve_esm_match(specifier, &cached_path, &package_json, ctx);
+                    }
+                }
             }
         }
-        Ok(None)
+        self.load_browser_field(cached_path, Some(specifier), &package_json, ctx)
     }
 
     /// RESOLVE_ESM_MATCH(MATCH)

tests/resolve_test.rs

@@ -1,6 +1,6 @@
 use std::{env, path::PathBuf};
 
-use oxc_resolver::{ResolveOptions, Resolver};
+use oxc_resolver::{ResolveError, ResolveOptions, Resolver};
 
 fn dir() -> PathBuf {
     env::current_dir().unwrap()
@@ -74,3 +74,22 @@ fn axios() {
     let resolution = Resolver::new(options).resolve(&path, specifier);
     assert_eq!(resolution.map(|r| r.into_path_buf()), Ok(module_path.join("dist/node/axios.cjs")));
 }
+
+#[test]
+fn postcss() {
+    let dir = dir();
+    let path = dir.join("fixtures/pnpm8");
+    let module_path = path.join("node_modules/postcss");
+    let resolver = Resolver::new(ResolveOptions {
+        alias_fields: vec![vec!["browser".into()]],
+        ..ResolveOptions::default()
+    });
+
+    // should ignore "path"
+    let resolution = resolver.resolve(&module_path, "path");
+    assert_eq!(resolution, Err(ResolveError::Ignored(module_path.clone())));
+
+    // should ignore "./lib/terminal-highlight"
+    let resolution = resolver.resolve(&module_path, "./lib/terminal-highlight");
+    assert_eq!(resolution, Err(ResolveError::Ignored(module_path.join("lib/terminal-highlight"))));
+}