Load import-only files through package.json exports (#2772)

See sass/sass#4224

Author: nex3

CHANGELOG.md

@@ -1,3 +1,11 @@
+## 1.101.0
+
+* **Potentially breaking bug fix:** The Node package importer now properly
+  supports resolving import-only variants of Sass files declared in the
+  `exports`, `sass`, and `style` fields of `package.json`. Previously, these
+  files were ignored even when loaded via `@import`, so any code relying on
+  loading module-system-only files this way may break.
+
 ## 1.100.0
 
 * Writing two compound selectors adjacent to one another without any whitespace

lib/src/importer/node_package.dart

@@ -80,7 +80,7 @@ class NodePackageImporter extends Importer {
     )
         case var resolved?) {
       if (_validExtensions.contains(p.extension(resolved))) {
-        return p.toUri(p.canonicalize(resolved));
+        return p.toUri(p.canonicalize(_resolveImportOnly(resolved)));
       } else {
         throw "The export for '${subpath ?? "root"}' in "
             "'$packageName' resolved to '${resolved.toString()}', "
@@ -144,18 +144,18 @@ class NodePackageImporter extends Importer {
   ) {
     if (packageManifest['sass'] case String sassValue
         when _validExtensions.contains(p.url.extension(sassValue))) {
-      return p.join(packageRoot, sassValue);
+      return _resolveImportOnly(p.join(packageRoot, sassValue));
     } else if (packageManifest['style'] case String styleValue
         when _validExtensions.contains(p.url.extension(styleValue))) {
-      return p.join(packageRoot, styleValue);
+      return _resolveImportOnly(p.join(packageRoot, styleValue));
     }
 
     var result = resolveImportPath(p.join(packageRoot, 'index'));
     return result;
   }
 
   /// Returns a file path specified by a `subpath` in the `exports` section of
-  /// package.json.
+  /// `packageManifest`.
   ///
   /// `packageName` is used for error reporting.
   String? _resolvePackageExports(
@@ -285,6 +285,16 @@ class NodePackageImporter extends Importer {
     };
   }
 
+  /// Returns either [path] or, if necessary, the import-only variant that
+  /// should be loaded instead.
+  String _resolveImportOnly(String path) {
+    if (!fromImport) return path;
+    var extension = p.extension(path);
+    assert(_validExtensions.contains(extension));
+    var importOnly = '${p.withoutExtension(path)}.import$extension';
+    return fileExists(importOnly) ? importOnly : path;
+  }
+
   /// Implementation of the `PATTERN_KEY_COMPARE` comparator from
   /// https://nodejs.org/api/esm.html#resolution-algorithm-specification.
   int _compareExpansionKeys(String keyA, String keyB) {

pkg/sass-parser/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.4.46
+
+* No user-visible changes.
+
 ## 0.4.45
 
 * No user-visible changes.

pkg/sass-parser/package.json

@@ -1,6 +1,6 @@
 {
   "name": "sass-parser",
-  "version": "0.4.45",
+  "version": "0.4.46",
   "description": "A PostCSS-compatible wrapper of the official Sass parser",
   "repository": "sass/dart-sass",
   "author": "Google Inc.",

pkg/sass_api/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 17.7.0
+
+* No user-visible changes.
+
 ## 17.6.0
 
 * Add a `logger` parameter to `SelectorList.parse()`, `ComplexSelector.parse()`,

pkg/sass_api/pubspec.yaml

@@ -2,15 +2,15 @@ name: sass_api
 # Note: Every time we add a new Sass AST node, we need to bump the *major*
 # version because it's a breaking change for anyone who's implementing the
 # visitor interface(s).
-version: 17.6.0
+version: 17.7.0
 description: Additional APIs for Dart Sass.
 homepage: https://github.com/sass/dart-sass
 
 environment:
   sdk: ">=3.6.0 <4.0.0"
 
 dependencies:
-  sass: 1.100.0
+  sass: 1.101.0
 
 dev_dependencies:
   dartdoc: ">=8.0.14 <10.0.0"

pubspec.yaml

@@ -1,5 +1,5 @@
 name: sass
-version: 1.100.0
+version: 1.101.0
 description: A Sass implementation in Dart.
 homepage: https://github.com/sass/dart-sass