Fix bug in --update with built-in modules (#1338)

Fixes #1335.

CHANGELOG.md

@@ -1,5 +1,8 @@
 ## 1.34.1
 
+* Fix a bug where `--update` would always compile any file that depends on a
+  built-in module.
+
 * Fix the URL for the `@-moz-document` deprecation message.
 
 * Fix a bug with `@for` loops nested inside property declarations.

lib/src/visitor/find_dependencies.dart

@@ -10,12 +10,13 @@ import 'recursive_statement.dart';
 /// Returns two lists of dependencies for [stylesheet].
 ///
 /// The first is a list of URLs from all `@use` and `@forward` rules in
-/// [stylesheet]. The second is a list of all imports in [stylesheet].
+/// [stylesheet] (excluding built-in modules). The second is a list of all
+/// imports in [stylesheet].
 Tuple2<List<Uri>, List<Uri>> findDependencies(Stylesheet stylesheet) =>
     _FindDependenciesVisitor().run(stylesheet);
 
 /// A visitor that traverses a stylesheet and records, all `@import`, `@use`,
-/// and `@forward` rules it contains.
+/// and `@forward` rules (excluding built-in modules) it contains.
 class _FindDependenciesVisitor extends RecursiveStatementVisitor {
   final _usesAndForwards = <Uri>[];
   final _imports = <Uri>[];
@@ -35,11 +36,11 @@ class _FindDependenciesVisitor extends RecursiveStatementVisitor {
   void visitSupportsCondition(SupportsCondition condition) {}
 
   void visitUseRule(UseRule node) {
-    _usesAndForwards.add(node.url);
+    if (node.url.scheme != 'sass') _usesAndForwards.add(node.url);
   }
 
   void visitForwardRule(ForwardRule node) {
-    _usesAndForwards.add(node.url);
+    if (node.url.scheme != 'sass') _usesAndForwards.add(node.url);
   }
 
   void visitImportRule(ImportRule node) {

pubspec.yaml

@@ -1,5 +1,5 @@
 name: sass
-version: 1.34.1-dev
+version: 1.34.1
 description: A Sass implementation in Dart.
 author: Sass Team
 homepage: https://github.com/sass/dart-sass

test/cli/shared/update.dart

@@ -183,6 +183,17 @@ void sharedTests(Future<TestProcess> runSass(Iterable<String> arguments)) {
 
       await d.file("dir/test.css", "a {b: c}").validate();
     });
+
+    test("that uses a built-in module", () async {
+      await d.file("test.scss", "@use 'sass:math'; a {b: c}").create();
+      await d.file("out.css", "x {y: z}").create();
+
+      var sass = await update(["test.scss:out.css"]);
+      expect(sass.stdout, emitsDone);
+      await sass.shouldExit(0);
+
+      await d.file("out.css", "x {y: z}").validate();
+    });
   });
 
   group("updates a CSS file", () {