Support for workspace syntax in pubspec.yaml (#4128)

lib/src/language_version.dart

@@ -70,6 +70,8 @@ class LanguageVersion implements Comparable<LanguageVersion> {
 
   bool get supportsNullSafety => this >= firstVersionWithNullSafety;
 
+  bool get supportsWorkspaces => this >= firstVersionWithWorkspaces;
+
   /// Minimum language version at which short hosted syntax is supported.
   ///
   /// This allows `hosted` dependencies to be expressed as:
@@ -106,6 +108,8 @@ class LanguageVersion implements Comparable<LanguageVersion> {
   static const defaultLanguageVersion = LanguageVersion(2, 7);
   static const firstVersionWithNullSafety = LanguageVersion(2, 12);
   static const firstVersionWithShorterHostedSyntax = LanguageVersion(2, 15);
+  // TODO(https://github.com/dart-lang/pub/issues/4127) update when we know actual version.
+  static const firstVersionWithWorkspaces = LanguageVersion(3, 7);
 
   /// Transform language version to string that can be parsed with
   /// [LanguageVersion.parse].

lib/src/pubspec.dart

@@ -64,6 +64,52 @@ class Pubspec extends PubspecBase {
   /// is unknown.
   Uri? get _location => fields.span.sourceUrl;
 
+  /// Directories of packages that should resolve together with this package.
+  late List<String> workspace = () {
+    final result = <String>[];
+    final r = fields.nodes['workspace'];
+    if (r != null && !languageVersion.supportsWorkspaces) {
+      _error(
+        '`workspace` and `resolution` requires at least language version ${LanguageVersion.firstVersionWithWorkspaces}',
+        r.span,
+      );
+    }
+    if (r == null || r.value == null) return <String>[];
+
+    if (r is! YamlList) {
+      _error('"workspace" must be a list of strings', r.span);
+    }
+    for (final t in r.nodes) {
+      final value = t.value;
+      if (value is! String) {
+        _error('"workspace" must be a list of strings', t.span);
+      }
+      result.add(value);
+    }
+    return result;
+  }();
+
+  /// The resolution mode.
+  late Resolution resolution = () {
+    final r = fields.nodes['resolution'];
+    if (r != null && !languageVersion.supportsWorkspaces) {
+      _error(
+        '`workspace` and `resolution` requires at least language version ${LanguageVersion.firstVersionWithWorkspaces}',
+        r.span,
+      );
+    }
+    return switch (r?.value) {
+      null => Resolution.none,
+      'local' => Resolution.local,
+      'workspace' => Resolution.workspace,
+      'external' => Resolution.external,
+      _ => _error(
+          '"resolution" must be one of `workspace`, `local`, `external`',
+          r!.span,
+        )
+    };
+  }();
+
   /// The additional packages this package depends on.
   Map<String, PackageRange> get dependencies =>
       _dependencies ??= _parseDependencies(
@@ -253,6 +299,7 @@ class Pubspec extends PubspecBase {
     Map? fields,
     SourceRegistry? sources,
     Map<String, SdkConstraint>? sdkConstraints,
+    this.workspace = const <String>[],
     this.dependencyOverridesFromOverridesFile = false,
   })  : _dependencies = dependencies == null
             ? null
@@ -727,3 +774,10 @@ class SdkConstraint {
   @override
   int get hashCode => Object.hash(effectiveConstraint, originalConstraint);
 }
+
+enum Resolution {
+  external,
+  workspace,
+  local,
+  none,
+}

lib/src/validator/pubspec_typo.dart

@@ -72,4 +72,6 @@ const _validPubspecKeys = [
   'funding',
   'topics',
   'ignored_advisories',
+  'workspace',
+  'resolution',
 ];

test/pubspec_test.dart

@@ -312,6 +312,101 @@ dependencies:
       );
     });
 
+    test('parses workspace', () {
+      expect(
+        Pubspec.parse(
+          '''
+environment:
+  sdk: ^3.7.0
+workspace: ['a', 'b', 'c']
+''',
+          sources,
+        ).workspace,
+        ['a', 'b', 'c'],
+      );
+    });
+
+    test('parses resolution', () {
+      expect(
+        Pubspec.parse(
+          '''
+environment:
+  sdk: ^3.7.0
+resolution: workspace
+''',
+          sources,
+        ).resolution,
+        Resolution.workspace,
+      );
+    });
+
+    test('errors on workspace for earlier language versions', () {
+      expectPubspecException(
+        '''
+environment:
+  sdk: ^1.2.3
+workspace: ['a', 'b', 'c']
+''',
+        (p) => p.workspace,
+      );
+      // but no error if you don't look at it.
+      expect(
+        Pubspec.parse(
+          '''
+name: foo
+environment:
+  sdk: ^1.2.3
+resolution: workspace
+''',
+          sources,
+        ).name,
+        'foo',
+      );
+    });
+
+    test('errors on resolution for earlier language versions', () {
+      expectPubspecException(
+        '''
+environment:
+  sdk: ^1.2.3
+resolution: local
+''',
+        (p) => p.resolution,
+      );
+    });
+
+    test('throws if workspace is not a list', () {
+      expectPubspecException(
+        '''
+environment:
+  sdk: ^3.7.0
+workspace: 'a string'
+''',
+        (pubspec) => pubspec.workspace,
+      );
+    });
+
+    test('throws if workspace is a list of not-strings', () {
+      expectPubspecException(
+        '''
+environment:
+  sdk: ^3.7.0
+workspace: ['a string', 24]
+''',
+        (pubspec) => pubspec.workspace,
+      );
+    });
+
+    test('throws if resolution is not a reasonable string', () {
+      expectPubspecException(
+        '''
+environment:
+  sdk: ^3.7.0
+resolution: "sometimes"''',
+        (pubspec) => pubspec.resolution,
+      );
+    });
+
     test('allows comment-only files', () {
       var pubspec = Pubspec.parse(
         '''