Make a RootDescription not depend on the root Package

lib/src/command/add.dart

@@ -208,7 +208,7 @@ Specify multiple sdk packages with descriptors.''');
       solveResult = await resolveVersions(
         SolveType.upgrade,
         cache,
-        Package.inMemory(resolutionPubspec),
+        Package(resolutionPubspec, entrypoint.rootDir),
       );
     } on GitException {
       final name = updates.first.ref.name;

lib/src/command/dependency_services.dart

@@ -69,13 +69,13 @@ class DependencyServicesReportCommand extends PubCommand {
     final breakingPubspec = stripVersionBounds(compatiblePubspec);
 
     final compatiblePackagesResult = await _tryResolve(
-      compatiblePubspec,
+      Package(compatiblePubspec, entrypoint.rootDir),
       cache,
       additionalConstraints: additionalConstraints,
     );
 
     final breakingPackagesResult = await _tryResolve(
-      breakingPubspec,
+      Package(breakingPubspec, entrypoint.rootDir),
       cache,
       additionalConstraints: additionalConstraints,
     );
@@ -110,8 +110,10 @@ class DependencyServicesReportCommand extends PubCommand {
         dependencySet[package.name] = package
             .toRef()
             .withConstraint(stripUpperBound(package.toRange().constraint));
-        final singleBreakingPackagesResult =
-            await _tryResolve(singleBreakingPubspec, cache);
+        final singleBreakingPackagesResult = await _tryResolve(
+          Package(singleBreakingPubspec, entrypoint.rootDir),
+          cache,
+        );
         singleBreakingVersion = singleBreakingPackagesResult
             ?.firstWhereOrNull((element) => element.name == package.name);
       }
@@ -126,7 +128,7 @@ class DependencyServicesReportCommand extends PubCommand {
         );
 
         final smallestUpgradeResult = await _tryResolve(
-          atLeastCurrentPubspec,
+          Package(atLeastCurrentPubspec, entrypoint.rootDir),
           cache,
           solveType: SolveType.downgrade,
           additionalConstraints: additionalConstraints,
@@ -214,7 +216,8 @@ class DependencyServicesListCommand extends PubCommand {
 
     final currentPackages = fileExists(entrypoint.lockFilePath)
         ? entrypoint.lockFile.packages.values.toList()
-        : (await _tryResolve(pubspec, cache) ?? <PackageId>[]);
+        : (await _tryResolve(Package(pubspec, entrypoint.rootDir), cache) ??
+            <PackageId>[]);
 
     final dependencies = <Object>[];
     final result = <String, Object>{'dependencies': dependencies};
@@ -418,12 +421,13 @@ class DependencyServicesApplyCommand extends PubCommand {
         final solveResult = await resolveVersions(
           SolveType.get,
           cache,
-          Package.inMemory(
+          Package(
             Pubspec.parse(
               updatedPubspec,
               cache.sources,
               location: toUri(entrypoint.pubspecPath),
             ),
+            entrypoint.rootDir,
           ),
           lockFile: updatedLockfile,
         );
@@ -635,18 +639,18 @@ bool _lockFileHasContentHashes(dynamic lockfile) {
   return false;
 }
 
-/// Try to solve [pubspec] return [PackageId]s in the resolution or `null` if no
+/// Try to solve [package] return [PackageId]s in the resolution or `null` if no
 /// resolution was found.
 Future<List<PackageId>?> _tryResolve(
-  Pubspec pubspec,
+  Package package,
   SystemCache cache, {
   SolveType solveType = SolveType.upgrade,
   Iterable<ConstraintAndCause>? additionalConstraints,
 }) async {
   final solveResult = await tryResolveVersions(
     solveType,
     cache,
-    Package.inMemory(pubspec),
+    package,
     additionalConstraints: additionalConstraints,
   );
 
@@ -686,7 +690,7 @@ Future<Map<String, PackageId>> _computeCurrentPackages(
   if (fileExists(entrypoint.lockFilePath)) {
     currentPackages = Map<String, PackageId>.from(entrypoint.lockFile.packages);
   } else {
-    final resolution = await _tryResolve(entrypoint.root.pubspec, cache) ??
+    final resolution = await _tryResolve(entrypoint.root, cache) ??
         (throw DataException('Failed to resolve pubspec'));
     currentPackages = Map<String, PackageId>.fromIterable(
       resolution,
@@ -730,7 +734,7 @@ Future<List<Object>> _computeUpgradeSet(
         ? SolveType.downgrade
         : SolveType.get,
     cache,
-    Package.inMemory(pubspec),
+    Package(pubspec, entrypoint.rootDir),
     lockFile: lockFile,
     additionalConstraints: additionalConstraints,
   );

lib/src/command/outdated.dart

@@ -145,15 +145,15 @@ Consider using the Dart 2.19 sdk to migrate to null safety.''');
       'Resolving',
       () async {
         final upgradablePackagesResult = await _tryResolve(
-          upgradablePubspec,
+          Package(upgradablePubspec, entrypoint.rootDir),
           cache,
           lockFile: entrypoint.lockFile,
         );
         hasUpgradableResolution = upgradablePackagesResult != null;
         upgradablePackages = upgradablePackagesResult ?? [];
 
         final resolvablePackagesResult = await _tryResolve(
-          resolvablePubspec,
+          Package(resolvablePubspec, entrypoint.rootDir),
           cache,
           lockFile: entrypoint.lockFile,
         );
@@ -407,14 +407,14 @@ Consider using the Dart 2.19 sdk to migrate to null safety.''');
 /// Try to solve [pubspec] return [PackageId]s in the resolution or `null` if no
 /// resolution was found.
 Future<List<PackageId>?> _tryResolve(
-  Pubspec pubspec,
+  Package package,
   SystemCache cache, {
   LockFile? lockFile,
 }) async {
   final solveResult = await tryResolveVersions(
     SolveType.upgrade,
     cache,
-    Package.inMemory(pubspec),
+    package,
     lockFile: lockFile,
   );
 

lib/src/command/upgrade.dart

@@ -278,7 +278,7 @@ be direct 'dependencies' or 'dev_dependencies', following packages are not:
         return await resolveVersions(
           SolveType.upgrade,
           cache,
-          Package.inMemory(resolvablePubspec),
+          Package(resolvablePubspec, entrypoint.rootDir),
         );
       },
       condition: _shouldShowSpinner,
@@ -328,7 +328,10 @@ be direct 'dependencies' or 'dev_dependencies', following packages are not:
       final solveResult = await resolveVersions(
         SolveType.upgrade,
         cache,
-        Package.inMemory(_updatedPubspec(newPubspecText, entrypoint)),
+        Package(
+          _updatedPubspec(newPubspecText, entrypoint),
+          entrypoint.rootDir,
+        ),
       );
       changes = tighten(
         entrypoint.root.pubspec,

lib/src/entrypoint.dart

@@ -235,7 +235,7 @@ class Entrypoint {
     this.rootDir,
     this.cache, {
     Pubspec? pubspec,
-  })  : _root = pubspec == null ? null : Package.inMemory(pubspec),
+  })  : _root = pubspec == null ? null : Package(pubspec, rootDir),
         globalDir = null {
     if (p.isWithin(cache.rootDir, rootDir)) {
       fail('Cannot operate on packages inside the cache.');
@@ -251,7 +251,7 @@ class Entrypoint {
       _example,
       _packageGraph,
       cache,
-      Package.inMemory(pubspec),
+      Package(pubspec, rootDir),
       globalDir,
     );
   }

lib/src/global_packages.dart

@@ -212,12 +212,13 @@ class GlobalPackages {
     final originalLockFile = _describeActive(name, cache);
 
     // Create a dummy package with just [dep] so we can do resolution on it.
-    var root = Package.inMemory(
+    var root = Package(
       Pubspec(
         'pub global activate',
         dependencies: [dep],
         sources: cache.sources,
       ),
+      _packageDir(name),
     );
 
     // Resolve it and download its dependencies.

lib/src/package.dart

@@ -17,7 +17,8 @@ import 'pubspec.dart';
 import 'system_cache.dart';
 import 'utils.dart';
 
-/// A named, versioned, unit of code and resource reuse.
+/// A Package is a [Pubspec] and a directory where it belongs that can be used
+/// for version solving or as a node in a package graph.
 class Package {
   /// Compares [a] and [b] orders them by name then version number.
   ///
@@ -31,24 +32,8 @@ class Package {
     return a.version.compareTo(b.version);
   }
 
-  final String? _dir;
-
   /// The path to the directory containing the package.
-  ///
-  /// It is an error to access this on an in-memory package.
-  String get dir {
-    if (isInMemory) {
-      throw UnsupportedError(
-        'Package directory cannot be used for an in-memory package',
-      );
-    }
-
-    return _dir!;
-  }
-
-  /// An in-memory package can be created for doing a resolution without having
-  /// a package on disk. Paths should not be resolved for these.
-  bool get isInMemory => _dir == null;
+  final String dir;
 
   /// The name of the package.
   String get name => pubspec.name;
@@ -99,7 +84,7 @@ class Package {
   late final bool inGitRepo = computeInGitRepoCache();
 
   bool computeInGitRepoCache() {
-    if (isInMemory || !git.isInstalled) {
+    if (!git.isInstalled) {
       return false;
     } else {
       // If the entire package directory is ignored, don't consider it part of a
@@ -134,21 +119,14 @@ class Package {
       expectedName: name,
       allowOverridesFile: withPubspecOverrides,
     );
-    return Package._(dir, pubspec);
+    return Package(pubspec, dir);
   }
 
-  Package._(
-    this._dir,
-    this.pubspec,
-  );
-
-  /// Constructs a package with the given pubspec.
+  /// Creates a package with [pubspec] associated with [dir].
   ///
-  /// The package will have no directory associated with it.
-  Package.inMemory(this.pubspec) : _dir = null;
-
-  /// Creates a package with [pubspec] located at [dir].
-  Package(this.pubspec, String this._dir);
+  /// For temporary resolution attempts [pubspec] does not have to correspond
+  /// to the one at disk.
+  Package(this.pubspec, this.dir);
 
   /// Given a relative path within this package, returns its absolute path.
   ///
@@ -164,20 +142,12 @@ class Package {
     String? part6,
     String? part7,
   ]) {
-    if (isInMemory) {
-      throw StateError("Package $name is in-memory and doesn't have paths "
-          'on disk.');
-    }
     return p.join(dir, part1, part2, part3, part4, part5, part6, part7);
   }
 
   /// Given an absolute path within this package (such as that returned by
   /// [path] or [listFiles]), returns it relative to the package root.
   String relative(String path) {
-    if (isInMemory) {
-      throw StateError("Package $name is in-memory and doesn't have paths "
-          'on disk.');
-    }
     return p.relative(path, from: dir);
   }
 
@@ -209,9 +179,6 @@ class Package {
   ///
   /// To convert them to paths relative to the package root, use [p.relative].
   List<String> listFiles({String? beneath, bool recursive = true}) {
-    // An in-memory package has no files.
-    if (isInMemory) return [];
-
     var packageDir = dir;
     var root = git.repoRoot(packageDir) ?? packageDir;
     beneath = p

lib/src/package_name.dart

@@ -27,7 +27,7 @@ class PackageRef {
 
   /// Creates a reference to the given root package.
   static PackageRef root(Package package) =>
-      PackageRef(package.name, RootDescription(package));
+      PackageRef(package.name, RootDescription(package.dir));
 
   @override
   String toString([PackageDetail? detail]) {
@@ -88,7 +88,7 @@ class PackageId {
   static PackageId root(Package package) => PackageId(
         package.name,
         package.version,
-        ResolvedRootDescription(RootDescription(package)),
+        ResolvedRootDescription(RootDescription(package.dir)),
       );
 
   @override