Revert "Support relative paths in path dependencies."

utils/pub/path_source.dart

Index: utils/pub/path_source.dart
diff --git a/utils/pub/path_source.dart b/utils/pub/path_source.dart
index b985a4afc8cd2461611c43f2303bab0af51dfd5a..123a3086c2ed0b3a8c5d546e6a12521cf3e897d2 100644
--- a/utils/pub/path_source.dart
+++ b/utils/pub/path_source.dart
@@ -25,77 +25,45 @@ class PathSource extends Source {
   Future<Pubspec> describe(PackageId id) {
     return defer(() {
       _validatePath(id.name, id.description);
-      return new Pubspec.load(id.name, id.description["path"],
-          systemCache.sources);
+      return new Pubspec.load(id.name, id.description, systemCache.sources);
     });
   }
 
-  Future<bool> install(PackageId id, String destination) {
+  Future<bool> install(PackageId id, String path) {
     return defer(() {
       try {
         _validatePath(id.name, id.description);
       } on FormatException catch(err) {
         return false;
       }
-
-      return createPackageSymlink(id.name, destination, id.description["path"],
-          relative: id.description["relative"]);
+      return createPackageSymlink(id.name, id.description, path);
     }).then((_) => true);
   }
 
-  /// Parses a path dependency. This takes in a path string and returns a map.
-  /// The "path" key will be the original path but resolves relative to the
-  /// containing path. The "relative" key will be `true` if the original path
-  /// was relative.
-  ///
-  /// A path coming from a pubspec is a simple string. From a lock file, it's
-  /// an expanded {"path": ..., "relative": ...} map.
-  dynamic parseDescription(String containingPath, description,
-                           {bool fromLockFile: false}) {
-    if (fromLockFile) {
-      if (description is! Map) {
-        throw new FormatException("The description must be a map.");
-      }
-
-      if (description["path"] is! String) {
-        throw new FormatException("The 'path' field of the description must "
-            "be a string.");
-      }
-
-      if (description["relative"] is! bool) {
-        throw new FormatException("The 'relative' field of the description "
-            "must be a boolean.");
-      }
-
-      return description;
-    }
-
+  void validateDescription(description, {bool fromLockFile: false}) {
     if (description is! String) {
       throw new FormatException("The description must be a path string.");
     }
-
-    // Resolve the path relative to the containing file path, and remember
-    // whether the original path was relative or absolute.
-    bool isRelative = path.isRelative(description);
-    if (path.isRelative(description)) {
-      // Can't handle relative paths coming from pubspecs that are not on the
-      // local file system.
-      assert(containingPath != null);
-
-      description = path.join(path.dirname(containingPath), description);
-    }
-
-    return {
-      "path": description,
-      "relative": isRelative
-    };
   }
 
-  /// Ensures that [description] is a valid path description. It must be a map,
-  /// with a "path" key containing a path that points to an existing directory.
-  /// Throws a [FormatException] if the path is invalid.
-  void _validatePath(String name, description) {
-    var dir = description["path"];
+  /// Ensures that [dir] is a valid path. It must be an absolute path that
+  /// points to an existing directory. Throws a [FormatException] if the path
+  /// is invalid.
+  void _validatePath(String name, String dir) {
+    // Relative paths are not (currently) allowed because the user would expect
+    // them to be relative to the pubspec where the dependency appears. That in
+    // turn means that two pubspecs in different locations with the same
+    // relative path dependency could refer to two different packages. That
+    // violates pub's rule that a description should uniquely identify a
+    // package.
+    //
+    // At some point, we may want to loosen this, but it will mean tracking
+    // where a given PackageId appeared.
+    if (!path.isAbsolute(dir)) {
+      throw new FormatException(
+          "Path dependency for package '$name' must be an absolute path. "
+          "Was '$dir'.");
+    }
 
     if (fileExists(dir)) {
       throw new FormatException(