Adhere to XDG base directory spec

pkg/analysis_server/benchmark/benchmarks.dart

@@ -48,7 +48,7 @@ String get analysisServerSrcPath {
 }
 
 void deleteServerCache() {
-  // ~/.dartServer/.analysis-driver/
+  // ~/.config/dartServer/.analysis-driver/
   var resourceProvider = PhysicalResourceProvider.INSTANCE;
   var stateLocation = resourceProvider.getStateLocation('.analysis-driver');
   try {

pkg/analyzer/lib/file_system/physical_file_system.dart

@@ -14,11 +14,11 @@ import 'package:watcher/watcher.dart';
 
 /// The name of the directory containing plugin specific subfolders used to
 /// store data across sessions.
-const String _serverDir = ".dartServer";
+string _serverdir;
 
 /// Returns the path to default state location.
 ///
-/// Generally this is ~/.dartServer. It can be overridden via the
+/// Generally this is ~/.config/dartServer. It can be overridden via the
 /// ANALYZER_STATE_LOCATION_OVERRIDE environment variable, in which case this
 /// method will return the contents of that environment variable.
 String? _getStandardStateLocation() {
@@ -27,10 +27,18 @@ String? _getStandardStateLocation() {
     return env['ANALYZER_STATE_LOCATION_OVERRIDE'];
   }
 
-  final home = io.Platform.isWindows ? env['LOCALAPPDATA'] : env['HOME'];
-  return home != null && io.FileSystemEntity.isDirectorySync(home)
-      ? join(home, _serverDir)
-      : null;
+  if (Platform.isLinux) {
+    var xdgConfigHome = Platform.environment['XDG_CONFIG_HOME'];
+    if (xdgConfigHome != null) {
+      return '$xdgConfigHome/dartServer';
+    } else {
+      return '${Platform.environment['HOME']}/.config/dartServer';
+    }
+  } else if (Platform.isMacOS) {
+    return '${Platform.environment['HOME']}/Library/Application Support/dartServer';
+  } else if (Platform.isWindows) {
+    return '${Platform.environment['APPDATA']}/dartServer';
+  }
 }
 
 /// A `dart:io` based implementation of [ResourceProvider].

pkg/dartdev/lib/src/analytics.dart

@@ -33,15 +33,14 @@ const String analyticsDisabledNoticeMessage = '''
   ╚════════════════════════════════════════════════════════════════════════════╝
 ''';
 const String _appName = 'dartdev';
-const String _dartDirectoryName = '.dart';
 const String _settingsFileName = 'dartdev.json';
 const String _trackingId = 'UA-26406144-37';
 const String _readmeFileName = 'README.txt';
 const String _readmeFileContents = '''
 This directory contains user-level settings for the Dart programming language
 (https://dart.dev).
 ''';
-
+String _dartDirectoryName;
 const String eventCategory = 'dartdev';
 const String exitCodeParam = 'exitCode';
 
@@ -102,7 +101,7 @@ Directory? get homeDir {
 
 /// The directory used to store the analytics settings file.
 ///
-/// Typically, the directory is `~/.dart/` (and the settings file is
+/// Typically, the directory is `~/.config/dart/` (and the settings file is
 /// `dartdev.json`).
 ///
 /// This can return null under some conditions, including when the user's home
@@ -112,7 +111,22 @@ Directory? getDartStorageDirectory() {
   if (dir == null) {
     return null;
   } else {
-    return Directory(path.join(dir.path, _dartDirectoryName));
+    if (Platform.environment.containsKey('DART_CONFIG_DIR')) {
+      return Platform.environment['DART_CONFIG_DIR'];
+    } else {
+      if (Platform.isLinux) {
+        var xdgConfigHome = Platform.environment['XDG_CONFIG_HOME'];
+        if (xdgConfigHome != null) {
+          return '$xdgConfigHome/dart';
+        } else {
+          return '${Platform.environment['HOME']}/.config/dart';
+        }
+      } else if (Platform.isMacOS) {
+        return '${Platform.environment['HOME']}/Library/Application Support/dart';
+      } else if (Platform.isWindows) {
+        return '${Platform.environment['APPDATA']}/dart';
+      }
+    }
   }
 }