[flutter_tools] add custom tool analysis to analyze.dart, lint Future.catchError (#140122)

Ensure tool code does not use Future.catchError or Future.onError, because it is not statically safe: https://github.com/dart-lang/sdk/issues/51248.

This was proposed upstream in dart-lang/linter in https://github.com/dart-lang/linter/issues/4071 and https://github.com/dart-lang/linter/pull/4068, but not accepted.

dev/bots/analyze.dart

@@ -18,6 +18,7 @@ import 'package:path/path.dart' as path;
 
 import 'allowlist.dart';
 import 'custom_rules/analyze.dart';
+import 'custom_rules/avoid_future_catcherror.dart';
 import 'custom_rules/no_double_clamp.dart';
 import 'custom_rules/no_stop_watches.dart';
 import 'run_command.dart';
@@ -186,6 +187,10 @@ Future<void> run(List<String> arguments) async {
     await analyzeWithRules(flutterRoot, testRules,
       includePaths: <String>['packages/flutter/test'],
     );
+    final List<AnalyzeRule> toolRules = <AnalyzeRule>[AvoidFutureCatchError()];
+    final String toolRuleNames = toolRules.map((AnalyzeRule rule) => '\n * $rule').join();
+    printProgress('Analyzing code in the tool with the following rules:$toolRuleNames');
+    await analyzeToolWithRules(flutterRoot, toolRules);
   } else {
     printProgress('Skipped performing further analysis in the framework because "flutter analyze" finished with a non-zero exit code.');
   }

dev/bots/custom_rules/analyze.dart

@@ -64,6 +64,41 @@ Future<void> analyzeWithRules(String flutterRootDirectory, List<AnalyzeRule> rul
   }
 }
 
+Future<void> analyzeToolWithRules(String flutterRootDirectory, List<AnalyzeRule> rules) async {
+  final String libPath = path.canonicalize('$flutterRootDirectory/packages/flutter_tools/lib');
+  if (!Directory(libPath).existsSync()) {
+    foundError(<String>['Analyzer error: the specified $libPath does not exist.']);
+  }
+  final String testPath = path.canonicalize('$flutterRootDirectory/packages/flutter_tools/test');
+  final AnalysisContextCollection collection = AnalysisContextCollection(
+    includedPaths: <String>[libPath, testPath],
+  );
+
+  final List<String> analyzerErrors = <String>[];
+  for (final AnalysisContext context in collection.contexts) {
+    final Iterable<String> analyzedFilePaths = context.contextRoot.analyzedFiles();
+    final AnalysisSession session = context.currentSession;
+
+    for (final String filePath in analyzedFilePaths) {
+      final SomeResolvedUnitResult unit = await session.getResolvedUnit(filePath);
+      if (unit is ResolvedUnitResult) {
+        for (final AnalyzeRule rule in rules) {
+          rule.applyTo(unit);
+        }
+      } else {
+        analyzerErrors.add('Analyzer error: file $unit could not be resolved. Expected "ResolvedUnitResult", got ${unit.runtimeType}.');
+      }
+    }
+  }
+
+  if (analyzerErrors.isNotEmpty) {
+    foundError(analyzerErrors);
+  }
+  for (final AnalyzeRule verifier in rules) {
+    verifier.reportViolations(flutterRootDirectory);
+  }
+}
+
 /// An interface that defines a set of best practices, and collects information
 /// about code that violates the best practices in a [ResolvedUnitResult].
 ///

dev/bots/custom_rules/avoid_future_catcherror.dart

@@ -0,0 +1,89 @@
+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:analyzer/dart/analysis/results.dart';
+import 'package:analyzer/dart/ast/ast.dart';
+import 'package:analyzer/dart/ast/visitor.dart';
+import 'package:analyzer/dart/element/type.dart';
+
+import '../utils.dart';
+import 'analyze.dart';
+
+/// Don't use Future.catchError or Future.onError.
+///
+/// See https://github.com/flutter/flutter/pull/130662 for more context.
+///
+/// **BAD:**
+///
+/// ```dart
+/// Future<Object?> doSomething() {
+///   return doSomethingAsync().catchError((_) => null);
+/// }
+///
+/// Future<Object?> doSomethingAsync() {
+///   return Future<Object>.error(Exception('error'));
+/// }
+/// ```
+///
+/// **GOOD:**
+///
+/// ```dart
+/// Future<Object?> doSomething() {
+///   return doSomethingAsync().then(
+///     (Object? obj) => obj,
+///     onError: (_) => null,
+///   );
+/// }
+///
+/// Future<Object?> doSomethingAsync() {
+///   return Future<Object>.error(Exception('error'));
+/// }
+/// ```
+class AvoidFutureCatchError extends AnalyzeRule {
+  final Map<ResolvedUnitResult, List<AstNode>> _errors = <ResolvedUnitResult, List<AstNode>>{};
+
+  @override
+  void applyTo(ResolvedUnitResult unit) {
+    final _Visitor visitor = _Visitor();
+    unit.unit.visitChildren(visitor);
+    if (visitor._offendingNodes.isNotEmpty) {
+      _errors.putIfAbsent(unit, () => <AstNode>[]).addAll(visitor._offendingNodes);
+    }
+  }
+
+  @override
+  void reportViolations(String workingDirectory) {
+    if (_errors.isEmpty) {
+      return;
+    }
+
+    foundError(<String>[
+      for (final MapEntry<ResolvedUnitResult, List<AstNode>> entry in _errors.entries)
+        for (final AstNode node in entry.value)
+          '${locationInFile(entry.key, node, workingDirectory)}: ${node.parent}',
+      '\n${bold}Future.catchError and Future.onError are not type safe--instead use Future.then: https://github.com/dart-lang/sdk/issues/51248$reset',
+    ]);
+  }
+
+  @override
+  String toString() => 'Avoid "Future.catchError" and "Future.onError"';
+}
+
+class _Visitor extends RecursiveAstVisitor<void> {
+  _Visitor();
+
+  final List<AstNode> _offendingNodes = <AstNode>[];
+
+  @override
+  void visitMethodInvocation(MethodInvocation node) {
+    if (node.methodName.name != 'onError' && node.methodName.name != 'catchError') {
+      return;
+    }
+    final DartType? targetType = node.realTarget?.staticType;
+    if (targetType == null || !targetType.isDartAsyncFuture) {
+      return;
+    }
+    _offendingNodes.add(node);
+  }
+}

dev/bots/custom_rules/no_double_clamp.dart

@@ -7,7 +7,6 @@ import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
-import 'package:path/path.dart' as path;
 
 import '../utils.dart';
 import 'analyze.dart';
@@ -39,14 +38,10 @@ class _NoDoubleClamp implements AnalyzeRule {
       return;
     }
 
-    String locationInFile(ResolvedUnitResult unit, AstNode node) {
-      return '${path.relative(path.relative(unit.path, from: workingDirectory))}:${unit.lineInfo.getLocation(node.offset).lineNumber}';
-    }
-
     foundError(<String>[
       for (final MapEntry<ResolvedUnitResult, List<AstNode>> entry in _errors.entries)
         for (final AstNode node in entry.value)
-          '${locationInFile(entry.key, node)}: ${node.parent}',
+          '${locationInFile(entry.key, node, workingDirectory)}: ${node.parent}',
       '\n${bold}For performance reasons, we use a custom "clampDouble" function instead of using "double.clamp".$reset',
     ]);
   }

dev/bots/utils.dart

@@ -8,7 +8,10 @@ import 'dart:io' as system show exit;
 import 'dart:io' hide exit;
 import 'dart:math' as math;
 
+import 'package:analyzer/dart/analysis/results.dart';
+import 'package:analyzer/dart/ast/ast.dart';
 import 'package:meta/meta.dart';
+import 'package:path/path.dart' as path;
 
 const Duration _quietTimeout = Duration(minutes: 10); // how long the output should be hidden between calls to printProgress before just being verbose
 
@@ -253,3 +256,7 @@ Future<bool> _isPortAvailable(int port) async {
     return true;
   }
 }
+
+String locationInFile(ResolvedUnitResult unit, AstNode node, String workingDirectory) {
+  return '${path.relative(path.relative(unit.path, from: workingDirectory))}:${unit.lineInfo.getLocation(node.offset).lineNumber}';
+}

packages/flutter_tools/lib/src/daemon.dart

@@ -190,10 +190,10 @@ class DaemonStreams {
     final Future<Socket> socketFuture = Socket.connect(host, port);
     final StreamController<List<int>> inputStreamController = StreamController<List<int>>();
     final StreamController<List<int>> outputStreamController = StreamController<List<int>>();
-    socketFuture.then((Socket socket) {
+    socketFuture.then<void>((Socket socket) {
       inputStreamController.addStream(socket);
       socket.addStream(outputStreamController.stream);
-    }).onError((Object error, StackTrace stackTrace) {
+    }, onError: (Object error, StackTrace stackTrace) {
       logger.printError('Socket error: $error');
       logger.printTrace('$stackTrace');
       // Propagate the error to the streams.