[null-safety] migrate to _almost_ null safety (dart-lang/file#162)

Remove record/replay functionality and update to almost null-safety.

analysis_options.yaml

@@ -1,4 +1,6 @@
 analyzer:
+  enable-experiment:
+    - non-nullable
   strong-mode:
     implicit-casts: false
     implicit-dynamic: false

appveyor.yml

@@ -11,4 +11,4 @@ install:
 build: off
 
 test_script:
-  - pub run test -j1
+  - pub run --enable-experiment=non-nullable test -j1

dev/bots/travis_script.sh

@@ -11,10 +11,10 @@ elif [[ "$SHARD" == "analyze" ]]; then
   for package in "${PACKAGES[@]}"; do
     echo "Analyzing packages/$package"
     cd $ROOT/packages/$package
-    dartanalyzer --options=$ROOT/analysis_options.yaml . || exit $?
+    dartanalyzer --enable-experiment=non-nullable --options=$ROOT/analysis_options.yaml . || exit $?
   done
 else
   # tests shard
   cd $ROOT/packages/file
-  pub run test -j1 -rexpanded || exit $?
+  pub run --enable-experiment=non-nullable test -j1 -rexpanded || exit $?
 fi

pkgs/file/CHANGELOG.md

@@ -1,6 +1,8 @@
-#### 5.2.2-dev
+#### 6.0.0-nullsafety
 
-* Made `MemoryRandomAccessFile` and `MemoryFile.openWrite` handle the file
+* Update to null safety.
+* Remove record/replay functionality.
+* Made `MemoryRandomAccessFile` and `MemoryFile.openWrite` handle the file.
   being removed or renamed while open.
 * Fixed incorrect formatting in `NoMatchingInvocationError.toString()`.
 * Fixed more test flakiness.

pkgs/file/lib/chroot.dart

@@ -2,5 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// @dart=2.10
+
 /// A file system that provides a view into _another_ `FileSystem` via a path.
 export 'src/backends/chroot.dart';

pkgs/file/lib/file.dart

@@ -2,6 +2,8 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// @dart=2.10
+
 /// Core interfaces containing the abstract `FileSystem` interface definition
 /// and all associated types used by `FileSystem`.
 export 'src/forwarding.dart';

pkgs/file/lib/local.dart

@@ -2,6 +2,8 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// @dart=2.10
+
 /// A local file system implementation. This relies on the use of `dart:io`
 /// and is thus not suitable for use in the browser.
 export 'src/backends/local.dart';

pkgs/file/lib/memory.dart

@@ -2,6 +2,8 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// @dart=2.10
+
 /// An implementation of `FileSystem` that exists entirely in memory with an
 /// internal representation loosely based on the Filesystem Hierarchy Standard.
 export 'src/backends/memory.dart';

pkgs/file/lib/src/backends/chroot.dart

@@ -2,6 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// @dart=2.10
 library file.src.backends.chroot;
 
 import 'dart:async';

pkgs/file/lib/src/backends/chroot/chroot_directory.dart

@@ -2,6 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// @dart=2.10
 part of file.src.backends.chroot;
 
 class _ChrootDirectory extends _ChrootFileSystemEntity<Directory, io.Directory>

pkgs/file/lib/src/backends/chroot/chroot_file.dart

@@ -2,6 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// @dart=2.10
 part of file.src.backends.chroot;
 
 typedef _SetupCallback = dynamic Function();
@@ -251,7 +252,7 @@ class _ChrootFile extends _ChrootFileSystemEntity<File, io.File>
       getDelegate(followLinks: true).openSync(mode: mode);
 
   @override
-  Stream<Uint8List> openRead([int start, int end]) =>
+  Stream<Uint8List> openRead([int? start, int? end]) =>
       getDelegate(followLinks: true).openRead(start, end).cast<Uint8List>();
 
   @override

pkgs/file/lib/src/backends/chroot/chroot_file_system.dart

@@ -2,6 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// @dart=2.10
 part of file.src.backends.chroot;
 
 const String _thisDir = '.';
@@ -51,10 +52,10 @@ class ChrootFileSystem extends FileSystem {
   /// Directory in [delegate] file system that is treated as the root here.
   final String root;
 
-  String _systemTemp;
+  String? _systemTemp;
 
   /// Path to the synthetic current working directory in this file system.
-  String _cwd;
+  late String _cwd;
 
   /// Gets the root path, as seen by entities in this file system.
   String get _localRoot => delegate.path.rootPrefix(root);
@@ -255,7 +256,7 @@ class ChrootFileSystem extends FileSystem {
   ///     the partially resolved path will be returned.
   String _resolve(
     String path, {
-    String from,
+    String? from,
     bool followLinks = true,
     _NotFoundBehavior notFound = _NotFoundBehavior.allow,
   }) {
@@ -366,14 +367,16 @@ enum _NotFoundBehavior {
 class _NotFoundFileStat implements FileStat {
   const _NotFoundFileStat();
 
+  static final DateTime _empty = DateTime(0);
+
   @override
-  DateTime get changed => null;
+  DateTime get changed => _empty;
 
   @override
-  DateTime get modified => null;
+  DateTime get modified => _empty;
 
   @override
-  DateTime get accessed => null;
+  DateTime get accessed => _empty;
 
   @override
   FileSystemEntityType get type => FileSystemEntityType.notFound;

pkgs/file/lib/src/backends/chroot/chroot_file_system_entity.dart

@@ -2,6 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// @dart=2.10
 part of file.src.backends.chroot;
 
 abstract class _ChrootFileSystemEntity<T extends FileSystemEntity,

pkgs/file/lib/src/backends/chroot/chroot_link.dart

@@ -2,6 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// @dart=2.10
 part of file.src.backends.chroot;
 
 class _ChrootLink extends _ChrootFileSystemEntity<Link, io.Link>

pkgs/file/lib/src/backends/local.dart

@@ -2,4 +2,5 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// @dart=2.10
 export 'local/local_file_system.dart' show LocalFileSystem;

pkgs/file/lib/src/backends/local/local_directory.dart

@@ -2,6 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// @dart=2.10
 import 'package:file/src/common.dart' as common;
 import 'package:file/src/forwarding.dart';
 import 'package:file/src/io.dart' as io;

pkgs/file/lib/src/backends/local/local_file.dart

@@ -2,6 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// @dart=2.10
 import 'package:file/src/forwarding.dart';
 import 'package:file/src/io.dart' as io;
 import 'package:file/file.dart';

pkgs/file/lib/src/backends/local/local_file_system.dart

@@ -2,6 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// @dart=2.10
 import 'dart:async';
 
 import 'package:file/src/io.dart' as io;

pkgs/file/lib/src/backends/local/local_file_system_entity.dart

@@ -2,6 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// @dart=2.10
 import 'package:file/src/forwarding.dart';
 import 'package:file/src/io.dart' as io;
 import 'package:file/file.dart';

pkgs/file/lib/src/backends/local/local_link.dart

@@ -2,6 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// @dart=2.10
 import 'package:file/src/forwarding.dart';
 import 'package:file/src/io.dart' as io;
 import 'package:file/file.dart';

pkgs/file/lib/src/backends/memory.dart

@@ -2,5 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// @dart=2.10
 export 'memory/memory_file_system.dart' show MemoryFileSystem;
 export 'memory/style.dart' show FileSystemStyle, StyleableFileSystem;

pkgs/file/lib/src/backends/memory/clock.dart

@@ -2,6 +2,8 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// @dart=2.10
+
 /// Interface describing clocks used by the [MemoryFileSystem].
 ///
 /// The [MemoryFileSystem] uses a clock to determine the modification times of
@@ -39,7 +41,7 @@ class _RealtimeClock extends Clock {
 
 class _MonotonicTestClock extends Clock {
   _MonotonicTestClock({
-    DateTime start,
+    DateTime? start,
   }) : _current = start ?? DateTime(2000);
 
   DateTime _current;

pkgs/file/lib/src/backends/memory/common.dart

@@ -2,13 +2,14 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// @dart=2.10
 import 'package:file/src/common.dart' as common;
 
 /// Generates a path to use in error messages.
 typedef PathGenerator = dynamic Function();
 
 /// Throws a `FileSystemException` if [object] is null.
-void checkExists(Object object, PathGenerator path) {
+void checkExists(Object? object, PathGenerator path) {
   if (object == null) {
     throw common.noSuchFileOrDirectory(path() as String);
   }

pkgs/file/lib/src/backends/memory/memory_directory.dart

@@ -2,6 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// @dart=2.10
 import 'dart:async';
 
 import 'package:file/file.dart';
@@ -39,7 +40,7 @@ class MemoryDirectory extends MemoryFileSystemEntity
   }
 
   @override
-  bool existsSync() => backingOrNull?.stat?.type == expectedType;
+  bool existsSync() => backingOrNull?.stat.type == expectedType;
 
   @override
   Future<Directory> create({bool recursive = false}) async {
@@ -49,7 +50,7 @@ class MemoryDirectory extends MemoryFileSystemEntity
 
   @override
   void createSync({bool recursive = false}) {
-    Node node = internalCreateSync(
+    Node? node = internalCreateSync(
       followTailLink: true,
       visitLinks: true,
       createChild: (DirectoryNode parent, bool isFinalSegment) {
@@ -59,17 +60,18 @@ class MemoryDirectory extends MemoryFileSystemEntity
         return null;
       },
     );
-    if (node.type != expectedType) {
+    if (node?.type != expectedType) {
       // There was an existing non-directory node at this object's path
       throw common.notADirectory(path);
     }
   }
 
   @override
-  Future<Directory> createTemp([String prefix]) async => createTempSync(prefix);
+  Future<Directory> createTemp([String? prefix]) async =>
+      createTempSync(prefix);
 
   @override
-  Directory createTempSync([String prefix]) {
+  Directory createTempSync([String? prefix]) {
     prefix = (prefix ?? '') + 'rand';
     String fullPath = fileSystem.path.join(path, prefix);
     String dirname = fileSystem.path.dirname(fullPath);
@@ -142,7 +144,7 @@ class MemoryDirectory extends MemoryFileSystemEntity
         while (followLinks &&
             utils.isLink(child) &&
             breadcrumbs.add(child as LinkNode)) {
-          Node referent = (child as LinkNode).referentOrNull;
+          Node? referent = child.referentOrNull;
           if (referent != null) {
             child = referent;
           }