[VM/libraries] Fix more analyzer errors in patch files.

Change-Id: I51c4aaa38a3eb01f2a6914a0e4b5d25f103fa797
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/132449
Commit-Queue: Siva Annamalai <asiva@google.com>
Reviewed-by: Alexander Markov <alexmarkov@google.com>

Author: a-siva

sdk_nnbd/lib/_internal/vm/lib/array.dart

@@ -241,7 +241,7 @@ class _FixedSizeArrayIterator<E> implements Iterator<E> {
   final List<E> _array;
   final int _length; // Cache array length for faster access.
   int _index;
-  E _current;
+  E? _current;
 
   _FixedSizeArrayIterator(List<E> array)
       : _array = array,
@@ -250,7 +250,7 @@ class _FixedSizeArrayIterator<E> implements Iterator<E> {
     assert(array is _List<E> || array is _ImmutableList<E>);
   }
 
-  E get current => _current;
+  E get current => _current as E;
 
   @pragma("vm:prefer-inline")
   bool moveNext() {

sdk_nnbd/lib/_internal/vm/lib/async_patch.dart

@@ -140,7 +140,7 @@ class _AsyncStarStreamController<T> {
   bool onListenReceived = false;
   bool isScheduled = false;
   bool isSuspendedAtYield = false;
-  _Future cancellationFuture = null;
+  _Future? cancellationFuture = null;
 
   Stream<T> get stream {
     final Stream<T> local = controller.stream;
@@ -231,11 +231,11 @@ class _AsyncStarStreamController<T> {
     controller.close();
   }
 
-  _AsyncStarStreamController(this.asyncStarBody) {
-    controller = new StreamController(
-        onListen: this.onListen,
-        onResume: this.onResume,
-        onCancel: this.onCancel);
+  _AsyncStarStreamController(this.asyncStarBody)
+      : controller = new StreamController() {
+    controller.onListen = this.onListen;
+    controller.onResume = this.onResume;
+    controller.onCancel = this.onCancel;
   }
 
   onListen() {
@@ -273,17 +273,17 @@ void _rethrow(Object error, StackTrace stackTrace) native "Async_rethrow";
 @patch
 class _Future<T> {
   /// The closure implementing the async[*]-body that is `await`ing this future.
-  Function _awaiter;
+  Function? _awaiter;
 }
 
 @patch
 class _StreamImpl<T> {
   /// The closure implementing the async[*]-body that is `await`ing this future.
-  Function _awaiter;
+  Function? _awaiter;
 
   /// The closure implementing the async-generator body that is creating events
   /// for this stream.
-  Function _generator;
+  Function? _generator;
 }
 
 @pragma("vm:entry-point", "call")

sdk_nnbd/lib/_internal/vm/lib/collection_patch.dart

@@ -186,7 +186,7 @@ class _HashMap<K, V> extends MapBase<K, V> implements HashMap<K, V> {
   }
 
   void clear() {
-    _buckets = new List(_INITIAL_CAPACITY);
+    _buckets = new List.filled(_INITIAL_CAPACITY, null);
     if (_elementCount > 0) {
       _elementCount = 0;
       _modificationCount = (_modificationCount + 1) & _MODIFICATION_COUNT_MASK;
@@ -503,21 +503,21 @@ abstract class _HashMapIterator<K, V, E> implements Iterator<E> {
 
 class _HashMapKeyIterator<K, V> extends _HashMapIterator<K, V, K> {
   _HashMapKeyIterator(_HashMap<K, V> map) : super(map);
-  K get current => _entry?.key;
+  K get current => _entry!.key;
 }
 
 class _HashMapValueIterator<K, V> extends _HashMapIterator<K, V, V> {
   _HashMapValueIterator(_HashMap<K, V> map) : super(map);
-  V get current => _entry?.value;
+  V get current => _entry!.value;
 }
 
 @patch
 class HashSet<E> {
   @patch
   factory HashSet(
-      {bool equals(E e1, E e2),
-      int hashCode(E e),
-      bool isValidKey(potentialKey)}) {
+      {bool equals(E e1, E e2)?,
+      int hashCode(E e)?,
+      bool isValidKey(potentialKey)?}) {
     if (isValidKey == null) {
       if (hashCode == null) {
         if (equals == null) {
@@ -771,7 +771,7 @@ class _CustomHashSet<E> extends _HashSet<E> {
   }
 
   bool containsAll(Iterable<Object?> elements) {
-    for (Object element in elements) {
+    for (Object? element in elements) {
       if (!_validKey(element) || !this.contains(element)) return false;
     }
     return true;
@@ -798,7 +798,7 @@ class _HashSetEntry<E> {
   _HashSetEntry<E>? next;
   _HashSetEntry(this.key, this.hashCode, this.next);
 
-  _HashSetEntry<E> remove() {
+  _HashSetEntry<E>? remove() {
     final result = next;
     next = null;
     return result;

sdk_nnbd/lib/_internal/vm/lib/compact_hash.dart

@@ -441,7 +441,7 @@ class _CompactIterator<E> implements Iterator<E> {
   int _offset;
   final int _step;
   final int _checkSum;
-  E current;
+  E? _current;
 
   _CompactIterator(
       _HashBase table, this._data, this._len, this._offset, this._step)
@@ -456,13 +456,15 @@ class _CompactIterator<E> implements Iterator<E> {
       _offset += _step;
     } while (_offset < _len && _HashBase._isDeleted(_data, _data[_offset]));
     if (_offset < _len) {
-      current = internal.unsafeCast<E>(_data[_offset]);
+      _current = internal.unsafeCast<E>(_data[_offset]);
       return true;
     } else {
-      current = null;
+      _current = null;
       return false;
     }
   }
+
+  E get current => _current as E;
 }
 
 // Set implementation, analogous to _CompactLinkedHashMap.
@@ -482,7 +484,7 @@ class _CompactLinkedHashSet<E> extends _HashFieldBase
     for (int offset = 0; offset < _usedData; offset++) {
       Object current = _data[offset];
       if (!_HashBase._isDeleted(_data, current)) {
-        return current;
+        return current as E;
       }
     }
     throw IterableElementError.noElement();
@@ -492,7 +494,7 @@ class _CompactLinkedHashSet<E> extends _HashFieldBase
     for (int offset = _usedData - 1; offset >= 0; offset--) {
       Object current = _data[offset];
       if (!_HashBase._isDeleted(_data, current)) {
-        return current;
+        return current as E;
       }
     }
     throw IterableElementError.noElement();

sdk_nnbd/lib/_internal/vm/lib/date_patch.dart

@@ -49,8 +49,9 @@ class DateTime {
       int second, int millisecond, int microsecond, bool isUtc)
       : this.isUtc = isUtc,
         this._value = _brokenDownDateToValue(year, month, day, hour, minute,
-            second, millisecond, microsecond, isUtc) {
-    if (_value == null) throw new ArgumentError();
+                second, millisecond, microsecond, isUtc) ??
+            -1 {
+    if (_value == -1) throw new ArgumentError();
     if (isUtc == null) throw new ArgumentError();
   }
 
@@ -347,7 +348,7 @@ class DateTime {
     }
     if (microsecondsSinceEpoch.abs() >
         _maxMillisecondsSinceEpoch * Duration.microsecondsPerMillisecond) {
-      return null;
+      throw new ArgumentError();
     }
     return microsecondsSinceEpoch;
   }

sdk_nnbd/lib/_internal/vm/lib/deferred_load_patch.dart

@@ -12,7 +12,7 @@ class DeferredLibrary {
   Future<Null> load() {
     // Dummy implementation that should eventually be replaced by real
     // implementation.
-    Future future = new Future<Null>.value(null);
+    Future<Null> future = new Future<Null>.value(null);
     _loadedLibraries.add(libraryName);
     return future;
   }

sdk_nnbd/lib/_internal/vm/lib/double_patch.dart

@@ -91,7 +91,7 @@ class double {
     return sign * (doubleValue * P10[exponent]);
   }
 
-  static double? _parse(String str) {
+  static double? _parse(var str) {
     int len = str.length;
     int start = str._firstNonWhitespace();
     if (start == len) return null; // All whitespace.
@@ -104,7 +104,7 @@ class double {
 
   @patch
   static double parse(String source,
-      [@deprecated double onError(String source)]) {
+      [@deprecated double onError(String source)?]) {
     var result = _parse(source);
     if (result == null) {
       if (onError == null) throw new FormatException("Invalid double", source);

sdk_nnbd/lib/_internal/vm/lib/errors_patch.dart

@@ -17,7 +17,7 @@ class Error {
   }
 
   @patch
-  StackTrace get stackTrace => _stackTrace!;
+  StackTrace? get stackTrace => _stackTrace;
 
   @pragma("vm:entry-point")
   StackTrace? _stackTrace;
@@ -32,11 +32,11 @@ class _AssertionError extends Error implements AssertionError {
   // out of the script. It expects a Dart stack frame from class
   // _AssertionError. Thus we need a Dart stub that calls the native code.
   @pragma("vm:entry-point", "call")
-  static _throwNew(int assertionStart, int assertionEnd, Object message) {
+  static _throwNew(int assertionStart, int assertionEnd, Object? message) {
     _doThrowNew(assertionStart, assertionEnd, message);
   }
 
-  static _doThrowNew(int assertionStart, int assertionEnd, Object message)
+  static _doThrowNew(int assertionStart, int assertionEnd, Object? message)
       native "AssertionError_throwNew";
 
   @pragma("vm:entry-point", "call")
@@ -54,9 +54,10 @@ class _AssertionError extends Error implements AssertionError {
   }
 
   String get _messageString {
-    if (message == null) return "is not true.";
-    if (message is String) return message;
-    return Error.safeToString(message);
+    final msg = message;
+    if (msg == null) return "is not true.";
+    if (msg is String) return msg;
+    return Error.safeToString(msg);
   }
 
   String toString() {
@@ -77,7 +78,7 @@ class _AssertionError extends Error implements AssertionError {
   final String _url;
   final int _line;
   final int _column;
-  final Object message;
+  final Object? message;
 }
 
 class _TypeError extends _AssertionError implements TypeError {
@@ -88,7 +89,7 @@ class _TypeError extends _AssertionError implements TypeError {
   static _throwNew(int location, Object srcValue, _Type dstType, String dstName)
       native "TypeError_throwNew";
 
-  String toString() => super.message;
+  String toString() => super.message as String;
 }
 
 class _CastError extends Error implements CastError {
@@ -224,7 +225,7 @@ class NoSuchMethodError {
   @patch
   NoSuchMethodError(Object receiver, Symbol memberName,
       List positionalArguments, Map<Symbol, dynamic> namedArguments,
-      [List existingArgumentNames = null])
+      [List? existingArgumentNames = null])
       : _receiver = receiver,
         _invocation = null,
         _memberName = memberName,
@@ -277,34 +278,37 @@ class NoSuchMethodError {
   @patch
   String toString() {
     // TODO(regis): Remove this null check once dart2js is updated.
-    if (_invocation == null) {
+    final localInvocation = _invocation;
+    if (localInvocation == null) {
       // Use deprecated version of toString.
       return _toStringDeprecated();
     }
     String memberName =
-        internal.Symbol.computeUnmangledName(_invocation.memberName);
-    var level = (_invocation._type >> _InvocationMirror._LEVEL_SHIFT) &
+        internal.Symbol.computeUnmangledName(localInvocation.memberName);
+
+    var level = (localInvocation._type >> _InvocationMirror._LEVEL_SHIFT) &
         _InvocationMirror._LEVEL_MASK;
-    var kind = _invocation._type & _InvocationMirror._KIND_MASK;
+    var kind = localInvocation._type & _InvocationMirror._KIND_MASK;
     if (kind == _InvocationMirror._LOCAL_VAR) {
       return "NoSuchMethodError: Cannot assign to final variable '$memberName'";
     }
 
-    StringBuffer typeArgumentsBuf = null;
-    var typeArguments = _invocation.typeArguments;
+    StringBuffer? typeArgumentsBuf = null;
+    final typeArguments = localInvocation.typeArguments;
     if ((typeArguments != null) && (typeArguments.length > 0)) {
-      typeArgumentsBuf = new StringBuffer();
-      typeArgumentsBuf.write("<");
+      final argsBuf = new StringBuffer();
+      argsBuf.write("<");
       for (int i = 0; i < typeArguments.length; i++) {
         if (i > 0) {
-          typeArgumentsBuf.write(", ");
+          argsBuf.write(", ");
         }
-        typeArgumentsBuf.write(Error.safeToString(typeArguments[i]));
+        argsBuf.write(Error.safeToString(typeArguments[i]));
       }
-      typeArgumentsBuf.write(">");
+      argsBuf.write(">");
+      typeArgumentsBuf = argsBuf;
     }
     StringBuffer argumentsBuf = new StringBuffer();
-    var positionalArguments = _invocation.positionalArguments;
+    var positionalArguments = localInvocation.positionalArguments;
     int argumentCount = 0;
     if (positionalArguments != null) {
       for (; argumentCount < positionalArguments.length; argumentCount++) {
@@ -315,7 +319,7 @@ class NoSuchMethodError {
             .write(Error.safeToString(positionalArguments[argumentCount]));
       }
     }
-    var namedArguments = _invocation.namedArguments;
+    var namedArguments = localInvocation.namedArguments;
     if (namedArguments != null) {
       namedArguments.forEach((Symbol key, var value) {
         if (argumentCount > 0) {
@@ -328,7 +332,7 @@ class NoSuchMethodError {
       });
     }
     String existingSig =
-        _existingMethodSignature(_receiver, memberName, _invocation._type);
+        _existingMethodSignature(_receiver, memberName, localInvocation._type);
     String argsMsg = existingSig != null ? " with matching arguments" : "";
 
     assert(kind >= 0 && kind < 5);
@@ -441,25 +445,24 @@ class NoSuchMethodError {
 
     StringBuffer arguments = new StringBuffer();
     int argumentCount = 0;
-    if (_arguments != null) {
-      for (; argumentCount < _arguments.length; argumentCount++) {
+    final args = _arguments;
+    if (args != null) {
+      for (; argumentCount < args.length; argumentCount++) {
         if (argumentCount > 0) {
           arguments.write(", ");
         }
-        arguments.write(Error.safeToString(_arguments[argumentCount]));
+        arguments.write(Error.safeToString(args[argumentCount]));
       }
     }
-    if (_namedArguments != null) {
-      _namedArguments.forEach((Symbol key, var value) {
-        if (argumentCount > 0) {
-          arguments.write(", ");
-        }
-        arguments.write(internal.Symbol.computeUnmangledName(key));
-        arguments.write(": ");
-        arguments.write(Error.safeToString(value));
-        argumentCount++;
-      });
-    }
+    _namedArguments?.forEach((Symbol key, var value) {
+      if (argumentCount > 0) {
+        arguments.write(", ");
+      }
+      arguments.write(internal.Symbol.computeUnmangledName(key));
+      arguments.write(": ");
+      arguments.write(Error.safeToString(value));
+      argumentCount++;
+    });
     bool argsMismatch = _existingArgumentNames != null;
     String argsMessage = argsMismatch ? " with matching arguments" : "";
 
@@ -549,11 +552,12 @@ class NoSuchMethodError {
 
     if (argsMismatch) {
       StringBuffer formalParameters = new StringBuffer();
-      for (int i = 0; i < _existingArgumentNames.length; i++) {
+      final argumentNames = _existingArgumentNames!;
+      for (int i = 0; i < argumentNames.length; i++) {
         if (i > 0) {
           formalParameters.write(", ");
         }
-        formalParameters.write(_existingArgumentNames[i]);
+        formalParameters.write(argumentNames[i]);
       }
       msgBuf.write("\nFound: $memberName($formalParameters)");
     }