Fix ConvertTypeCheckPatternToNullCheck

src/coreclr/System.Private.CoreLib/src/System/Attribute.CoreCLR.cs

@@ -301,7 +301,7 @@ private static Attribute[] InternalParamGetCustomAttributes(ParameterInfo param,
                 count = 0;
                 for (int i = 0; i < objAttr.Length; i++)
                 {
-                    if (objAttr[i] is object attr)
+                    if (objAttr[i] is { } attr)
                     {
                         attributes[count] = (Attribute)attr;
                         count++;

src/coreclr/System.Private.CoreLib/src/System/MulticastDelegate.CoreCLR.cs

@@ -149,7 +149,7 @@ private static bool TrySetSlot(object?[] a, int index, object o)
 
             // The slot may be already set because we have added and removed the same method before.
             // Optimize this case, because it's cheaper than copying the array.
-            if (a[index] is object ai)
+            if (a[index] is { } ai)
             {
                 MulticastDelegate d = (MulticastDelegate)o;
                 MulticastDelegate dd = (MulticastDelegate)ai;

src/coreclr/System.Private.CoreLib/src/System/Runtime/ControlledExecution.CoreCLR.cs

@@ -99,7 +99,7 @@ public static void Run(Action action, CancellationToken cancellationToken)
                 // an OperationCanceledException, preserving stack trace details from the ThreadAbortException in
                 // order to aid in diagnostics and debugging.
                 OperationCanceledException e = cancellationToken.IsCancellationRequested ? new(cancellationToken) : new();
-                if (tae.StackTrace is string stackTrace)
+                if (tae.StackTrace is { } stackTrace)
                 {
                     ExceptionDispatchInfo.SetRemoteStackTrace(e, stackTrace);
                 }

src/coreclr/System.Private.CoreLib/src/System/RuntimeHandles.cs

@@ -215,7 +215,7 @@ internal static object CreateInstanceForAnotherGenericParameter(
             [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicParameterlessConstructor)] RuntimeType type,
             RuntimeType genericParameter)
         {
-            Debug.Assert(type.GetConstructor(Type.EmptyTypes) is ConstructorInfo c && c.IsPublic,
+            Debug.Assert(type.GetConstructor(Type.EmptyTypes) is { } c && c.IsPublic,
                 $"CreateInstanceForAnotherGenericParameter requires {nameof(type)} to have a public parameterless constructor so it can be annotated for trimming without preserving private constructors.");
 
             object? instantiatedObject = null;
@@ -239,7 +239,7 @@ internal static object CreateInstanceForAnotherGenericParameter(
             RuntimeType genericParameter1,
             RuntimeType genericParameter2)
         {
-            Debug.Assert(type.GetConstructor(Type.EmptyTypes) is ConstructorInfo c && c.IsPublic,
+            Debug.Assert(type.GetConstructor(Type.EmptyTypes) is { } c && c.IsPublic,
                 $"CreateInstanceForAnotherGenericParameter requires {nameof(type)} to have a public parameterless constructor so it can be annotated for trimming without preserving private constructors.");
 
             object? instantiatedObject = null;

src/coreclr/System.Private.CoreLib/src/System/RuntimeType.CoreCLR.cs

@@ -2383,7 +2383,7 @@ private static bool FilterApplyMethodBase(
                             for (int i = 0; i < parameterInfos.Length; i++)
                             {
                                 // a null argument type implies a null arg which is always a perfect match
-                                if (argumentTypes[i] is Type t && !t.MatchesParameterTypeExactly(parameterInfos[i]))
+                                if (argumentTypes[i] is { } t && !t.MatchesParameterTypeExactly(parameterInfos[i]))
                                     return false;
                             }
                         }
@@ -3899,7 +3899,7 @@ private void CreateInstanceCheckThis()
                 Type[] argsType = args.Length != 0 ? new Type[args.Length] : EmptyTypes;
                 for (int i = 0; i < args.Length; i++)
                 {
-                    if (args[i] is object arg)
+                    if (args[i] is { } arg)
                     {
                         argsType[i] = arg.GetType();
                     }

src/libraries/Common/src/Roslyn/GetBestTypeByMetadataName.cs

@@ -64,7 +64,7 @@ internal static class RoslynExtensions
                                 continue;
                         }
 
-                        if (type is object)
+                        if (type is not null)
                         {
                             // Multiple visible types with the same metadata name are present
                             return null;

src/libraries/Common/src/System/Threading/Tasks/TaskToAsyncResult.cs

@@ -79,7 +79,7 @@ public static Task Unwrap(IAsyncResult asyncResult)
             }
 #endif
 
-            if ((asyncResult as TaskAsyncResult)?._task is not Task task)
+            if ((asyncResult as TaskAsyncResult)?._task is not { } task)
             {
                 throw new ArgumentException(null, nameof(asyncResult));
             }

src/libraries/System.Private.CoreLib/gen/IntrinsicsInSystemPrivateCoreLibAnalyzer.cs

@@ -291,7 +291,7 @@ private static INamedTypeSymbol[][] DecomposePropertySymbolForIsSupportedGroups_
             if (propertyDefiningSyntax != null)
             {
                 if (propertyDefiningSyntax is PropertyDeclarationSyntax propertyDeclaration
-                    && propertyDeclaration.ExpressionBody is ArrowExpressionClauseSyntax arrowExpression)
+                    && propertyDeclaration.ExpressionBody is { } arrowExpression)
                 {
                     if (model.SyntaxTree != arrowExpression.SyntaxTree)
                     {

src/libraries/System.Private.CoreLib/src/Microsoft/Win32/SafeHandles/SafeFileHandle.Unix.cs

@@ -107,7 +107,7 @@ private static SafeFileHandle Open(string path, Interop.Sys.OpenFlags flags, int
                     return handle;
                 }
 
-                if (createOpenException?.Invoke(error, flags, path) is Exception ex)
+                if (createOpenException?.Invoke(error, flags, path) is { } ex)
                 {
                     throw ex;
                 }

src/libraries/System.Private.CoreLib/src/System/Buffers/SharedArrayPool.cs

@@ -523,7 +523,7 @@ private static bool TryGetInt32EnvironmentVariable(string variable, out int resu
         {
             // Avoid globalization stack, as it might in turn be using ArrayPool.
 
-            if (Environment.GetEnvironmentVariableCore_NoArrayPool(variable) is string envVar &&
+            if (Environment.GetEnvironmentVariableCore_NoArrayPool(variable) is { } envVar &&
                 envVar.Length is > 0 and <= 32) // arbitrary limit that allows for some spaces around the maximum length of a non-negative Int32 (10 digits)
             {
                 ReadOnlySpan<char> value = envVar.AsSpan().Trim(' ');

src/libraries/System.Private.CoreLib/src/System/Collections/ArrayList.cs

@@ -876,7 +876,7 @@ public override int IndexOf(object? value, int startIndex, int count)
                 else
                 {
                     for (int i = startIndex; i < endIndex; i++)
-                        if (_list[i] is object o && o.Equals(value))
+                        if (_list[i] is { } o && o.Equals(value))
                             return i;
                     return -1;
                 }
@@ -944,7 +944,7 @@ public override int LastIndexOf(object? value, int startIndex, int count)
                 else
                 {
                     for (int i = startIndex; i >= endIndex; i--)
-                        if (_list[i] is object o && o.Equals(value))
+                        if (_list[i] is { } o && o.Equals(value))
                             return i;
                     return -1;
                 }
@@ -2268,7 +2268,7 @@ public override bool Contains(object? item)
                 else
                 {
                     for (int i = 0; i < _baseSize; i++)
-                        if (_baseList[_baseIndex + i] is object o && o.Equals(item))
+                        if (_baseList[_baseIndex + i] is { } o && o.Equals(item))
                             return true;
                     return false;
                 }

src/libraries/System.Private.CoreLib/src/System/Collections/Generic/Dictionary.cs

@@ -70,7 +70,7 @@ public Dictionary(int capacity, IEqualityComparer<TKey>? comparer)
                 // We use a non-randomized comparer for improved perf, falling back to a randomized comparer if the
                 // hash buckets become unbalanced.
                 if (typeof(TKey) == typeof(string) &&
-                    NonRandomizedStringEqualityComparer.GetStringComparer(_comparer!) is IEqualityComparer<string> stringComparer)
+                    NonRandomizedStringEqualityComparer.GetStringComparer(_comparer!) is { } stringComparer)
                 {
                     _comparer = (IEqualityComparer<TKey>)stringComparer;
                 }

src/libraries/System.Private.CoreLib/src/System/Collections/Generic/HashSet.cs

@@ -69,7 +69,7 @@ public HashSet(IEqualityComparer<T>? comparer)
                 // We use a non-randomized comparer for improved perf, falling back to a randomized comparer if the
                 // hash buckets become unbalanced.
                 if (typeof(T) == typeof(string) &&
-                    NonRandomizedStringEqualityComparer.GetStringComparer(_comparer) is IEqualityComparer<string> stringComparer)
+                    NonRandomizedStringEqualityComparer.GetStringComparer(_comparer) is { } stringComparer)
                 {
                     _comparer = (IEqualityComparer<T>)stringComparer;
                 }

src/libraries/System.Private.CoreLib/src/System/Diagnostics/Debug.cs

@@ -307,7 +307,7 @@ public AssertInterpolatedStringHandler(int literalLength, int formattedCount, bo
             /// <summary>Extracts the built string from the handler.</summary>
             internal string ToStringAndClear()
             {
-                string s = _stringBuilderHandler._stringBuilder is StringBuilder sb ?
+                string s = _stringBuilderHandler._stringBuilder is { } sb ?
                     sb.ToString() :
                     string.Empty;
                 _stringBuilderHandler = default;
@@ -402,7 +402,7 @@ public WriteIfInterpolatedStringHandler(int literalLength, int formattedCount, b
             /// <summary>Extracts the built string from the handler.</summary>
             internal string ToStringAndClear()
             {
-                string s = _stringBuilderHandler._stringBuilder is StringBuilder sb ?
+                string s = _stringBuilderHandler._stringBuilder is { } sb ?
                     StringBuilderCache.GetStringAndRelease(sb) :
                     string.Empty;
                 _stringBuilderHandler = default;

src/libraries/System.Private.CoreLib/src/System/Diagnostics/Tracing/EventSource.cs

@@ -3376,7 +3376,7 @@ private static bool AttributeTypeNamesMatch(Type attributeType, Type reflectedAt
                             if (manifest.HasResources)
                             {
                                 string eventKey = "event_" + eventName;
-                                if (manifest.GetLocalizedMessage(eventKey, CultureInfo.CurrentUICulture, etwFormat: false) is string msg)
+                                if (manifest.GetLocalizedMessage(eventKey, CultureInfo.CurrentUICulture, etwFormat: false) is { } msg)
                                 {
                                     // overwrite inline message with the localized message
                                     eventAttribute.Message = msg;
@@ -5856,7 +5856,7 @@ private void WriteMessageAttrib(StringBuilder? stringBuilder, string elementName
             {
                 // resource fallback: strings in the neutral culture will take precedence over inline strings
                 key = elementName + "_" + name;
-                if (resources.GetString(key, CultureInfo.InvariantCulture) is string localizedString)
+                if (resources.GetString(key, CultureInfo.InvariantCulture) is { } localizedString)
                     value = localizedString;
             }
 

src/libraries/System.Private.CoreLib/src/System/Enum.cs

@@ -1863,7 +1863,7 @@ private static bool TryFormatPrimitiveDefault<TUnderlying, TStorage>(RuntimeType
 
             if (!enumInfo.HasFlagsAttribute)
             {
-                if (GetNameInlined(enumInfo, Unsafe.BitCast<TUnderlying, TStorage>(value)) is string enumName)
+                if (GetNameInlined(enumInfo, Unsafe.BitCast<TUnderlying, TStorage>(value)) is { } enumName)
                 {
                     if (enumName.TryCopyTo(destination))
                     {
@@ -1967,7 +1967,7 @@ private static bool TryFormatFlagNames<TStorage>(EnumInfo<TStorage> enumInfo, TS
             TStorage[] values = enumInfo.Values;
             Debug.Assert(names.Length == values.Length);
 
-            if (GetSingleFlagsEnumNameForValue(resultValue, names, values, out int index) is string singleEnumFlagsFormat)
+            if (GetSingleFlagsEnumNameForValue(resultValue, names, values, out int index) is { } singleEnumFlagsFormat)
             {
                 if (singleEnumFlagsFormat.TryCopyTo(destination))
                 {

src/libraries/System.Private.CoreLib/src/System/IO/Enumeration/FileSystemEnumerator.Unix.cs

@@ -240,13 +240,13 @@ private void InternalDispose(bool disposing)
 
                     CloseDirectoryHandle();
 
-                    if (_pathBuffer is char[] pathBuffer)
+                    if (_pathBuffer is { } pathBuffer)
                     {
                         _pathBuffer = null;
                         ArrayPool<char>.Shared.Return(pathBuffer);
                     }
 
-                    if (_entryBuffer is byte[] entryBuffer)
+                    if (_entryBuffer is { } entryBuffer)
                     {
                         _entryBuffer = null;
                         ArrayPool<byte>.Shared.Return(entryBuffer);

src/libraries/System.Private.CoreLib/src/System/MemoryExtensions.cs

@@ -3987,7 +3987,7 @@ private static bool TryWrite<TArg0, TArg1, TArg2>(Span<char> destination, IForma
                 foreach ((string? Literal, int ArgIndex, int Alignment, string? Format) segment in format._segments)
                 {
                     bool appended;
-                    if (segment.Literal is string literal)
+                    if (segment.Literal is { } literal)
                     {
                         appended = handler.AppendLiteral(literal);
                     }
@@ -4548,7 +4548,7 @@ private bool AppendCustomFormatter<T>(T value, string? format)
                 ICustomFormatter? formatter = (ICustomFormatter?)_provider.GetFormat(typeof(ICustomFormatter));
                 Debug.Assert(formatter != null, "An incorrectly written provider said it implemented ICustomFormatter, and then didn't");
 
-                if (formatter is not null && formatter.Format(format, value, _provider) is string customFormatted)
+                if (formatter is not null && formatter.Format(format, value, _provider) is { } customFormatted)
                 {
                     return AppendLiteral(customFormatted);
                 }

src/libraries/System.Private.CoreLib/src/System/Reflection/NullabilityInfoContext.cs

@@ -451,7 +451,7 @@ private static MemberInfo GetMemberMetadataDefinition(MemberInfo member)
 
         private static Type GetPropertyMetaType(PropertyInfo property)
         {
-            if (property.GetGetMethod(true) is MethodInfo method)
+            if (property.GetGetMethod(true) is { } method)
             {
                 return method.ReturnType;
             }

src/libraries/System.Private.CoreLib/src/System/Runtime/CompilerServices/AsyncTaskMethodBuilderT.cs

@@ -339,7 +339,7 @@ public ref ExecutionContext? Context
             {
                 get
                 {
-                    Debug.Assert(m_stateObject is null or ExecutionContext, $"Expected {nameof(m_stateObject)} to be null or an ExecutionContext but was {(m_stateObject is object o ? o.GetType().ToString() : "(null)")}.");
+                    Debug.Assert(m_stateObject is null or ExecutionContext, $"Expected {nameof(m_stateObject)} to be null or an ExecutionContext but was {(m_stateObject is { } o ? o.GetType().ToString() : "(null)")}.");
                     return ref Unsafe.As<object?, ExecutionContext?>(ref m_stateObject);
                 }
             }

src/libraries/System.Private.CoreLib/src/System/Runtime/CompilerServices/DefaultInterpolatedStringHandler.cs

@@ -525,7 +525,7 @@ private void AppendCustomFormatter<T>(T value, string? format)
             ICustomFormatter? formatter = (ICustomFormatter?)_provider.GetFormat(typeof(ICustomFormatter));
             Debug.Assert(formatter != null, "An incorrectly written provider said it implemented ICustomFormatter, and then didn't");
 
-            if (formatter is not null && formatter.Format(format, value, _provider) is string customFormatted)
+            if (formatter is not null && formatter.Format(format, value, _provider) is { } customFormatted)
             {
                 AppendLiteral(customFormatted);
             }

src/libraries/System.Private.CoreLib/src/System/Runtime/InteropServices/PosixSignalRegistration.Unix.cs

@@ -57,7 +57,7 @@ private void Unregister()
         {
             lock (s_registrations)
             {
-                if (_token is Token token)
+                if (_token is { } token)
                 {
                     _token = null;
 

src/libraries/System.Private.CoreLib/src/System/SearchValues/Strings/Helpers/RabinKarp.cs

@@ -81,7 +81,7 @@ public RabinKarp(ReadOnlySpan<string> values)
 
                 // Start with a bucket containing 1 element and reallocate larger ones if needed.
                 // As MaxValues is similar to BucketCount, we will have 1 value per bucket on average.
-                if (buckets[bucket] is string[] existingBucket)
+                if (buckets[bucket] is { } existingBucket)
                 {
                     newBucket = new string[existingBucket.Length + 1];
                     existingBucket.AsSpan().CopyTo(newBucket);
@@ -132,7 +132,7 @@ private readonly int IndexOfAnyCore<TCaseSensitivity>(ReadOnlySpan<char> span)
                 {
                     ValidateReadPosition(span, ref current);
 
-                    if (Unsafe.Add(ref bucketsRef, hash % BucketCount) is string[] bucket)
+                    if (Unsafe.Add(ref bucketsRef, hash % BucketCount) is { } bucket)
                     {
                         int startOffset = (int)((nuint)Unsafe.ByteOffset(ref MemoryMarshal.GetReference(span), ref current) / sizeof(char));
 

src/libraries/System.Private.CoreLib/src/System/String.Manipulation.cs

@@ -659,7 +659,7 @@ private static string Format<TArg0, TArg1, TArg2>(IFormatProvider? provider, Com
             // Format each segment.
             foreach ((string? Literal, int ArgIndex, int Alignment, string? Format) segment in format._segments)
             {
-                if (segment.Literal is string literal)
+                if (segment.Literal is { } literal)
                 {
                     handler.AppendLiteral(literal);
                 }
@@ -1078,7 +1078,7 @@ private static string JoinCore(ReadOnlySpan<char> separator, ReadOnlySpan<string
 
                 // We range check again to avoid buffer overflows if this happens.
 
-                if (values[i] is string value)
+                if (values[i] is { } value)
                 {
                     int valueLen = value.Length;
                     if (valueLen > totalLength - copiedLength)

src/libraries/System.Private.CoreLib/src/System/Text/CompositeFormat.cs

@@ -45,7 +45,7 @@ private CompositeFormat(string format, (string? Literal, int ArgIndex, int Align
             {
                 Debug.Assert((segment.Literal is not null) ^ (segment.ArgIndex >= 0), "The segment should represent a literal or a format hole, but not both.");
 
-                if (segment.Literal is string literal)
+                if (segment.Literal is { } literal)
                 {
                     literalLength += literal.Length; // no concern about overflow as these were parsed out of a single string
                 }

src/libraries/System.Private.CoreLib/src/System/Text/StringBuilder.cs

@@ -1897,7 +1897,7 @@ private StringBuilder AppendFormat<TArg0, TArg1, TArg2>(IFormatProvider? provide
             // Append each segment.
             foreach ((string? Literal, int ArgIndex, int Alignment, string? Format) segment in format._segments)
             {
-                if (segment.Literal is string literal)
+                if (segment.Literal is { } literal)
                 {
                     handler.AppendLiteral(literal);
                 }

src/libraries/System.Private.CoreLib/src/System/Text/Unicode/Utf8.cs

@@ -658,7 +658,7 @@ private bool AppendCustomFormatter<T>(T value, string? format)
                 Debug.Assert(formatter is not null, "An incorrectly written provider said it implemented ICustomFormatter, and then didn't");
 
                 if (formatter is not null &&
-                    formatter.Format(format, value, _provider) is string customFormatted)
+                    formatter.Format(format, value, _provider) is { } customFormatted)
                 {
                     return AppendFormatted(customFormatted.AsSpan());
                 }