Fixed warnings on null assignments

src/BenchmarkDotNet.Diagnostics.Windows/InliningDiagnoser.cs

@@ -13,7 +13,7 @@ public class InliningDiagnoser : JitDiagnoser<object>, IProfiler
 
         private readonly bool logFailuresOnly = true;
         private readonly bool filterByNamespace = true;
-        private readonly string[] allowedNamespaces = null;
+        private readonly string[]? allowedNamespaces = null;
         private string defaultNamespace;
 
         // ReSharper disable once EmptyConstructor parameterless ctor is mandatory for DiagnosersLoader.CreateDiagnoser

src/BenchmarkDotNet.Diagnostics.Windows/Tracing/NativeMemoryLogParser.cs

@@ -95,7 +95,7 @@ private IEnumerable<Metric> Parse(TraceLog traceLog)
             var heapParser = new HeapTraceProviderTraceEventParser(eventSource);
             // We index by heap address and then within the heap we remember the allocation stack
             var heaps = new Dictionary<Address, Dictionary<Address, long>>();
-            Dictionary<Address, long> lastHeapAllocs = null;
+            Dictionary<Address, long>? lastHeapAllocs = null;
 
             Address lastHeapHandle = 0;
 

src/BenchmarkDotNet.Disassembler.x64/SourceCodeProvider.cs

@@ -134,7 +134,7 @@ private static SourceLocation FindNearestLine(PdbFunction function, int ilOffset
                 return null;
 
             int distance = int.MaxValue;
-            SourceLocation nearest = null;
+            SourceLocation? nearest = null;
 
             foreach (PdbSequencePointCollection sequenceCollection in function.SequencePoints)
             {
@@ -183,7 +183,7 @@ private static PdbReader GetReaderForMethod(ClrMethod method)
             ClrModule module = method?.Type?.Module;
             PdbInfo info = module?.Pdb;
 
-            PdbReader reader = null;
+            PdbReader? reader = null;
             if (info != null)
             {
                 if (!s_pdbReaders.TryGetValue(info, out reader))

src/BenchmarkDotNet/Characteristics/Characteristic.cs

@@ -86,7 +86,7 @@ protected Characteristic(
 
         private object FallbackValue { get; }
 
-        public object this[CharacteristicObject obj]
+        public object? this[CharacteristicObject obj]
         {
             get { return obj.GetValue(this); }
             set { obj.SetValue(this, value); }

src/BenchmarkDotNet/Disassemblers/MonoDisassembler.cs

@@ -128,7 +128,7 @@ private static DisassemblyResult CreateErrorResult(IReadOnlyList<string?> input,
             //line example 2: 0000000000000000  subq    $0x28, %rsp
             private static readonly Regex InstructionRegex = new Regex(@"\s*(?<address>[0-9a-f]+)(\:\s+([0-9a-f]{2}\s+)+)?\s+(?<instruction>.*)\s*", RegexOptions.Compiled);
 
-            private static bool TryParseInstruction(string line, out MonoCode instruction)
+            private static bool TryParseInstruction(string line, out MonoCode? instruction)
             {
                 instruction = null;
                 var match = InstructionRegex.Match(line);

src/BenchmarkDotNet/Disassemblers/SourceCodeProvider.cs

@@ -150,7 +150,7 @@ private static ManagedSymbolModule GetReaderForMethod(ClrMethod method)
             ClrModule module = method?.Type?.Module;
             PdbInfo info = module?.Pdb;
 
-            ManagedSymbolModule reader = null;
+            ManagedSymbolModule? reader = null;
             if (info != null)
             {
                 if (!s_pdbReaders.TryGetValue(info, out reader))

src/BenchmarkDotNet/Engines/AnonymousPipesHost.cs

@@ -63,7 +63,7 @@ public void SendSignal(HostSignal hostSignal)
         public void ReportResults(RunResults runResults) => runResults.Print(outWriter);
 
         [PublicAPI] // called from generated code
-        public static bool TryGetFileHandles(string[] args, out string writeHandle, out string readHandle)
+        public static bool TryGetFileHandles(string[] args, out string? writeHandle, out string? readHandle)
         {
             for (int i = 0; i < args.Length; i++)
             {

src/BenchmarkDotNet/Engines/Consumer.cs

@@ -31,7 +31,7 @@ private static readonly HashSet<Type> SupportedTypes
         private double doubleHolder;
         private long longHolder;
         private ulong ulongHolder;
-        private volatile object objectHolder;
+        private volatile object? objectHolder;
         private volatile IntPtr ptrHolder;
         private volatile UIntPtr uptrHolder;
 #pragma warning restore IDE0052 // Remove unread private members
@@ -157,7 +157,7 @@ public void Consume<T>(in T value)
         internal static bool IsConsumable(Type type)
             => SupportedTypes.Contains(type) || type.GetTypeInfo().IsClass || type.GetTypeInfo().IsInterface;
 
-        internal static bool HasConsumableField(Type type, out FieldInfo consumableField)
+        internal static bool HasConsumableField(Type type, out FieldInfo? consumableField)
         {
             var typeInfo = type.GetTypeInfo();
 

src/BenchmarkDotNet/Environments/ProcessorBrandStringHelper.cs

@@ -94,7 +94,7 @@ private static string GetBrandStyledActualFrequency(Frequency? frequency)
         {
             var data = ResourceHelper.LoadResource("BenchmarkDotNet.Environments.microarchitectures.txt").Split('\r', '\n');
             var dictionary = new Dictionary<string, string>();
-            string currentMicroarchitecture = null;
+            string? currentMicroarchitecture = null;
             foreach (string line in data)
             {
                if (line.StartsWith("//") || string.IsNullOrWhiteSpace(line))

src/BenchmarkDotNet/Environments/Runtimes/CoreRuntime.cs

@@ -77,7 +77,7 @@ internal static CoreRuntime FromVersion(Version version)
             }
         }
 
-        internal static bool TryGetVersion(out Version version)
+        internal static bool TryGetVersion(out Version? version)
         {
             // we can't just use System.Runtime.InteropServices.RuntimeInformation.FrameworkDescription
             // because it can be null and it reports versions like 4.6.* for .NET Core 2.*
@@ -124,7 +124,7 @@ internal static bool TryGetVersion(out Version version)
         // sample input:
         // for dotnet run: C:\Program Files\dotnet\shared\Microsoft.NETCore.App\2.1.12\
         // for dotnet publish: C:\Users\adsitnik\source\repos\ConsoleApp25\ConsoleApp25\bin\Release\netcoreapp2.0\win-x64\publish\
-        internal static bool TryGetVersionFromRuntimeDirectory(string runtimeDirectory, out Version version)
+        internal static bool TryGetVersionFromRuntimeDirectory(string runtimeDirectory, out Version? version)
         {
             if (!string.IsNullOrEmpty(runtimeDirectory) && Version.TryParse(GetParsableVersionPart(new DirectoryInfo(runtimeDirectory).Name), out version))
             {
@@ -141,7 +141,7 @@ internal static bool TryGetVersionFromRuntimeDirectory(string runtimeDirectory,
         // 2.2: 4.6.27817.03 @BuiltBy: dlab14-DDVSOWINAGE101 @Branch: release/2.2 @SrcCode: https://github.com/dotnet/coreclr/tree/ce1d090d33b400a25620c0145046471495067cc7, Microsoft .NET Framework
         // 3.0: 3.0.0-preview8.19379.2+ac25be694a5385a6a1496db40de932df0689b742, Microsoft .NET Core
         // 5.0: 5.0.0-alpha1.19413.7+0ecefa44c9d66adb8a997d5778dc6c246ad393a7, Microsoft .NET Core
-        internal static bool TryGetVersionFromProductInfo(string productVersion, string productName, out Version version)
+        internal static bool TryGetVersionFromProductInfo(string productVersion, string productName, out Version? version)
         {
             if (!string.IsNullOrEmpty(productVersion) && !string.IsNullOrEmpty(productName))
             {
@@ -175,7 +175,7 @@ internal static bool TryGetVersionFromProductInfo(string productVersion, string
         // sample input:
         // .NETCoreApp,Version=v2.0
         // .NETCoreApp,Version=v2.1
-        internal static bool TryGetVersionFromFrameworkName(string frameworkName, out Version version)
+        internal static bool TryGetVersionFromFrameworkName(string frameworkName, out Version? version)
         {
             const string versionPrefix = ".NETCoreApp,Version=v";
             if (!string.IsNullOrEmpty(frameworkName) && frameworkName.StartsWith(versionPrefix))

src/BenchmarkDotNet/Exporters/Xml/XmlSerializer.cs

@@ -110,7 +110,7 @@ private void WriteCollectionProperty(object source, PropertyInfo property)
 
             writer.WriteStartElement(property.Name);
 
-            string itemName = null;
+            string? itemName = null;
 
             foreach (var item in collection)
             {

src/BenchmarkDotNet/Loggers/Broker.cs

@@ -78,9 +78,8 @@ private void ProcessDataBlocking()
             using StreamWriter writer = new (acknowledgments, AnonymousPipesHost.UTF8NoBOM, bufferSize: 1);
             // Flush the data to the Stream after each write, otherwise the client will wait for input endlessly!
             writer.AutoFlush = true;
-            string line = null;
 
-            while ((line = reader.ReadLine()) is not null)
+            while (reader.ReadLine() is { } line)
             {
                 // TODO: implement Silent mode here
                 logger.WriteLine(LogKind.Default, line);

src/BenchmarkDotNet/Loggers/LinqPadLogger.cs

@@ -16,7 +16,7 @@ public sealed class LinqPadLogger : ILogger
         public static readonly Lazy<LinqPadLogger> lazyInstance = new Lazy<LinqPadLogger>(() =>
         {
             // Detect if being run from LINQPad; see https://github.com/dotnet/BenchmarkDotNet/issues/445#issuecomment-300723741
-            MethodInfo withStyle = null;
+            MethodInfo? withStyle = null;
             if (AppDomain.CurrentDomain.FriendlyName.StartsWith("LINQPad", StringComparison.OrdinalIgnoreCase))
             {
                 try

src/BenchmarkDotNet/Toolchains/CsProj/CsProjGenerator.cs

@@ -121,7 +121,7 @@ protected virtual string GetRuntimeSettings(GcMode gcMode, IResolver resolver)
             // custom SDKs are not added for non-netcoreapp apps (like net471), so when the TFM != netcoreapp we dont parse "<Import Sdk="
             // we don't allow for that mostly to prevent from edge cases like the following
             // <Import Sdk="Microsoft.NET.Sdk.WindowsDesktop" Project="Sdk.props" Condition="'$(TargetFramework)'=='netcoreapp3.0'"/>
-            string sdkName = null;
+            string? sdkName = null;
             if (TargetFrameworkMoniker.StartsWith("netcoreapp", StringComparison.InvariantCultureIgnoreCase))
             {
                 foreach (XmlElement importElement in projectElement.GetElementsByTagName("Import"))
@@ -161,8 +161,8 @@ protected virtual string GetRuntimeSettings(GcMode gcMode, IResolver resolver)
                 sdkName = DefaultSdkName;
             }
 
-            XmlDocument itemGroupsettings = null;
-            XmlDocument propertyGroupSettings = null;
+            XmlDocument? itemGroupsettings = null;
+            XmlDocument? propertyGroupSettings = null;
 
             GetSettingsThatNeedToBeCopied(projectElement, ref itemGroupsettings, ref propertyGroupSettings, projectFile);
 

src/BenchmarkDotNet/Toolchains/InProcess/Emit/Implementation/Emitters/ConsumeEmitter.cs

@@ -31,9 +31,9 @@ protected ConsumeEmitter(ConsumableTypeInfo consumableTypeInfo)
 
         protected ConsumableTypeInfo ConsumableInfo { get; }
 
-        protected ILGenerator IlBuilder { get; private set; }
-        protected MethodBuilder ActionMethodBuilder { get; private set; }
-        protected MethodInfo ActionInvokeMethod { get; private set; }
+        protected ILGenerator? IlBuilder { get; private set; }
+        protected MethodBuilder? ActionMethodBuilder { get; private set; }
+        protected MethodInfo? ActionInvokeMethod { get; private set; }
         protected RunnableActionKind? ActionKind { get; private set; }
 
         [AssertionMethod]

src/BenchmarkDotNet/Toolchains/InProcess/Emit/Implementation/Emitters/RunnableEmitter.cs

@@ -434,7 +434,7 @@ private void DefineFields()
 
                 Type argLocalsType;
                 Type argFieldType;
-                MethodInfo opConversion = null;
+                MethodInfo? opConversion = null;
                 if (parameterType.IsByRef)
                 {
                     argLocalsType = parameterType;
@@ -833,8 +833,8 @@ .locals init (
             var skipFirstArg = workloadMethod.IsStatic;
             var argLocals = EmitDeclareArgLocals(ilBuilder, skipFirstArg);
 
-            LocalBuilder callResultLocal = null;
-            LocalBuilder awaiterLocal = null;
+            LocalBuilder? callResultLocal = null;
+            LocalBuilder? awaiterLocal = null;
             if (consumableInfo.IsAwaitable)
             {
                 var callResultType = consumableInfo.OriginMethodReturnType;

src/BenchmarkDotNet/Toolchains/InProcess/Emit/InProcessEmitBuilder.cs

@@ -11,8 +11,8 @@ public class InProcessEmitBuilder : IBuilder
     {
         public BuildResult Build(GenerateResult generateResult, BuildPartition buildPartition, ILogger logger)
         {
-            Assembly assembly = null;
-            Exception buildError = null;
+            Assembly? assembly = null;
+            Exception? buildError = null;
             try
             {
                 assembly = RunnableEmitter.EmitPartitionAssembly(generateResult, buildPartition, logger);

src/BenchmarkDotNet/Toolchains/NativeAot/NativeAotToolchainBuilder.cs

@@ -17,7 +17,7 @@ public class NativeAotToolchainBuilder : CustomDotNetCliToolchainBuilder
         private bool ilcGenerateCompleteTypeMetadata = true;
         private bool ilcGenerateStackTraceData = true;
         private string ilcOptimizationPreference = "Speed";
-        private string ilcInstructionSet = null;
+        private string? ilcInstructionSet = null;
 
         private bool isIlCompilerConfigured;
 

src/BenchmarkDotNet/Toolchains/Toolchain.cs

@@ -57,7 +57,7 @@ public virtual IEnumerable<ValidationError> Validate(BenchmarkCase benchmarkCase
             }
         }
 
-        internal static bool IsCliPathInvalid(string customDotNetCliPath, BenchmarkCase benchmarkCase, out ValidationError validationError)
+        internal static bool IsCliPathInvalid(string customDotNetCliPath, BenchmarkCase benchmarkCase, out ValidationError? validationError)
         {
             validationError = null;
 

src/BenchmarkDotNet/Validators/ExecutionValidatorBase.cs

@@ -52,7 +52,7 @@ public IEnumerable<ValidationError> Validate(ValidationParameters validationPara
             return errors;
         }
 
-        private bool TryCreateBenchmarkTypeInstance(Type type, List<ValidationError> errors, out object instance)
+        private bool TryCreateBenchmarkTypeInstance(Type type, List<ValidationError> errors, out object? instance)
         {
             try
             {

tests/BenchmarkDotNet.IntegrationTests/BenchmarkSwitcherTest.cs

@@ -135,7 +135,7 @@ public void WhenDisableLogFileWeDontWriteToFile()
             var logger = new OutputLogger(Output);
             var config = ManualConfig.CreateEmpty().AddLogger(logger).WithOptions(ConfigOptions.DisableLogFile).AddJob(Job.Dry);
 
-            string logFilePath = null;
+            string? logFilePath = null;
             try
             {
                 var summaries = BenchmarkSwitcher
@@ -161,7 +161,7 @@ public void EnsureLogFileIsWritten()
             var logger = new OutputLogger(Output);
             var config = ManualConfig.CreateEmpty().AddLogger(logger).AddJob(Job.Dry);
 
-            string logFilePath = null;
+            string? logFilePath = null;
             try
             {
                 var summaries = BenchmarkSwitcher

tests/BenchmarkDotNet.IntegrationTests/ExporterIOTests.cs

@@ -81,7 +81,7 @@ public void ExporterUsesFullyQualifiedTypeNameAsFileName()
             var exporter = new MockExporter();
             var mockSummary = GetMockSummary(resultsDirectoryPath, config: null, typeof(Generic<int>));
             var expectedFilePath = $"{Path.Combine(mockSummary.ResultsDirectoryPath, "BenchmarkDotNet.IntegrationTests.Generic_Int32_")}-report.txt";
-            string actualFilePath = null;
+            string? actualFilePath = null;
 
             try
             {
@@ -104,7 +104,7 @@ public void ExporterUsesSummaryTitleAsFileNameWhenBenchmarksJoinedToSingleSummar
             var joinConfig = ManualConfig.CreateEmpty().WithOptions(ConfigOptions.JoinSummary);
             var mockSummary = GetMockSummary(resultsDirectoryPath, joinConfig, typeof(ClassA), typeof(ClassB));
             var expectedFilePath = $"{Path.Combine(mockSummary.ResultsDirectoryPath, mockSummary.Title)}-report.txt";
-            string actualFilePath = null;
+            string? actualFilePath = null;
 
             try
             {

tests/BenchmarkDotNet.IntegrationTests/InProcessTest.cs

@@ -123,7 +123,7 @@ private void TestInvoke<T>(Expression<Func<BenchmarkAllCases, T>> methodCall, in
 
             bool isValueTask = typeof(T).IsConstructedGenericType && typeof(T).GetGenericTypeDefinition() == typeof(ValueTask<>);
 
-            object idleExpected;
+            object? idleExpected;
             if (isValueTask)
                 idleExpected = GetDefault(typeof(T).GetGenericArguments()[0]);
             else if (typeof(T).GetTypeInfo().IsValueType)

tests/BenchmarkDotNet.Tests/Builders/HostEnvironmentInfoBuilder.cs

@@ -12,7 +12,7 @@ public class HostEnvironmentInfoBuilder
         private string benchmarkDotNetVersion = "0.10.x-mock";
         private Frequency chronometerFrequency = new Frequency(2531248);
         private string configuration = "CONFIGURATION";
-        private string dotNetSdkVersion = "1.0.x.mock";
+        private string? dotNetSdkVersion = "1.0.x.mock";
         private HardwareTimerKind hardwareTimerKind = HardwareTimerKind.Tsc;
         private bool hasAttachedDebugger = false;
         private bool hasRyuJit = true;
@@ -31,7 +31,7 @@ public class HostEnvironmentInfoBuilder
                                               maxFrequency: Frequency.FromMHz(3100),
                                               minFrequency: Frequency.FromMHz(3100));
 
-        private VirtualMachineHypervisor virtualMachineHypervisor = HyperV.Default;
+        private VirtualMachineHypervisor? virtualMachineHypervisor = HyperV.Default;
 
         public HostEnvironmentInfoBuilder WithVMHypervisor(VirtualMachineHypervisor hypervisor)
         {