Nullability In BenchmarkDotNet project

src/BenchmarkDotNet/Analysers/Conclusion.cs

@@ -38,7 +38,7 @@ public static Conclusion CreateWarning(string analyserId, string message, Benchm
         public static Conclusion CreateError(string analyserId, string message, BenchmarkReport? report = null, bool mergeable = true)
             => new Conclusion(analyserId, ConclusionKind.Error, message, report, mergeable);
 
-        public bool Equals(Conclusion other)
+        public bool Equals(Conclusion? other)
         {
             if (ReferenceEquals(null, other))
                 return false;
@@ -49,7 +49,7 @@ public bool Equals(Conclusion other)
             return string.Equals(AnalyserId, other.AnalyserId) && Kind == other.Kind && string.Equals(Message, other.Message);
         }
 
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             if (ReferenceEquals(null, obj))
                 return false;

src/BenchmarkDotNet/Analysers/ZeroMeasurementHelper.cs

@@ -20,7 +20,7 @@ public static bool CheckZeroMeasurementOneSample(double[] results, double thresh
         /// Checks distribution against Zero Measurement hypothesis in case of two samples
         /// </summary>
         /// <returns>True if measurement is ZeroMeasurement</returns>
-        public static bool CheckZeroMeasurementTwoSamples(double[] workload, double[] overhead, Threshold threshold = null)
+        public static bool CheckZeroMeasurementTwoSamples(double[] workload, double[] overhead, Threshold? threshold = null)
         {
             if (workload.Length < 3 || overhead.Length < 3)
                 return false;

src/BenchmarkDotNet/Attributes/Filters/AotFilterAttribute.cs

@@ -4,7 +4,7 @@ namespace BenchmarkDotNet.Attributes.Filters
 {
     public class AotFilterAttribute : FilterConfigBaseAttribute
     {
-        public AotFilterAttribute(string reason = null)
+        public AotFilterAttribute(string? reason = null)
             : base(new SimpleFilter(benchmark => !benchmark.GetRuntime().IsAOT))
         {
         }

src/BenchmarkDotNet/Attributes/Jobs/SimpleJobAttribute.cs

@@ -18,7 +18,7 @@ public class SimpleJobAttribute : JobConfigBaseAttribute
             int warmupCount = DefaultValue,
             int iterationCount = DefaultValue,
             int invocationCount = DefaultValue,
-            string id = null,
+            string? id = null,
             bool baseline = false
         ) : base(CreateJob(id, launchCount, warmupCount, iterationCount, invocationCount, null, baseline)) { }
 
@@ -29,7 +29,7 @@ public class SimpleJobAttribute : JobConfigBaseAttribute
             int warmupCount = DefaultValue,
             int iterationCount = DefaultValue,
             int invocationCount = DefaultValue,
-            string id = null,
+            string? id = null,
             bool baseline = false
         ) : base(CreateJob(id, launchCount, warmupCount, iterationCount, invocationCount, runStrategy, baseline)) { }
 
@@ -40,7 +40,7 @@ public class SimpleJobAttribute : JobConfigBaseAttribute
             int warmupCount = DefaultValue,
             int iterationCount = DefaultValue,
             int invocationCount = DefaultValue,
-            string id = null,
+            string? id = null,
             bool baseline = false
         ) : base(CreateJob(id, launchCount, warmupCount, iterationCount, invocationCount, null, baseline, runtimeMoniker)) { }
 
@@ -52,11 +52,11 @@ public class SimpleJobAttribute : JobConfigBaseAttribute
             int warmupCount = DefaultValue,
             int iterationCount = DefaultValue,
             int invocationCount = DefaultValue,
-            string id = null,
+            string? id = null,
             bool baseline = false
         ) : base(CreateJob(id, launchCount, warmupCount, iterationCount, invocationCount, runStrategy, baseline, runtimeMoniker)) { }
 
-        private static Job CreateJob(string id, int launchCount, int warmupCount, int iterationCount, int invocationCount, RunStrategy? runStrategy,
+        private static Job CreateJob(string? id, int launchCount, int warmupCount, int iterationCount, int invocationCount, RunStrategy? runStrategy,
             bool baseline, RuntimeMoniker runtimeMoniker = RuntimeMoniker.HostProcess)
         {
             var job = new Job(id);

src/BenchmarkDotNet/Characteristics/CharacteristicObject.cs

@@ -44,7 +44,7 @@ protected CharacteristicObject()
             sharedValues = new Dictionary<Characteristic, object>();
         }
 
-        protected CharacteristicObject(string id) : this()
+        protected CharacteristicObject(string? id) : this()
         {
             if (!string.IsNullOrEmpty(id))
             {
@@ -98,7 +98,7 @@ private static void AssertIsAssignable(Characteristic characteristic, object val
 
         #region Properties
 
-        private CharacteristicObject Owner { get; set; }
+        private CharacteristicObject? Owner { get; set; }
 
         protected CharacteristicObject OwnerOrSelf => Owner ?? this;
 

src/BenchmarkDotNet/Characteristics/CharacteristicObject`1.cs

@@ -8,7 +8,7 @@ public abstract class CharacteristicObject<T> : CharacteristicObject
     {
         protected CharacteristicObject() { }
 
-        protected CharacteristicObject(string id) : base(id) { }
+        protected CharacteristicObject(string? id) : base(id) { }
 
         public new T Apply(CharacteristicObject other) => (T)ApplyCore(other);
 

src/BenchmarkDotNet/Characteristics/Characteristic`1.cs

@@ -8,7 +8,7 @@ public class Characteristic<[DynamicallyAccessedMembers(CharacteristicObject.Cha
         internal Characteristic(
             string id,
             Type declaringType,
-            Func<CharacteristicObject, T, T> resolver,
+            Func<CharacteristicObject, T, T>? resolver,
             T fallbackValue,
             bool ignoreOnApply,
             bool dontShowInSummary = false)
@@ -18,7 +18,7 @@ public class Characteristic<[DynamicallyAccessedMembers(CharacteristicObject.Cha
             FallbackValue = fallbackValue;
         }
 
-        private Func<CharacteristicObject, T, T> Resolver { get; }
+        private Func<CharacteristicObject, T, T>? Resolver { get; }
 
         public T FallbackValue { get; }
 

src/BenchmarkDotNet/Code/ArrayParam.cs

@@ -10,15 +10,15 @@ namespace BenchmarkDotNet.Code
     internal static class ArrayParam
     {
         public static string GetDisplayString(Array array)
-            => $"{array.GetType().GetElementType().GetDisplayName()}[{array.Length}]";
+            => $"{array.GetType().GetElementType()?.GetDisplayName()}[{array.Length}]";
     }
 
     public class ArrayParam<T> : IParam
     {
         private readonly T[] array;
-        private readonly Func<T, string> toSourceCode;
+        private readonly Func<T, string>? toSourceCode;
 
-        private ArrayParam(T[] array, Func<T, string> toSourceCode = null)
+        private ArrayParam(T[] array, Func<T, string>? toSourceCode = null)
         {
             this.array = array;
             this.toSourceCode = toSourceCode;
@@ -45,19 +45,22 @@ public string ToSourceCode()
         /// </param>
         [PublicAPI] public static ArrayParam<T> ForComplexTypes(T[] array, Func<T, string> toSourceCode) => new ArrayParam<T>(array, toSourceCode);
 
-        internal static IParam FromObject(object array)
+        internal static IParam? FromObject(object array)
         {
             var type = array.GetType();
             if (!type.IsArray)
                 throw new InvalidOperationException("The argument must be an array");
-            if (!SourceCodeHelper.IsCompilationTimeConstant(type.GetElementType()))
+            var elementType = type.GetElementType();
+            if (elementType == null)
+                throw new InvalidOperationException("Failed to determine type of array elements");
+            if (!SourceCodeHelper.IsCompilationTimeConstant(elementType))
                 throw new InvalidOperationException("The argument must be an array of primitives");
 
-            var arrayParamType = typeof(ArrayParam<>).MakeGenericType(type.GetElementType());
+            var arrayParamType = typeof(ArrayParam<>).MakeGenericType(elementType);
 
             var methodInfo = arrayParamType.GetMethod(nameof(ForPrimitives), BindingFlags.Public | BindingFlags.Static)
                 ?? throw new InvalidOperationException($"{nameof(ForPrimitives)} not found");
-            return (IParam)methodInfo.Invoke(null, new[]{ array});
+            return (IParam?)methodInfo.Invoke(null, new[]{ array});
         }
     }
 }

src/BenchmarkDotNet/Code/CodeGenerator.cs

@@ -93,7 +93,7 @@ internal static string Generate(BuildPartition buildPartition)
 
         private static void AddNonEmptyUnique(HashSet<string> items, string value)
         {
-            if (!string.IsNullOrEmpty(value) && !items.Contains(value))
+            if (!string.IsNullOrEmpty(value))
                 items.Add(value);
         }
 
@@ -296,7 +296,7 @@ public SmartStringBuilder(string text)
                 builder = new StringBuilder(text);
             }
 
-            public SmartStringBuilder Replace(string oldValue, string newValue)
+            public SmartStringBuilder Replace(string oldValue, string? newValue)
             {
                 if (originalText.Contains(oldValue))
                     builder.Replace(oldValue, newValue);

src/BenchmarkDotNet/Jobs/Job.cs

@@ -30,9 +30,9 @@ public sealed class Job : JobMode<Job>
         public static readonly Job InProcess = new Job(nameof(InProcess), InfrastructureMode.InProcess);
         public static readonly Job InProcessDontLogOutput = new Job(nameof(InProcessDontLogOutput), InfrastructureMode.InProcessDontLogOutput);
 
-        public Job() : this((string)null) { }
+        public Job() : this((string?)null) { }
 
-        public Job(string id) : base(id)
+        public Job(string? id) : base(id)
         {
             EnvironmentCharacteristic[this] = new EnvironmentMode();
             RunCharacteristic[this] = new RunMode();
@@ -41,20 +41,20 @@ public Job(string id) : base(id)
             MetaCharacteristic[this] = new MetaMode();
         }
 
-        public Job(CharacteristicObject other) : this((string)null, other)
+        public Job(CharacteristicObject other) : this((string?)null, other)
         {
         }
 
         public Job(params CharacteristicObject[] others) : this(null, others)
         {
         }
 
-        public Job(string id, CharacteristicObject other) : this(id)
+        public Job(string? id, CharacteristicObject other) : this(id)
         {
             Apply(other);
         }
 
-        public Job(string id, params CharacteristicObject[] others) : this(id)
+        public Job(string? id, params CharacteristicObject[] others) : this(id)
         {
             Apply(others);
         }

src/BenchmarkDotNet/Jobs/JobMode`1.cs

@@ -9,7 +9,7 @@ public abstract class JobMode<T> : CharacteristicObject<T> where T : JobMode<T>,
 
         protected JobMode() { }
 
-        protected JobMode(string id) : base(id) { }
+        protected JobMode(string? id) : base(id) { }
 
         [PublicAPI] public Job Job => OwnerOrSelf as Job;
     }