Simplify HashCode

Author: YegorStepanov

src/BenchmarkDotNet/Analysers/Conclusion.cs

@@ -64,15 +64,9 @@ public override bool Equals(object obj)
 
         public override int GetHashCode()
         {
-            unchecked
-            {
-                int hashCode = AnalyserId.GetHashCode();
-                hashCode = (hashCode * 397) ^ (int) Kind;
-                hashCode = Mergeable
-                           ? (hashCode * 397) ^ Message.GetHashCode()
-                           : (hashCode * 397) ^ Report?.ToString().GetHashCode() ?? string.Empty.GetHashCode();
-                return hashCode;
-            }
+            return Mergeable
+                ? HashCode.Combine(AnalyserId, Kind, Message)
+                : HashCode.Combine(AnalyserId, Kind, Report?.ToString());
         }
     }
 }

src/BenchmarkDotNet/Columns/SizeUnit.cs

@@ -66,16 +66,7 @@ public override bool Equals(object obj)
             return Equals((SizeUnit) obj);
         }
 
-        public override int GetHashCode()
-        {
-            unchecked
-            {
-                int hashCode = (Name != null ? Name.GetHashCode() : 0);
-                hashCode = (hashCode * 397) ^ (Description != null ? Description.GetHashCode() : 0);
-                hashCode = (hashCode * 397) ^ ByteAmount.GetHashCode();
-                return hashCode;
-            }
-        }
+        public override int GetHashCode() => HashCode.Combine(Name, Description, ByteAmount);
 
         public static bool operator ==(SizeUnit left, SizeUnit right) => Equals(left, right);
 

src/BenchmarkDotNet/Engines/GcStats.cs

@@ -223,17 +223,6 @@ private static long CalculateAllocationQuantumSize()
 
         public override bool Equals(object obj) => obj is GcStats other && Equals(other);
 
-        public override int GetHashCode()
-        {
-            unchecked
-            {
-                int hashCode = Gen0Collections;
-                hashCode = (hashCode * 397) ^ Gen1Collections;
-                hashCode = (hashCode * 397) ^ Gen2Collections;
-                hashCode = (hashCode * 397) ^ AllocatedBytes.GetHashCode();
-                hashCode = (hashCode * 397) ^ TotalOperations.GetHashCode();
-                return hashCode;
-            }
-        }
+        public override int GetHashCode() => HashCode.Combine(Gen0Collections, Gen1Collections, Gen2Collections, AllocatedBytes, TotalOperations);
     }
 }

src/BenchmarkDotNet/Engines/ThreadingStats.cs

@@ -86,15 +86,6 @@ private static Func<long> CreateGetterDelegate(Type type, string propertyName)
 
         public override bool Equals(object obj) => obj is ThreadingStats other && Equals(other);
 
-        public override int GetHashCode()
-        {
-            unchecked
-            {
-                int hashCode = CompletedWorkItemCount.GetHashCode();
-                hashCode = (hashCode * 397) ^ LockContentionCount.GetHashCode();
-                hashCode = (hashCode * 397) ^ TotalOperations.GetHashCode();
-                return hashCode;
-            }
-        }
+        public override int GetHashCode() => HashCode.Combine(CompletedWorkItemCount, LockContentionCount, TotalOperations);
     }
 }

src/BenchmarkDotNet/Environments/Runtimes/ClrRuntime.cs

@@ -40,7 +40,7 @@ public static ClrRuntime CreateForLocalFullNetFrameworkBuild(string version)
 
         public bool Equals(ClrRuntime other) => other != null && base.Equals(other) && Version == other.Version;
 
-        public override int GetHashCode() => base.GetHashCode() ^ (Version?.GetHashCode() ?? 0);
+        public override int GetHashCode() => HashCode.Combine(base.GetHashCode(), Version);
 
         internal static ClrRuntime GetCurrentVersion()
         {

src/BenchmarkDotNet/Environments/Runtimes/MonoAotLLVMRuntime.cs

@@ -44,6 +44,6 @@ public bool Equals(MonoAotLLVMRuntime other)
             => other != null && base.Equals(other) && other.AOTCompilerPath == AOTCompilerPath;
 
         public override int GetHashCode()
-            => base.GetHashCode() ^ AOTCompilerPath.GetHashCode();
+            => HashCode.Combine(base.GetHashCode(), AOTCompilerPath);
     }
 }

src/BenchmarkDotNet/Environments/Runtimes/MonoRuntime.cs

@@ -32,6 +32,6 @@ public bool Equals(MonoRuntime other)
             => base.Equals(other) && Name == other?.Name && CustomPath == other?.CustomPath && AotArgs == other?.AotArgs && MonoBclPath == other?.MonoBclPath;
 
         public override int GetHashCode()
-            => base.GetHashCode() ^ Name.GetHashCode() ^ (CustomPath?.GetHashCode() ?? 0) ^ (AotArgs?.GetHashCode() ?? 0) ^ (MonoBclPath?.GetHashCode() ?? 0);
+            => HashCode.Combine(base.GetHashCode(), Name, CustomPath, AotArgs, MonoBclPath);
     }
 }

src/BenchmarkDotNet/Environments/Runtimes/Runtime.cs

@@ -41,6 +41,6 @@ public bool Equals(Runtime other)
 
         public override bool Equals(object obj) => obj is Runtime other && Equals(other);
 
-        public override int GetHashCode() => Name.GetHashCode() ^ (int)RuntimeMoniker ^ MsBuildMoniker.GetHashCode();
+        public override int GetHashCode() => HashCode.Combine(Name, RuntimeMoniker, MsBuildMoniker);
     }
 }

src/BenchmarkDotNet/Environments/Runtimes/WasmRuntime.cs

@@ -46,6 +46,6 @@ public bool Equals(WasmRuntime other)
             => other != null && base.Equals(other) && other.JavaScriptEngine == JavaScriptEngine && other.JavaScriptEngineArguments == JavaScriptEngineArguments && other.Aot == Aot;
 
         public override int GetHashCode()
-            => base.GetHashCode() ^ (JavaScriptEngine?.GetHashCode() ?? 0) ^ (JavaScriptEngineArguments?.GetHashCode() ?? 0 ^ Aot.GetHashCode());
+            => HashCode.Combine(base.GetHashCode(), JavaScriptEngine, JavaScriptEngineArguments, Aot);
     }
 }

src/BenchmarkDotNet/Jobs/EnvironmentVariable.cs

@@ -33,12 +33,6 @@ public override bool Equals(object obj)
             return Equals((EnvironmentVariable) obj);
         }
 
-        public override int GetHashCode()
-        {
-            unchecked
-            {
-                return (Key.GetHashCode() * 397) ^ Value.GetHashCode();
-            }
-        }
+        public override int GetHashCode() => HashCode.Combine(Key, Value);
     }
 }