chore: Add PolySharp dev dependency and cleanup #if-#endif preprocessor

src/BenchmarkDotNet/BenchmarkDotNet.csproj

@@ -58,4 +58,14 @@
   <ItemGroup>
     <Compile Include="..\BenchmarkDotNet.Disassembler.x64\DataContracts.cs" Link="Disassemblers\DataContracts.cs" />
   </ItemGroup>
+  <!-- Settings for PolySharp -->
+  <PropertyGroup>
+    <PolySharpIncludeRuntimeSupportedAttributes>true</PolySharpIncludeRuntimeSupportedAttributes>
+  </PropertyGroup>
+  <ItemGroup>
+    <PackageReference Include="PolySharp" Version="1.15.0">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
+  </ItemGroup>
 </Project>

src/BenchmarkDotNet/Detectors/Cpu/Windows/MosCpuDetector.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Management;
+using System.Runtime.Versioning;
 using BenchmarkDotNet.Extensions;
 using BenchmarkDotNet.Portability;
 using Perfolizer.Horology;
@@ -11,16 +12,12 @@ namespace BenchmarkDotNet.Detectors.Cpu.Windows;
 
 internal class MosCpuDetector : ICpuDetector
 {
-#if NET6_0_OR_GREATER
-    [System.Runtime.Versioning.SupportedOSPlatform("windows")]
-#endif
+    [SupportedOSPlatform("windows")]
     public bool IsApplicable() => OsDetector.IsWindows() &&
                                   RuntimeInformation.IsFullFramework &&
                                   !RuntimeInformation.IsMono;
 
-#if NET6_0_OR_GREATER
-    [System.Runtime.Versioning.SupportedOSPlatform("windows")]
-#endif
+    [SupportedOSPlatform("windows")]
     public CpuInfo? Detect()
     {
         if (!IsApplicable()) return null;

src/BenchmarkDotNet/Detectors/Cpu/Windows/PowershellWmiCpuDetector.cs

@@ -21,9 +21,7 @@ internal class PowershellWmiCpuDetector : ICpuDetector
 
     public bool IsApplicable() => OsDetector.IsWindows();
 
-    #if NET6_0_OR_GREATER
     [SupportedOSPlatform("windows")]
-    #endif
     public CpuInfo? Detect()
     {
         if (!IsApplicable()) return null;

src/BenchmarkDotNet/Detectors/OsDetector.cs

@@ -8,6 +8,7 @@
 using Perfolizer.Models;
 using static System.Runtime.InteropServices.RuntimeInformation;
 using RuntimeEnvironment = Microsoft.DotNet.PlatformAbstractions.RuntimeEnvironment;
+using System.Runtime.Versioning;
 
 namespace BenchmarkDotNet.Detectors;
 
@@ -113,29 +114,24 @@ private static bool IsUnderWsl()
         return null;
     }
 
-#if NET6_0_OR_GREATER
-    [System.Runtime.Versioning.SupportedOSPlatformGuard("windows")]
-#endif
+    [SupportedOSPlatformGuard("windows")]
     internal static bool IsWindows() =>
 #if NET6_0_OR_GREATER
         OperatingSystem.IsWindows(); // prefer linker-friendly OperatingSystem APIs
 #else
         IsOSPlatform(OSPlatform.Windows);
 #endif
 
-#if NET6_0_OR_GREATER
-    [System.Runtime.Versioning.SupportedOSPlatformGuard("linux")]
-#endif
+
+    [SupportedOSPlatformGuard("linux")]
     internal static bool IsLinux() =>
 #if NET6_0_OR_GREATER
         OperatingSystem.IsLinux();
 #else
         IsOSPlatform(OSPlatform.Linux);
 #endif
 
-#if NET6_0_OR_GREATER
-    [System.Runtime.Versioning.SupportedOSPlatformGuard("macos")]
-#endif
+    [SupportedOSPlatformGuard("macos")]
     // ReSharper disable once InconsistentNaming
     internal static bool IsMacOS() =>
 #if NET6_0_OR_GREATER
@@ -144,19 +140,15 @@ internal static bool IsMacOS() =>
         IsOSPlatform(OSPlatform.OSX);
 #endif
 
-#if NET6_0_OR_GREATER
-    [System.Runtime.Versioning.SupportedOSPlatformGuard("android")]
-#endif
+    [SupportedOSPlatformGuard("android")]
     internal static bool IsAndroid() =>
 #if NET6_0_OR_GREATER
         OperatingSystem.IsAndroid();
 #else
         Type.GetType("Java.Lang.Object, Mono.Android") != null;
 #endif
 
-#if NET6_0_OR_GREATER
-    [System.Runtime.Versioning.SupportedOSPlatformGuard("ios")]
-#endif
+    [SupportedOSPlatformGuard("ios")]
     // ReSharper disable once InconsistentNaming
     internal static bool IsIOS() =>
 #if NET6_0_OR_GREATER
@@ -165,9 +157,7 @@ internal static bool IsIOS() =>
         Type.GetType("Foundation.NSObject, Xamarin.iOS") != null;
 #endif
 
-#if NET6_0_OR_GREATER
-    [System.Runtime.Versioning.SupportedOSPlatformGuard("tvos")]
-#endif
+    [SupportedOSPlatformGuard("tvos")]
     // ReSharper disable once InconsistentNaming
     internal static bool IsTvOS() =>
 #if NET6_0_OR_GREATER

src/BenchmarkDotNet/Helpers/FrameworkVersionHelper.cs

@@ -83,10 +83,7 @@ internal static string MapToReleaseVersion(string servicingVersion)
             return "4.8.1"; // most probably the last major release of Full .NET Framework
         }
 
-
-#if NET6_0_OR_GREATER
         [SupportedOSPlatform("windows")]
-#endif
         private static int? GetReleaseNumberFromWindowsRegistry()
         {
             using var baseKey = RegistryKey.OpenBaseKey(RegistryHive.LocalMachine, RegistryView.Registry32);
@@ -96,9 +93,7 @@ internal static string MapToReleaseVersion(string servicingVersion)
             return Convert.ToInt32(ndpKey.GetValue("Release"));
         }
 
-#if NET6_0_OR_GREATER
         [SupportedOSPlatform("windows")]
-#endif
         internal static string? GetLatestNetDeveloperPackVersion()
         {
             if (GetReleaseNumberFromWindowsRegistry() is not int releaseNumber)

src/BenchmarkDotNet/Helpers/PowerShellLocator.cs

@@ -16,9 +16,7 @@ internal class PowerShellLocator
         $"{Environment.SystemDirectory}{Path.DirectorySeparatorChar}WindowsPowerShell{Path.DirectorySeparatorChar}" +
         $"v1.0{Path.DirectorySeparatorChar}powershell.exe";
 
-#if NET6_0_OR_GREATER
         [SupportedOSPlatform("windows")]
-#endif
     internal static string? LocateOnWindows()
     {
         if (OsDetector.IsWindows() == false)

src/BenchmarkDotNet/Portability/RuntimeInformation.cs

@@ -6,6 +6,7 @@
 using System.Management;
 using System.Reflection;
 using System.Runtime.InteropServices;
+using System.Runtime.Versioning;
 using System.Text.RegularExpressions;
 using BenchmarkDotNet.Detectors;
 using BenchmarkDotNet.Environments;
@@ -42,8 +43,8 @@ internal static class RuntimeInformation
             FrameworkDescription.StartsWith(".NET Framework", StringComparison.OrdinalIgnoreCase);
 #endif
 
+        [SupportedOSPlatformGuard("browser")]
 #if NET6_0_OR_GREATER
-        [System.Runtime.Versioning.SupportedOSPlatformGuard("browser")]
         public static readonly bool IsWasm = OperatingSystem.IsBrowser();
 #else
         public static readonly bool IsWasm = IsOSPlatform(OSPlatform.Create("BROWSER"));

src/BenchmarkDotNet/Running/ConsoleTitler.cs

@@ -1,5 +1,6 @@
 using System;
 using System.IO;
+using System.Runtime.Versioning;
 using BenchmarkDotNet.Detectors;
 using BenchmarkDotNet.Helpers;
 
@@ -60,9 +61,7 @@ public ConsoleTitler(string initialTitle)
             }
         }
 
-#if NET6_0_OR_GREATER
-        [System.Runtime.Versioning.SupportedOSPlatformGuard("windows")]
-#endif
+        [SupportedOSPlatformGuard("windows")]
         private static bool PlatformSupportsTitleRead() => OsDetector.IsWindows();
 
         /// <summary>

src/BenchmarkDotNet/Toolchains/InProcess/NoEmit/InProcessNoEmitRunner.cs

@@ -16,9 +16,7 @@ namespace BenchmarkDotNet.Toolchains.InProcess.NoEmit
     /// </summary>
     internal class InProcessNoEmitRunner
     {
-#if NET6_0_OR_GREATER
         [DynamicDependency(DynamicallyAccessedMemberTypes.All, typeof(Runnable))]
-#endif
         public static int Run(IHost host, BenchmarkCase benchmarkCase)
         {
             // the first thing to do is to let diagnosers hook in before anything happens

tests/BenchmarkDotNet.IntegrationTests/WakeLockTests.cs

@@ -85,9 +85,7 @@ public class IgnoreWakeLock
         [Benchmark] public void Sleep() { }
     }
 
-#if !NET462
     [SupportedOSPlatform("windows")]
-#endif
     [TheoryEnvSpecific(EnvRequirement.WindowsOnly, EnvRequirement.NeedsPrivilegedProcess)]
     [InlineData(typeof(Default), "SYSTEM")]
     [InlineData(typeof(None), "")]
@@ -124,9 +122,7 @@ public class Default : Base { }
     public class Base
     {
         [Benchmark]
-#if !NET462
         [SupportedOSPlatform("windows")]
-#endif
         public void SignalBenchmarkRunningAndWaitForGetPowerRequests()
         {
             using EventWaitHandle