Removed CsProjWithRoslynFallbackToolchain, default to CsProjClassicNetToolchain instead.

Author: timcassell

src/BenchmarkDotNet/Toolchains/CsProj/CsProjClassicNetToolchain.cs

@@ -47,9 +47,12 @@ public override IEnumerable<ValidationError> Validate(BenchmarkCase benchmarkCas
                     $"Classic .NET toolchain is supported only for Windows, benchmark '{benchmarkCase.DisplayInfo}' will not be executed",
                     benchmarkCase);
             }
-            else if (IsCliPathInvalid(customDotNetCliPath: null, benchmarkCase, out var invalidCliError))
+            else if (IsCliPathInvalid(customDotNetCliPath: null, benchmarkCase, out _))
             {
-                yield return invalidCliError;
+                yield return new ValidationError(true,
+                    "CsProjClassicNetToolchain requires dotnet SDK to be installed or path to local dotnet cli provided in explicit way using `--cli` argument." +
+                    $" You may also use RoslynToolchain instead. Benchmark '{benchmarkCase.DisplayInfo}' will not be executed",
+                    benchmarkCase);
             }
         }
     }

src/BenchmarkDotNet/Toolchains/CsProj/CsProjWithRoslynFallbackBuilder.cs

@@ -5,12 +5,10 @@ namespace BenchmarkDotNet.Toolchains.Results
 {
     public class GenerateResult
     {
-        public virtual ArtifactsPaths ArtifactsPaths { get; }
-        public virtual bool IsGenerateSuccess { get; }
-        public virtual Exception GenerateException { get; }
-        public virtual IReadOnlyCollection<string> ArtifactsToCleanup { get; }
-
-        public GenerateResult() { }
+        public ArtifactsPaths ArtifactsPaths { get; }
+        public bool IsGenerateSuccess { get; }
+        public Exception GenerateException { get; }
+        public IReadOnlyCollection<string> ArtifactsToCleanup { get; }
 
         public GenerateResult(ArtifactsPaths artifactsPaths, bool isGenerateSuccess, Exception generateException,
             IReadOnlyCollection<string> artifactsToCleanup)

src/BenchmarkDotNet/Toolchains/CsProj/CsProjWithRoslynFallbackGenerateResult.cs

@@ -27,26 +27,23 @@ private static IToolchain GetToolchain(Job job, Descriptor descriptor)
                 ? toolchain
                 : GetToolchain(
                     job.ResolveValue(EnvironmentMode.RuntimeCharacteristic, EnvironmentResolver.Instance),
-                    descriptor,
-                    job.HasValue(InfrastructureMode.NuGetReferencesCharacteristic) || job.HasValue(InfrastructureMode.BuildConfigurationCharacteristic));
+                    descriptor);
 
-        internal static IToolchain GetToolchain(this Runtime runtime, Descriptor descriptor = null, bool preferMsBuildToolchains = false)
+        internal static IToolchain GetToolchain(this Runtime runtime, Descriptor descriptor = null)
         {
             switch (runtime)
             {
                 case ClrRuntime clrRuntime:
-                {
-                    var toolchain = clrRuntime.RuntimeMoniker != RuntimeMoniker.NotRecognized
+                    // Integration tests take too much time, because each benchmark run rebuilds the test suite and BenchmarkDotNet itself.
+                    // To reduce the total duration of the CI workflows, we just use RoslynToolchain.
+                    if (RuntimeInformation.IsFullFramework && XUnitHelper.IsIntegrationTest.Value)
+                        return RoslynToolchain.Instance;
+
+                    // Default to CsProjClassicNetToolchain, even if the host is Full Framework.
+                    // If it doesn't work because the user doesn't have dotnet SDK installed, they can manually use RoslynToolchain in their config.
+                    return clrRuntime.RuntimeMoniker != RuntimeMoniker.NotRecognized
                         ? GetToolchain(clrRuntime.RuntimeMoniker)
                         : CsProjClassicNetToolchain.From(clrRuntime.MsBuildMoniker);
-                    return RuntimeInformation.IsNetCore || preferMsBuildToolchains
-                        ? toolchain
-                        // Integration tests take too much time because each benchmark run rebuilds the test suite and BenchmarkDotNet itself.
-                        // To reduce the total duration of the CI workflows, we just use RoslynToolchain.
-                        : XUnitHelper.IsIntegrationTest.Value
-                        ? RoslynToolchain.Instance
-                        : new CsProjWithRoslynFallbackToolchain(toolchain);
-                }
 
                 case MonoRuntime mono:
                     if (RuntimeInformation.IsAndroid())

src/BenchmarkDotNet/Toolchains/CsProj/CsProjWithRoslynFallbackGenerator.cs

@@ -21,7 +21,7 @@ public NuGetReferenceTests(ITestOutputHelper output) : base(output)
         [FactEnvSpecific("For some reason this test is unstable on Ubuntu for both AzureDevOps and Travis CI", EnvRequirement.NonLinux)]
         public void UserCanSpecifyCustomNuGetPackageDependency()
         {
-            var toolchain = RuntimeInformation.GetCurrentRuntime().GetToolchain(preferMsBuildToolchains: true);
+            var toolchain = RuntimeInformation.GetCurrentRuntime().GetToolchain();
 
             var job = Job.Dry.WithToolchain(toolchain).WithNuGet("Newtonsoft.Json", "13.0.2");
             var config = CreateSimpleConfig(job: job);