Update gather references (dotnet#2921)

* Use a wrapper project to build the source project.

* Use default template to build for references.

* Don't remove ProjectReference outside of Mono.

Author: timcassell

src/BenchmarkDotNet/Environments/Runtimes/CoreRuntime.cs

@@ -232,7 +232,7 @@ private static CoreRuntime GetPlatformSpecific(CoreRuntime fallback, Assembly? a
                 ? new CoreRuntime(fallback.RuntimeMoniker, $"{fallback.MsBuildMoniker}-{platform}", fallback.Name)
                 : fallback;
 
-        internal static bool TryGetTargetPlatform(Assembly? assembly, [NotNullWhen(true)] out string? platform)
+        private static bool TryGetTargetPlatform(Assembly? assembly, [NotNullWhen(true)] out string? platform)
         {
             platform = null;
 
@@ -252,11 +252,8 @@ internal static bool TryGetTargetPlatform(Assembly? assembly, [NotNullWhen(true)
             if (platformNameProperty is null)
                 return false;
 
-            if (platformNameProperty.GetValue(attributeInstance) is not string platformName)
-                return false;
-
-            platform = platformName;
-            return true;
+            platform = platformNameProperty.GetValue(attributeInstance) as string;
+            return platform.IsNotBlank();
         }
     }
 }

src/BenchmarkDotNet/Helpers/FrameworkVersionHelper.cs

@@ -1,10 +1,8 @@
 using System;
-using System.Diagnostics.CodeAnalysis;
 using System.IO;
 using System.Linq;
 using System.Reflection;
 using System.Runtime.Versioning;
-using BenchmarkDotNet.Environments;
 using Microsoft.Win32;
 
 namespace BenchmarkDotNet.Helpers
@@ -124,44 +122,5 @@ private static bool IsDeveloperPackInstalled(string version) => Directory.Exists
             Environment.Is64BitOperatingSystem
                 ? Environment.SpecialFolder.ProgramFilesX86
                 : Environment.SpecialFolder.ProgramFiles);
-
-        internal static string? GetTfm(Assembly assembly)
-        {
-            // We don't support exotic frameworks like Silverlight, WindowsPhone, Xamarin.Mac, etc.
-            const string CorePrefix = ".NETCoreApp,Version=v";
-            const string FrameworkPrefix = ".NETFramework,Version=v";
-            const string StandardPrefix = ".NETStandard,Version=v";
-
-            // Look for a TargetFrameworkAttribute with a supported Framework version.
-            string? framework = assembly.GetCustomAttribute<TargetFrameworkAttribute>()?.FrameworkName;
-            if (TryParseVersion(CorePrefix, out var version))
-            {
-                return version.Major < 5
-                    ? $"netcoreapp{version.Major}.{version.Minor}"
-                    : CoreRuntime.TryGetTargetPlatform(assembly, out var platform)
-                        ? $"net{version.Major}.{version.Minor}-{platform}"
-                        : $"net{version.Major}.{version.Minor}";
-            }
-            if (TryParseVersion(FrameworkPrefix, out version))
-            {
-                return version.Build > 0
-                    ? $"net{version.Major}{version.Minor}{version.Build}"
-                    : $"net{version.Major}{version.Minor}";
-            }
-            if (!TryParseVersion(StandardPrefix, out version))
-            {
-                return $"netstandard{version.Major}.{version.Minor}";
-            }
-
-            // TargetFrameworkAttribute not found, or the assembly targeted a framework we don't support.
-            return null;
-
-            bool TryParseVersion(string prefix, [NotNullWhen(true)] out Version? version)
-            {
-                version = null;
-                return framework?.StartsWith(prefix) == true
-                    && Version.TryParse(framework[prefix.Length..], out version);
-            }
-        }
     }
 }

src/BenchmarkDotNet/Toolchains/CsProj/CsProjGenerator.cs

@@ -14,6 +14,7 @@
 using BenchmarkDotNet.Loggers;
 using BenchmarkDotNet.Running;
 using BenchmarkDotNet.Toolchains.DotNetCli;
+using BenchmarkDotNet.Toolchains.Mono;
 using BenchmarkDotNet.Toolchains.Results;
 using JetBrains.Annotations;
 
@@ -71,16 +72,29 @@ protected override void GenerateBuildScript(BuildPartition buildPartition, Artif
 
             var content = new StringBuilder(300)
                 .AppendLine($"call {CliPath ?? "dotnet"} {DotNetCliCommand.GetRestoreCommand(artifactsPaths, buildPartition, projectFilePath)}")
-                .AppendLine($"call {CliPath ?? "dotnet"} {DotNetCliCommand.GetPublishCommand(artifactsPaths, buildPartition, projectFilePath, TargetFrameworkMoniker)}")
+                .AppendLine($"call {CliPath ?? "dotnet"} {DotNetCliCommand.GetBuildCommand(artifactsPaths, buildPartition, projectFilePath, TargetFrameworkMoniker)}")
                 .AppendLine($"call {CliPath ?? "dotnet"} {DotNetCliCommand.GetRestoreCommand(artifactsPaths, buildPartition, artifactsPaths.ProjectFilePath)}")
-                .AppendLine($"call {CliPath ?? "dotnet"} {DotNetCliCommand.GetPublishCommand(artifactsPaths, buildPartition, artifactsPaths.ProjectFilePath, TargetFrameworkMoniker)}")
+                .AppendLine($"call {CliPath ?? "dotnet"} {DotNetCliCommand.GetBuildCommand(artifactsPaths, buildPartition, artifactsPaths.ProjectFilePath, TargetFrameworkMoniker)}")
                 .ToString();
 
             File.WriteAllText(artifactsPaths.BuildScriptFilePath, content);
         }
 
         [SuppressMessage("ReSharper", "StringLiteralTypo")] // R# complains about $variables$
         protected override void GenerateProject(BuildPartition buildPartition, ArtifactsPaths artifactsPaths, ILogger logger)
+        {
+            File.WriteAllText(artifactsPaths.ProjectFilePath,
+                GenerateBuildProject(buildPartition, artifactsPaths, logger)
+            );
+
+            // Integration tests are built without dependencies, so we skip gathering dlls.
+            if (!buildPartition.ForcedNoDependenciesForIntegrationTests)
+            {
+                GatherReferences(buildPartition, artifactsPaths, logger);
+            }
+        }
+
+        private string GenerateBuildProject(BuildPartition buildPartition, ArtifactsPaths artifactsPaths, ILogger logger)
         {
             var benchmark = buildPartition.RepresentativeBenchmarkCase;
             var projectFile = GetProjectFilePath(benchmark.Descriptor.Type, logger);
@@ -89,7 +103,7 @@ protected override void GenerateProject(BuildPartition buildPartition, Artifacts
             xmlDoc.Load(projectFile.FullName);
             var (customProperties, sdkName) = GetSettingsThatNeedToBeCopied(xmlDoc, projectFile);
 
-            var content = new StringBuilder(ResourceHelper.LoadTemplate("CsProj.txt"))
+            return new StringBuilder(ResourceHelper.LoadTemplate("CsProj.txt"))
                 .Replace("$PLATFORM$", buildPartition.Platform.ToConfig())
                 .Replace("$CODEFILENAME$", Path.GetFileName(artifactsPaths.ProgramCodePath))
                 .Replace("$CSPROJPATH$", projectFile.FullName)
@@ -99,43 +113,62 @@ protected override void GenerateProject(BuildPartition buildPartition, Artifacts
                 .Replace("$COPIEDSETTINGS$", customProperties)
                 .Replace("$SDKNAME$", sdkName)
                 .ToString();
-
-            File.WriteAllText(artifactsPaths.ProjectFilePath, content);
-
-            // Integration tests are built without dependencies, so we skip gathering dlls.
-            if (!buildPartition.ForcedNoDependenciesForIntegrationTests)
-            {
-                GatherReferences(projectFile.FullName, buildPartition, artifactsPaths, logger);
-            }
         }
 
-        protected void GatherReferences(string projectFilePath, BuildPartition buildPartition, ArtifactsPaths artifactsPaths, ILogger logger)
+        private static string GetDllGathererPath(string filePath)
+            => Path.Combine(Path.GetDirectoryName(filePath), $"DllGatherer{Path.GetExtension(filePath)}");
+
+        protected void GatherReferences(BuildPartition buildPartition, ArtifactsPaths artifactsPaths, ILogger logger)
         {
-            // Build the original project then reference all of the built dlls.
-            BuildResult buildResult = BuildProject(TargetFrameworkMoniker);
+            // Create a project using the default template to build the original project for all necessary runtime dlls.
+            // We can't just build the original project directly because it could be a library project, so we need an exe project to reference it.
+            var xmlDoc = new XmlDocument();
+            xmlDoc.LoadXml(GenerateBuildProject(buildPartition, artifactsPaths, logger));
+            var projectElement = xmlDoc.DocumentElement;
+
+            // Replace the default C# file with an empty Main method to satisfy the exe build.
+            var compileNode = projectElement.SelectSingleNode("ItemGroup/Compile");
+            string emptyMainFile = GetDllGathererPath(artifactsPaths.ProgramCodePath);
+            compileNode.Attributes["Include"].Value = emptyMainFile;
+            string gathererProject = GetDllGathererPath(artifactsPaths.ProjectFilePath);
+            xmlDoc.Save(gathererProject);
+
+            File.WriteAllText(emptyMainFile, """
+                namespace BenchmarkDotNet.Autogenerated
+                {
+                    public class UniqueProgramName
+                    {
+                        public static int Main(string[] args)
+                        {
+                            return 0;
+                        }
+                    }
+                }
+                """);
 
-            // The build could fail because the project doesn't have a tfm that matches the runtime, e.g. netstandard2.0 vs net10.0,
-            // So we try to get the actual tfm of the assembly and build again.
-            if (!buildResult.IsBuildSuccess
-                && FrameworkVersionHelper.GetTfm(buildPartition.RepresentativeBenchmarkCase.Descriptor.Type.Assembly) is { } actualTfm
-                && actualTfm != TargetFrameworkMoniker)
-            {
-                buildResult = BuildProject(actualTfm);
-            }
+            // Build the original project then reference all of the built dlls.
+            BuildResult buildResult = new DotNetCliCommand(
+                CliPath,
+                gathererProject,
+                TargetFrameworkMoniker,
+                null,
+                GenerateResult.Success(artifactsPaths, []),
+                logger,
+                buildPartition,
+                [],
+                buildPartition.Timeout
+            ).RestoreThenBuild();
 
             if (!buildResult.IsBuildSuccess)
             {
-                if (!buildResult.TryToExplainFailureReason(out string reason))
-                {
-                    reason = buildResult.ErrorMessage;
-                }
-                logger.WriteLineWarning($"Failed to build source project to obtain dll references. Moving forward without it. Reason: {reason}");
-                return;
+                throw buildResult.TryToExplainFailureReason(out string reason)
+                    ? new Exception(reason)
+                    : new Exception(buildResult.ErrorMessage);
             }
 
-            var xmlDoc = new XmlDocument();
+            xmlDoc = new XmlDocument();
             xmlDoc.Load(artifactsPaths.ProjectFilePath);
-            XmlElement projectElement = xmlDoc.DocumentElement;
+            projectElement = xmlDoc.DocumentElement;
             var itemGroup = xmlDoc.CreateElement("ItemGroup");
             projectElement.AppendChild(itemGroup);
             foreach (var assemblyFile in Directory.GetFiles(artifactsPaths.BinariesDirectoryPath, "*.dll"))
@@ -151,26 +184,13 @@ protected void GatherReferences(string projectFilePath, BuildPartition buildPart
             }
 
             // Mono80IsSupported test fails when BenchmarkDotNet is restored for net9.0 if we don't remove the ProjectReference.
-            if (XUnitHelper.IsIntegrationTest.Value)
+            // We still need to preserve the ProjectReference in every other case for disassembly, though.
+            if (XUnitHelper.IsIntegrationTest.Value && this is MonoGenerator)
             {
                 projectElement.RemoveChild(projectElement.SelectSingleNode("ItemGroup/ProjectReference").ParentNode);
             }
 
             xmlDoc.Save(artifactsPaths.ProjectFilePath);
-
-            BuildResult BuildProject(string tfm)
-                => new DotNetCliCommand(
-                    CliPath,
-                    projectFilePath,
-                    tfm,
-                    null,
-                    GenerateResult.Success(artifactsPaths, []),
-                    logger,
-                    buildPartition,
-                    [],
-                    buildPartition.Timeout
-                )
-                .RestoreThenBuild();
         }
 
         /// <summary>

src/BenchmarkDotNet/Toolchains/MonoAotLLVM/MonoAotLLVMGenerator.cs

@@ -52,7 +52,7 @@ protected override void GenerateProject(BuildPartition buildPartition, Artifacts
 
             File.WriteAllText(artifactsPaths.ProjectFilePath, content);
 
-            GatherReferences(projectFile.FullName, buildPartition, artifactsPaths, logger);
+            GatherReferences(buildPartition, artifactsPaths, logger);
         }
 
         protected override string GetPublishDirectoryPath(string buildArtifactsDirectoryPath, string configuration)

src/BenchmarkDotNet/Toolchains/MonoWasm/WasmGenerator.cs

@@ -63,7 +63,7 @@ protected void GenerateProjectFile(BuildPartition buildPartition, ArtifactsPaths
 
             File.WriteAllText(artifactsPaths.ProjectFilePath, content);
 
-            GatherReferences(projectFile.FullName, buildPartition, artifactsPaths, logger);
+            GatherReferences(buildPartition, artifactsPaths, logger);
         }
 
         protected void GenerateLinkerDescriptionFile(ArtifactsPaths artifactsPaths)

src/BenchmarkDotNet/Toolchains/NativeAot/Generator.cs

@@ -119,7 +119,7 @@ protected override void GenerateProject(BuildPartition buildPartition, Artifacts
 
             File.WriteAllText(artifactsPaths.ProjectFilePath, GenerateProjectForNuGetBuild(projectFile, buildPartition, artifactsPaths, logger));
 
-            GatherReferences(projectFile, buildPartition, artifactsPaths, logger);
+            GatherReferences(buildPartition, artifactsPaths, logger);
             GenerateReflectionFile(artifactsPaths);
         }
 

tests/BenchmarkDotNet.IntegrationTests/DisassemblyDiagnoserTests.cs

@@ -173,7 +173,14 @@ private IConfig CreateConfig(Jit jit, Platform platform, IToolchain toolchain, I
                 .AddJob(Job.Dry.WithJit(jit)
                     .WithPlatform(platform)
                     .WithToolchain(toolchain)
-                    .WithStrategy(runStrategy))
+                    .WithStrategy(runStrategy)
+                    // Ensure the build goes through the full process and doesn't build without dependencies like most of the integration tests do.
+#if RELEASE
+                    .WithCustomBuildConfiguration("Release")
+#else
+                    .WithCustomBuildConfiguration("Debug")
+#endif
+                )
                 .AddLogger(DefaultConfig.Instance.GetLoggers().ToArray())
                 .AddColumnProvider(DefaultColumnProviders.Instance)
                 .AddDiagnoser(disassemblyDiagnoser)