Restore in-process source generation for vs4mac below 16.0

src/Uno.SourceGeneration.Engine.Shared/SourceGeneratorEngine.cs

@@ -47,8 +47,12 @@ namespace Uno.SourceGeneration.Host
 		public SourceGeneratorEngine(BuildEnvironment environment, Func<string, MetadataReferenceProperties, PortableExecutableReference> assemblyReferenceProvider)
 		{
 			_environment = environment;
+
+			if (assemblyReferenceProvider != null)
+			{
 				_resolver = new Resolver(assemblyReferenceProvider);
 			}
+		}
 
 		public string[] Generate()
 		{
@@ -296,7 +300,11 @@ namespace Uno.SourceGeneration.Host
 					};
 
 				var project = await ws.OpenProjectAsync(_environment.ProjectFile);
+
+				if (_resolver != null)
+				{
 					project = project.WithCompilationOptions(new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary, metadataReferenceResolver: _resolver));
+				}
 
 				var metadataLessProjects = ws
 					.CurrentSolution

src/Uno.SourceGeneration.Engine.Shared/Uno.SourceGeneration.Engine.Shared.projitems

@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <PropertyGroup>
+    <MSBuildAllProjects>$(MSBuildAllProjects);$(MSBuildThisFileFullPath)</MSBuildAllProjects>
+    <HasSharedItems>true</HasSharedItems>
+    <SharedGUID>08631d97-b757-4226-897f-9839b1205ab5</SharedGUID>
+  </PropertyGroup>
+  <PropertyGroup Label="Configuration">
+    <Import_RootNamespace>Uno.SourceGeneration.Engine.Shared</Import_RootNamespace>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="$(MSBuildThisFileDirectory)GeneratorLogger.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)InternalSourceGeneratorContext.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)ProjectDetails.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)ProjectLoader.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)SourceGeneratorEngine.cs" />
+  </ItemGroup>
+</Project>

src/Uno.SourceGeneration.Engine.Shared/Uno.SourceGeneration.Engine.Shared.shproj

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <PropertyGroup Label="Globals">
+    <ProjectGuid>08631d97-b757-4226-897f-9839b1205ab5</ProjectGuid>
+    <MinimumVisualStudioVersion>14.0</MinimumVisualStudioVersion>
+  </PropertyGroup>
+  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
+  <Import Project="$(MSBuildExtensionsPath32)\Microsoft\VisualStudio\v$(VisualStudioVersion)\CodeSharing\Microsoft.CodeSharing.Common.Default.props" />
+  <Import Project="$(MSBuildExtensionsPath32)\Microsoft\VisualStudio\v$(VisualStudioVersion)\CodeSharing\Microsoft.CodeSharing.Common.props" />
+  <PropertyGroup />
+  <Import Project="Uno.SourceGeneration.Engine.Shared.projitems" Label="Shared" />
+  <Import Project="$(MSBuildExtensionsPath32)\Microsoft\VisualStudio\v$(VisualStudioVersion)\CodeSharing\Microsoft.CodeSharing.CSharp.targets" />
+</Project>

src/Uno.SourceGeneration.Host/Uno.SourceGeneration.Host.csproj

@@ -162,6 +162,6 @@
   </ItemGroup>
 
   <Import Project="..\Uno.SourceGenerationHost.Shared\Uno.SourceGenerationHost.Shared.projitems" Label="Shared" />
-
+  <Import Project="..\Uno.SourceGeneration.Engine.Shared\Uno.SourceGeneration.Engine.Shared.projitems" Label="Shared" />
   <Import Project="..\Uno.SourceGeneration.Protocol\Uno.SourceGeneration.Protocol.projitems" Label="Shared" />
 </Project>

src/Uno.SourceGenerator.sln

@@ -54,8 +54,12 @@ Project("{D954291E-2A0B-460D-934E-DC6B0785DB48}") = "Uno.SourceGeneration.Host.S
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Samples", "Samples", "{67EB84F7-DAA3-4657-B6D0-D7FA9FD23C45}"
 EndProject
+Project("{D954291E-2A0B-460D-934E-DC6B0785DB48}") = "Uno.SourceGeneration.Engine.Shared", "Uno.SourceGeneration.Engine.Shared\Uno.SourceGeneration.Engine.Shared.shproj", "{08631D97-B757-4226-897F-9839B1205AB5}"
+EndProject
 Global
 	GlobalSection(SharedMSBuildProjectFiles) = preSolution
+		Uno.SourceGeneration.Engine.Shared\Uno.SourceGeneration.Engine.Shared.projitems*{08631d97-b757-4226-897f-9839b1205ab5}*SharedItemsImports = 13
+		Uno.SourceGeneration.Engine.Shared\Uno.SourceGeneration.Engine.Shared.projitems*{0a1cc471-6080-415f-8947-e41d8534395e}*SharedItemsImports = 4
 		Uno.SourceGeneration.Protocol\Uno.SourceGeneration.Protocol.projitems*{0a1cc471-6080-415f-8947-e41d8534395e}*SharedItemsImports = 4
 		Uno.SourceGeneration.Protocol\Uno.SourceGeneration.Protocol.projitems*{76548c37-4928-45e7-8db1-63a85a7f65d6}*SharedItemsImports = 13
 	EndGlobalSection

src/Uno.SourceGeneratorTasks.Dev15.0/Tasks/HostCollection.cs

@@ -1,60 +0,0 @@
-using System;
-using System.Collections.Concurrent;
-using System.Collections.Generic;
-using System.IO;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-
-namespace Uno.SourceGeneration.Host.GenerationServer
-{
-	public class HostCollection
-	{
-		private readonly DateTime _hostOwnerFileTimeStamp;
-		private readonly DateTime[] _analyzersTimeStamps;
-		private readonly DomainEntry _entry;
-
-		public ConcurrentBag<(string Wrapper, AppDomain Domain)> Hosts { get; } = new ConcurrentBag<(string, AppDomain)>();
-
-		public HostCollection(DomainEntry entry)
-		{
-			_entry = entry;
-			_hostOwnerFileTimeStamp = File.GetLastWriteTime(entry.OwnerFile);
-			_analyzersTimeStamps = entry.Analyzers.Select(e => File.GetLastWriteTime(e)).ToArray();
-		}
-
-		public bool IsInvalid =>
-			File.GetLastWriteTime(Entry.OwnerFile) != _hostOwnerFileTimeStamp
-			|| !Entry.Analyzers.Select(e => File.GetLastWriteTime(e)).SequenceEqual(_analyzersTimeStamps);
-
-		public DomainEntry Entry => _entry;
-	}
-
-	public class DomainEntry
-	{
-		public DomainEntry(string ownerFile, string platform, string[] analyzers)
-		{
-			OwnerFile = ownerFile;
-			Analyzers = analyzers;
-			Platform = platform;
-		}
-
-		public string[] Analyzers { get; }
-
-		public string OwnerFile { get; }
-
-		/// <remarks>
-		/// Platform segregation is required as domains may load assemblies that are 
-		/// not redirected the same way. (e.g. Xamarin.Android vs. Xamarin.iOS).
-		/// </remarks>
-		public string Platform { get; }
-
-		public override bool Equals(object o)
-			=> o is DomainEntry other
-			&& OwnerFile == other.OwnerFile
-			&& Platform == other.Platform
-			&& Analyzers.SequenceEqual(other.Analyzers);
-
-		public override int GetHashCode() => OwnerFile.GetHashCode() ^ Platform.GetHashCode();
-	}
-}

src/Uno.SourceGeneratorTasks.Dev15.0/Tasks/SourceGenerationTask.cs

@@ -28,6 +28,7 @@ using Uno.SourceGeneration.Host.GenerationClient;
 using Uno.SourceGeneration.Host.Messages;
 using Uno.SourceGeneratorTasks.Helpers;
 using System.Runtime.InteropServices;
+using Uno.SourceGeneration.Host;
 
 [assembly: CommitHashAttribute("<developer build>")]
 
@@ -105,10 +106,14 @@ namespace Uno.SourceGeneratorTasks
 				{
 					GenerateWithHostController();
 				}
-				else
+				else if(IsMonoMSBuildCompatible)
 				{
 					GenerateWithHost();
 				}
+				else
+				{
+					GenerateInProcess();
+				}
 
 				return true;
 			}
@@ -137,6 +142,8 @@ namespace Uno.SourceGeneratorTasks
 				}
 			}
 		}
+
+
 		public bool SupportsGenerationController
 			=> (bool.TryParse(UseGenerationController, out var result) && result)
 			&& (
@@ -333,6 +340,7 @@ namespace Uno.SourceGeneratorTasks
 			}
 		}
 
+
 		private string GetHostPath()
 		{
 			var currentPath = Path.GetDirectoryName(new Uri(GetType().Assembly.CodeBase).LocalPath);
@@ -361,6 +369,33 @@ namespace Uno.SourceGeneratorTasks
 			
 		}
 
+		private void GenerateInProcess()
+		{
+			new SourceGeneratorEngine(CreateBuildEnvironment(), null);
+		}
+
+		public bool IsMonoMSBuildCompatible =>
+			// Starting from vs16.0 the following errors does not happen. Below this version, we continue to use
+			// the current process to run the generators.
+			// 
+			// System.TypeInitializationException: The type initializer for 'Microsoft.Build.Collections.MSBuildNameIgnoreCaseComparer' threw an exception. ---> System.EntryPointNotFoundException: GetSystemInfo
+			//   at(wrapper managed-to-native) Microsoft.Build.Shared.NativeMethodsShared.GetSystemInfo(Microsoft.Build.Shared.NativeMethodsShared/SYSTEM_INFO&)
+			//   at Microsoft.Build.Shared.NativeMethodsShared+SystemInformationData..ctor ()[0x00023] in <61115f75067146fab35b10183e6ee379>:0 
+			//   at Microsoft.Build.Shared.NativeMethodsShared.get_SystemInformation ()[0x0001e] in <61115f75067146fab35b10183e6ee379>:0 
+			//   at Microsoft.Build.Shared.NativeMethodsShared.get_ProcessorArchitecture ()[0x00000] in <61115f75067146fab35b10183e6ee379>:0 
+			//   at Microsoft.Build.Collections.MSBuildNameIgnoreCaseComparer..cctor ()[0x00010] in <61115f75067146fab35b10183e6ee379>:0 
+			//    --- End of inner exception stack trace ---
+			//   at Microsoft.Build.Collections.PropertyDictionary`1[T]..ctor ()[0x00006] in <61115f75067146fab35b10183e6ee379>:0 
+			//   at Microsoft.Build.Evaluation.ProjectCollection..ctor (System.Collections.Generic.IDictionary`2[TKey, TValue] globalProperties, System.Collections.Generic.IEnumerable`1[T] loggers, System.Collections.Generic.IEnumerable`1[T] remoteLoggers, Microsoft.Build.Evaluation.ToolsetDefinitionLocations toolsetDefinitionLocations, System.Int32 maxNodeCount, System.Boolean onlyLogCriticalEvents) [0x00112] in <61115f75067146fab35b10183e6ee379>:0 
+			//   at Microsoft.Build.Evaluation.ProjectCollection..ctor(System.Collections.Generic.IDictionary`2[TKey, TValue] globalProperties, System.Collections.Generic.IEnumerable`1[T] loggers, Microsoft.Build.Evaluation.ToolsetDefinitionLocations toolsetDefinitionLocations) [0x00000] in <61115f75067146fab35b10183e6ee379>:0 
+			//   at Microsoft.Build.Evaluation.ProjectCollection..ctor(System.Collections.Generic.IDictionary`2[TKey, TValue] globalProperties) [0x00000] in <61115f75067146fab35b10183e6ee379>:0 
+			//   at Microsoft.Build.Evaluation.ProjectCollection..ctor() [0x00000] in <61115f75067146fab35b10183e6ee379>:0 
+			//   at Uno.SourceGeneration.Host.ProjectLoader.LoadProjectDetails(Uno.SourceGeneratorTasks.BuildEnvironment environment) [0x00216] in <b845ad5dce324939bc8243d198321524>:0 
+			//   at Uno.SourceGeneration.Host.SourceGeneratorHost.Generate() [0x00014] in <b845ad5dce324939bc8243d198321524>:0 
+
+			string.Compare(FileVersionInfo.GetVersionInfo(new Uri(typeof(Microsoft.Build.Utilities.Task).Assembly.Location).LocalPath).FileVersion, "16.0") >= 0;
+
+
 		private BuildEnvironment CreateBuildEnvironment()
 			=> new BuildEnvironment
 			{

src/Uno.SourceGeneratorTasks.Dev15.0/Uno.SourceGeneratorTasks.Dev15.0.csproj

@@ -120,7 +120,6 @@
       <Link>AssemblyVersion.cs</Link>
     </Compile>
     <Compile Include="Properties\AssemblyInfo.cs" />
-    <Compile Include="Tasks\HostCollection.cs" />
     <Compile Include="Tasks\SourceGenerationTask.cs" />
   </ItemGroup>
   <ItemGroup>
@@ -141,6 +140,7 @@
     <None Include="Uno.SourceGenerationTasks.targets" />
   </ItemGroup>
   <Import Project="..\Uno.SourceGeneration.Protocol\Uno.SourceGeneration.Protocol.projitems" Label="Shared" />
+  <Import Project="..\Uno.SourceGeneration.Engine.Shared\Uno.SourceGeneration.Engine.Shared.projitems" Label="Shared" />
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
   <PropertyGroup>
   </PropertyGroup>