Merge pull request #1157 from DustinCampbell/fix-xaml-markup-compiler…

…-task

Set MSBuild property to allow the XAML markup compiler task to run

src/OmniSharp.MSBuild/ProjectFile/PropertyNames.cs

@@ -3,6 +3,7 @@
     internal static class PropertyNames
     {
         public const string AllowUnsafeBlocks = nameof(AllowUnsafeBlocks);
+        public const string AlwaysCompileMarkupFilesInSeparateDomain = nameof(AlwaysCompileMarkupFilesInSeparateDomain);
         public const string AssemblyName = nameof(AssemblyName);
         public const string AssemblyOriginatorKeyFile = nameof(AssemblyOriginatorKeyFile);
         public const string BuildProjectReferences = nameof(BuildProjectReferences);

src/OmniSharp.MSBuild/ProjectLoader.cs

@@ -37,6 +37,13 @@ private static Dictionary<string, string> CreateGlobalProperties(
                 { PropertyNames._ResolveReferenceDependencies, "true" },
                 { PropertyNames.SolutionDir, solutionDirectory + Path.DirectorySeparatorChar },
 
+                // Setting this property will cause any XAML markup compiler tasks to run in the
+                // current AppDomain, rather than creating a new one. This is important because
+                // our AppDomain.AssemblyResolve handler for MSBuild will not be connected to
+                // the XAML markup compiler's AppDomain, causing the task not to be able to find
+                // MSBuild.
+                { PropertyNames.AlwaysCompileMarkupFilesInSeparateDomain, "false" },
+
                 // This properties allow the design-time build to handle the Compile target without actually invoking the compiler.
                 // See https://github.com/dotnet/roslyn/pull/4604 for details.
                 { PropertyNames.ProvideCommandLineArgs, "true" },