Use PrecompilationTagHelperTypeResolver to locate TagHelpers during

precompilation.

Fixes #2298

src/Microsoft.AspNet.Mvc.Razor/Precompilation/PrecompilationTagHelperDescriptorResolver.cs

@@ -1,88 +0,0 @@
-// Copyright (c) .NET Foundation. All rights reserved.
-// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
-
-using System;
-using System.Collections.Generic;
-using System.IO;
-using System.Linq;
-using System.Reflection;
-using System.Threading;
-using Microsoft.AspNet.Razor.Runtime.TagHelpers;
-using Microsoft.Dnx.Compilation.CSharp;
-using Microsoft.Dnx.Runtime;
-using Microsoft.Framework.Internal;
-
-namespace Microsoft.AspNet.Mvc.Razor.Precompilation
-{
-    /// <summary>
-    /// <see cref="TagHelperDescriptorResolver"/> used during Razor precompilation.
-    /// </summary>
-    public class PrecompilationTagHelperTypeResolver : TagHelperTypeResolver
-    {
-        private static readonly string TagHelperTypeName = typeof(ITagHelper).FullName;
-        private readonly BeforeCompileContext _compileContext;
-        private readonly IAssemblyLoadContext _loadContext;
-        private object _compilationLock = new object();
-        private bool _assemblyEmited;
-        private TypeInfo[] _exportedTypeInfos;
-
-        /// <summary>
-        /// Initializes a new instance of <see cref="PrecompilationTagHelperTypeResolver"/>.
-        /// </summary>
-        /// <param name="compileContext">The <see cref="BeforeCompileContext"/>.</param>
-        /// <param name="loadContext">The <see cref="IAssemblyLoadContext"/>.</param>
-        public PrecompilationTagHelperTypeResolver([NotNull] BeforeCompileContext compileContext,
-                                                   [NotNull] IAssemblyLoadContext loadContext)
-        {
-            _compileContext = compileContext;
-            _loadContext = loadContext;
-        }
-
-        /// <inheritdoc />
-        protected override IEnumerable<TypeInfo> GetExportedTypes([NotNull] AssemblyName assemblyName)
-        {
-            var compilingAssemblyName = _compileContext.Compilation.AssemblyName;
-            if (string.Equals(assemblyName.Name, compilingAssemblyName, StringComparison.Ordinal))
-            {
-                return LazyInitializer.EnsureInitialized(ref _exportedTypeInfos,
-                                                         ref _assemblyEmited,
-                                                         ref _compilationLock,
-                                                         GetExportedTypesFromCompilation);
-            }
-
-            return GetExportedTypesCore(assemblyName);
-        }
-
-        private IEnumerable<TypeInfo> GetExportedTypesCore(AssemblyName assemblyName)
-        {
-            var assembly = _loadContext.Load(assemblyName.Name);
-
-            return assembly.ExportedTypes.Select(type => type.GetTypeInfo());
-        }
-
-        private TypeInfo[] GetExportedTypesFromCompilation()
-        {
-            using (var stream = new MemoryStream())
-            {
-                var assemblyName = string.Join(".", _compileContext.Compilation.AssemblyName,
-                                                    nameof(PrecompilationTagHelperTypeResolver),
-                                                    Path.GetRandomFileName());
-
-                var emitResult = _compileContext.Compilation
-                                                .WithAssemblyName(assemblyName)
-                                                .Emit(stream);
-                if (!emitResult.Success)
-                {
-                    // Return an empty sequence. Compilation will fail once precompilation completes.
-                    return new TypeInfo[0];
-                }
-
-                stream.Position = 0;
-                var assembly = _loadContext.LoadStream(stream, assemblySymbols: null);
-                return assembly.ExportedTypes
-                               .Select(type => type.GetTypeInfo())
-                               .ToArray();
-            }
-        }
-    }
-}

src/Microsoft.AspNet.Mvc.Razor/Precompilation/RazorPreCompileModule.cs

@@ -6,9 +6,7 @@ using System.Collections.Generic;
 using System.Runtime.Versioning;
 using Microsoft.AspNet.FileProviders;
 using Microsoft.Dnx.Compilation.CSharp;
-using Microsoft.Dnx.Runtime;
 using Microsoft.Framework.Caching.Memory;
-using Microsoft.Framework.DependencyInjection;
 using Microsoft.Framework.Internal;
 
 namespace Microsoft.AspNet.Mvc.Razor.Precompilation
@@ -18,20 +16,10 @@ namespace Microsoft.AspNet.Mvc.Razor.Precompilation
     /// </summary>
     public abstract class RazorPreCompileModule : ICompileModule
     {
-        private readonly IAssemblyLoadContext _loadContext;
         private readonly object _memoryCacheLookupLock = new object();
         private readonly Dictionary<PrecompilationCacheKey, MemoryCache> _memoryCacheLookup =
             new Dictionary<PrecompilationCacheKey, MemoryCache>();
 
-        /// <summary>
-        /// Instantiates a new <see cref="RazorPreCompileModule"/> instance.
-        /// </summary>
-        /// <param name="services">The <see cref="IServiceProvider"/> for the application.</param>
-        public RazorPreCompileModule(IServiceProvider services)
-        {
-            _loadContext = services.GetRequiredService<IAssemblyLoadContext>();
-        }
-
         /// <summary>
         /// Gets or sets a value that determines if symbols (.pdb) file for the precompiled views is generated.
         /// </summary>
@@ -65,7 +53,6 @@ namespace Microsoft.AspNet.Mvc.Razor.Precompilation
 
             var viewCompiler = new RazorPreCompiler(
                 context,
-                _loadContext,
                 fileProvider,
                 memoryCache)
             {

src/Microsoft.AspNet.Mvc.Razor/Precompilation/RazorPreCompiler.cs

@@ -3,21 +3,21 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.IO;
 using System.Linq;
-using System.Reflection;
 using System.Threading.Tasks;
 using Microsoft.AspNet.FileProviders;
 using Microsoft.AspNet.Mvc.Internal;
 using Microsoft.AspNet.Mvc.Razor.Compilation;
 using Microsoft.AspNet.Mvc.Razor.Directives;
 using Microsoft.AspNet.Mvc.Razor.Internal;
+using Microsoft.AspNet.Razor.Runtime.Precompilation;
 using Microsoft.AspNet.Razor.Runtime.TagHelpers;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.Dnx.Compilation;
 using Microsoft.Dnx.Compilation.CSharp;
-using Microsoft.Dnx.Runtime;
 using Microsoft.Framework.Caching.Memory;
 using Microsoft.Framework.Internal;
 
@@ -27,22 +27,22 @@ namespace Microsoft.AspNet.Mvc.Razor.Precompilation
     {
         public RazorPreCompiler(
             [NotNull] BeforeCompileContext compileContext,
-            [NotNull] IAssemblyLoadContext loadContext,
             [NotNull] IFileProvider fileProvider,
             [NotNull] IMemoryCache precompilationCache)
         {
             CompileContext = compileContext;
-            LoadContext = loadContext;
             FileProvider = fileProvider;
+            // There should always be a syntax tree even if there are no files (we generate one)
+            Debug.Assert(compileContext.Compilation.SyntaxTrees.Length > 0);
+            var defines = compileContext.Compilation.SyntaxTrees[0].Options.PreprocessorSymbolNames;
             CompilationSettings = new CompilationSettings
             {
                 CompilationOptions = compileContext.Compilation.Options,
-                // REVIEW: There should always be a syntax tree even if there are no files (we generate one)
-                Defines = compileContext.Compilation.SyntaxTrees[0].Options.PreprocessorSymbolNames,
+                Defines = defines,
                 LanguageVersion = compileContext.Compilation.LanguageVersion
             };
             PreCompilationCache = precompilationCache;
-            TagHelperTypeResolver = new PrecompilationTagHelperTypeResolver(CompileContext, LoadContext);
+            TagHelperTypeResolver = new PrecompilationTagHelperTypeResolver(CompileContext.Compilation);
         }
 
         /// <summary>
@@ -54,8 +54,6 @@ namespace Microsoft.AspNet.Mvc.Razor.Precompilation
 
         protected BeforeCompileContext CompileContext { get; }
 
-        protected IAssemblyLoadContext LoadContext { get; }
-
         protected CompilationSettings CompilationSettings { get; }
 
         protected IMemoryCache PreCompilationCache { get; }

src/Microsoft.AspNet.Mvc.Razor/project.json

@@ -11,6 +11,7 @@
   "dependencies": {
     "Microsoft.AspNet.Mvc.Razor.Host": "6.0.0-*",
     "Microsoft.AspNet.Mvc.ViewFeatures": "6.0.0-*",
+    "Microsoft.AspNet.Razor.Runtime.Precompilation":  "4.0.0-*",
     "Microsoft.AspNet.PageExecutionInstrumentation.Interfaces": "1.0.0-*",
     "Microsoft.Framework.HashCodeCombiner.Sources": { "version": "1.0.0-*", "type": "build" },
     "Microsoft.Framework.NotNullAttribute.Sources": { "version": "1.0.0-*", "type": "build" },

test/WebSites/PrecompilationWebSite/compiler/preprocess/RazorPreCompilation.cs

@@ -8,8 +8,7 @@ namespace PrecompilationWebSite
 {
     public class RazorPreCompilation : RazorPreCompileModule
     {
-        public RazorPreCompilation(IServiceProvider provider)
-            : base(provider)
+        public RazorPreCompilation()
         {
         }
     }