Remove assembly loading light-up from scripting (#74409)

src/Scripting/Core/Hosting/AssemblyLoader/AssemblyAndLocation.cs

@@ -2,42 +2,14 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-#nullable disable
-
-using System;
-using System.Diagnostics;
 using System.Reflection;
-using Roslyn.Utilities;
-
-namespace Microsoft.CodeAnalysis.Scripting.Hosting
-{
-    internal readonly struct AssemblyAndLocation : IEquatable<AssemblyAndLocation>
-    {
-        public Assembly Assembly { get; }
-        public string Location { get; }
-        public bool GlobalAssemblyCache { get; }
-
-        internal AssemblyAndLocation(Assembly assembly, string location, bool fromGac)
-        {
-            Debug.Assert(assembly != null && location != null);
 
-            Assembly = assembly;
-            Location = location;
-            GlobalAssemblyCache = fromGac;
-        }
+namespace Microsoft.CodeAnalysis.Scripting.Hosting;
 
-        public bool IsDefault => Assembly == null;
-
-        public bool Equals(AssemblyAndLocation other)
-            => Assembly == other.Assembly && Location == other.Location && GlobalAssemblyCache == other.GlobalAssemblyCache;
-
-        public override int GetHashCode()
-            => Hash.Combine(Assembly, Hash.Combine(Location, Hash.Combine(GlobalAssemblyCache, 0)));
-
-        public override bool Equals(object obj)
-            => obj is AssemblyAndLocation && Equals((AssemblyAndLocation)obj);
+internal readonly record struct AssemblyAndLocation(Assembly Assembly, string Location, bool GlobalAssemblyCache)
+{
+    public bool IsDefault => Assembly == null;
 
-        public override string ToString()
-            => Assembly + " @ " + (GlobalAssemblyCache ? "<GAC>" : Location);
-    }
+    public override string ToString()
+        => Assembly + " @ " + (GlobalAssemblyCache ? "<GAC>" : Location);
 }

src/Scripting/Core/Hosting/AssemblyLoader/AssemblyLoadResult.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-#nullable disable
-
 namespace Microsoft.CodeAnalysis.Scripting.Hosting
 {
     /// <summary>

src/Scripting/Core/Hosting/AssemblyLoader/AssemblyLoaderImpl.cs

@@ -2,43 +2,22 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-#nullable disable
-
 using System;
 using System.IO;
 using System.Reflection;
-using System.Runtime.CompilerServices;
-using Roslyn.Utilities;
 
 namespace Microsoft.CodeAnalysis.Scripting.Hosting
 {
-    internal abstract class AssemblyLoaderImpl : IDisposable
+    internal abstract class AssemblyLoaderImpl(InteractiveAssemblyLoader loader) : IDisposable
     {
-        internal readonly InteractiveAssemblyLoader Loader;
-
-        protected AssemblyLoaderImpl(InteractiveAssemblyLoader loader)
-        {
-            Loader = loader;
-        }
+        internal readonly InteractiveAssemblyLoader Loader = loader;
 
         public static AssemblyLoaderImpl Create(InteractiveAssemblyLoader loader)
-        {
-            if (CoreClrShim.AssemblyLoadContext.Type != null)
-            {
-                return CreateCoreImpl(loader);
-            }
-            else
-            {
-                return new DesktopAssemblyLoaderImpl(loader);
-            }
-        }
-
-        // NoInlining to avoid loading AssemblyLoadContext if not available.
-        [MethodImpl(MethodImplOptions.NoInlining)]
-        private static AssemblyLoaderImpl CreateCoreImpl(InteractiveAssemblyLoader loader)
-        {
-            return new CoreAssemblyLoaderImpl(loader);
-        }
+#if NET
+            => new CoreAssemblyLoaderImpl(loader);
+#else
+            => new DesktopAssemblyLoaderImpl(loader);
+#endif            
 
         public abstract Assembly LoadFromStream(Stream peStream, Stream pdbStream);
         public abstract AssemblyAndLocation LoadFromPath(string path);

src/Scripting/Core/Hosting/AssemblyLoader/CoreAssemblyLoaderImpl.cs

@@ -2,10 +2,8 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-#nullable disable
+#if NET
 
-using System;
-using System.Diagnostics;
 using System.IO;
 using System.Reflection;
 using System.Runtime.Loader;
@@ -34,7 +32,7 @@ public override AssemblyAndLocation LoadFromPath(string path)
             // but there is no need to reuse contexts.
             var assembly = new LoadContext(Loader, Path.GetDirectoryName(path)).LoadFromAssemblyPath(path);
 
-            return new AssemblyAndLocation(assembly, path, fromGac: false);
+            return new AssemblyAndLocation(assembly, path, GlobalAssemblyCache: false);
         }
 
         public override void Dispose()
@@ -44,15 +42,13 @@ public override void Dispose()
 
         private sealed class LoadContext : AssemblyLoadContext
         {
-            private readonly string _loadDirectoryOpt;
+            private readonly string? _loadDirectory;
             private readonly InteractiveAssemblyLoader _loader;
 
-            internal LoadContext(InteractiveAssemblyLoader loader, string loadDirectoryOpt)
+            internal LoadContext(InteractiveAssemblyLoader loader, string? loadDirectory)
             {
-                Debug.Assert(loader != null);
-
                 _loader = loader;
-                _loadDirectoryOpt = loadDirectoryOpt;
+                _loadDirectory = loadDirectory;
 
                 // CoreCLR resolves assemblies in steps:
                 //
@@ -68,10 +64,11 @@ internal LoadContext(InteractiveAssemblyLoader loader, string loadDirectoryOpt)
                 // This order is necessary to avoid loading assemblies twice (by the host App and by interactive loader).
 
                 Resolving += (_, assemblyName) =>
-                    _loader.ResolveAssembly(AssemblyIdentity.FromAssemblyReference(assemblyName), _loadDirectoryOpt);
+                    _loader.ResolveAssembly(AssemblyIdentity.FromAssemblyReference(assemblyName), _loadDirectory);
             }
 
-            protected override Assembly Load(AssemblyName assemblyName) => null;
+            protected override Assembly? Load(AssemblyName assemblyName) => null;
         }
     }
 }
+#endif

src/Scripting/Core/Hosting/AssemblyLoader/DesktopAssemblyLoaderImpl.cs

@@ -2,7 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-#nullable disable
+#if !NET
 
 using System;
 using System.IO;
@@ -13,31 +13,28 @@ namespace Microsoft.CodeAnalysis.Scripting.Hosting
 {
     internal sealed class DesktopAssemblyLoaderImpl : AssemblyLoaderImpl
     {
-        private readonly Func<string, Assembly, Assembly> _assemblyResolveHandlerOpt;
-
         public DesktopAssemblyLoaderImpl(InteractiveAssemblyLoader loader)
             : base(loader)
         {
-            _assemblyResolveHandlerOpt = loader.ResolveAssembly;
-            CoreLightup.Desktop.AddAssemblyResolveHandler(_assemblyResolveHandlerOpt);
+            AppDomain.CurrentDomain.AssemblyResolve += CurrentDomain_AssemblyResolve;
         }
 
         public override void Dispose()
         {
-            if (_assemblyResolveHandlerOpt != null)
-            {
-                CoreLightup.Desktop.RemoveAssemblyResolveHandler(_assemblyResolveHandlerOpt);
-            }
+            AppDomain.CurrentDomain.AssemblyResolve -= CurrentDomain_AssemblyResolve;
         }
 
+        private Assembly CurrentDomain_AssemblyResolve(object sender, ResolveEventArgs args)
+            => Loader.ResolveAssembly(args.Name, args.RequestingAssembly);
+
         public override Assembly LoadFromStream(Stream peStream, Stream pdbStream)
         {
-            byte[] peImage = new byte[peStream.Length];
+            var peImage = new byte[peStream.Length];
             peStream.TryReadAll(peImage, 0, peImage.Length);
 
             if (pdbStream != null)
             {
-                byte[] pdbImage = new byte[pdbStream.Length];
+                var pdbImage = new byte[pdbStream.Length];
                 pdbStream.TryReadAll(pdbImage, 0, pdbImage.Length);
 
                 return Assembly.Load(peImage, pdbImage);
@@ -52,9 +49,8 @@ public override AssemblyAndLocation LoadFromPath(string path)
             // Assembly.LoadFile(string) automatically redirects to GAC if the assembly has a strong name and there is an equivalent assembly in GAC. 
 
             var assembly = Assembly.LoadFile(path);
-            var location = assembly.Location;
-            var fromGac = CoreLightup.Desktop.IsAssemblyFromGlobalAssemblyCache(assembly);
-            return new AssemblyAndLocation(assembly, location, fromGac);
+            return new AssemblyAndLocation(assembly, assembly.Location, assembly.GlobalAssemblyCache);
         }
     }
 }
+#endif