Lift some artificial restrictions to PEFile in WholeProjectDecompiler and ReflectionDisassembler.

ICSharpCode.Decompiler/CSharp/ProjectDecompiler/IProjectFileWriter.cs

@@ -36,6 +36,6 @@ namespace ICSharpCode.Decompiler.CSharp.ProjectDecompiler
 		/// <param name="project">The information about the project being created.</param>
 		/// <param name="files">A collection of source files to be included into the project.</param>
 		/// <param name="module">The module being decompiled.</param>
-		void Write(TextWriter target, IProjectInfoProvider project, IEnumerable<ProjectItemInfo> files, PEFile module);
+		void Write(TextWriter target, IProjectInfoProvider project, IEnumerable<ProjectItemInfo> files, MetadataFile module);
 	}
 }

ICSharpCode.Decompiler/CSharp/ProjectDecompiler/ProjectFileWriterDefault.cs

@@ -45,10 +45,10 @@ namespace ICSharpCode.Decompiler.CSharp.ProjectDecompiler
 			TextWriter target,
 			IProjectInfoProvider project,
 			IEnumerable<ProjectItemInfo> files,
-			PEFile module)
+			MetadataFile module)
 		{
 			const string ns = "http://schemas.microsoft.com/developer/msbuild/2003";
-			string platformName = TargetServices.GetPlatformName(module);
+			string platformName = module is PEFile peFile ? TargetServices.GetPlatformName(peFile) : "AnyCPU";
 			var targetFramework = TargetServices.DetectTargetFramework(module);
 			if (targetFramework.Identifier == ".NETFramework" && targetFramework.VersionNumber == 200)
 				targetFramework = TargetServices.DetectTargetFrameworkNET20(module, project.AssemblyResolver, targetFramework);
@@ -80,26 +80,22 @@ namespace ICSharpCode.Decompiler.CSharp.ProjectDecompiler
 				w.WriteValue(platformName);
 				w.WriteEndElement(); // </Platform>
 
-				if (module.Reader.PEHeaders.IsDll)
-				{
-					w.WriteElementString("OutputType", "Library");
-				}
-				else
+				string outputType;
+
+				switch ((module as PEFile)?.Reader.PEHeaders.PEHeader.Subsystem)
 				{
-					switch (module.Reader.PEHeaders.PEHeader.Subsystem)
-					{
-						case Subsystem.WindowsGui:
-							w.WriteElementString("OutputType", "WinExe");
-							break;
-						case Subsystem.WindowsCui:
-							w.WriteElementString("OutputType", "Exe");
-							break;
-						default:
-							w.WriteElementString("OutputType", "Library");
-							break;
-					}
+					case Subsystem.WindowsGui:
+						outputType = "WinExe";
+						break;
+					case Subsystem.WindowsCui:
+						outputType = "Exe";
+						break;
+					default:
+						outputType = "Library";
+						break;
 				}
 
+				w.WriteElementString("OutputType", outputType);
 				w.WriteElementString("LangVersion", project.LanguageVersion.ToString().Replace("CSharp", "").Replace('_', '.'));
 
 				w.WriteElementString("AssemblyName", module.Name);
@@ -123,7 +119,8 @@ namespace ICSharpCode.Decompiler.CSharp.ProjectDecompiler
 				w.WriteStartElement("PropertyGroup"); // platform-specific
 				w.WriteAttributeString("Condition", " '$(Platform)' == '" + platformName + "' ");
 				w.WriteElementString("PlatformTarget", platformName);
-				if (targetFramework.VersionNumber > 400 && platformName == "AnyCPU" && (module.Reader.PEHeaders.CorHeader.Flags & CorFlags.Prefers32Bit) == 0)
+				if (targetFramework.VersionNumber > 400 && platformName == "AnyCPU"
+					&& ((module as PEFile)?.Reader.PEHeaders.CorHeader.Flags & CorFlags.Prefers32Bit) == 0)
 				{
 					w.WriteElementString("Prefer32Bit", "false");
 				}

ICSharpCode.Decompiler/CSharp/ProjectDecompiler/ProjectFileWriterSdkStyle.cs

@@ -67,7 +67,7 @@ namespace ICSharpCode.Decompiler.CSharp.ProjectDecompiler
 			TextWriter target,
 			IProjectInfoProvider project,
 			IEnumerable<ProjectItemInfo> files,
-			PEFile module)
+			MetadataFile module)
 		{
 			using (XmlTextWriter xmlWriter = new XmlTextWriter(target))
 			{
@@ -76,7 +76,7 @@ namespace ICSharpCode.Decompiler.CSharp.ProjectDecompiler
 			}
 		}
 
-		static void Write(XmlTextWriter xml, IProjectInfoProvider project, IEnumerable<ProjectItemInfo> files, PEFile module)
+		static void Write(XmlTextWriter xml, IProjectInfoProvider project, IEnumerable<ProjectItemInfo> files, MetadataFile module)
 		{
 			xml.WriteStartElement("Project");
 
@@ -105,18 +105,30 @@ namespace ICSharpCode.Decompiler.CSharp.ProjectDecompiler
 			}
 		}
 
-		static void WriteAssemblyInfo(XmlTextWriter xml, PEFile module, IProjectInfoProvider project, ProjectType projectType)
+		static void WriteAssemblyInfo(XmlTextWriter xml, MetadataFile module, IProjectInfoProvider project, ProjectType projectType)
 		{
 			xml.WriteElementString("AssemblyName", module.Name);
 
 			// Since we create AssemblyInfo.cs manually, we need to disable the auto-generation
 			xml.WriteElementString("GenerateAssemblyInfo", FalseString);
 
-			WriteOutputType(xml, module.Reader.PEHeaders.IsDll, module.Reader.PEHeaders.PEHeader.Subsystem, projectType);
+			string platformName;
+			CorFlags flags;
+			if (module is PEFile { Reader.PEHeaders: var headers } peFile)
+			{
+				WriteOutputType(xml, headers.IsDll, headers.PEHeader.Subsystem, projectType);
+				platformName = TargetServices.GetPlatformName(peFile);
+				flags = headers.CorHeader.Flags;
+			}
+			else
+			{
+				WriteOutputType(xml, isDll: true, Subsystem.Unknown, projectType);
+				platformName = AnyCpuString;
+				flags = 0;
+			}
 
 			WriteDesktopExtensions(xml, projectType);
 
-			string platformName = TargetServices.GetPlatformName(module);
 			var targetFramework = TargetServices.DetectTargetFramework(module);
 			if (targetFramework.Identifier == ".NETFramework" && targetFramework.VersionNumber == 200)
 				targetFramework = TargetServices.DetectTargetFrameworkNET20(module, project.AssemblyResolver, targetFramework);
@@ -134,7 +146,7 @@ namespace ICSharpCode.Decompiler.CSharp.ProjectDecompiler
 				xml.WriteElementString("PlatformTarget", platformName);
 			}
 
-			if (platformName == AnyCpuString && (module.Reader.PEHeaders.CorHeader.Flags & CorFlags.Prefers32Bit) != 0)
+			if (platformName == AnyCpuString && (flags & CorFlags.Prefers32Bit) != 0)
 			{
 				xml.WriteElementString("Prefer32Bit", TrueString);
 			}
@@ -238,7 +250,7 @@ namespace ICSharpCode.Decompiler.CSharp.ProjectDecompiler
 			}
 		}
 
-		static void WriteReferences(XmlTextWriter xml, PEFile module, IProjectInfoProvider project, ProjectType projectType)
+		static void WriteReferences(XmlTextWriter xml, MetadataFile module, IProjectInfoProvider project, ProjectType projectType)
 		{
 			bool isNetCoreApp = TargetServices.DetectTargetFramework(module).Identifier == ".NETCoreApp";
 			var targetPacks = new HashSet<string>();
@@ -292,7 +304,7 @@ namespace ICSharpCode.Decompiler.CSharp.ProjectDecompiler
 			}
 		}
 
-		static ProjectType GetProjectType(PEFile module)
+		static ProjectType GetProjectType(MetadataFile module)
 		{
 			foreach (var referenceName in module.AssemblyReferences.Select(r => r.Name))
 			{

ICSharpCode.Decompiler/CSharp/ProjectDecompiler/TargetServices.cs

@@ -39,7 +39,7 @@ namespace ICSharpCode.Decompiler.CSharp.ProjectDecompiler
 		/// <param name="module">The module to get the target framework description for. Cannot be null.</param>
 		/// <returns>A new instance of the <see cref="TargetFramework"/> class that describes the specified <paramref name="module"/>.
 		/// </returns>
-		public static TargetFramework DetectTargetFramework(PEFile module)
+		public static TargetFramework DetectTargetFramework(MetadataFile module)
 		{
 			if (module is null)
 			{

ICSharpCode.Decompiler/CSharp/ProjectDecompiler/WholeProjectDecompiler.cs

@@ -133,10 +133,6 @@ namespace ICSharpCode.Decompiler.CSharp.ProjectDecompiler
 
 		public void DecompileProject(MetadataFile file, string targetDirectory, CancellationToken cancellationToken = default(CancellationToken))
 		{
-			if (file is not PEFile)
-			{
-				throw new NotSupportedException("Module is not a valid PE file!");
-			}
 			string projectFileName = Path.Combine(targetDirectory, CleanUpFileName(file.Name) + ".csproj");
 			using (var writer = new StreamWriter(projectFileName))
 			{
@@ -146,10 +142,6 @@ namespace ICSharpCode.Decompiler.CSharp.ProjectDecompiler
 
 		public ProjectId DecompileProject(MetadataFile file, string targetDirectory, TextWriter projectFileWriter, CancellationToken cancellationToken = default(CancellationToken))
 		{
-			if (file is not PEFile module)
-			{
-				throw new NotSupportedException("Module is not a valid PE file!");
-			}
 			if (string.IsNullOrEmpty(targetDirectory))
 			{
 				throw new InvalidOperationException("Must set TargetDirectory");
@@ -159,15 +151,19 @@ namespace ICSharpCode.Decompiler.CSharp.ProjectDecompiler
 			var resources = WriteResourceFilesInProject(file).ToList();
 			var files = WriteCodeFilesInProject(file, resources.SelectMany(r => r.PartialTypes ?? Enumerable.Empty<PartialTypeInfo>()).ToList(), cancellationToken).ToList();
 			files.AddRange(resources);
-			files.AddRange(WriteMiscellaneousFilesInProject(module));
+			var module = file as PEFile;
+			if (module != null)
+			{
+				files.AddRange(WriteMiscellaneousFilesInProject(module));
+			}
 			if (StrongNameKeyFile != null)
 			{
 				File.Copy(StrongNameKeyFile, Path.Combine(targetDirectory, Path.GetFileName(StrongNameKeyFile)), overwrite: true);
 			}
 
-			projectWriter.Write(projectFileWriter, this, files, module);
+			projectWriter.Write(projectFileWriter, this, files, file);
 
-			string platformName = TargetServices.GetPlatformName(module);
+			string platformName = module != null ? TargetServices.GetPlatformName(module) : "AnyCPU";
 			return new ProjectId(platformName, ProjectGuid, ProjectTypeGuids.CSharpWindows);
 		}
 
@@ -764,7 +760,7 @@ namespace ICSharpCode.Decompiler.CSharp.ProjectDecompiler
 			}
 		}
 
-		public static bool CanUseSdkStyleProjectFormat(PEFile module)
+		public static bool CanUseSdkStyleProjectFormat(MetadataFile module)
 		{
 			return TargetServices.DetectTargetFramework(module).Moniker != null;
 		}

ICSharpCode.Decompiler/Disassembler/ReflectionDisassembler.cs

@@ -1955,7 +1955,7 @@ namespace ICSharpCode.Decompiler.Disassembler
 			}
 		}
 
-		public void WriteAssemblyHeader(PEFile module)
+		public void WriteAssemblyHeader(MetadataFile module)
 		{
 			var metadata = module.Metadata;
 			if (!metadata.IsAssembly)
@@ -2018,7 +2018,7 @@ namespace ICSharpCode.Decompiler.Disassembler
 			}
 		}
 
-		public void WriteModuleHeader(PEFile module, bool skipMVID = false)
+		public void WriteModuleHeader(MetadataFile module, bool skipMVID = false)
 		{
 			var metadata = module.Metadata;
 
@@ -2085,17 +2085,20 @@ namespace ICSharpCode.Decompiler.Disassembler
 				output.WriteLine("// MVID: {0}", metadata.GetGuid(moduleDefinition.Mvid).ToString("B").ToUpperInvariant());
 			}
 
-			var headers = module.Reader.PEHeaders;
-			output.WriteLine(".imagebase 0x{0:x8}", headers.PEHeader.ImageBase);
-			output.WriteLine(".file alignment 0x{0:x8}", headers.PEHeader.FileAlignment);
-			output.WriteLine(".stackreserve 0x{0:x8}", headers.PEHeader.SizeOfStackReserve);
-			output.WriteLine(".subsystem 0x{0:x} // {1}", headers.PEHeader.Subsystem, headers.PEHeader.Subsystem.ToString());
-			output.WriteLine(".corflags 0x{0:x} // {1}", headers.CorHeader.Flags, headers.CorHeader.Flags.ToString());
+			if (module is PEFile peFile)
+			{
+				var headers = peFile.Reader.PEHeaders;
+				output.WriteLine(".imagebase 0x{0:x8}", headers.PEHeader.ImageBase);
+				output.WriteLine(".file alignment 0x{0:x8}", headers.PEHeader.FileAlignment);
+				output.WriteLine(".stackreserve 0x{0:x8}", headers.PEHeader.SizeOfStackReserve);
+				output.WriteLine(".subsystem 0x{0:x} // {1}", headers.PEHeader.Subsystem, headers.PEHeader.Subsystem.ToString());
+				output.WriteLine(".corflags 0x{0:x} // {1}", headers.CorHeader.Flags, headers.CorHeader.Flags.ToString());
+			}
 
 			WriteAttributes(module, metadata.GetCustomAttributes(EntityHandle.ModuleDefinition));
 		}
 
-		public void WriteModuleContents(PEFile module)
+		public void WriteModuleContents(MetadataFile module)
 		{
 			foreach (var handle in Process(module, module.Metadata.GetTopLevelTypeDefinitions().ToArray()))
 			{

ILSpy/Commands/IProtocolHandler.cs

@@ -1,18 +1,30 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
+// Copyright (c) 2018 Siegfried Pammer
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy of this
+// software and associated documentation files (the "Software"), to deal in the Software
+// without restriction, including without limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
+// to whom the Software is furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in all copies or
+// substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
+// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
 using System.Reflection.Metadata;
-using System.Text;
-using System.Threading.Tasks;
 
 using ICSharpCode.Decompiler.Metadata;
 using ICSharpCode.ILSpy.TreeNodes;
-using ICSharpCode.TreeView;
 
 namespace ICSharpCode.ILSpy
 {
 	public interface IProtocolHandler
 	{
-		ILSpyTreeNode Resolve(string protocol, PEFile module, Handle handle, out bool newTabPage);
+		ILSpyTreeNode Resolve(string protocol, MetadataFile module, Handle handle, out bool newTabPage);
 	}
 }

ILSpy/Languages/CSharpLanguage.cs

@@ -393,7 +393,7 @@ namespace ICSharpCode.ILSpy
 
 		public override ProjectId DecompileAssembly(LoadedAssembly assembly, ITextOutput output, DecompilationOptions options)
 		{
-			var module = assembly.GetMetadataFileOrNull() as PEFile;
+			var module = assembly.GetMetadataFileOrNull();
 			if (module == null)
 			{
 				return null;
@@ -427,38 +427,49 @@ namespace ICSharpCode.ILSpy
 				}
 				var metadata = module.Metadata;
 				var corHeader = module.CorHeader;
-				var entrypointHandle = MetadataTokenHelpers.EntityHandleOrNil(corHeader.EntryPointTokenOrRelativeVirtualAddress);
-				if (!entrypointHandle.IsNil && entrypointHandle.Kind == HandleKind.MethodDefinition)
+				if (module is PEFile peFile && corHeader != null)
 				{
-					var entrypoint = typeSystem.MainModule.ResolveMethod(entrypointHandle, new Decompiler.TypeSystem.GenericContext());
-					if (entrypoint != null)
+					var entrypointHandle = MetadataTokenHelpers.EntityHandleOrNil(corHeader.EntryPointTokenOrRelativeVirtualAddress);
+					if (!entrypointHandle.IsNil && entrypointHandle.Kind == HandleKind.MethodDefinition)
 					{
-						output.Write("// Entry point: ");
-						output.WriteReference(entrypoint, EscapeName(entrypoint.DeclaringType.FullName + "." + entrypoint.Name));
-						output.WriteLine();
+						var entrypoint = typeSystem.MainModule.ResolveMethod(entrypointHandle, new Decompiler.TypeSystem.GenericContext());
+						if (entrypoint != null)
+						{
+							output.Write("// Entry point: ");
+							output.WriteReference(entrypoint, EscapeName(entrypoint.DeclaringType.FullName + "." + entrypoint.Name));
+							output.WriteLine();
+						}
+					}
+					output.WriteLine("// Architecture: " + GetPlatformDisplayName(peFile));
+					if ((corHeader.Flags & System.Reflection.PortableExecutable.CorFlags.ILOnly) == 0)
+					{
+						output.WriteLine("// This assembly contains unmanaged code.");
+					}
+					string runtimeName = GetRuntimeDisplayName(module);
+					if (runtimeName != null)
+					{
+						output.WriteLine("// Runtime: " + runtimeName);
+					}
+					if ((corHeader.Flags & System.Reflection.PortableExecutable.CorFlags.StrongNameSigned) != 0)
+					{
+						output.WriteLine("// This assembly is signed with a strong name key.");
+					}
+					if (peFile.Reader.ReadDebugDirectory().Any(d => d.Type == DebugDirectoryEntryType.Reproducible))
+					{
+						output.WriteLine("// This assembly was compiled using the /deterministic option.");
+					}
+					if (module.Metadata.MetadataKind != MetadataKind.Ecma335)
+					{
+						output.WriteLine("// This assembly was loaded with Windows Runtime projections applied.");
 					}
 				}
-				output.WriteLine("// Architecture: " + GetPlatformDisplayName(module));
-				if ((corHeader.Flags & System.Reflection.PortableExecutable.CorFlags.ILOnly) == 0)
-				{
-					output.WriteLine("// This assembly contains unmanaged code.");
-				}
-				string runtimeName = GetRuntimeDisplayName(module);
-				if (runtimeName != null)
-				{
-					output.WriteLine("// Runtime: " + runtimeName);
-				}
-				if ((corHeader.Flags & System.Reflection.PortableExecutable.CorFlags.StrongNameSigned) != 0)
-				{
-					output.WriteLine("// This assembly is signed with a strong name key.");
-				}
-				if (module.Reader.ReadDebugDirectory().Any(d => d.Type == DebugDirectoryEntryType.Reproducible))
-				{
-					output.WriteLine("// This assembly was compiled using the /deterministic option.");
-				}
-				if (module.Metadata.MetadataKind != MetadataKind.Ecma335)
+				else
 				{
-					output.WriteLine("// This assembly was loaded with Windows Runtime projections applied.");
+					string runtimeName = GetRuntimeDisplayName(module);
+					if (runtimeName != null)
+					{
+						output.WriteLine("// Runtime: " + runtimeName);
+					}
 				}
 				if (metadata.IsAssembly)
 				{

ILSpy/Languages/ILLanguage.cs

@@ -165,12 +165,7 @@ namespace ICSharpCode.ILSpy
 		{
 			output.WriteLine("// " + assembly.FileName);
 			output.WriteLine();
-			var module = assembly.GetMetadataFileOrNull() as PEFile;
-
-			if (module == null)
-			{
-				throw new NotSupportedException("This file is not a PE file");
-			}
+			var module = assembly.GetMetadataFileOrNull();
 
 			if (options.FullDecompilation && options.SaveAsProjectDirectory != null)
 			{

ILSpy/Languages/Language.cs

@@ -561,7 +561,7 @@ namespace ICSharpCode.ILSpy
 			}
 		}
 
-		public static string GetRuntimeDisplayName(PEFile module)
+		public static string GetRuntimeDisplayName(MetadataFile module)
 		{
 			return module.Metadata.MetadataVersion;
 		}

ILSpy/MainWindow.xaml.cs

@@ -826,12 +826,6 @@ namespace ICSharpCode.ILSpy
 
 		static bool CanResolveTypeInPEFile(MetadataFile module, ITypeReference typeRef, out EntityHandle typeHandle)
 		{
-			if (module is not PEFile)
-			{
-				typeHandle = default;
-				return false;
-			}
-
 			// We intentionally ignore reference assemblies, so that the loop continues looking for another assembly that might have a usable definition.
 			if (module.IsReferenceAssembly())
 			{
@@ -1314,7 +1308,7 @@ namespace ICSharpCode.ILSpy
 					break;
 				case EntityReference unresolvedEntity:
 					string protocol = unresolvedEntity.Protocol ?? "decompile";
-					PEFile file = unresolvedEntity.ResolveAssembly(assemblyList) as PEFile;
+					var file = unresolvedEntity.ResolveAssembly(assemblyList);
 					if (file == null)
 					{
 						break;

ILSpy/Metadata/GoToTokenCommand.cs

@@ -35,7 +35,7 @@ namespace ICSharpCode.ILSpy.Commands
 	{
 		public void Execute(TextViewContext context)
 		{
-			int token = GetSelectedToken(context.DataGrid, out PEFile module).Value;
+			int token = GetSelectedToken(context.DataGrid, out MetadataFile module).Value;
 			MainWindow.Instance.JumpToReference(new EntityReference(module, MetadataTokens.Handle(token), protocol: "metadata"));
 		}
 
@@ -49,7 +49,7 @@ namespace ICSharpCode.ILSpy.Commands
 			return context.DataGrid?.Name == "MetadataView" && GetSelectedToken(context.DataGrid, out _) != null;
 		}
 
-		private int? GetSelectedToken(DataGrid grid, out PEFile module)
+		private int? GetSelectedToken(DataGrid grid, out MetadataFile module)
 		{
 			module = null;
 			if (grid == null)
@@ -62,7 +62,7 @@ namespace ICSharpCode.ILSpy.Commands
 			var moduleField = type.GetField("module", BindingFlags.NonPublic | BindingFlags.Instance);
 			if (property == null || property.PropertyType != typeof(int) || !property.GetCustomAttributes(false).Any(a => a is ColumnInfoAttribute { Kind: ColumnKind.Token } c))
 				return null;
-			module = (PEFile)moduleField.GetValue(cell.Item);
+			module = (MetadataFile)moduleField.GetValue(cell.Item);
 			return (int)property.GetValue(cell.Item);
 		}
 	}

ILSpy/Metadata/MetadataProtocolHandler.cs

@@ -28,7 +28,7 @@ namespace ICSharpCode.ILSpy.Metadata
 	[Export(typeof(IProtocolHandler))]
 	class MetadataProtocolHandler : IProtocolHandler
 	{
-		public ILSpyTreeNode Resolve(string protocol, PEFile module, Handle handle, out bool newTabPage)
+		public ILSpyTreeNode Resolve(string protocol, MetadataFile module, Handle handle, out bool newTabPage)
 		{
 			newTabPage = true;
 			if (protocol != "metadata")

ILSpy/TextView/DecompilerTextView.cs

@@ -51,7 +51,6 @@ using ICSharpCode.Decompiler;
 using ICSharpCode.Decompiler.CSharp.OutputVisitor;
 using ICSharpCode.Decompiler.CSharp.ProjectDecompiler;
 using ICSharpCode.Decompiler.Documentation;
-using ICSharpCode.Decompiler.Metadata;
 using ICSharpCode.Decompiler.TypeSystem;
 using ICSharpCode.ILSpy.AvalonEdit;
 using ICSharpCode.ILSpy.Options;
@@ -411,7 +410,7 @@ namespace ICSharpCode.ILSpy.TextView
 			}
 			else if (segment.Reference is EntityReference unresolvedEntity)
 			{
-				var module = unresolvedEntity.ResolveAssembly(MainWindow.Instance.CurrentAssemblyList) as PEFile;
+				var module = unresolvedEntity.ResolveAssembly(MainWindow.Instance.CurrentAssemblyList);
 				if (module == null)
 					return null;
 				var typeSystem = new DecompilerTypeSystem(module,

ILSpy/TreeNodes/AssemblyTreeNode.cs

@@ -129,7 +129,7 @@ namespace ICSharpCode.ILSpy.TreeNodes
 				if (tooltip == null && LoadedAssembly.IsLoaded)
 				{
 					tooltip = new TextBlock();
-					var module = LoadedAssembly.GetMetadataFileOrNull() as PEFile;
+					var module = LoadedAssembly.GetMetadataFileOrNull();
 					var metadata = module?.Metadata;
 					if (metadata?.IsAssembly == true && metadata.TryGetFullAssemblyName(out var assemblyName))
 					{
@@ -141,9 +141,12 @@ namespace ICSharpCode.ILSpy.TreeNodes
 					tooltip.Inlines.Add(new Run(LoadedAssembly.FileName));
 					if (module != null)
 					{
-						tooltip.Inlines.Add(new LineBreak());
-						tooltip.Inlines.Add(new Bold(new Run("Architecture: ")));
-						tooltip.Inlines.Add(new Run(Language.GetPlatformDisplayName(module)));
+						if (module is PEFile peFile)
+						{
+							tooltip.Inlines.Add(new LineBreak());
+							tooltip.Inlines.Add(new Bold(new Run("Architecture: ")));
+							tooltip.Inlines.Add(new Run(Language.GetPlatformDisplayName(peFile)));
+						}
 						string runtimeName = Language.GetRuntimeDisplayName(module);
 						if (runtimeName != null)
 						{