Fix #3247: InvalidOperationException thrown when reading debug metadata files

ICSharpCode.Decompiler/Metadata/MetadataFile.cs

@@ -61,6 +61,7 @@ namespace ICSharpCode.Decompiler.Metadata
 
 		public virtual int MetadataOffset { get; }
 		public virtual bool IsEmbedded { get; }
+		public virtual bool IsMetadataOnly { get; } = true;
 
 		public bool IsAssembly => Metadata.IsAssembly;
 

ICSharpCode.Decompiler/Metadata/PEFile.cs

@@ -53,6 +53,7 @@ namespace ICSharpCode.Decompiler.Metadata
 
 		public override bool IsEmbedded => false;
 		public override int MetadataOffset => Reader.PEHeaders.MetadataStartOffset;
+		public override bool IsMetadataOnly => false;
 
 		public void Dispose()
 		{

ICSharpCode.Decompiler/Metadata/WebCilFile.cs

@@ -183,6 +183,7 @@ namespace ICSharpCode.Decompiler.Metadata
 		}
 
 		public override int MetadataOffset { get; }
+		public override bool IsMetadataOnly => false;
 
 		private static int GetContainingSectionIndex(IEnumerable<SectionHeader> sections, int rva)
 		{

ICSharpCode.ILSpyX/Analyzers/AnalyzerScope.cs

@@ -72,7 +72,7 @@ namespace ICSharpCode.ILSpyX.Analyzers
 		{
 			return assemblyListSnapshot.GetAllAssembliesAsync().GetAwaiter().GetResult()
 				.Select(asm => asm.GetMetadataFileOrNull())
-				.Where(x => x != null)!;
+				.Where(x => x != null && !x.IsMetadataOnly)!;
 		}
 
 		public DecompilerTypeSystem ConstructTypeSystem(MetadataFile module)
@@ -207,7 +207,7 @@ namespace ICSharpCode.ILSpyX.Analyzers
 					if (friendAssemblies.Contains(assembly.ShortName))
 					{
 						var module = assembly.GetMetadataFileOrNull();
-						if (module == null)
+						if (module == null || module.IsMetadataOnly)
 							continue;
 						if (ModuleReferencesScopeType(module.Metadata, typeScope.Name, typeScope.Namespace))
 							yield return module;

ICSharpCode.ILSpyX/LoadedAssembly.cs

@@ -211,7 +211,7 @@ namespace ICSharpCode.ILSpyX
 		{
 			return LazyInitializer.EnsureInitialized(ref this.typeSystem, () => {
 				var module = GetMetadataFileOrNull();
-				if (module == null)
+				if (module == null || module.IsMetadataOnly)
 					return null!;
 				return new SimpleCompilation(
 					module.WithOptions(TypeSystemOptions.Default | TypeSystemOptions.Uncached | TypeSystemOptions.KeepModifiers),
@@ -230,7 +230,7 @@ namespace ICSharpCode.ILSpyX
 				if (typeSystemWithOptions != null && options == currentTypeSystemOptions)
 					return typeSystemWithOptions;
 				var module = GetMetadataFileOrNull();
-				if (module == null)
+				if (module == null || module.IsMetadataOnly)
 					return null;
 				currentTypeSystemOptions = options;
 				return typeSystemWithOptions = new SimpleCompilation(

ILSpy/TreeNodes/AssemblyTreeNode.cs

@@ -467,7 +467,16 @@ namespace ICSharpCode.ILSpy.TreeNodes
 				var loadResult = LoadedAssembly.GetLoadResultAsync().GetAwaiter().GetResult();
 				if (loadResult.MetadataFile != null)
 				{
-					language.DecompileAssembly(LoadedAssembly, output, options);
+					switch (loadResult.MetadataFile.Kind)
+					{
+						case MetadataFile.MetadataFileKind.ProgramDebugDatabase:
+						case MetadataFile.MetadataFileKind.Metadata:
+							output.WriteLine("// " + LoadedAssembly.FileName);
+							break;
+						default:
+							language.DecompileAssembly(LoadedAssembly, output, options);
+							break;
+					}
 				}
 				else if (loadResult.Package != null)
 				{