Rename IAssembly -> IModule.

While support for multi-module assemblies isn't fully working yet; it is clear at this point that we want
to treat each module in a multi-module assembly separately for the purposes of the type system.

ICSharpCode.Decompiler.Tests/Semantics/OverloadResolutionTests.cs

@@ -49,7 +49,7 @@ namespace ICSharpCode.Decompiler.Tests.Semantics
 
 		IMethod MakeMethod(params object[] parameterTypesOrDefaultValues)
 		{
-			var context = new SimpleTypeResolveContext(compilation.MainAssembly);
+			var context = new SimpleTypeResolveContext(compilation.MainModule);
 			var m = new FakeMethod(compilation, SymbolKind.Method);
 			m.Name = "Method";
 			var parameters = new List<IParameter>();

ICSharpCode.Decompiler.Tests/TypeSystem/TypeSystemLoaderTests.cs

@@ -159,7 +159,7 @@ namespace ICSharpCode.Decompiler.Tests.TypeSystem
 		[Test]
 		public void AssemblyAttribute()
 		{
-			var attributes = compilation.MainAssembly.GetAssemblyAttributes().ToList();
+			var attributes = compilation.MainModule.GetAssemblyAttributes().ToList();
 			var typeTest = attributes.Single(a => a.AttributeType.FullName == typeof(TypeTestAttribute).FullName);
 			Assert.AreEqual(3, typeTest.FixedArguments.Length);
 			// first argument is (int)42
@@ -185,7 +185,7 @@ namespace ICSharpCode.Decompiler.Tests.TypeSystem
 		[Test]
 		public void TypeForwardedTo_Attribute()
 		{
-			var attributes = compilation.MainAssembly.GetAssemblyAttributes().ToList();
+			var attributes = compilation.MainModule.GetAssemblyAttributes().ToList();
 			var forwardAttribute = attributes.Single(a => a.AttributeType.FullName == typeof(TypeForwardedToAttribute).FullName);
 			Assert.AreEqual(1, forwardAttribute.FixedArguments.Length);
 			var rt = (IType)forwardAttribute.FixedArguments[0].Value;
@@ -1813,7 +1813,7 @@ namespace ICSharpCode.Decompiler.Tests.TypeSystem
 			var typeRef = ReflectionHelper.ParseReflectionName("System.Func`2, System.Core");
 			ITypeDefinition c = typeRef.Resolve(compilationWithSystemCore.TypeResolveContext).GetDefinition();
 			Assert.IsNotNull(c, "System.Func<,> not found");
-			Assert.AreEqual("mscorlib", c.ParentAssembly.AssemblyName);
+			Assert.AreEqual("mscorlib", c.ParentModule.AssemblyName);
 		}
 
 		public void DelegateIsClass()

ICSharpCode.Decompiler/CSharp/CSharpDecompiler.cs

@@ -374,7 +374,7 @@ namespace ICSharpCode.Decompiler.CSharp
 		/// </summary>
 		public SyntaxTree DecompileModuleAndAssemblyAttributes()
 		{
-			var decompilationContext = new SimpleTypeResolveContext(typeSystem.MainAssembly);
+			var decompilationContext = new SimpleTypeResolveContext(typeSystem.MainModule);
 			var decompileRun = new DecompileRun(settings) {
 				DocumentationProvider = DocumentationProvider ?? CreateDefaultDocumentationProvider(),
 				CancellationToken = CancellationToken
@@ -396,13 +396,13 @@ namespace ICSharpCode.Decompiler.CSharp
 
 		void DoDecompileModuleAndAssemblyAttributes(DecompileRun decompileRun, ITypeResolveContext decompilationContext, SyntaxTree syntaxTree)
 		{
-			foreach (var a in typeSystem.Compilation.MainAssembly.GetAssemblyAttributes()) {
+			foreach (var a in typeSystem.Compilation.MainModule.GetAssemblyAttributes()) {
 				var astBuilder = CreateAstBuilder(decompilationContext);
 				var attrSection = new AttributeSection(astBuilder.ConvertAttribute(a));
 				attrSection.AttributeTarget = "assembly";
 				syntaxTree.AddChild(attrSection, SyntaxTree.MemberRole);
 			}
-			foreach (var a in typeSystem.Compilation.MainAssembly.GetModuleAttributes()) {
+			foreach (var a in typeSystem.Compilation.MainModule.GetModuleAttributes()) {
 				var astBuilder = CreateAstBuilder(decompilationContext);
 				var attrSection = new AttributeSection(astBuilder.ConvertAttribute(a));
 				attrSection.AttributeTarget = "module";
@@ -439,7 +439,7 @@ namespace ICSharpCode.Decompiler.CSharp
 		/// </summary>
 		public SyntaxTree DecompileWholeModuleAsSingleFile()
 		{
-			var decompilationContext = new SimpleTypeResolveContext(typeSystem.MainAssembly);
+			var decompilationContext = new SimpleTypeResolveContext(typeSystem.MainModule);
 			var decompileRun = new DecompileRun(settings) {
 				DocumentationProvider = DocumentationProvider ?? CreateDefaultDocumentationProvider(),
 				CancellationToken = CancellationToken
@@ -566,7 +566,7 @@ namespace ICSharpCode.Decompiler.CSharp
 		{
 			if (types == null)
 				throw new ArgumentNullException(nameof(types));
-			var decompilationContext = new SimpleTypeResolveContext(typeSystem.MainAssembly);
+			var decompilationContext = new SimpleTypeResolveContext(typeSystem.MainModule);
 			var decompileRun = new DecompileRun(settings) {
 				DocumentationProvider = DocumentationProvider ?? CreateDefaultDocumentationProvider(),
 				CancellationToken = CancellationToken
@@ -606,7 +606,7 @@ namespace ICSharpCode.Decompiler.CSharp
 			var type = typeSystem.Compilation.FindType(fullTypeName.TopLevelTypeName).GetDefinition();
 			if (type == null)
 				throw new InvalidOperationException($"Could not find type definition {fullTypeName} in type system.");
-			var decompilationContext = new SimpleTypeResolveContext(typeSystem.MainAssembly);
+			var decompilationContext = new SimpleTypeResolveContext(typeSystem.MainModule);
 			var decompileRun = new DecompileRun(settings) {
 				DocumentationProvider = DocumentationProvider ?? CreateDefaultDocumentationProvider(),
 				CancellationToken = CancellationToken
@@ -697,7 +697,7 @@ namespace ICSharpCode.Decompiler.CSharp
 						throw new NotSupportedException(entity.Kind.ToString());
 				}
 			}
-			RunTransforms(syntaxTree, decompileRun, parentTypeDef != null ? new SimpleTypeResolveContext(parentTypeDef) : new SimpleTypeResolveContext(typeSystem.MainAssembly));
+			RunTransforms(syntaxTree, decompileRun, parentTypeDef != null ? new SimpleTypeResolveContext(parentTypeDef) : new SimpleTypeResolveContext(typeSystem.MainModule));
 			return syntaxTree;
 		}
 
@@ -776,7 +776,7 @@ namespace ICSharpCode.Decompiler.CSharp
 		{
 			bool addNewModifier = false;
 			var entity = (IEntity)member.GetSymbol();
-			var lookup = new MemberLookup(entity.DeclaringTypeDefinition, entity.ParentAssembly);
+			var lookup = new MemberLookup(entity.DeclaringTypeDefinition, entity.ParentModule);
 
 			var baseTypes = entity.DeclaringType.GetNonInterfaceBaseTypes().Where(t => entity.DeclaringType != t);
 			if (entity is ITypeDefinition) {

ICSharpCode.Decompiler/CSharp/CallBuilder.cs

@@ -611,7 +611,7 @@ namespace ICSharpCode.Decompiler.CSharp
 			out IParameterizedMember foundMember)
 		{
 			foundMember = null;
-			var lookup = new MemberLookup(resolver.CurrentTypeDefinition, resolver.CurrentTypeDefinition.ParentAssembly);
+			var lookup = new MemberLookup(resolver.CurrentTypeDefinition, resolver.CurrentTypeDefinition.ParentModule);
 			var or = new OverloadResolution(resolver.Compilation,
 				arguments.SelectArray(a => a.ResolveResult),
 				argumentNames: argumentNames,
@@ -674,7 +674,7 @@ namespace ICSharpCode.Decompiler.CSharp
 					return false;
 				foundMember = result.Member;
 			} else {
-				var lookup = new MemberLookup(resolver.CurrentTypeDefinition, resolver.CurrentTypeDefinition.ParentAssembly);
+				var lookup = new MemberLookup(resolver.CurrentTypeDefinition, resolver.CurrentTypeDefinition.ParentModule);
 				if (method.AccessorOwner.SymbolKind == SymbolKind.Indexer) {
 					var or = new OverloadResolution(resolver.Compilation,
 						arguments.SelectArray(a => a.ResolveResult),
@@ -848,7 +848,7 @@ namespace ICSharpCode.Decompiler.CSharp
 			}
 			MemberLookup lookup = null;
 			if (requireTarget) {
-				lookup = new MemberLookup(resolver.CurrentTypeDefinition, resolver.CurrentTypeDefinition.ParentAssembly);
+				lookup = new MemberLookup(resolver.CurrentTypeDefinition, resolver.CurrentTypeDefinition.ParentModule);
 				var rr = lookup.Lookup(target.ResolveResult, method.Name, method.TypeArguments, false) ;
 				needsCast = true;
 				result = rr;

ICSharpCode.Decompiler/CSharp/ExpressionBuilder.cs

@@ -86,7 +86,7 @@ namespace ICSharpCode.Decompiler.CSharp
 			this.settings = settings;
 			this.cancellationToken = cancellationToken;
 			this.compilation = decompilationContext.Compilation;
-			this.resolver = new CSharpResolver(new CSharpTypeResolveContext(compilation.MainAssembly, null, decompilationContext.CurrentTypeDefinition, decompilationContext.CurrentMember));
+			this.resolver = new CSharpResolver(new CSharpTypeResolveContext(compilation.MainModule, null, decompilationContext.CurrentTypeDefinition, decompilationContext.CurrentMember));
 			this.astBuilder = new TypeSystemAstBuilder(resolver);
 			this.astBuilder.AlwaysUseShortTypeNames = true;
 			this.astBuilder.AddResolveResultAnnotations = true;
@@ -209,7 +209,7 @@ namespace ICSharpCode.Decompiler.CSharp
 					var result = resolver.ResolveSimpleName(field.Name, EmptyList<IType>.Instance, isInvocationTarget: false) as MemberResolveResult;
 					return !(result == null || result.IsError || !result.Member.Equals(field, NormalizeTypeVisitor.TypeErasure));
 				} else {
-					var lookup = new MemberLookup(resolver.CurrentTypeDefinition, resolver.CurrentTypeDefinition.ParentAssembly);
+					var lookup = new MemberLookup(resolver.CurrentTypeDefinition, resolver.CurrentTypeDefinition.ParentModule);
 					var result = lookup.Lookup(target.ResolveResult, field.Name, EmptyList<IType>.Instance, false) as MemberResolveResult;
 					return !(result == null || result.IsError || !result.Member.Equals(field, NormalizeTypeVisitor.TypeErasure));
 				}

ICSharpCode.Decompiler/CSharp/RequiredNamespaceCollector.cs

@@ -22,7 +22,7 @@ namespace ICSharpCode.Decompiler.CSharp
 	{
 		public static void CollectNamespaces(DecompilerTypeSystem typeSystem, HashSet<string> namespaces)
 		{
-			foreach (var type in typeSystem.MainAssembly.TypeDefinitions) {
+			foreach (var type in typeSystem.MainModule.TypeDefinitions) {
 				CollectNamespaces(type, typeSystem, namespaces);
 			}
 			CollectAttributeNamespaces(typeSystem, namespaces);
@@ -30,8 +30,8 @@ namespace ICSharpCode.Decompiler.CSharp
 
 		public static void CollectAttributeNamespaces(DecompilerTypeSystem typeSystem, HashSet<string> namespaces)
 		{
-			HandleAttributes(typeSystem.MainAssembly.GetAssemblyAttributes(), namespaces);
-			HandleAttributes(typeSystem.MainAssembly.GetModuleAttributes(), namespaces);
+			HandleAttributes(typeSystem.MainModule.GetAssemblyAttributes(), namespaces);
+			HandleAttributes(typeSystem.MainModule.GetModuleAttributes(), namespaces);
 		}
 
 		public static void CollectNamespaces(IEntity entity, DecompilerTypeSystem typeSystem,
@@ -42,7 +42,7 @@ namespace ICSharpCode.Decompiler.CSharp
 			switch (entity) {
 				case ITypeDefinition td:
 					if (mappingInfo == null)
-						mappingInfo = CSharpDecompiler.GetCodeMappingInfo(entity.ParentAssembly.PEFile, entity.MetadataToken);
+						mappingInfo = CSharpDecompiler.GetCodeMappingInfo(entity.ParentModule.PEFile, entity.MetadataToken);
 					namespaces.Add(td.Namespace);
 					HandleAttributes(td.GetAttributes(), namespaces);
 
@@ -91,7 +91,7 @@ namespace ICSharpCode.Decompiler.CSharp
 					}
 					if (!method.MetadataToken.IsNil && method.HasBody) {
 						if (mappingInfo == null)
-							mappingInfo = CSharpDecompiler.GetCodeMappingInfo(entity.ParentAssembly.PEFile, entity.MetadataToken);
+							mappingInfo = CSharpDecompiler.GetCodeMappingInfo(entity.ParentModule.PEFile, entity.MetadataToken);
 						var reader = typeSystem.ModuleDefinition.Reader;
 						var parts = mappingInfo.GetMethodParts((MethodDefinitionHandle)method.MetadataToken).ToList();
 						foreach (var part in parts) {

ICSharpCode.Decompiler/CSharp/Resolver/CSharpOperators.cs

@@ -175,8 +175,8 @@ namespace ICSharpCode.Decompiler.CSharp.Resolver
 				get { return false; }
 			}
 			
-			IAssembly IEntity.ParentAssembly {
-				get { return compilation.MainAssembly; }
+			IModule IEntity.ParentModule {
+				get { return compilation.MainModule; }
 			}
 			
 			TypeParameterSubstitution IMember.Substitution {

ICSharpCode.Decompiler/CSharp/Resolver/CSharpResolver.cs

@@ -52,7 +52,7 @@ namespace ICSharpCode.Decompiler.CSharp.Resolver
 				throw new ArgumentNullException("compilation");
 			this.compilation = compilation;
 			this.conversions = CSharpConversions.Get(compilation);
-			this.context = new CSharpTypeResolveContext(compilation.MainAssembly);
+			this.context = new CSharpTypeResolveContext(compilation.MainModule);
 		}
 		
 		public CSharpResolver(CSharpTypeResolveContext context)
@@ -94,8 +94,8 @@ namespace ICSharpCode.Decompiler.CSharp.Resolver
 			get { return context; }
 		}
 
-		IAssembly ITypeResolveContext.CurrentAssembly {
-			get { return context.CurrentAssembly; }
+		IModule ITypeResolveContext.CurrentModule {
+			get { return context.CurrentModule; }
 		}
 		
 		CSharpResolver WithContext(CSharpTypeResolveContext newContext)
@@ -1536,7 +1536,7 @@ namespace ICSharpCode.Decompiler.CSharp.Resolver
 		bool TopLevelTypeDefinitionIsAccessible(ITypeDefinition typeDef)
 		{
 			if (typeDef.Accessibility == Accessibility.Internal) {
-				return typeDef.ParentAssembly.InternalsVisibleTo(compilation.MainAssembly);
+				return typeDef.ParentModule.InternalsVisibleTo(compilation.MainModule);
 			}
 			return true;
 		}
@@ -1651,7 +1651,7 @@ namespace ICSharpCode.Decompiler.CSharp.Resolver
 			ITypeDefinition currentTypeDefinition = this.CurrentTypeDefinition;
 			bool isInEnumMemberInitializer = this.CurrentMember != null && this.CurrentMember.SymbolKind == SymbolKind.Field
 				&& currentTypeDefinition != null && currentTypeDefinition.Kind == TypeKind.Enum;
-			return new MemberLookup(currentTypeDefinition, this.Compilation.MainAssembly, isInEnumMemberInitializer);
+			return new MemberLookup(currentTypeDefinition, this.Compilation.MainModule, isInEnumMemberInitializer);
 		}
 		
 		/// <summary>
@@ -1664,7 +1664,7 @@ namespace ICSharpCode.Decompiler.CSharp.Resolver
 				// for accessibility purposes.
 				// This avoids a stack overflow when referencing a protected class nested inside the base class
 				// of a parent class. (NameLookupTests.InnerClassInheritingFromProtectedBaseInnerClassShouldNotCauseStackOverflow)
-				return new MemberLookup(this.CurrentTypeDefinition.DeclaringTypeDefinition, this.Compilation.MainAssembly, false);
+				return new MemberLookup(this.CurrentTypeDefinition.DeclaringTypeDefinition, this.Compilation.MainModule, false);
 			} else {
 				return CreateMemberLookup();
 			}

ICSharpCode.Decompiler/CSharp/Resolver/MemberLookup.cs

@@ -47,13 +47,13 @@ namespace ICSharpCode.Decompiler.CSharp.Resolver
 		#endregion
 		
 		readonly ITypeDefinition currentTypeDefinition;
-		readonly IAssembly currentAssembly;
+		readonly IModule currentModule;
 		readonly bool isInEnumMemberInitializer;
 		
-		public MemberLookup(ITypeDefinition currentTypeDefinition, IAssembly currentAssembly, bool isInEnumMemberInitializer = false)
+		public MemberLookup(ITypeDefinition currentTypeDefinition, IModule currentModule, bool isInEnumMemberInitializer = false)
 		{
 			this.currentTypeDefinition = currentTypeDefinition;
-			this.currentAssembly = currentAssembly;
+			this.currentModule = currentModule;
 			this.isInEnumMemberInitializer = isInEnumMemberInitializer;
 		}
 		
@@ -116,19 +116,19 @@ namespace ICSharpCode.Decompiler.CSharp.Resolver
 				case Accessibility.Protected:
 					return IsProtectedAccessible(allowProtectedAccess, entity);
 				case Accessibility.Internal:
-					return IsInternalAccessible(entity.ParentAssembly);
+					return IsInternalAccessible(entity.ParentModule);
 				case Accessibility.ProtectedOrInternal:
-					return IsInternalAccessible(entity.ParentAssembly) || IsProtectedAccessible(allowProtectedAccess, entity);
+					return IsInternalAccessible(entity.ParentModule) || IsProtectedAccessible(allowProtectedAccess, entity);
 				case Accessibility.ProtectedAndInternal:
-					return IsInternalAccessible(entity.ParentAssembly) && IsProtectedAccessible(allowProtectedAccess, entity);
+					return IsInternalAccessible(entity.ParentModule) && IsProtectedAccessible(allowProtectedAccess, entity);
 				default:
 					throw new Exception("Invalid value for Accessibility");
 			}
 		}
 		
-		bool IsInternalAccessible(IAssembly assembly)
+		bool IsInternalAccessible(IModule module)
 		{
-			return assembly != null && currentAssembly != null && assembly.InternalsVisibleTo(currentAssembly);
+			return module != null && currentModule != null && module.InternalsVisibleTo(currentModule);
 		}
 		
 		bool IsProtectedAccessible(bool allowProtectedAccess, IEntity entity)

ICSharpCode.Decompiler/CSharp/Resolver/ReducedExtensionMethod.cs

@@ -231,9 +231,9 @@ namespace ICSharpCode.Decompiler.CSharp.Resolver
 			}
 		}
 
-		public IAssembly ParentAssembly {
+		public IModule ParentModule {
 			get {
-				return baseMethod.ParentAssembly;
+				return baseMethod.ParentModule;
 			}
 		}
 

ICSharpCode.Decompiler/CSharp/Syntax/TypeSystemAstBuilder.cs

@@ -204,7 +204,7 @@ namespace ICSharpCode.Decompiler.CSharp.Syntax
 		public AstType ConvertType(FullTypeName fullTypeName)
 		{
 			if (resolver != null) {
-				foreach (var asm in resolver.Compilation.Assemblies) {
+				foreach (var asm in resolver.Compilation.Modules) {
 					var def = asm.GetTypeDefinition(fullTypeName);
 					if (def != null) {
 						return ConvertType(def);

ICSharpCode.Decompiler/CSharp/Transforms/IntroduceExtensionMethods.cs

@@ -56,7 +56,7 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 					usingScope = new UsingScope(usingScope, ns);
 				}
 			}
-			var currentContext = new CSharpTypeResolveContext(context.TypeSystem.MainAssembly, usingScope.Resolve(context.TypeSystem.Compilation), context.DecompiledTypeDefinition);
+			var currentContext = new CSharpTypeResolveContext(context.TypeSystem.MainModule, usingScope.Resolve(context.TypeSystem.Compilation), context.DecompiledTypeDefinition);
 			this.resolveContextStack.Push(currentContext);
 			this.resolver = new CSharpResolver(currentContext);
 		}
@@ -68,7 +68,7 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 			foreach (string ident in namespaceDeclaration.Identifiers) {
 				usingScope = new UsingScope(usingScope, ident);
 			}
-			var currentContext = new CSharpTypeResolveContext(previousContext.CurrentAssembly, usingScope.Resolve(previousContext.Compilation));
+			var currentContext = new CSharpTypeResolveContext(previousContext.CurrentModule, usingScope.Resolve(previousContext.Compilation));
 			resolveContextStack.Push(currentContext);
 			try {
 				this.resolver = new CSharpResolver(currentContext);

ICSharpCode.Decompiler/CSharp/Transforms/IntroduceUsingDeclarations.cs

@@ -130,7 +130,7 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 						usingScope = new UsingScope(usingScope, ns);
 					}
 				}
-				var currentContext = new CSharpTypeResolveContext(context.TypeSystem.MainAssembly, usingScope.Resolve(context.TypeSystem.Compilation), context.DecompiledTypeDefinition);
+				var currentContext = new CSharpTypeResolveContext(context.TypeSystem.MainModule, usingScope.Resolve(context.TypeSystem.Compilation), context.DecompiledTypeDefinition);
 				this.context.Push(currentContext);
 				this.astBuilder = CreateAstBuilder(currentContext);
 			}
@@ -150,7 +150,7 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 				foreach (string ident in namespaceDeclaration.Identifiers) {
 					usingScope = new UsingScope(usingScope, ident);
 				}
-				var currentContext = new CSharpTypeResolveContext(previousContext.CurrentAssembly, usingScope.Resolve(previousContext.Compilation));
+				var currentContext = new CSharpTypeResolveContext(previousContext.CurrentModule, usingScope.Resolve(previousContext.Compilation));
 				context.Push(currentContext);
 				try {
 					astBuilder = CreateAstBuilder(currentContext);
@@ -179,7 +179,7 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 			{
 				if (methodDeclaration.GetSymbol() is IMethod method && CSharpDecompiler.IsWindowsFormsInitializeComponentMethod(method)) {
 					var previousContext = context.Peek();
-					var currentContext = new CSharpTypeResolveContext(previousContext.CurrentAssembly);
+					var currentContext = new CSharpTypeResolveContext(previousContext.CurrentModule);
 					context.Push(currentContext);
 					try {
 						astBuilder = CreateAstBuilder(currentContext);

ICSharpCode.Decompiler/CSharp/Transforms/TransformContext.cs

@@ -51,10 +51,10 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 		}
 
 		/// <summary>
-		/// Returns the assembly that is being decompiled.
+		/// Returns the module that is being decompiled.
 		/// </summary>
-		public IAssembly DecompiledAssembly {
-			get { return decompilationContext.CurrentAssembly; }
+		public IModule DecompiledModule {
+			get { return decompilationContext.CurrentModule; }
 		}
 
 		/// <summary>

ICSharpCode.Decompiler/CSharp/TypeSystem/CSharpTypeResolveContext.cs

@@ -23,25 +23,25 @@ namespace ICSharpCode.Decompiler.CSharp.TypeSystem
 {
 	public sealed class CSharpTypeResolveContext : ITypeResolveContext
 	{
-		readonly IAssembly assembly;
+		readonly IModule module;
 		readonly ResolvedUsingScope currentUsingScope;
 		readonly ITypeDefinition currentTypeDefinition;
 		readonly IMember currentMember;
 		readonly string[] methodTypeParameterNames;
 		
-		public CSharpTypeResolveContext(IAssembly assembly, ResolvedUsingScope usingScope = null, ITypeDefinition typeDefinition = null, IMember member = null)
+		public CSharpTypeResolveContext(IModule module, ResolvedUsingScope usingScope = null, ITypeDefinition typeDefinition = null, IMember member = null)
 		{
-			if (assembly == null)
-				throw new ArgumentNullException("assembly");
-			this.assembly = assembly;
+			if (module == null)
+				throw new ArgumentNullException(nameof(module));
+			this.module = module;
 			this.currentUsingScope = usingScope;
 			this.currentTypeDefinition = typeDefinition;
 			this.currentMember = member;
 		}
 		
-		private CSharpTypeResolveContext(IAssembly assembly, ResolvedUsingScope usingScope, ITypeDefinition typeDefinition, IMember member, string[] methodTypeParameterNames)
+		private CSharpTypeResolveContext(IModule module, ResolvedUsingScope usingScope, ITypeDefinition typeDefinition, IMember member, string[] methodTypeParameterNames)
 		{
-			this.assembly = assembly;
+			this.module = module;
 			this.currentUsingScope = usingScope;
 			this.currentTypeDefinition = typeDefinition;
 			this.currentMember = member;
@@ -53,11 +53,11 @@ namespace ICSharpCode.Decompiler.CSharp.TypeSystem
 		}
 		
 		public ICompilation Compilation {
-			get { return assembly.Compilation; }
+			get { return module.Compilation; }
 		}
 		
-		public IAssembly CurrentAssembly {
-			get { return assembly; }
+		public IModule CurrentModule {
+			get { return module; }
 		}
 		
 		public ITypeDefinition CurrentTypeDefinition {
@@ -70,7 +70,7 @@ namespace ICSharpCode.Decompiler.CSharp.TypeSystem
 		
 		public CSharpTypeResolveContext WithCurrentTypeDefinition(ITypeDefinition typeDefinition)
 		{
-			return new CSharpTypeResolveContext(assembly, currentUsingScope, typeDefinition, currentMember, methodTypeParameterNames);
+			return new CSharpTypeResolveContext(module, currentUsingScope, typeDefinition, currentMember, methodTypeParameterNames);
 		}
 		
 		ITypeResolveContext ITypeResolveContext.WithCurrentTypeDefinition(ITypeDefinition typeDefinition)
@@ -80,7 +80,7 @@ namespace ICSharpCode.Decompiler.CSharp.TypeSystem
 		
 		public CSharpTypeResolveContext WithCurrentMember(IMember member)
 		{
-			return new CSharpTypeResolveContext(assembly, currentUsingScope, currentTypeDefinition, member, methodTypeParameterNames);
+			return new CSharpTypeResolveContext(module, currentUsingScope, currentTypeDefinition, member, methodTypeParameterNames);
 		}
 		
 		ITypeResolveContext ITypeResolveContext.WithCurrentMember(IMember member)
@@ -90,7 +90,7 @@ namespace ICSharpCode.Decompiler.CSharp.TypeSystem
 		
 		public CSharpTypeResolveContext WithUsingScope(ResolvedUsingScope usingScope)
 		{
-			return new CSharpTypeResolveContext(assembly, usingScope, currentTypeDefinition, currentMember, methodTypeParameterNames);
+			return new CSharpTypeResolveContext(module, usingScope, currentTypeDefinition, currentMember, methodTypeParameterNames);
 		}
 	}
 }

ICSharpCode.Decompiler/CSharp/TypeSystem/ResolvedUsingScope.cs

@@ -184,8 +184,8 @@ namespace ICSharpCode.Decompiler.CSharp.TypeSystem
 				get { return EmptyList<ITypeDefinition>.Instance; }
 			}
 			
-			IEnumerable<IAssembly> INamespace.ContributingAssemblies {
-				get { return EmptyList<IAssembly>.Instance; }
+			IEnumerable<IModule> INamespace.ContributingModules {
+				get { return EmptyList<IModule>.Instance; }
 			}
 			
 			ICompilation ICompilationProvider.Compilation {

ICSharpCode.Decompiler/CSharp/TypeSystem/TypeOrNamespaceReference.cs

@@ -56,7 +56,7 @@ namespace ICSharpCode.Decompiler.CSharp.TypeSystem
 			// nested compilation and not in this, we wouldn't be able to map it anyways.
 			var ctx = context as CSharpTypeResolveContext;
 			if (ctx == null) {
-				ctx = new CSharpTypeResolveContext(context.CurrentAssembly ?? context.Compilation.MainAssembly, null, context.CurrentTypeDefinition, context.CurrentMember);
+				ctx = new CSharpTypeResolveContext(context.CurrentModule ?? context.Compilation.MainModule, null, context.CurrentTypeDefinition, context.CurrentMember);
 			}
 			return ResolveType(new CSharpResolver(ctx));
 			

ICSharpCode.Decompiler/CSharp/TypeSystem/UsingScope.cs

@@ -154,7 +154,7 @@ namespace ICSharpCode.Decompiler.CSharp.TypeSystem
 			CacheManager cache = compilation.CacheManager;
 			ResolvedUsingScope resolved = cache.GetShared(this) as ResolvedUsingScope;
 			if (resolved == null) {
-				var csContext = new CSharpTypeResolveContext(compilation.MainAssembly, parent != null ? parent.Resolve(compilation) : null);
+				var csContext = new CSharpTypeResolveContext(compilation.MainModule, parent != null ? parent.Resolve(compilation) : null);
 				resolved = (ResolvedUsingScope)cache.GetOrAddShared(this, new ResolvedUsingScope(csContext, this));
 			}
 			return resolved;

ICSharpCode.Decompiler/DebugInfo/PortablePdbWriter.cs

@@ -126,13 +126,13 @@ namespace ICSharpCode.Decompiler.DebugInfo
 			if (scope == null)
 				return default;
 
-			Dictionary<IAssembly, AssemblyReferenceHandle> assemblyReferences = new Dictionary<IAssembly, AssemblyReferenceHandle>();
+			Dictionary<IModule, AssemblyReferenceHandle> assemblyReferences = new Dictionary<IModule, AssemblyReferenceHandle>();
 
 			var writer = new BlobBuilder();
 
 			foreach (var import in scope.Usings) {
-				foreach (var asm in import.ContributingAssemblies) {
-					if (asm == compilation.MainAssembly) {
+				foreach (var asm in import.ContributingModules) {
+					if (asm == compilation.MainModule) {
 						writer.WriteByte(1);
 						writer.WriteCompressedInteger(MetadataTokens.GetHeapOffset(metadata.GetOrAddBlobUTF8(import.FullName)));
 					} else {

ICSharpCode.Decompiler/Documentation/GetPotentiallyNestedClassTypeReference.cs

@@ -44,7 +44,7 @@ namespace ICSharpCode.Decompiler.Documentation
 		public IType Resolve(ITypeResolveContext context)
 		{
 			string[] parts = typeName.Split('.');
-			var assemblies = new [] { context.CurrentAssembly }.Concat(context.Compilation.Assemblies);
+			var assemblies = new [] { context.CurrentModule }.Concat(context.Compilation.Modules);
 			for (int i = parts.Length - 1; i >= 0; i--) {
 				string ns = string.Join(".", parts, 0, i);
 				string name = parts[i];

ICSharpCode.Decompiler/Documentation/IdStringProvider.cs

@@ -18,6 +18,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.Text;
 using ICSharpCode.Decompiler.TypeSystem;
 using ICSharpCode.Decompiler.TypeSystem.Implementation;
@@ -61,10 +62,10 @@ namespace ICSharpCode.Decompiler.Documentation
 				AppendTypeName(b, member.DeclaringType, false);
 				b.Append('.');
 			}
-			/*if (member.IsExplicitInterfaceImplementation && member.Name.IndexOf('.') < 0 && member.ImplementedInterfaceMembers.Count == 1) {
-				AppendTypeName(b, member.ImplementedInterfaceMembers[0].DeclaringType, true);
+			if (member.IsExplicitInterfaceImplementation && member.Name.IndexOf('.') < 0 && member.ExplicitlyImplementedInterfaceMembers.Count() == 1) {
+				AppendTypeName(b, member.ExplicitlyImplementedInterfaceMembers.First().DeclaringType, true);
 				b.Append('#');
-			}*/
+			}
 			b.Append(member.Name.Replace('.', '#'));
 			IMethod method = member as IMethod;
 			if (method != null && method.TypeParameters.Count > 0) {
@@ -186,7 +187,7 @@ namespace ICSharpCode.Decompiler.Documentation
 		/// <returns>A member reference that represents the ID string.</returns>
 		/// <exception cref="ReflectionNameParseException">The syntax of the ID string is invalid</exception>
 		/// <remarks>
-		/// The member reference will look in <see cref="ITypeResolveContext.CurrentAssembly"/> first,
+		/// The member reference will look in <see cref="ITypeResolveContext.CurrentModule"/> first,
 		/// and if the member is not found there,
 		/// it will look in all other assemblies of the compilation.
 		/// </remarks>
@@ -228,7 +229,7 @@ namespace ICSharpCode.Decompiler.Documentation
 		/// <exception cref="ReflectionNameParseException">The syntax of the ID string is invalid</exception>
 		/// <remarks>
 		/// <para>
-		/// The type reference will look in <see cref="ITypeResolveContext.CurrentAssembly"/> first,
+		/// The type reference will look in <see cref="ITypeResolveContext.CurrentModule"/> first,
 		/// and if the type is not found there,
 		/// it will look in all other assemblies of the compilation.
 		/// </para>

ICSharpCode.Decompiler/Documentation/XmlDocKeyProvider.cs

@@ -186,7 +186,7 @@ namespace ICSharpCode.Decompiler.Documentation
 		/// <returns>A member reference that represents the ID string.</returns>
 		/// <exception cref="ReflectionNameParseException">The syntax of the ID string is invalid</exception>
 		/// <remarks>
-		/// The member reference will look in <see cref="ITypeResolveContext.CurrentAssembly"/> first,
+		/// The member reference will look in <see cref="ITypeResolveContext.CurrentModule"/> first,
 		/// and if the member is not found there,
 		/// it will look in all other assemblies of the compilation.
 		/// </remarks>
@@ -228,7 +228,7 @@ namespace ICSharpCode.Decompiler.Documentation
 		/// <exception cref="ReflectionNameParseException">The syntax of the ID string is invalid</exception>
 		/// <remarks>
 		/// <para>
-		/// The type reference will look in <see cref="ITypeResolveContext.CurrentAssembly"/> first,
+		/// The type reference will look in <see cref="ITypeResolveContext.CurrentModule"/> first,
 		/// and if the type is not found there,
 		/// it will look in all other assemblies of the compilation.
 		/// </para>

ICSharpCode.Decompiler/ICSharpCode.Decompiler.csproj

@@ -360,9 +360,9 @@
     <Compile Include="TypeSystem\Implementation\MetadataTypeDefinition.cs" />
     <Compile Include="TypeSystem\Implementation\MetadataTypeParameter.cs" />
     <Compile Include="TypeSystem\Implementation\SpecializedParameter.cs" />
-    <Compile Include="TypeSystem\MetadataAssembly.cs" />
+    <Compile Include="TypeSystem\MetadataModule.cs" />
     <Compile Include="TypeSystem\ModifiedType.cs" />
-    <Compile Include="TypeSystem\Implementation\TypeSpecification.cs" />
+    <Compile Include="TypeSystem\Implementation\PinnedType.cs" />
     <Compile Include="Metadata\MetadataExtensions.cs" />
     <Compile Include="Semantics\TupleResolveResult.cs" />
     <Compile Include="TypeSystem\NormalizeTypeVisitor.cs" />

ICSharpCode.Decompiler/IL/Transforms/NullPropagationTransform.cs

@@ -260,7 +260,7 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 			{
 				return CSharp.Transforms.IntroduceExtensionMethods.CanTransformToExtensionMethodCall(
 					call.Method, new CSharp.TypeSystem.CSharpTypeResolveContext(
-						context.TypeSystem.Compilation.MainAssembly, context.UsingScope
+						context.TypeSystem.Compilation.MainModule, context.UsingScope
 					)
 				);
 			}

ICSharpCode.Decompiler/IL/Transforms/TransformCollectionAndObjectInitializers.cs

@@ -178,7 +178,7 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 				possibleIndexVariables.Add(stloc.Variable, (stloc.ChildIndex, stloc.Value));
 				return true;
 			}
-			var resolveContext = new CSharpTypeResolveContext(context.TypeSystem.Compilation.MainAssembly, context.UsingScope);
+			var resolveContext = new CSharpTypeResolveContext(context.TypeSystem.Compilation.MainModule, context.UsingScope);
 			(var kind, var newPath, var values, var targetVariable) = AccessPathElement.GetAccessPath(instructions[pos], rootType, context.Settings, resolveContext, possibleIndexVariables);
 			if (kind == AccessPathKind.Invalid || target != targetVariable)
 				return false;

ICSharpCode.Decompiler/Metadata/MetadataExtensions.cs

@@ -89,12 +89,12 @@ namespace ICSharpCode.Decompiler.Metadata
 			return Disassembler.DisassemblerHelpers.Escape(name);
 		}
 
-		public static TypeSystem.IAssemblyReference GetDeclaringAssembly(this TypeReferenceHandle handle, MetadataReader reader)
+		public static IModuleReference GetDeclaringModule(this TypeReferenceHandle handle, MetadataReader reader)
 		{
 			var tr = reader.GetTypeReference(handle);
 			switch (tr.ResolutionScope.Kind) {
 				case HandleKind.TypeReference:
-					return ((TypeReferenceHandle)tr.ResolutionScope).GetDeclaringAssembly(reader);
+					return ((TypeReferenceHandle)tr.ResolutionScope).GetDeclaringModule(reader);
 				case HandleKind.AssemblyReference:
 					var asmRef = reader.GetAssemblyReference((AssemblyReferenceHandle)tr.ResolutionScope);
 					return new DefaultAssemblyReference(reader.GetString(asmRef.Name));

ICSharpCode.Decompiler/Metadata/PEFile.cs

@@ -28,7 +28,20 @@ using ICSharpCode.Decompiler.Util;
 
 namespace ICSharpCode.Decompiler.Metadata
 {
-	public class PEFile : IDisposable, TypeSystem.IAssemblyReference
+	/// <summary>
+	/// PEFile is the main class the decompiler uses to represent a metadata assembly/module.
+	/// Every file on disk can be loaded into a standalone PEFile instance.
+	/// 
+	/// A PEFile can be combined with its referenced assemblies/modules to form a type system,
+	/// in that case the <see cref="MetadataModule"/> class is used instead.
+	/// </summary>
+	/// <remarks>
+	/// In addition to wrapping a <c>System.Reflection.Metadata.PEReader</c>, this class
+	/// contains a few decompiled-specific caches to allow efficiently constructing a type
+	/// system from multiple PEFiles. This allows the caches to be shared across multiple
+	/// decompiled type systems.
+	/// </remarks>
+	public class PEFile : IDisposable, TypeSystem.IModuleReference
 	{
 		public string FileName { get; }
 		public PEReader Reader { get; }
@@ -157,17 +170,17 @@ namespace ICSharpCode.Decompiler.Metadata
 			}
 		}
 
-		public TypeSystem.IAssemblyReference WithOptions(TypeSystemOptions options)
+		public TypeSystem.IModuleReference WithOptions(TypeSystemOptions options)
 		{
 			return new PEFileWithOptions(this, options);
 		}
 
-		IAssembly TypeSystem.IAssemblyReference.Resolve(ITypeResolveContext context)
+		IModule TypeSystem.IModuleReference.Resolve(ITypeResolveContext context)
 		{
-			return new MetadataAssembly(context.Compilation, this, TypeSystemOptions.Default);
+			return new MetadataModule(context.Compilation, this, TypeSystemOptions.Default);
 		}
 
-		private class PEFileWithOptions : TypeSystem.IAssemblyReference
+		private class PEFileWithOptions : TypeSystem.IModuleReference
 		{
 			readonly PEFile peFile;
 			readonly TypeSystemOptions options;
@@ -178,9 +191,9 @@ namespace ICSharpCode.Decompiler.Metadata
 				this.options = options;
 			}
 
-			IAssembly TypeSystem.IAssemblyReference.Resolve(ITypeResolveContext context)
+			IModule TypeSystem.IModuleReference.Resolve(ITypeResolveContext context)
 			{
-				return new MetadataAssembly(context.Compilation, peFile, options);
+				return new MetadataModule(context.Compilation, peFile, options);
 			}
 		}
 	}

ICSharpCode.Decompiler/SRMExtensions.cs

@@ -403,7 +403,7 @@ namespace ICSharpCode.Decompiler
 				var typeDef = typeSystem.ResolveAsType(handle).GetDefinition();
 				if (typeDef == null || typeDef.MetadataToken.IsNil)
 					return 0;
-				reader = typeDef.ParentAssembly.PEFile.Metadata;
+				reader = typeDef.ParentModule.PEFile.Metadata;
 				var td = reader.GetTypeDefinition((TypeDefinitionHandle)typeDef.MetadataToken);
 				return td.GetLayout().Size;
 			}
@@ -413,7 +413,7 @@ namespace ICSharpCode.Decompiler
 				var typeDef = typeSystem.ResolveAsType(handle).GetDefinition();
 				if (typeDef == null || typeDef.MetadataToken.IsNil)
 					return 0;
-				reader = typeDef.ParentAssembly.PEFile.Metadata;
+				reader = typeDef.ParentModule.PEFile.Metadata;
 				var td = reader.GetTypeDefinition((TypeDefinitionHandle)typeDef.MetadataToken);
 				return td.GetLayout().Size;
 			}

ICSharpCode.Decompiler/TypeSystem/ApplyAttributeTypeVisitor.cs

@@ -126,7 +126,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		{
 			if (useTupleTypes && TupleType.IsTupleCompatible(type, out int tupleCardinality)) {
 				if (tupleCardinality > 1) {
-					var valueTupleAssembly = type.GetDefinition()?.ParentAssembly;
+					var valueTupleAssembly = type.GetDefinition()?.ParentModule;
 					ImmutableArray<string> elementNames = default;
 					if (tupleElementNames != null && tupleTypeIndex < tupleElementNames.Length) {
 						string[] extractedValues = new string[tupleCardinality];

ICSharpCode.Decompiler/TypeSystem/AssemblyQualifiedTypeName.cs

@@ -33,7 +33,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		
 		public AssemblyQualifiedTypeName(ITypeDefinition typeDefinition)
 		{
-			this.AssemblyName = typeDefinition.ParentAssembly.AssemblyName;
+			this.AssemblyName = typeDefinition.ParentModule.AssemblyName;
 			this.TypeName = typeDefinition.FullTypeName;
 		}
 		

ICSharpCode.Decompiler/TypeSystem/DecompilerTypeSystem.cs

@@ -80,7 +80,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		readonly ICompilation compilation;
 		readonly IAssemblyResolver assemblyResolver;
 		readonly TypeSystemOptions typeSystemOptions;
-		readonly MetadataAssembly mainAssembly;
+		readonly MetadataModule mainModule;
 
 		public DecompilerTypeSystem(Metadata.PEFile moduleDefinition, IAssemblyResolver assemblyResolver)
 			: this(moduleDefinition, assemblyResolver, new DecompilerSettings())
@@ -103,7 +103,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 			var mainAssembly = moduleDefinition.WithOptions(typeSystemOptions);
 			// Load referenced assemblies and type-forwarder references.
 			// This is necessary to make .NET Core/PCL binaries work better.
-			var referencedAssemblies = new List<IAssemblyReference>();
+			var referencedAssemblies = new List<IModuleReference>();
 			var assemblyReferenceQueue = new Queue<(bool IsAssembly, PEFile MainModule, object Reference)>();
 			var mainMetadata = moduleDefinition.Metadata;
 			foreach (var h in mainMetadata.GetModuleReferences()) {
@@ -158,15 +158,15 @@ namespace ICSharpCode.Decompiler.TypeSystem
 				referencedAssemblies.Add(MinimalCorlib.Instance);
 				compilation = new SimpleCompilation(mainAssembly, referencedAssemblies);
 			}
-			this.mainAssembly = (MetadataAssembly)compilation.MainAssembly;
+			this.mainModule = (MetadataModule)compilation.MainModule;
 		}
 
 		public ICompilation Compilation {
 			get { return compilation; }
 		}
 		
-		public MetadataAssembly MainAssembly {
-			get { return mainAssembly; }
+		public MetadataModule MainModule {
+			get { return mainModule; }
 		}
 
 		public Metadata.PEFile ModuleDefinition {
@@ -174,14 +174,6 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		}
 
 		public SRM.MetadataReader GetMetadata() => moduleDefinition.Metadata;
-
-		public Metadata.PEFile GetModuleDefinition(IAssembly assembly)
-		{
-			if (assembly is MetadataAssembly asm) {
-				return asm.PEFile;
-			}
-			return null;
-		}
 		
 		public IMember ResolveAsMember(SRM.EntityHandle memberReference)
 		{
@@ -212,27 +204,27 @@ namespace ICSharpCode.Decompiler.TypeSystem
 
 		public IType ResolveAsType(SRM.EntityHandle typeReference)
 		{
-			return mainAssembly.ResolveType(typeReference, new GenericContext());
+			return mainModule.ResolveType(typeReference, new GenericContext());
 		}
 
 		public IMethod ResolveAsMethod(SRM.EntityHandle methodReference)
 		{
-			return mainAssembly.ResolveMethod(methodReference);
+			return mainModule.ResolveMethod(methodReference);
 		}
 
 		public IField ResolveAsField(SRM.EntityHandle fieldReference)
 		{
-			return mainAssembly.ResolveEntity(fieldReference, new GenericContext()) as IField;
+			return mainModule.ResolveEntity(fieldReference, new GenericContext()) as IField;
 		}
 
 		public IProperty ResolveAsProperty(SRM.EntityHandle propertyReference)
 		{
-			return mainAssembly.ResolveEntity(propertyReference, new GenericContext()) as IProperty;
+			return mainModule.ResolveEntity(propertyReference, new GenericContext()) as IProperty;
 		}
 
 		public IEvent ResolveAsEvent(SRM.EntityHandle eventReference)
 		{
-			return mainAssembly.ResolveEntity(eventReference, new GenericContext()) as IEvent;
+			return mainModule.ResolveEntity(eventReference, new GenericContext()) as IEvent;
 		}
 
 		public SRM.MethodSignature<IType> DecodeMethodSignature(SRM.StandaloneSignatureHandle handle)
@@ -241,7 +233,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 			if (standaloneSignature.GetKind() != SRM.StandaloneSignatureKind.Method)
 				throw new InvalidOperationException("Expected Method signature");
 			var sig = standaloneSignature.DecodeMethodSignature(
-				mainAssembly.TypeProvider,
+				mainModule.TypeProvider,
 				new GenericContext()
 			);
 			return new SRM.MethodSignature<IType>(
@@ -261,7 +253,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 			if (standaloneSignature.GetKind() != SRM.StandaloneSignatureKind.LocalVariables)
 				throw new InvalidOperationException("Expected Local signature");
 			var types = standaloneSignature.DecodeLocalSignature(
-				mainAssembly.TypeProvider,
+				mainModule.TypeProvider,
 				new GenericContext()
 			);
 			return ImmutableArray.CreateRange(types, ApplyAttributesToType);

ICSharpCode.Decompiler/TypeSystem/IAssembly.cs

@@ -17,23 +17,35 @@
 // DEALINGS IN THE SOFTWARE.
 
 using System.Collections.Generic;
-using System.Reflection.Metadata;
 using ICSharpCode.Decompiler.Metadata;
 
 namespace ICSharpCode.Decompiler.TypeSystem
 {
-	public interface IAssemblyReference
+	/// <summary>
+	/// Interface used to help with construction of the type system.
+	/// </summary>
+	/// <remarks>
+	/// The type system is an immutable cyclic data structure:
+	/// the compilation (ICompilation) has references to all modules,
+	/// and each module has a reference back to the compilation.
+	/// 
+	/// Module references are used to solve this cyclic dependency:
+	/// The compilation constructor accepts module references,
+	/// and only the IModuleReference.Resolve() function can observe a
+	/// partially-constructed compilation; but not any user code.
+	/// </remarks>
+	public interface IModuleReference
 	{
 		/// <summary>
-		/// Resolves this assembly.
+		/// Resolves this metadata module.
 		/// </summary>
-		IAssembly Resolve(ITypeResolveContext context);
+		IModule Resolve(ITypeResolveContext context);
 	}
 	
 	/// <summary>
-	/// Represents an assembly.
+	/// Represents a metadata module.
 	/// </summary>
-	public interface IAssembly : ICompilationProvider
+	public interface IModule : ICompilationProvider
 	{
 		/// <summary>
 		/// Gets the underlying metadata file. May return null, if the IAssembly was not created from a PE file.
@@ -43,7 +55,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		/// <summary>
 		/// Gets whether this assembly is the main assembly of the compilation.
 		/// </summary>
-		bool IsMainAssembly { get; }
+		bool IsMainModule { get; }
 		
 		/// <summary>
 		/// Gets the assembly name (short name).
@@ -68,13 +80,15 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		/// <summary>
 		/// Gets whether the internals of this assembly are visible in the specified assembly.
 		/// </summary>
-		bool InternalsVisibleTo(IAssembly assembly);
+		bool InternalsVisibleTo(IModule module);
 		
 		/// <summary>
-		/// Gets the root namespace for this assembly.
+		/// Gets the root namespace for this module.
 		/// </summary>
 		/// <remarks>
 		/// This always is the namespace without a name - it's unrelated to the 'root namespace' project setting.
+		/// It contains only subnamespaces and types defined in this module -- use ICompilation.RootNamespace
+		/// to get the combined view of all referenced assemblies.
 		/// </remarks>
 		INamespace RootNamespace { get; }
 		

ICSharpCode.Decompiler/TypeSystem/ICompilation.cs

@@ -25,28 +25,30 @@ namespace ICSharpCode.Decompiler.TypeSystem
 	public interface ICompilation
 	{
 		/// <summary>
-		/// Gets the current assembly.
+		/// Gets the primary module.
+		/// This is the module being (de)compiled; all other modules in the compilation are the other assemblies/modules
+		/// referenced by the main module.
 		/// </summary>
-		IAssembly MainAssembly { get; }
+		IModule MainModule { get; }
 		
 		/// <summary>
 		/// Gets the type resolve context that specifies this compilation and no current assembly or entity.
 		/// </summary>
 		ITypeResolveContext TypeResolveContext { get; }
-		
+
 		/// <summary>
-		/// Gets the list of all assemblies in the compilation.
+		/// Gets the list of all modules in the compilation.
 		/// </summary>
 		/// <remarks>
-		/// This main assembly is the first entry in the list.
+		/// This main module is the first entry in the list.
 		/// </remarks>
-		IList<IAssembly> Assemblies { get; }
+		IList<IModule> Modules { get; }
 		
 		/// <summary>
-		/// Gets the referenced assemblies.
-		/// This list does not include the main assembly.
+		/// Gets the referenced modules.
+		/// This list does not include the main module.
 		/// </summary>
-		IList<IAssembly> ReferencedAssemblies { get; }
+		IList<IModule> ReferencedModules { get; }
 		
 		/// <summary>
 		/// Gets the root namespace of this compilation.

ICSharpCode.Decompiler/TypeSystem/IDecompilerTypeSystem.cs

@@ -28,6 +28,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 	public interface IDecompilerTypeSystem
 	{
 		ICompilation Compilation { get; }
+		MetadataModule MainModule { get; }
 
 		MethodSignature<IType> DecodeMethodSignature(StandaloneSignatureHandle standaloneSignatureHandle);
 		ImmutableArray<IType> DecodeLocalSignature(StandaloneSignatureHandle standaloneSignatureHandle);
@@ -39,7 +40,6 @@ namespace ICSharpCode.Decompiler.TypeSystem
 
 		MetadataReader GetMetadata();
 		PEFile ModuleDefinition { get; }
-		PEFile GetModuleDefinition(IAssembly assembly);
 
 		/// <summary>
 		/// Gets a type system instance that automatically specializes the results

ICSharpCode.Decompiler/TypeSystem/IEntity.cs

@@ -56,10 +56,9 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		IType DeclaringType { get; }
 		
 		/// <summary>
-		/// The assembly in which this entity is defined.
-		/// This property never returns null.
+		/// The module in which this entity is defined.
 		/// </summary>
-		IAssembly ParentAssembly { get; }
+		IModule ParentModule { get; }
 
 		/// <summary>
 		/// Gets the attributes on this entity.

ICSharpCode.Decompiler/TypeSystem/INamespace.cs

@@ -62,9 +62,9 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		IEnumerable<ITypeDefinition> Types { get; }
 		
 		/// <summary>
-		/// Gets the assemblies that contribute types to this namespace (or to child namespaces).
+		/// Gets the modules that contribute types to this namespace (or to child namespaces).
 		/// </summary>
-		IEnumerable<IAssembly> ContributingAssemblies { get; }
+		IEnumerable<IModule> ContributingModules { get; }
 		
 		/// <summary>
 		/// Gets a direct child namespace by its short name.

ICSharpCode.Decompiler/TypeSystem/ITypeReference.cs

@@ -50,10 +50,10 @@ namespace ICSharpCode.Decompiler.TypeSystem
 	public interface ITypeResolveContext : ICompilationProvider
 	{
 		/// <summary>
-		/// Gets the current assembly.
-		/// This property may return null if this context does not specify any assembly.
+		/// Gets the current module.
+		/// This property may return null if this context does not specify any module.
 		/// </summary>
-		IAssembly CurrentAssembly { get; }
+		IModule CurrentModule { get; }
 		
 		/// <summary>
 		/// Gets the current type definition.

ICSharpCode.Decompiler/TypeSystem/Implementation/AttributeListBuilder.cs

@@ -32,20 +32,20 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 {
 	readonly struct AttributeListBuilder
 	{
-		readonly MetadataAssembly assembly;
+		readonly MetadataModule module;
 		readonly List<IAttribute> attributes;
 
-		public AttributeListBuilder(MetadataAssembly assembly)
+		public AttributeListBuilder(MetadataModule module)
 		{
-			Debug.Assert(assembly != null);
-			this.assembly = assembly;
+			Debug.Assert(module != null);
+			this.module = module;
 			this.attributes = new List<IAttribute>();
 		}
 
-		public AttributeListBuilder(MetadataAssembly assembly, int capacity)
+		public AttributeListBuilder(MetadataModule module, int capacity)
 		{
-			Debug.Assert(assembly != null);
-			this.assembly = assembly;
+			Debug.Assert(module != null);
+			this.module = module;
 			this.attributes = new List<IAttribute>(capacity);
 		}
 
@@ -60,7 +60,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		public void Add(KnownAttribute type)
 		{
 			// use the assemblies' cache for simple attributes
-			Add(assembly.MakeAttribute(type));
+			Add(module.MakeAttribute(type));
 		}
 
 		/// <summary>
@@ -68,7 +68,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		/// </summary>
 		public void Add(KnownAttribute type, KnownTypeCode argType, object argValue)
 		{
-			Add(type, ImmutableArray.Create(new CustomAttributeTypedArgument<IType>(assembly.Compilation.FindType(argType), argValue)));
+			Add(type, ImmutableArray.Create(new CustomAttributeTypedArgument<IType>(module.Compilation.FindType(argType), argValue)));
 		}
 
 		/// <summary>
@@ -76,7 +76,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		/// </summary>
 		public void Add(KnownAttribute type, TopLevelTypeName argType, object argValue)
 		{
-			Add(type, ImmutableArray.Create(new CustomAttributeTypedArgument<IType>(assembly.Compilation.FindType(argType), argValue)));
+			Add(type, ImmutableArray.Create(new CustomAttributeTypedArgument<IType>(module.Compilation.FindType(argType), argValue)));
 		}
 
 		/// <summary>
@@ -84,7 +84,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		/// </summary>
 		public void Add(KnownAttribute type, ImmutableArray<CustomAttributeTypedArgument<IType>> fixedArguments)
 		{
-			Add(new DefaultAttribute(assembly.GetAttributeType(type), fixedArguments,
+			Add(new DefaultAttribute(module.GetAttributeType(type), fixedArguments,
 				ImmutableArray.Create<CustomAttributeNamedArgument<IType>>()));
 		}
 		
@@ -92,7 +92,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		internal void AddMarshalInfo(BlobHandle marshalInfo)
 		{
 			if (marshalInfo.IsNil) return;
-			var metadata = assembly.metadata;
+			var metadata = module.metadata;
 			Add(ConvertMarshalInfo(metadata.GetBlobReader(marshalInfo)));
 		}
 
@@ -100,8 +100,8 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 
 		IAttribute ConvertMarshalInfo(SRM.BlobReader marshalInfo)
 		{
-			var b = new AttributeBuilder(assembly, KnownAttribute.MarshalAs);
-			IType unmanagedTypeType = assembly.Compilation.FindType(new TopLevelTypeName(InteropServices, nameof(UnmanagedType)));
+			var b = new AttributeBuilder(module, KnownAttribute.MarshalAs);
+			IType unmanagedTypeType = module.Compilation.FindType(new TopLevelTypeName(InteropServices, nameof(UnmanagedType)));
 
 			int type = marshalInfo.ReadByte();
 			b.AddFixedArg(unmanagedTypeType, type);
@@ -170,15 +170,15 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		#region Custom Attributes (ReadAttribute)
 		public void Add(CustomAttributeHandleCollection attributes)
 		{
-			var metadata = assembly.metadata;
+			var metadata = module.metadata;
 			foreach (var handle in attributes) {
 				var attribute = metadata.GetCustomAttribute(handle);
-				var ctor = assembly.ResolveMethod(attribute.Constructor);
+				var ctor = module.ResolveMethod(attribute.Constructor);
 				var type = ctor.DeclaringType;
 				if (IgnoreAttribute(type)) {
 					continue;
 				}
-				Add(new CustomAttribute(assembly, ctor, handle));
+				Add(new CustomAttribute(module, ctor, handle));
 			}
 		}
 
@@ -188,7 +188,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 				return false;
 			switch (attributeType.Namespace) {
 				case "System.Runtime.CompilerServices":
-					var options = assembly.TypeSystemOptions;
+					var options = module.TypeSystemOptions;
 					switch (attributeType.Name) {
 						case "DynamicAttribute":
 							return (options & TypeSystemOptions.Dynamic) != 0;
@@ -212,7 +212,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		#region Security Attributes
 		public void AddSecurityAttributes(DeclarativeSecurityAttributeHandleCollection securityDeclarations)
 		{
-			var metadata = assembly.metadata;
+			var metadata = module.metadata;
 			foreach (var secDecl in securityDeclarations) {
 				if (secDecl.IsNil)
 					continue;
@@ -222,9 +222,9 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 
 		public void AddSecurityAttributes(DeclarativeSecurityAttribute secDecl)
 		{
-			var securityActionType = assembly.Compilation.FindType(new TopLevelTypeName("System.Security.Permissions", "SecurityAction"));
+			var securityActionType = module.Compilation.FindType(new TopLevelTypeName("System.Security.Permissions", "SecurityAction"));
 			var securityAction = new CustomAttributeTypedArgument<IType>(securityActionType, (int)secDecl.Action);
-			var metadata = assembly.metadata;
+			var metadata = module.metadata;
 			var reader = metadata.GetBlobReader(secDecl.PermissionSet);
 			if (reader.ReadByte() == '.') {
 				// binary attribute
@@ -242,7 +242,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		private void ReadXmlSecurityAttribute(ref SRM.BlobReader reader, CustomAttributeTypedArgument<IType> securityAction)
 		{
 			string xml = reader.ReadUTF16(reader.RemainingBytes);
-			var b = new AttributeBuilder(assembly, KnownAttribute.PermissionSet);
+			var b = new AttributeBuilder(module, KnownAttribute.PermissionSet);
 			b.AddFixedArg(securityAction);
 			b.AddNamedArg("XML", KnownTypeCode.String, xml);
 		}
@@ -250,13 +250,13 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		private IAttribute ReadBinarySecurityAttribute(ref SRM.BlobReader reader, CustomAttributeTypedArgument<IType> securityAction)
 		{
 			string attributeTypeName = reader.ReadSerializedString();
-			IType attributeType = assembly.TypeProvider.GetTypeFromSerializedName(attributeTypeName);
+			IType attributeType = module.TypeProvider.GetTypeFromSerializedName(attributeTypeName);
 
 			reader.ReadCompressedInteger(); // ??
 											// The specification seems to be incorrect here, so I'm using the logic from Cecil instead.
 			int numNamed = reader.ReadCompressedInteger();
 
-			var decoder = new Metadata.CustomAttributeDecoder<IType>(assembly.TypeProvider, assembly.metadata);
+			var decoder = new Metadata.CustomAttributeDecoder<IType>(module.TypeProvider, module.metadata);
 			var namedArgs = decoder.DecodeNamedArguments(ref reader, numNamed);
 
 			return new DefaultAttribute(
@@ -282,14 +282,14 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		ImmutableArray<CustomAttributeTypedArgument<IType>>.Builder fixedArgs;
 		ImmutableArray<CustomAttributeNamedArgument<IType>>.Builder namedArgs;
 
-		public AttributeBuilder(MetadataAssembly assembly, KnownAttribute attributeType)
-			: this(assembly, assembly.GetAttributeType(attributeType))
+		public AttributeBuilder(MetadataModule module, KnownAttribute attributeType)
+			: this(module, module.GetAttributeType(attributeType))
 		{
 		}
 
-		public AttributeBuilder(MetadataAssembly assembly, IType attributeType)
+		public AttributeBuilder(MetadataModule module, IType attributeType)
 		{
-			this.compilation = assembly.Compilation;
+			this.compilation = module.Compilation;
 			this.attributeType = attributeType;
 			this.fixedArgs = ImmutableArray.CreateBuilder<CustomAttributeTypedArgument<IType>>();
 			this.namedArgs = ImmutableArray.CreateBuilder<CustomAttributeNamedArgument<IType>>();

ICSharpCode.Decompiler/TypeSystem/Implementation/CustomAttribute.cs

@@ -34,7 +34,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 	/// </summary>
 	sealed class CustomAttribute : IAttribute
 	{
-		readonly MetadataAssembly assembly;
+		readonly MetadataModule module;
 		readonly SRM.CustomAttributeHandle handle;
 		public IMethod Constructor { get; }
 
@@ -42,12 +42,12 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		SRM.CustomAttributeValue<IType> value;
 		bool valueDecoded;
 
-		internal CustomAttribute(MetadataAssembly assembly, IMethod attrCtor, SRM.CustomAttributeHandle handle)
+		internal CustomAttribute(MetadataModule module, IMethod attrCtor, SRM.CustomAttributeHandle handle)
 		{
-			Debug.Assert(assembly != null);
+			Debug.Assert(module != null);
 			Debug.Assert(attrCtor != null);
 			Debug.Assert(!handle.IsNil);
-			this.assembly = assembly;
+			this.module = module;
 			this.Constructor = attrCtor;
 			this.handle = handle;
 		}
@@ -72,9 +72,9 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		{
 			lock (this) {
 				if (!valueDecoded) {
-					var metadata = assembly.metadata;
+					var metadata = module.metadata;
 					var attr = metadata.GetCustomAttribute(handle);
-					value = attr.DecodeValue(assembly.TypeProvider);
+					value = attr.DecodeValue(module.TypeProvider);
 					valueDecoded = true;
 				}
 			}

ICSharpCode.Decompiler/TypeSystem/Implementation/DefaultAssemblyReference.cs

@@ -24,9 +24,9 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 	/// References an existing assembly by name.
 	/// </summary>
 	[Serializable]
-	public sealed class DefaultAssemblyReference : IAssemblyReference, ISupportsInterning
+	public sealed class DefaultAssemblyReference : IModuleReference, ISupportsInterning
 	{
-		public static readonly IAssemblyReference CurrentAssembly = new CurrentAssemblyReference();
+		public static readonly IModuleReference CurrentAssembly = new CurrentModuleReference();
 		
 		readonly string shortName;
 		
@@ -39,12 +39,12 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 				shortName = assemblyName;
 		}
 		
-		public IAssembly Resolve(ITypeResolveContext context)
+		public IModule Resolve(ITypeResolveContext context)
 		{
-			IAssembly current = context.CurrentAssembly;
+			IModule current = context.CurrentModule;
 			if (current != null && string.Equals(shortName, current.AssemblyName, StringComparison.OrdinalIgnoreCase))
 				return current;
-			foreach (IAssembly asm in context.Compilation.Assemblies) {
+			foreach (IModule asm in context.Compilation.Modules) {
 				if (string.Equals(shortName, asm.AssemblyName, StringComparison.OrdinalIgnoreCase))
 					return asm;
 			}
@@ -70,11 +70,11 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		}
 		
 		[Serializable]
-		sealed class CurrentAssemblyReference : IAssemblyReference
+		sealed class CurrentModuleReference : IModuleReference
 		{
-			public IAssembly Resolve(ITypeResolveContext context)
+			public IModule Resolve(ITypeResolveContext context)
 			{
-				IAssembly asm = context.CurrentAssembly;
+				IModule asm = context.CurrentModule;
 				if (asm == null)
 					throw new ArgumentException("A reference to the current assembly cannot be resolved in the compilation's global type resolve context.");
 				return asm;

ICSharpCode.Decompiler/TypeSystem/Implementation/FakeMember.cs

@@ -56,7 +56,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 
 		public IType DeclaringType { get; set; }
 
-		IAssembly IEntity.ParentAssembly => DeclaringType?.GetDefinition()?.ParentAssembly;
+		IModule IEntity.ParentModule => DeclaringType?.GetDefinition()?.ParentModule;
 
 		IEnumerable<IAttribute> IEntity.GetAttributes() => EmptyList<IAttribute>.Instance;
 

ICSharpCode.Decompiler/TypeSystem/Implementation/GetClassTypeReference.cs

@@ -26,7 +26,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 	[Serializable]
 	public sealed class GetClassTypeReference : ITypeReference, ISupportsInterning
 	{
-		readonly IAssemblyReference assembly;
+		readonly IModuleReference module;
 		readonly FullTypeName fullTypeName;
 		readonly bool? isReferenceType;
 
@@ -34,14 +34,14 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		/// Creates a new GetClassTypeReference that searches a type definition.
 		/// </summary>
 		/// <param name="fullTypeName">The full name of the type.</param>
-		/// <param name="assembly">A reference to the assembly containing this type.
+		/// <param name="module">A reference to the module containing this type.
 		/// If this parameter is null, the GetClassTypeReference will search in all
 		/// assemblies belonging to the compilation.
 		/// </param>
-		public GetClassTypeReference(FullTypeName fullTypeName, IAssemblyReference assembly = null, bool? isReferenceType = null)
+		public GetClassTypeReference(FullTypeName fullTypeName, IModuleReference module = null, bool? isReferenceType = null)
 		{
 			this.fullTypeName = fullTypeName;
-			this.assembly = assembly;
+			this.module = module;
 			this.isReferenceType = isReferenceType;
 		}
 		
@@ -60,14 +60,14 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		/// <summary>
 		/// Creates a new GetClassTypeReference that searches a top-level type in the specified assembly.
 		/// </summary>
-		/// <param name="assembly">A reference to the assembly containing this type.
+		/// <param name="module">A reference to the assembly containing this type.
 		/// If this parameter is null, the GetClassTypeReference will search in all assemblies belonging to the ICompilation.</param>
 		/// <param name="namespaceName">The namespace name containing the type, e.g. "System.Collections.Generic".</param>
 		/// <param name="name">The name of the type, e.g. "List".</param>
 		/// <param name="typeParameterCount">The number of type parameters, (e.g. 1 for List&lt;T&gt;).</param>
-		public GetClassTypeReference(IAssemblyReference assembly, string namespaceName, string name, int typeParameterCount = 0, bool? isReferenceType = null)
+		public GetClassTypeReference(IModuleReference module, string namespaceName, string name, int typeParameterCount = 0, bool? isReferenceType = null)
 		{
-			this.assembly = assembly;
+			this.module = module;
 			this.fullTypeName = new TopLevelTypeName(namespaceName, name, typeParameterCount);
 			this.isReferenceType = isReferenceType;
 		}
@@ -77,7 +77,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		/// This property returns null if the GetClassTypeReference is searching in all assemblies
 		/// of the compilation.
 		/// </summary>
-		public IAssemblyReference Assembly { get { return assembly; } }
+		public IModuleReference Module { get { return module; } }
 		
 		/// <summary>
 		/// Gets the full name of the type this reference is searching for.
@@ -87,7 +87,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		IType ResolveInAllAssemblies(ITypeResolveContext context)
 		{
 			var compilation = context.Compilation;
-			foreach (var asm in compilation.Assemblies) {
+			foreach (var asm in compilation.Modules) {
 				IType type = asm.GetTypeDefinition(fullTypeName);
 				if (type != null)
 					return type;
@@ -101,10 +101,10 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 				throw new ArgumentNullException("context");
 			
 			IType type = null;
-			if (assembly == null) {
+			if (module == null) {
 				// No assembly specified: look in all assemblies, but prefer the current assembly
-				if (context.CurrentAssembly != null) {
-					type = context.CurrentAssembly.GetTypeDefinition(fullTypeName);
+				if (context.CurrentModule != null) {
+					type = context.CurrentModule.GetTypeDefinition(fullTypeName);
 				}
 				if (type == null) {
 					type = ResolveInAllAssemblies(context);
@@ -114,7 +114,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 				// But if that's not loaded in the compilation, allow fall back to other assemblies.
 				// (the non-loaded assembly might be a facade containing type forwarders -
 				//  for example, when referencing a portable library from a non-portable project)
-				IAssembly asm = assembly.Resolve(context);
+				IModule asm = module.Resolve(context);
 				if (asm != null) {
 					type = asm.GetTypeDefinition(fullTypeName);
 				} else {
@@ -126,20 +126,20 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		
 		public override string ToString()
 		{
-			return fullTypeName.ToString() + (assembly != null ? ", " + assembly.ToString() : null);
+			return fullTypeName.ToString() + (module != null ? ", " + module.ToString() : null);
 		}
 		
 		int ISupportsInterning.GetHashCodeForInterning()
 		{
 			unchecked {
-				return 33 * assembly.GetHashCode() + fullTypeName.GetHashCode();
+				return 33 * module.GetHashCode() + fullTypeName.GetHashCode();
 			}
 		}
 		
 		bool ISupportsInterning.EqualsForInterning(ISupportsInterning other)
 		{
 			GetClassTypeReference o = other as GetClassTypeReference;
-			return o != null && assembly == o.assembly && fullTypeName == o.fullTypeName && isReferenceType == o.isReferenceType;
+			return o != null && module == o.module && fullTypeName == o.fullTypeName && isReferenceType == o.isReferenceType;
 		}
 	}
 }

ICSharpCode.Decompiler/TypeSystem/Implementation/KnownTypeCache.cs

@@ -48,7 +48,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 			if (typeRef == null)
 				return SpecialType.UnknownType;
 			var typeName = new TopLevelTypeName(typeRef.Namespace, typeRef.Name, typeRef.TypeParameterCount);
-			foreach (IAssembly asm in compilation.Assemblies) {
+			foreach (IModule asm in compilation.Modules) {
 				var typeDef = asm.GetTypeDefinition(typeName);
 				if (typeDef != null)
 					return typeDef;

ICSharpCode.Decompiler/TypeSystem/Implementation/MergedNamespace.cs

@@ -99,8 +99,8 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 			get { return compilation; }
 		}
 		
-		public IEnumerable<IAssembly> ContributingAssemblies {
-			get { return namespaces.SelectMany(ns => ns.ContributingAssemblies); }
+		public IEnumerable<IModule> ContributingModules {
+			get { return namespaces.SelectMany(ns => ns.ContributingModules); }
 		}
 		
 		public IEnumerable<INamespace> ChildNamespaces {

ICSharpCode.Decompiler/TypeSystem/Implementation/MetadataEvent.cs

@@ -32,7 +32,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 {
 	sealed class MetadataEvent : IEvent
 	{
-		readonly MetadataAssembly assembly;
+		readonly MetadataModule module;
 		readonly EventDefinitionHandle handle;
 		readonly EventAccessors accessors;
 		readonly string name;
@@ -40,14 +40,14 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		// lazy-loaded:
 		IType returnType;
 
-		internal MetadataEvent(MetadataAssembly assembly, EventDefinitionHandle handle)
+		internal MetadataEvent(MetadataModule module, EventDefinitionHandle handle)
 		{
-			Debug.Assert(assembly != null);
+			Debug.Assert(module != null);
 			Debug.Assert(!handle.IsNil);
-			this.assembly = assembly;
+			this.module = module;
 			this.handle = handle;
 
-			var metadata = assembly.metadata;
+			var metadata = module.metadata;
 			var ev = metadata.GetEventDefinition(handle);
 			accessors = ev.GetAccessors();
 			name = metadata.GetString(ev.Name);
@@ -66,10 +66,10 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		public bool CanAdd => !accessors.Adder.IsNil;
 		public bool CanRemove => !accessors.Remover.IsNil;
 		public bool CanInvoke => !accessors.Raiser.IsNil;
-		public IMethod AddAccessor => assembly.GetDefinition(accessors.Adder);
-		public IMethod RemoveAccessor => assembly.GetDefinition(accessors.Remover);
-		public IMethod InvokeAccessor => assembly.GetDefinition(accessors.Raiser);
-		IMethod AnyAccessor => assembly.GetDefinition(accessors.GetAny());
+		public IMethod AddAccessor => module.GetDefinition(accessors.Adder);
+		public IMethod RemoveAccessor => module.GetDefinition(accessors.Remover);
+		public IMethod InvokeAccessor => module.GetDefinition(accessors.Raiser);
+		IMethod AnyAccessor => module.GetDefinition(accessors.GetAny());
 
 		#region Signature (ReturnType + Parameters)
 		public IType ReturnType {
@@ -77,10 +77,10 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 				var returnType = LazyInit.VolatileRead(ref this.returnType);
 				if (returnType != null)
 					return returnType;
-				var metadata = assembly.metadata;
+				var metadata = module.metadata;
 				var ev = metadata.GetEventDefinition(handle);
 				var context = new GenericContext(DeclaringTypeDefinition?.TypeParameters);
-				returnType = assembly.ResolveType(ev.Type, context, ev.GetCustomAttributes());
+				returnType = module.ResolveType(ev.Type, context, ev.GetCustomAttributes());
 				return LazyInit.GetOrSet(ref this.returnType, returnType);
 			}
 		}
@@ -104,8 +104,8 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		#region Attributes
 		public IEnumerable<IAttribute> GetAttributes()
 		{
-			var b = new AttributeListBuilder(assembly);
-			var metadata = assembly.metadata;
+			var b = new AttributeListBuilder(module);
+			var metadata = module.metadata;
 			var eventDef = metadata.GetEventDefinition(handle);
 			b.Add(eventDef.GetCustomAttributes());
 			return b.Build();
@@ -120,8 +120,8 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		public bool IsOverride => AnyAccessor?.IsOverride ?? false;
 		public bool IsOverridable => AnyAccessor?.IsOverridable ?? false;
 
-		public IAssembly ParentAssembly => assembly;
-		public ICompilation Compilation => assembly.Compilation;
+		public IModule ParentModule => module;
+		public ICompilation Compilation => module.Compilation;
 
 		public string FullName => $"{DeclaringType?.FullName}.{Name}";
 		public string ReflectionName => $"{DeclaringType?.ReflectionName}.{Name}";
@@ -130,14 +130,14 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		public override bool Equals(object obj)
 		{
 			if (obj is MetadataEvent ev) {
-				return handle == ev.handle && assembly.PEFile == ev.assembly.PEFile;
+				return handle == ev.handle && module.PEFile == ev.module.PEFile;
 			}
 			return false;
 		}
 
 		public override int GetHashCode()
 		{
-			return 0x7937039a ^ assembly.PEFile.GetHashCode() ^ handle.GetHashCode();
+			return 0x7937039a ^ module.PEFile.GetHashCode() ^ handle.GetHashCode();
 		}
 
 		bool IMember.Equals(IMember obj, TypeVisitor typeNormalization)

ICSharpCode.Decompiler/TypeSystem/Implementation/MetadataField.cs

@@ -32,7 +32,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 	/// </summary>
 	sealed class MetadataField : IField
 	{
-		readonly MetadataAssembly assembly;
+		readonly MetadataModule module;
 		readonly FieldDefinitionHandle handle;
 		readonly FieldAttributes attributes;
 
@@ -44,13 +44,13 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		bool isVolatile; // initialized together with this.type
 		byte decimalConstant; // 0=no, 1=yes, 2=unknown
 
-		internal MetadataField(MetadataAssembly assembly, FieldDefinitionHandle handle)
+		internal MetadataField(MetadataModule module, FieldDefinitionHandle handle)
 		{
-			Debug.Assert(assembly != null);
+			Debug.Assert(module != null);
 			Debug.Assert(!handle.IsNil);
-			this.assembly = assembly;
+			this.module = module;
 			this.handle = handle;
-			var def = assembly.metadata.GetFieldDefinition(handle);
+			var def = module.metadata.GetFieldDefinition(handle);
 			this.attributes = def.Attributes;
 			if ((attributes & (FieldAttributes.Static | FieldAttributes.InitOnly)) == (FieldAttributes.Static | FieldAttributes.InitOnly)) {
 				decimalConstant = 2; // may be decimal constant
@@ -69,7 +69,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 				string name = LazyInit.VolatileRead(ref this.name);
 				if (name != null)
 					return name;
-				var metadata = assembly.metadata;
+				var metadata = module.metadata;
 				var fieldDef = metadata.GetFieldDefinition(handle);
 				return LazyInit.GetOrSet(ref this.name, metadata.GetString(fieldDef.Name));
 			}
@@ -116,21 +116,21 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 				if (declType != null) {
 					return declType;
 				} else {
-					var def = assembly.metadata.GetFieldDefinition(handle);
+					var def = module.metadata.GetFieldDefinition(handle);
 					return LazyInit.GetOrSet(ref this.declaringType,
-						assembly.GetDefinition(def.GetDeclaringType()));
+						module.GetDefinition(def.GetDeclaringType()));
 				}
 			}
 		}
 
 		public IType DeclaringType => DeclaringTypeDefinition;
-		public IAssembly ParentAssembly => assembly;
-		public ICompilation Compilation => assembly.Compilation;
+		public IModule ParentModule => module;
+		public ICompilation Compilation => module.Compilation;
 		
 		public IEnumerable<IAttribute> GetAttributes()
 		{
-			var b = new AttributeListBuilder(assembly);
-			var metadata = assembly.metadata;
+			var b = new AttributeListBuilder(module);
+			var metadata = module.metadata;
 			var fieldDef = metadata.GetFieldDefinition(handle);
 
 			// FieldOffsetAttribute
@@ -175,15 +175,15 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 
 		private IType DecodeTypeAndVolatileFlag()
 		{
-			var metadata = assembly.metadata;
+			var metadata = module.metadata;
 			var fieldDef = metadata.GetFieldDefinition(handle);
-			var ty = fieldDef.DecodeSignature(assembly.TypeProvider, new GenericContext(DeclaringType?.TypeParameters));
+			var ty = fieldDef.DecodeSignature(module.TypeProvider, new GenericContext(DeclaringType?.TypeParameters));
 			if (ty is ModifiedType mod && mod.Modifier.Name == "IsVolatile" && mod.Modifier.Namespace == "System.Runtime.CompilerServices") {
 				Volatile.Write(ref this.isVolatile, true);
 				ty = mod.ElementType;
 			}
 			ty = ApplyAttributeTypeVisitor.ApplyAttributesToType(ty, Compilation,
-				fieldDef.GetCustomAttributes(), metadata, assembly.TypeSystemOptions);
+				fieldDef.GetCustomAttributes(), metadata, module.TypeSystemOptions);
 			return LazyInit.GetOrSet(ref this.type, ty);
 		}
 
@@ -192,7 +192,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		bool IsDecimalConstant {
 			get {
 				if (decimalConstant == 2) {
-					var metadata = assembly.metadata;
+					var metadata = module.metadata;
 					var fieldDef = metadata.GetFieldDefinition(handle);
 					if (fieldDef.GetCustomAttributes().HasKnownAttribute(metadata, KnownAttribute.DecimalConstant))
 						decimalConstant = 1;
@@ -208,7 +208,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 				object val = LazyInit.VolatileRead(ref this.constantValue);
 				if (val != null)
 					return val;
-				var metadata = assembly.metadata;
+				var metadata = module.metadata;
 				var fieldDef = metadata.GetFieldDefinition(handle);
 				if (IsDecimalConstant) {
 					foreach (var attrHandle in fieldDef.GetCustomAttributes()) {
@@ -231,7 +231,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 
 		decimal? TryDecodeDecimalConstantAttribute(System.Reflection.Metadata.CustomAttribute attribute)
 		{
-			var attrValue = attribute.DecodeValue(assembly.TypeProvider);
+			var attrValue = attribute.DecodeValue(module.TypeProvider);
 			if (attrValue.FixedArguments.Length != 5)
 				return null;
 			// DecimalConstantAttribute has the arguments (byte scale, byte sign, uint hi, uint mid, uint low) or (byte scale, byte sign, int hi, int mid, int low)
@@ -258,14 +258,14 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		public override bool Equals(object obj)
 		{
 			if (obj is MetadataField f) {
-				return handle == f.handle && assembly.PEFile == f.assembly.PEFile;
+				return handle == f.handle && module.PEFile == f.module.PEFile;
 			}
 			return false;
 		}
 
 		public override int GetHashCode()
 		{
-			return 0x11dda32b ^ assembly.PEFile.GetHashCode() ^ handle.GetHashCode();
+			return 0x11dda32b ^ module.PEFile.GetHashCode() ^ handle.GetHashCode();
 		}
 
 		bool IMember.Equals(IMember obj, TypeVisitor typeNormalization)

ICSharpCode.Decompiler/TypeSystem/Implementation/MetadataMethod.cs

@@ -32,7 +32,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 {
 	sealed class MetadataMethod : IMethod
 	{
-		readonly MetadataAssembly assembly;
+		readonly MetadataModule module;
 		readonly MethodDefinitionHandle handle;
 
 		// eagerly loaded fields:
@@ -48,18 +48,18 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		IParameter[] parameters;
 		IType returnType;
 
-		internal MetadataMethod(MetadataAssembly assembly, MethodDefinitionHandle handle)
+		internal MetadataMethod(MetadataModule module, MethodDefinitionHandle handle)
 		{
-			Debug.Assert(assembly != null);
+			Debug.Assert(module != null);
 			Debug.Assert(!handle.IsNil);
-			this.assembly = assembly;
+			this.module = module;
 			this.handle = handle;
-			var metadata = assembly.metadata;
+			var metadata = module.metadata;
 			var def = metadata.GetMethodDefinition(handle);
 			this.attributes = def.Attributes;
 
 			this.symbolKind = SymbolKind.Method;
-			var (accessorOwner, semanticsAttribute) = assembly.PEFile.MethodSemanticsLookup.GetSemantics(handle);
+			var (accessorOwner, semanticsAttribute) = module.PEFile.MethodSemanticsLookup.GetSemantics(handle);
 			if (semanticsAttribute != 0) {
 				this.symbolKind = SymbolKind.Accessor;
 				this.accessorOwner = accessorOwner;
@@ -70,9 +70,9 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 				else if (name.StartsWith("op_", StringComparison.Ordinal))
 					this.symbolKind = SymbolKind.Operator;
 			}
-			this.typeParameters = MetadataTypeParameter.Create(assembly, this, def.GetGenericParameters());
+			this.typeParameters = MetadataTypeParameter.Create(module, this, def.GetGenericParameters());
 			this.IsExtensionMethod = (attributes & MethodAttributes.Static) == MethodAttributes.Static
-				&& (assembly.TypeSystemOptions & TypeSystemOptions.ExtensionMethods) == TypeSystemOptions.ExtensionMethods
+				&& (module.TypeSystemOptions & TypeSystemOptions.ExtensionMethods) == TypeSystemOptions.ExtensionMethods
 				&& def.GetCustomAttributes().HasKnownAttribute(metadata, KnownAttribute.Extension);
 		}
 
@@ -88,7 +88,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 				string name = LazyInit.VolatileRead(ref this.name);
 				if (name != null)
 					return name;
-				var metadata = assembly.metadata;
+				var metadata = module.metadata;
 				var methodDef = metadata.GetMethodDefinition(handle);
 				return LazyInit.GetOrSet(ref this.name, metadata.GetString(methodDef.Name));
 			}
@@ -103,7 +103,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		public bool IsOperator => symbolKind == SymbolKind.Operator;
 		public bool IsAccessor => symbolKind == SymbolKind.Accessor;
 
-		public bool HasBody => assembly.metadata.GetMethodDefinition(handle).HasBody();
+		public bool HasBody => module.metadata.GetMethodDefinition(handle).HasBody();
 
 
 		public IMember AccessorOwner {
@@ -111,9 +111,9 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 				if (accessorOwner.IsNil)
 					return null;
 				if (accessorOwner.Kind == HandleKind.PropertyDefinition)
-					return assembly.GetDefinition((PropertyDefinitionHandle)accessorOwner);
+					return module.GetDefinition((PropertyDefinitionHandle)accessorOwner);
 				else if (accessorOwner.Kind == HandleKind.EventDefinition)
-					return assembly.GetDefinition((EventDefinitionHandle)accessorOwner);
+					return module.GetDefinition((EventDefinitionHandle)accessorOwner);
 				else
 					return null;
 			}
@@ -142,17 +142,17 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 
 		private void DecodeSignature()
 		{
-			var methodDef = assembly.metadata.GetMethodDefinition(handle);
+			var methodDef = module.metadata.GetMethodDefinition(handle);
 			var genericContext = new GenericContext(DeclaringType.TypeParameters, this.TypeParameters);
-			var signature = methodDef.DecodeSignature(assembly.TypeProvider, genericContext);
-			var (returnType, parameters) = DecodeSignature(assembly, this, signature, methodDef.GetParameters());
+			var signature = methodDef.DecodeSignature(module.TypeProvider, genericContext);
+			var (returnType, parameters) = DecodeSignature(module, this, signature, methodDef.GetParameters());
 			LazyInit.GetOrSet(ref this.returnType, returnType);
 			LazyInit.GetOrSet(ref this.parameters, parameters);
 		}
 
-		internal static (IType, IParameter[]) DecodeSignature(MetadataAssembly assembly, IParameterizedMember owner, MethodSignature<IType> signature, ParameterHandleCollection? parameterHandles)
+		internal static (IType, IParameter[]) DecodeSignature(MetadataModule module, IParameterizedMember owner, MethodSignature<IType> signature, ParameterHandleCollection? parameterHandles)
 		{
-			var metadata = assembly.metadata;
+			var metadata = module.metadata;
 			int i = 0;
 			CustomAttributeHandleCollection? returnTypeAttributes = null;
 			IParameter[] parameters = new IParameter[signature.RequiredParameterCount
@@ -166,16 +166,16 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 					} else if (par.SequenceNumber > 0 && i < signature.RequiredParameterCount) {
 						Debug.Assert(par.SequenceNumber - 1 == i);
 						var parameterType = ApplyAttributeTypeVisitor.ApplyAttributesToType(
-							signature.ParameterTypes[i], assembly.Compilation,
-							par.GetCustomAttributes(), metadata, assembly.TypeSystemOptions);
-						parameters[i] = new MetadataParameter(assembly, owner, parameterType, parameterHandle);
+							signature.ParameterTypes[i], module.Compilation,
+							par.GetCustomAttributes(), metadata, module.TypeSystemOptions);
+						parameters[i] = new MetadataParameter(module, owner, parameterType, parameterHandle);
 						i++;
 					}
 				}
 			}
 			while (i < signature.RequiredParameterCount) {
 				var parameterType = ApplyAttributeTypeVisitor.ApplyAttributesToType(
-					signature.ParameterTypes[i], assembly.Compilation, null, metadata, assembly.TypeSystemOptions);
+					signature.ParameterTypes[i], module.Compilation, null, metadata, module.TypeSystemOptions);
 				parameters[i] = new DefaultParameter(parameterType, name: string.Empty, owner,
 					isRef: parameterType.Kind == TypeKind.ByReference);
 				i++;
@@ -186,7 +186,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 			}
 			Debug.Assert(i == parameters.Length);
 			var returnType = ApplyAttributeTypeVisitor.ApplyAttributesToType(signature.ReturnType,
-				assembly.Compilation, returnTypeAttributes, metadata, assembly.TypeSystemOptions);
+				module.Compilation, returnTypeAttributes, metadata, module.TypeSystemOptions);
 			return (returnType, parameters);
 		}
 		#endregion
@@ -217,38 +217,38 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 				if (declType != null) {
 					return declType;
 				} else {
-					var def = assembly.metadata.GetMethodDefinition(handle);
+					var def = module.metadata.GetMethodDefinition(handle);
 					return LazyInit.GetOrSet(ref this.declaringType,
-						assembly.GetDefinition(def.GetDeclaringType()));
+						module.GetDefinition(def.GetDeclaringType()));
 				}
 			}
 		}
 
 		public IType DeclaringType => DeclaringTypeDefinition;
 
-		public IAssembly ParentAssembly => assembly;
-		public ICompilation Compilation => assembly.Compilation;
+		public IModule ParentModule => module;
+		public ICompilation Compilation => module.Compilation;
 
 		#region Attributes
 		IType FindInteropType(string name)
 		{
-			return assembly.Compilation.FindType(new TopLevelTypeName(
+			return module.Compilation.FindType(new TopLevelTypeName(
 				"System.Runtime.InteropServices", name, 0
 			));
 		}
 
 		public IEnumerable<IAttribute> GetAttributes()
 		{
-			var b = new AttributeListBuilder(assembly);
+			var b = new AttributeListBuilder(module);
 
-			var metadata = assembly.metadata;
+			var metadata = module.metadata;
 			var def = metadata.GetMethodDefinition(handle);
 			MethodImplAttributes implAttributes = def.ImplAttributes & ~MethodImplAttributes.CodeTypeMask;
 
 			#region DllImportAttribute
 			var info = def.GetImport();
 			if ((attributes & MethodAttributes.PinvokeImpl) == MethodAttributes.PinvokeImpl && !info.Module.IsNil) {
-				var dllImport = new AttributeBuilder(assembly, KnownAttribute.DllImport);
+				var dllImport = new AttributeBuilder(module, KnownAttribute.DllImport);
 				dllImport.AddFixedArg(KnownTypeCode.String,
 					metadata.GetString(metadata.GetModuleReference(info.Module).Name));
 
@@ -356,8 +356,8 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		#region Return type attributes
 		public IEnumerable<IAttribute> GetReturnTypeAttributes()
 		{
-			var b = new AttributeListBuilder(assembly);
-			var metadata = assembly.metadata;
+			var b = new AttributeListBuilder(module);
+			var metadata = module.metadata;
 			var methodDefinition = metadata.GetMethodDefinition(handle);
 			var parameters = methodDefinition.GetParameters();
 			if (parameters.Count > 0) {
@@ -409,14 +409,14 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		public override bool Equals(object obj)
 		{
 			if (obj is MetadataMethod m) {
-				return handle == m.handle && assembly.PEFile == m.assembly.PEFile;
+				return handle == m.handle && module.PEFile == m.module.PEFile;
 			}
 			return false;
 		}
 
 		public override int GetHashCode()
 		{
-			return 0x5a00d671 ^ assembly.PEFile.GetHashCode() ^ handle.GetHashCode();
+			return 0x5a00d671 ^ module.PEFile.GetHashCode() ^ handle.GetHashCode();
 		}
 
 		bool IMember.Equals(IMember obj, TypeVisitor typeNormalization)

ICSharpCode.Decompiler/TypeSystem/Implementation/MetadataNamespace.cs

@@ -26,22 +26,22 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 {
 	sealed class MetadataNamespace : INamespace
 	{
-		readonly MetadataAssembly assembly;
+		readonly MetadataModule module;
 		readonly NamespaceDefinition ns;
 
 		public INamespace ParentNamespace { get; }
 		public string FullName { get; }
 		public string Name { get; }
 
-		public MetadataNamespace(MetadataAssembly assembly, INamespace parent, string fullName, NamespaceDefinition ns)
+		public MetadataNamespace(MetadataModule module, INamespace parent, string fullName, NamespaceDefinition ns)
 		{
-			Debug.Assert(assembly != null);
+			Debug.Assert(module != null);
 			Debug.Assert(fullName != null);
-			this.assembly = assembly;
+			this.module = module;
 			this.ParentNamespace = parent;
 			this.ns = ns;
 			this.FullName = fullName;
-			this.Name = assembly.GetString(ns.Name);
+			this.Name = module.GetString(ns.Name);
 		}
 
 		string INamespace.ExternAlias => string.Empty;
@@ -58,9 +58,9 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 				children = new INamespace[nsDefs.Length];
 				for (int i = 0; i < children.Length; i++) {
 					var nsHandle = nsDefs[i];
-					string fullName = assembly.metadata.GetString(nsHandle);
-					children[i] = new MetadataNamespace(assembly, this, fullName,
-						assembly.metadata.GetNamespaceDefinition(nsHandle));
+					string fullName = module.metadata.GetString(nsHandle);
+					children[i] = new MetadataNamespace(module, this, fullName,
+						module.metadata.GetNamespaceDefinition(nsHandle));
 				}
 				return LazyInit.GetOrSet(ref childNamespaces, children);
 			}
@@ -69,18 +69,18 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		IEnumerable<ITypeDefinition> INamespace.Types {
 			get {
 				foreach (var typeHandle in ns.TypeDefinitions) {
-					var def = assembly.GetDefinition(typeHandle);
+					var def = module.GetDefinition(typeHandle);
 					if (def != null)
 						yield return def;
 				}
 			}
 		}
 
-		IEnumerable<IAssembly> INamespace.ContributingAssemblies => new[] { assembly };
+		IEnumerable<IModule> INamespace.ContributingModules => new[] { module };
 
 		SymbolKind ISymbol.SymbolKind => SymbolKind.Namespace;
 
-		ICompilation ICompilationProvider.Compilation => assembly.Compilation;
+		ICompilation ICompilationProvider.Compilation => module.Compilation;
 
 		INamespace INamespace.GetChildNamespace(string name)
 		{
@@ -93,7 +93,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 
 		ITypeDefinition INamespace.GetTypeDefinition(string name, int typeParameterCount)
 		{
-			return assembly.GetTypeDefinition(FullName, name, typeParameterCount);
+			return module.GetTypeDefinition(FullName, name, typeParameterCount);
 		}
 	}
 }

ICSharpCode.Decompiler/TypeSystem/Implementation/MetadataParameter.cs

@@ -28,7 +28,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 {
 	sealed class MetadataParameter : IParameter
 	{
-		readonly MetadataAssembly assembly;
+		readonly MetadataModule module;
 		readonly ParameterHandle handle;
 		readonly ParameterAttributes attributes;
 
@@ -38,14 +38,14 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		// lazy-loaded:
 		string name;
 
-		internal MetadataParameter(MetadataAssembly assembly, IParameterizedMember owner, IType type, ParameterHandle handle)
+		internal MetadataParameter(MetadataModule module, IParameterizedMember owner, IType type, ParameterHandle handle)
 		{
-			this.assembly = assembly;
+			this.module = module;
 			this.Owner = owner;
 			this.Type = type;
 			this.handle = handle;
 
-			var param = assembly.metadata.GetParameter(handle);
+			var param = module.metadata.GetParameter(handle);
 			this.attributes = param.Attributes;
 		}
 
@@ -54,8 +54,8 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		#region Attributes
 		public IEnumerable<IAttribute> GetAttributes()
 		{
-			var b = new AttributeListBuilder(assembly);
-			var metadata = assembly.metadata;
+			var b = new AttributeListBuilder(module);
+			var metadata = module.metadata;
 			var parameter = metadata.GetParameter(handle);
 
 			if (!IsOut) {
@@ -80,7 +80,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 			get {
 				if (Type.Kind != TypeKind.Array)
 					return false;
-				var metadata = assembly.metadata;
+				var metadata = module.metadata;
 				var propertyDef = metadata.GetParameter(handle);
 				return propertyDef.GetCustomAttributes().HasKnownAttribute(metadata, KnownAttribute.ParamArray);
 			}
@@ -91,7 +91,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 				string name = LazyInit.VolatileRead(ref this.name);
 				if (name != null)
 					return name;
-				var metadata = assembly.metadata;
+				var metadata = module.metadata;
 				var propertyDef = metadata.GetParameter(handle);
 				return LazyInit.GetOrSet(ref this.name, metadata.GetString(propertyDef.Name));
 			}
@@ -101,7 +101,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 
 		public object ConstantValue {
 			get {
-				var metadata = assembly.metadata;
+				var metadata = module.metadata;
 				var propertyDef = metadata.GetParameter(handle);
 				var constantHandle = propertyDef.GetDefaultValue();
 				if (constantHandle.IsNil)

ICSharpCode.Decompiler/TypeSystem/Implementation/MetadataProperty.cs

@@ -16,16 +16,11 @@
 // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 // DEALINGS IN THE SOFTWARE.
 
-using System;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
-using System.Reflection;
 using System.Reflection.Metadata;
 using System.Reflection.Metadata.Ecma335;
-using System.Runtime.CompilerServices;
-using System.Runtime.InteropServices;
-using ICSharpCode.Decompiler.Semantics;
 using ICSharpCode.Decompiler.Util;
 
 namespace ICSharpCode.Decompiler.TypeSystem.Implementation
@@ -34,7 +29,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 	{
 		const Accessibility InvalidAccessibility = (Accessibility)0xff;
 
-		readonly MetadataAssembly assembly;
+		readonly MetadataModule module;
 		readonly PropertyDefinitionHandle propertyHandle;
 		readonly IMethod getter;
 		readonly IMethod setter;
@@ -46,18 +41,18 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		IParameter[] parameters;
 		IType returnType;
 
-		internal MetadataProperty(MetadataAssembly assembly, PropertyDefinitionHandle handle)
+		internal MetadataProperty(MetadataModule module, PropertyDefinitionHandle handle)
 		{
-			Debug.Assert(assembly != null);
+			Debug.Assert(module != null);
 			Debug.Assert(!handle.IsNil);
-			this.assembly = assembly;
+			this.module = module;
 			this.propertyHandle = handle;
 
-			var metadata = assembly.metadata;
+			var metadata = module.metadata;
 			var prop = metadata.GetPropertyDefinition(handle);
 			var accessors = prop.GetAccessors();
-			getter = assembly.GetDefinition(accessors.Getter);
-			setter = assembly.GetDefinition(accessors.Setter);
+			getter = module.GetDefinition(accessors.Getter);
+			setter = module.GetDefinition(accessors.Setter);
 			name = metadata.GetString(prop.Name);
 			if (name == (DeclaringTypeDefinition as MetadataTypeDefinition)?.DefaultMemberName) {
 				symbolKind = SymbolKind.Indexer;
@@ -111,18 +106,18 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 
 		private void DecodeSignature()
 		{
-			var propertyDef = assembly.metadata.GetPropertyDefinition(propertyHandle);
+			var propertyDef = module.metadata.GetPropertyDefinition(propertyHandle);
 			var genericContext = new GenericContext(DeclaringType.TypeParameters);
-			var signature = propertyDef.DecodeSignature(assembly.TypeProvider, genericContext);
+			var signature = propertyDef.DecodeSignature(module.TypeProvider, genericContext);
 			var accessors = propertyDef.GetAccessors();
 			ParameterHandleCollection? parameterHandles;
 			if (!accessors.Getter.IsNil)
-				parameterHandles = assembly.metadata.GetMethodDefinition(accessors.Getter).GetParameters();
+				parameterHandles = module.metadata.GetMethodDefinition(accessors.Getter).GetParameters();
 			else if (!accessors.Setter.IsNil)
-				parameterHandles = assembly.metadata.GetMethodDefinition(accessors.Setter).GetParameters();
+				parameterHandles = module.metadata.GetMethodDefinition(accessors.Setter).GetParameters();
 			else
 				parameterHandles = null;
-			var (returnType, parameters) = MetadataMethod.DecodeSignature(assembly, this, signature, parameterHandles);
+			var (returnType, parameters) = MetadataMethod.DecodeSignature(module, this, signature, parameterHandles);
 			LazyInit.GetOrSet(ref this.returnType, returnType);
 			LazyInit.GetOrSet(ref this.parameters, parameters);
 		}
@@ -146,8 +141,8 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		#region Attributes
 		public IEnumerable<IAttribute> GetAttributes()
 		{
-			var b = new AttributeListBuilder(assembly);
-			var metadata = assembly.metadata;
+			var b = new AttributeListBuilder(module);
+			var metadata = module.metadata;
 			var propertyDef = metadata.GetPropertyDefinition(propertyHandle);
 			if (IsIndexer && Name != "Item" && !IsExplicitInterfaceImplementation) {
 				b.Add(KnownAttribute.IndexerName, KnownTypeCode.String, Name);
@@ -213,8 +208,8 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		public bool IsOverride => AnyAccessor?.IsOverride ?? false;
 		public bool IsOverridable => AnyAccessor?.IsOverridable ?? false;
 
-		public IAssembly ParentAssembly => assembly;
-		public ICompilation Compilation => assembly.Compilation;
+		public IModule ParentModule => module;
+		public ICompilation Compilation => module.Compilation;
 
 		public string FullName => $"{DeclaringType?.FullName}.{Name}";
 		public string ReflectionName => $"{DeclaringType?.ReflectionName}.{Name}";
@@ -223,14 +218,14 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		public override bool Equals(object obj)
 		{
 			if (obj is MetadataProperty p) {
-				return propertyHandle == p.propertyHandle && assembly.PEFile == p.assembly.PEFile;
+				return propertyHandle == p.propertyHandle && module.PEFile == p.module.PEFile;
 			}
 			return false;
 		}
 
 		public override int GetHashCode()
 		{
-			return 0x32b6a76c ^ assembly.PEFile.GetHashCode() ^ propertyHandle.GetHashCode();
+			return 0x32b6a76c ^ module.PEFile.GetHashCode() ^ propertyHandle.GetHashCode();
 		}
 
 		bool IMember.Equals(IMember obj, TypeVisitor typeNormalization)

ICSharpCode.Decompiler/TypeSystem/Implementation/MetadataTypeDefinition.cs

@@ -37,7 +37,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 	/// </summary>
 	sealed class MetadataTypeDefinition : ITypeDefinition
 	{
-		readonly MetadataAssembly assembly;
+		readonly MetadataModule module;
 		readonly TypeDefinitionHandle handle;
 
 		// eagerly loaded:
@@ -59,25 +59,25 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		List<IType> directBaseTypes;
 		string defaultMemberName;
 
-		internal MetadataTypeDefinition(MetadataAssembly assembly, TypeDefinitionHandle handle)
+		internal MetadataTypeDefinition(MetadataModule module, TypeDefinitionHandle handle)
 		{
-			Debug.Assert(assembly != null);
+			Debug.Assert(module != null);
 			Debug.Assert(!handle.IsNil);
-			this.assembly = assembly;
+			this.module = module;
 			this.handle = handle;
-			var metadata = assembly.metadata;
+			var metadata = module.metadata;
 			var td = metadata.GetTypeDefinition(handle);
 			this.attributes = td.Attributes;
 			this.fullTypeName = td.GetFullTypeName(metadata);
 			// Find DeclaringType + KnownTypeCode:
 			if (fullTypeName.IsNested) {
-				this.DeclaringTypeDefinition = assembly.GetDefinition(td.GetDeclaringType());
+				this.DeclaringTypeDefinition = module.GetDefinition(td.GetDeclaringType());
 				
 				// Create type parameters:
-				this.TypeParameters = MetadataTypeParameter.Create(assembly, this.DeclaringTypeDefinition, this, td.GetGenericParameters());
+				this.TypeParameters = MetadataTypeParameter.Create(module, this.DeclaringTypeDefinition, this, td.GetGenericParameters());
 			} else {
 				// Create type parameters:
-				this.TypeParameters = MetadataTypeParameter.Create(assembly, this, td.GetGenericParameters());
+				this.TypeParameters = MetadataTypeParameter.Create(module, this, td.GetGenericParameters());
 
 				var topLevelTypeName = fullTypeName.TopLevelTypeName;
 				for (int i = 0; i < KnownTypeReference.KnownTypeCodeCount; i++) {
@@ -93,7 +93,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 				this.Kind = TypeKind.Interface;
 			} else if (td.IsEnum(metadata, out var underlyingType)) {
 				this.Kind = TypeKind.Enum;
-				this.EnumUnderlyingType = assembly.Compilation.FindType(underlyingType.ToKnownTypeCode());
+				this.EnumUnderlyingType = module.Compilation.FindType(underlyingType.ToKnownTypeCode());
 			} else if (td.IsValueType(metadata)) {
 				if (KnownTypeCode == KnownTypeCode.Void) {
 					this.Kind = TypeKind.Void;
@@ -121,11 +121,11 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 				var nestedTypes = LazyInit.VolatileRead(ref this.nestedTypes);
 				if (nestedTypes != null)
 					return nestedTypes;
-				var metadata = assembly.metadata;
+				var metadata = module.metadata;
 				var nestedTypeCollection = metadata.GetTypeDefinition(handle).GetNestedTypes();
 				var nestedTypeList = new List<ITypeDefinition>(nestedTypeCollection.Length);
 				foreach (TypeDefinitionHandle h in nestedTypeCollection) {
-					nestedTypeList.Add(assembly.GetDefinition(h));
+					nestedTypeList.Add(module.GetDefinition(h));
 				}
 				return LazyInit.GetOrSet(ref this.nestedTypes, nestedTypeList.ToArray());
 			}
@@ -147,14 +147,14 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 				var fields = LazyInit.VolatileRead(ref this.fields);
 				if (fields != null)
 					return fields;
-				var metadata = assembly.metadata;
+				var metadata = module.metadata;
 				var fieldCollection = metadata.GetTypeDefinition(handle).GetFields();
 				var fieldList = new List<IField>(fieldCollection.Count);
 				foreach (FieldDefinitionHandle h in fieldCollection) {
 					var field = metadata.GetFieldDefinition(h);
 					var attr = field.Attributes;
-					if (assembly.IsVisible(attr) && (attr & FieldAttributes.SpecialName) == 0) {
-						fieldList.Add(assembly.GetDefinition(h));
+					if (module.IsVisible(attr) && (attr & FieldAttributes.SpecialName) == 0) {
+						fieldList.Add(module.GetDefinition(h));
 					}
 				}
 				return LazyInit.GetOrSet(ref this.fields, fieldList.ToArray());
@@ -166,16 +166,16 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 				var properties = LazyInit.VolatileRead(ref this.properties);
 				if (properties != null)
 					return properties;
-				var metadata = assembly.metadata;
+				var metadata = module.metadata;
 				var propertyCollection = metadata.GetTypeDefinition(handle).GetProperties();
 				var propertyList = new List<IProperty>(propertyCollection.Count);
 				foreach (PropertyDefinitionHandle h in propertyCollection) {
 					var property = metadata.GetPropertyDefinition(h);
 					var accessors = property.GetAccessors();
-					bool getterVisible = !accessors.Getter.IsNil && assembly.IsVisible(metadata.GetMethodDefinition(accessors.Getter).Attributes);
-					bool setterVisible = !accessors.Setter.IsNil && assembly.IsVisible(metadata.GetMethodDefinition(accessors.Setter).Attributes);
+					bool getterVisible = !accessors.Getter.IsNil && module.IsVisible(metadata.GetMethodDefinition(accessors.Getter).Attributes);
+					bool setterVisible = !accessors.Setter.IsNil && module.IsVisible(metadata.GetMethodDefinition(accessors.Setter).Attributes);
 					if (getterVisible || setterVisible) {
-						propertyList.Add(assembly.GetDefinition(h));
+						propertyList.Add(module.GetDefinition(h));
 					}
 				}
 				return LazyInit.GetOrSet(ref this.properties, propertyList.ToArray());
@@ -187,7 +187,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 				var events = LazyInit.VolatileRead(ref this.events);
 				if (events != null)
 					return events;
-				var metadata = assembly.metadata;
+				var metadata = module.metadata;
 				var eventCollection = metadata.GetTypeDefinition(handle).GetEvents();
 				var eventList = new List<IEvent>(eventCollection.Count);
 				foreach (EventDefinitionHandle h in eventCollection) {
@@ -196,8 +196,8 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 					if (accessors.Adder.IsNil)
 						continue;
 					var addMethod = metadata.GetMethodDefinition(accessors.Adder);
-					if (assembly.IsVisible(addMethod.Attributes)) {
-						eventList.Add(assembly.GetDefinition(h));
+					if (module.IsVisible(addMethod.Attributes)) {
+						eventList.Add(module.GetDefinition(h));
 					}
 				}
 				return LazyInit.GetOrSet(ref this.events, eventList.ToArray());
@@ -209,14 +209,14 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 				var methods = LazyInit.VolatileRead(ref this.methods);
 				if (methods != null)
 					return methods;
-				var metadata = assembly.metadata;
+				var metadata = module.metadata;
 				var methodsCollection = metadata.GetTypeDefinition(handle).GetMethods();
 				var methodsList = new List<IMethod>(methodsCollection.Count);
-				var methodSemantics = assembly.PEFile.MethodSemanticsLookup;
+				var methodSemantics = module.PEFile.MethodSemanticsLookup;
 				foreach (MethodDefinitionHandle h in methodsCollection) {
 					var md = metadata.GetMethodDefinition(h);
-					if (methodSemantics.GetSemantics(h).Item2 == 0 && assembly.IsVisible(md.Attributes)) {
-						methodsList.Add(assembly.GetDefinition(h));
+					if (methodSemantics.GetSemantics(h).Item2 == 0 && module.IsVisible(md.Attributes)) {
+						methodsList.Add(module.GetDefinition(h));
 					}
 				}
 				if (this.Kind == TypeKind.Struct || this.Kind == TypeKind.Enum) {
@@ -251,13 +251,13 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 				var baseTypes = LazyInit.VolatileRead(ref this.directBaseTypes);
 				if (baseTypes != null)
 					return baseTypes;
-				var metadata = assembly.metadata;
+				var metadata = module.metadata;
 				var td = metadata.GetTypeDefinition(handle);
 				var context = new GenericContext(TypeParameters);
 				var interfaceImplCollection = td.GetInterfaceImplementations();
 				baseTypes = new List<IType>(1 + interfaceImplCollection.Count);
 				if (!td.BaseType.IsNil) {
-					baseTypes.Add(assembly.ResolveType(td.BaseType, context));
+					baseTypes.Add(module.ResolveType(td.BaseType, context));
 				} else if (Kind == TypeKind.Interface) {
 					// td.BaseType.IsNil is always true for interfaces,
 					// but the type system expects every interface to derive from System.Object as well.
@@ -265,7 +265,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 				}
 				foreach (var h in interfaceImplCollection) {
 					var iface = metadata.GetInterfaceImplementation(h);
-					baseTypes.Add(assembly.ResolveType(iface.Interface, context, iface.GetCustomAttributes()));
+					baseTypes.Add(module.ResolveType(iface.Interface, context, iface.GetCustomAttributes()));
 				}
 				return LazyInit.GetOrSet(ref this.directBaseTypes, baseTypes);
 			}
@@ -276,13 +276,13 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		public FullTypeName FullTypeName => fullTypeName;
 		public string Name => fullTypeName.Name;
 
-		public IAssembly ParentAssembly => assembly;
+		public IModule ParentModule => module;
 
 		#region Type Attributes
 		public IEnumerable<IAttribute> GetAttributes()
 		{
-			var b = new AttributeListBuilder(assembly);
-			var metadata = assembly.metadata;
+			var b = new AttributeListBuilder(module);
+			var metadata = module.metadata;
 			var typeDefinition = metadata.GetTypeDefinition(handle);
 
 			// SerializableAttribute
@@ -318,7 +318,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 			var layout = typeDefinition.GetLayout();
 			LayoutKind defaultLayoutKind = Kind == TypeKind.Struct ? LayoutKind.Sequential : LayoutKind.Auto;
 			if (layoutKind != defaultLayoutKind || charSet != CharSet.Ansi || layout.PackingSize > 0 || layout.Size > 0) {
-				var structLayout = new AttributeBuilder(assembly, KnownAttribute.StructLayout);
+				var structLayout = new AttributeBuilder(module, KnownAttribute.StructLayout);
 				structLayout.AddFixedArg(
 					new TopLevelTypeName("System.Runtime.InteropServices", "LayoutKind"),
 					(int)layoutKind);
@@ -347,13 +347,13 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 				string defaultMemberName = LazyInit.VolatileRead(ref this.defaultMemberName);
 				if (defaultMemberName != null)
 					return defaultMemberName;
-				var metadata = assembly.metadata;
+				var metadata = module.metadata;
 				var typeDefinition = metadata.GetTypeDefinition(handle);
 				foreach (var h in typeDefinition.GetCustomAttributes()) {
 					var a = metadata.GetCustomAttribute(h);
 					if (!a.IsKnownAttribute(metadata, KnownAttribute.DefaultMember))
 						continue;
-					var value = a.DecodeValue(assembly.TypeProvider);
+					var value = a.DecodeValue(module.TypeProvider);
 					if (value.FixedArguments.Length == 1 && value.FixedArguments[0].Value is string name) {
 						defaultMemberName = name;
 						break;
@@ -393,7 +393,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 
 		public SymbolKind SymbolKind => SymbolKind.TypeDefinition;
 
-		public ICompilation Compilation => assembly.Compilation;
+		public ICompilation Compilation => module.Compilation;
 
 		public string FullName {
 			get {
@@ -425,14 +425,14 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		public override bool Equals(object obj)
 		{
 			if (obj is MetadataTypeDefinition td) {
-				return handle == td.handle && assembly.PEFile == td.assembly.PEFile;
+				return handle == td.handle && module.PEFile == td.module.PEFile;
 			}
 			return false;
 		}
 
 		public override int GetHashCode()
 		{
-			return 0x2e0520f2 ^ assembly.PEFile.GetHashCode() ^ handle.GetHashCode();
+			return 0x2e0520f2 ^ module.PEFile.GetHashCode() ^ handle.GetHashCode();
 		}
 
 		bool IEquatable<IType>.Equals(IType other)
@@ -595,18 +595,18 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		#region GetOverrides
 		internal IEnumerable<IMethod> GetOverrides(MethodDefinitionHandle method)
 		{
-			var metadata = assembly.metadata;
+			var metadata = module.metadata;
 			var td = metadata.GetTypeDefinition(handle);
 			foreach (var implHandle in td.GetMethodImplementations()) {
 				var impl = metadata.GetMethodImplementation(implHandle);
 				if (impl.MethodBody == method)
-					yield return assembly.ResolveMethod(impl.MethodDeclaration, new GenericContext(this.TypeParameters));
+					yield return module.ResolveMethod(impl.MethodDeclaration, new GenericContext(this.TypeParameters));
 			}
 		}
 
 		internal bool HasOverrides(MethodDefinitionHandle method)
 		{
-			var metadata = assembly.metadata;
+			var metadata = module.metadata;
 			var td = metadata.GetTypeDefinition(handle);
 			foreach (var implHandle in td.GetMethodImplementations()) {
 				var impl = metadata.GetMethodImplementation(implHandle);

ICSharpCode.Decompiler/TypeSystem/Implementation/MetadataTypeParameter.cs

@@ -28,7 +28,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 {
 	sealed class MetadataTypeParameter : AbstractTypeParameter
 	{
-		readonly MetadataAssembly assembly;
+		readonly MetadataModule module;
 		readonly GenericParameterHandle handle;
 
 		readonly GenericParameterAttributes attr;
@@ -36,7 +36,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		// lazy-loaded:
 		IReadOnlyList<IType> constraints;
 
-		public static ITypeParameter[] Create(MetadataAssembly assembly, ITypeDefinition copyFromOuter, IEntity owner, GenericParameterHandleCollection handles)
+		public static ITypeParameter[] Create(MetadataModule module, ITypeDefinition copyFromOuter, IEntity owner, GenericParameterHandleCollection handles)
 		{
 			if (handles.Count == 0)
 				return Empty<ITypeParameter>.Array;
@@ -47,38 +47,38 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 				if (i < outerTps.Count)
 					tps[i] = outerTps[i];
 				else
-					tps[i] = Create(assembly, owner, i, handle);
+					tps[i] = Create(module, owner, i, handle);
 				i++;
 			}
 			return tps;
 		}
 
-		public static ITypeParameter[] Create(MetadataAssembly assembly, IEntity owner, GenericParameterHandleCollection handles)
+		public static ITypeParameter[] Create(MetadataModule module, IEntity owner, GenericParameterHandleCollection handles)
 		{
 			if (handles.Count == 0)
 				return Empty<ITypeParameter>.Array;
 			var tps = new ITypeParameter[handles.Count];
 			int i = 0;
 			foreach (var handle in handles) {
-				tps[i] = Create(assembly, owner, i, handle);
+				tps[i] = Create(module, owner, i, handle);
 				i++;
 			}
 			return tps;
 		}
 
-		public static MetadataTypeParameter Create(MetadataAssembly assembly, IEntity owner, int index, GenericParameterHandle handle)
+		public static MetadataTypeParameter Create(MetadataModule module, IEntity owner, int index, GenericParameterHandle handle)
 		{
-			var metadata = assembly.metadata;
+			var metadata = module.metadata;
 			var gp = metadata.GetGenericParameter(handle);
 			Debug.Assert(gp.Index == index);
-			return new MetadataTypeParameter(assembly, owner, index, assembly.GetString(gp.Name), handle, gp.Attributes);
+			return new MetadataTypeParameter(module, owner, index, module.GetString(gp.Name), handle, gp.Attributes);
 		}
 
-		private MetadataTypeParameter(MetadataAssembly assembly, IEntity owner, int index, string name,
+		private MetadataTypeParameter(MetadataModule module, IEntity owner, int index, string name,
 			GenericParameterHandle handle, GenericParameterAttributes attr)
 			: base(owner, index, name, GetVariance(attr))
 		{
-			this.assembly = assembly;
+			this.module = module;
 			this.handle = handle;
 			this.attr = attr;
 		}
@@ -99,11 +99,11 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 
 		public override IEnumerable<IAttribute> GetAttributes()
 		{
-			var metadata = assembly.metadata;
+			var metadata = module.metadata;
 			var gp = metadata.GetGenericParameter(handle);
 
 			var attributes = gp.GetCustomAttributes();
-			var b = new AttributeListBuilder(assembly, attributes.Count);
+			var b = new AttributeListBuilder(module, attributes.Count);
 			b.Add(attributes);
 			return b.Build();
 		}
@@ -123,7 +123,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 
 		private IReadOnlyList<IType> DecodeConstraints()
 		{
-			var metadata = assembly.metadata;
+			var metadata = module.metadata;
 			var gp = metadata.GetGenericParameter(handle);
 
 			var constraintHandleCollection = gp.GetConstraints();
@@ -131,7 +131,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 			bool hasNonInterfaceConstraint = false;
 			foreach (var constraintHandle in constraintHandleCollection) {
 				var constraint = metadata.GetGenericParameterConstraint(constraintHandle);
-				var ty = assembly.ResolveType(constraint.Type, new GenericContext(Owner), constraint.GetCustomAttributes());
+				var ty = module.ResolveType(constraint.Type, new GenericContext(Owner), constraint.GetCustomAttributes());
 				result.Add(ty);
 				hasNonInterfaceConstraint |= (ty.Kind != TypeKind.Interface);
 			}
@@ -145,12 +145,12 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 
 		public override int GetHashCode()
 		{
-			return 0x51fc5b83 ^ assembly.PEFile.GetHashCode() ^ handle.GetHashCode();
+			return 0x51fc5b83 ^ module.PEFile.GetHashCode() ^ handle.GetHashCode();
 		}
 
 		public override bool Equals(IType other)
 		{
-			return other is MetadataTypeParameter tp && handle == tp.handle && assembly.PEFile == tp.assembly.PEFile;
+			return other is MetadataTypeParameter tp && handle == tp.handle && module.PEFile == tp.module.PEFile;
 		}
 
 		public override string ToString()

ICSharpCode.Decompiler/TypeSystem/Implementation/MinimalCorlib.cs

@@ -29,9 +29,9 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 	/// An artificial "assembly" that contains all known types (<see cref="KnownTypeCode"/>) and no other types.
 	/// It does not contain any members.
 	/// </summary>
-	public sealed class MinimalCorlib : IAssembly
+	public sealed class MinimalCorlib : IModule
 	{
-		public static readonly IAssemblyReference Instance = new CorlibAssemblyReference();
+		public static readonly IModuleReference Instance = new CorlibModuleReference();
 
 		public ICompilation Compilation { get; }
 		CorlibTypeDefinition[] typeDefinitions;
@@ -49,13 +49,13 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 			}
 		}
 
-		bool IAssembly.IsMainAssembly => Compilation.MainAssembly == this;
+		bool IModule.IsMainModule => Compilation.MainModule == this;
 
-		string IAssembly.AssemblyName => "corlib";
-		string IAssembly.FullAssemblyName => "corlib";
+		string IModule.AssemblyName => "corlib";
+		string IModule.FullAssemblyName => "corlib";
 
-		Metadata.PEFile IAssembly.PEFile => null;
-		INamespace IAssembly.RootNamespace => rootNamespace;
+		Metadata.PEFile IModule.PEFile => null;
+		INamespace IModule.RootNamespace => rootNamespace;
 
 		public IEnumerable<ITypeDefinition> TopLevelTypeDefinitions => typeDefinitions.Where(td => td != null);
 		public IEnumerable<ITypeDefinition> TypeDefinitions => TopLevelTypeDefinitions;
@@ -69,17 +69,17 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 			return null;
 		}
 
-		IEnumerable<IAttribute> IAssembly.GetAssemblyAttributes() => EmptyList<IAttribute>.Instance;
-		IEnumerable<IAttribute> IAssembly.GetModuleAttributes() => EmptyList<IAttribute>.Instance;
+		IEnumerable<IAttribute> IModule.GetAssemblyAttributes() => EmptyList<IAttribute>.Instance;
+		IEnumerable<IAttribute> IModule.GetModuleAttributes() => EmptyList<IAttribute>.Instance;
 
-		bool IAssembly.InternalsVisibleTo(IAssembly assembly)
+		bool IModule.InternalsVisibleTo(IModule module)
 		{
-			return assembly == this;
+			return module == this;
 		}
 
-		sealed class CorlibAssemblyReference : IAssemblyReference
+		sealed class CorlibModuleReference : IModuleReference
 		{
-			IAssembly IAssemblyReference.Resolve(ITypeResolveContext context)
+			IModule IModuleReference.Resolve(ITypeResolveContext context)
 			{
 				return new MinimalCorlib(context.Compilation);
 			}
@@ -106,7 +106,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 			IEnumerable<INamespace> INamespace.ChildNamespaces => childNamespaces;
 			IEnumerable<ITypeDefinition> INamespace.Types => corlib.TopLevelTypeDefinitions.Where(td => td.Namespace == FullName);
 
-			IEnumerable<IAssembly> INamespace.ContributingAssemblies => new[] { corlib };
+			IEnumerable<IModule> INamespace.ContributingModules => new[] { corlib };
 
 			SymbolKind ISymbol.SymbolKind => SymbolKind.Namespace;
 			ICompilation ICompilationProvider.Compilation => corlib.Compilation;
@@ -191,7 +191,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 
 			public string Name => KnownTypeReference.Get(typeCode).Name;
 
-			IAssembly IEntity.ParentAssembly => corlib;
+			IModule IEntity.ParentModule => corlib;
 
 			Accessibility IEntity.Accessibility => Accessibility.Public;
 

ICSharpCode.Decompiler/TypeSystem/Implementation/PinnedType.cs

@@ -48,71 +48,4 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 			return new PinnedType(newType);
 		}
 	}
-
-	public sealed class PinnedTypeReference : ITypeReference
-	{
-		public ITypeReference ElementType { get; }
-
-		public PinnedTypeReference(ITypeReference elementType)
-		{
-			ElementType = elementType;
-		}
-
-		public IType Resolve(ITypeResolveContext context)
-		{
-			return new PinnedType(ElementType.Resolve(context));
-		}
-	}
-
-	public sealed class ModifiedTypeReference : ITypeReference
-	{
-		public ITypeReference ElementType { get; }
-		public ITypeReference ModifierType { get; }
-		public bool IsRequired { get; }
-
-		public ModifiedTypeReference(ITypeReference elementType, ITypeReference modifierType, bool isRequired)
-		{
-			ElementType = elementType;
-			ModifierType = modifierType;
-			IsRequired = isRequired;
-		}
-
-		public IType Resolve(ITypeResolveContext context)
-		{
-			return ElementType.Resolve(context);
-		}
-	}
-	
-	sealed class TypeDefTokenTypeReference : ITypeReference
-	{
-		readonly SRM.TypeDefinitionHandle token;
-
-		public TypeDefTokenTypeReference(SRM.TypeDefinitionHandle token)
-		{
-			this.token = token;
-		}
-
-		public IType Resolve(ITypeResolveContext context)
-		{
-			ITypeDefinition td = ((MetadataAssembly)context.CurrentAssembly).GetDefinition(token);
-			if (td != null)
-				return td;
-			return SpecialType.UnknownType;
-		}
-	}
-
-	sealed class TypeSpecTypeReference : ITypeReference
-	{
-		readonly SRM.TypeSpecification typeSpec;
-
-		public TypeSpecTypeReference(SRM.TypeSpecification typeSpec)
-		{
-			this.typeSpec = typeSpec;
-		}
-
-		public IType Resolve(ITypeResolveContext context)
-		{
-			return typeSpec.DecodeSignature(new TypeProvider(context.CurrentAssembly), new GenericContext(context));
-		}
-	}
 }

ICSharpCode.Decompiler/TypeSystem/Implementation/SimpleCompilation.cs

@@ -30,29 +30,29 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		readonly ITypeResolveContext context;
 		readonly CacheManager cacheManager = new CacheManager();
 		readonly KnownTypeCache knownTypeCache;
-		readonly IAssembly mainAssembly;
-		readonly IList<IAssembly> assemblies;
-		readonly IList<IAssembly> referencedAssemblies;
+		readonly IModule mainModule;
+		readonly IList<IModule> assemblies;
+		readonly IList<IModule> referencedAssemblies;
 		INamespace rootNamespace;
 		
-		public SimpleCompilation(IAssemblyReference mainAssembly, params IAssemblyReference[] assemblyReferences)
-			: this(mainAssembly, (IEnumerable<IAssemblyReference>)assemblyReferences)
+		public SimpleCompilation(IModuleReference mainAssembly, params IModuleReference[] assemblyReferences)
+			: this(mainAssembly, (IEnumerable<IModuleReference>)assemblyReferences)
 		{
 		}
 		
-		public SimpleCompilation(IAssemblyReference mainAssembly, IEnumerable<IAssemblyReference> assemblyReferences)
+		public SimpleCompilation(IModuleReference mainAssembly, IEnumerable<IModuleReference> assemblyReferences)
 		{
 			if (mainAssembly == null)
 				throw new ArgumentNullException("mainAssembly");
 			if (assemblyReferences == null)
 				throw new ArgumentNullException("assemblyReferences");
 			this.context = new SimpleTypeResolveContext(this);
-			this.mainAssembly = mainAssembly.Resolve(context);
-			List<IAssembly> assemblies = new List<IAssembly>();
-			assemblies.Add(this.mainAssembly);
-			List<IAssembly> referencedAssemblies = new List<IAssembly>();
+			this.mainModule = mainAssembly.Resolve(context);
+			List<IModule> assemblies = new List<IModule>();
+			assemblies.Add(this.mainModule);
+			List<IModule> referencedAssemblies = new List<IModule>();
 			foreach (var asmRef in assemblyReferences) {
-				IAssembly asm;
+				IModule asm;
 				try {
 					asm = asmRef.Resolve(context);
 				} catch (InvalidOperationException) {
@@ -68,15 +68,15 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 			this.knownTypeCache = new KnownTypeCache(this);
 		}
 		
-		public IAssembly MainAssembly {
+		public IModule MainModule {
 			get {
-				if (mainAssembly == null)
+				if (mainModule == null)
 					throw new InvalidOperationException("Compilation isn't initialized yet");
-				return mainAssembly;
+				return mainModule;
 			}
 		}
 		
-		public IList<IAssembly> Assemblies {
+		public IList<IModule> Modules {
 			get {
 				if (assemblies == null)
 					throw new InvalidOperationException("Compilation isn't initialized yet");
@@ -84,7 +84,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 			}
 		}
 		
-		public IList<IAssembly> ReferencedAssemblies {
+		public IList<IModule> ReferencedModules {
 			get {
 				if (referencedAssemblies == null)
 					throw new InvalidOperationException("Compilation isn't initialized yet");
@@ -114,7 +114,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 			// SimpleCompilation does not support extern aliases; but derived classes might.
 			// CreateRootNamespace() is virtual so that derived classes can change the global namespace.
 			INamespace[] namespaces = new INamespace[referencedAssemblies.Count + 1];
-			namespaces[0] = mainAssembly.RootNamespace;
+			namespaces[0] = mainModule.RootNamespace;
 			for (int i = 0; i < referencedAssemblies.Count; i++) {
 				namespaces[i + 1] = referencedAssemblies[i].RootNamespace;
 			}
@@ -144,7 +144,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 		
 		public override string ToString()
 		{
-			return "[SimpleCompilation " + mainAssembly.AssemblyName + "]";
+			return "[SimpleCompilation " + mainModule.AssemblyName + "]";
 		}
 	}
 }

ICSharpCode.Decompiler/TypeSystem/Implementation/SpecializedMember.cs

@@ -201,8 +201,8 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 			get { return baseMember.Compilation; }
 		}
 		
-		public IAssembly ParentAssembly {
-			get { return baseMember.ParentAssembly; }
+		public IModule ParentModule {
+			get { return baseMember.ParentModule; }
 		}
 
 		public virtual IMember Specialize(TypeParameterSubstitution newSubstitution)

ICSharpCode.Decompiler/TypeSystem/MetadataModule.cs

@@ -31,11 +31,10 @@ using ICSharpCode.Decompiler.Util;
 namespace ICSharpCode.Decompiler.TypeSystem
 {
 	/// <summary>
-	/// Used as context object for metadata TS entities;
-	/// should be turned into IAssembly implementation when the TS refactoring is complete.
+	/// Type system implementation for Metadata.PEFile.
 	/// </summary>
-	[DebuggerDisplay("<MetadataAssembly: {AssemblyName}>")]
-	public class MetadataAssembly : IAssembly
+	[DebuggerDisplay("<MetadataModule: {AssemblyName}>")]
+	public class MetadataModule : IModule
 	{
 		public ICompilation Compilation { get; }
 		internal readonly MetadataReader metadata;
@@ -49,7 +48,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		readonly MetadataProperty[] propertyDefs;
 		readonly MetadataEvent[] eventDefs;
 
-		internal MetadataAssembly(ICompilation compilation, Metadata.PEFile peFile, TypeSystemOptions options)
+		internal MetadataModule(ICompilation compilation, Metadata.PEFile peFile, TypeSystemOptions options)
 		{
 			this.Compilation = compilation;
 			this.PEFile = peFile;
@@ -87,7 +86,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		#region IAssembly interface
 		public PEFile PEFile { get; }
 
-		public bool IsMainAssembly => this == Compilation.MainAssembly;
+		public bool IsMainModule => this == Compilation.MainModule;
 
 		public string AssemblyName { get; }
 		public string FullAssemblyName { get; }
@@ -111,12 +110,12 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		#endregion
 
 		#region InternalsVisibleTo
-		public bool InternalsVisibleTo(IAssembly assembly)
+		public bool InternalsVisibleTo(IModule module)
 		{
-			if (this == assembly)
+			if (this == module)
 				return true;
 			foreach (string shortName in GetInternalsVisibleTo()) {
-				if (string.Equals(assembly.AssemblyName, shortName, StringComparison.OrdinalIgnoreCase))
+				if (string.Equals(module.AssemblyName, shortName, StringComparison.OrdinalIgnoreCase))
 					return true;
 			}
 			return false;
@@ -572,13 +571,13 @@ namespace ICSharpCode.Decompiler.TypeSystem
 
 		IType ResolveForwardedType(ExportedType forwarder)
 		{
-			IAssembly assembly = ResolveAssembly(forwarder);
+			IModule module = ResolveModule(forwarder);
 			var typeName = forwarder.GetFullTypeName(metadata);
-			if (assembly == null)
+			if (module == null)
 				return new UnknownType(typeName);
 			using (var busyLock = BusyManager.Enter(this)) {
 				if (busyLock.Success) {
-					var td = assembly.GetTypeDefinition(typeName);
+					var td = module.GetTypeDefinition(typeName);
 					if (td != null) {
 						return td;
 					}
@@ -586,7 +585,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 			}
 			return new UnknownType(typeName);
 
-			IAssembly ResolveAssembly(ExportedType type)
+			IModule ResolveModule(ExportedType type)
 			{
 				switch (type.Implementation.Kind) {
 					case HandleKind.AssemblyFile:
@@ -594,11 +593,11 @@ namespace ICSharpCode.Decompiler.TypeSystem
 						return this;
 					case HandleKind.ExportedType:
 						var outerType = metadata.GetExportedType((ExportedTypeHandle)type.Implementation);
-						return ResolveAssembly(outerType);
+						return ResolveModule(outerType);
 					case HandleKind.AssemblyReference:
 						var asmRef = metadata.GetAssemblyReference((AssemblyReferenceHandle)type.Implementation);
 						string shortName = metadata.GetString(asmRef.Name);
-						foreach (var asm in Compilation.Assemblies) {
+						foreach (var asm in Compilation.Modules) {
 							if (string.Equals(asm.AssemblyName, shortName, StringComparison.OrdinalIgnoreCase)) {
 								return asm;
 							}

ICSharpCode.Decompiler/TypeSystem/ReflectionHelper.cs

@@ -110,7 +110,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 				string name = SplitTypeParameterCountFromReflectionName(type.Name, out typeParameterCount);
 				return new NestedTypeReference(baseTypeRef, name, typeParameterCount);
 			} else {
-				IAssemblyReference assemblyReference = new DefaultAssemblyReference(type.Assembly.FullName);
+				IModuleReference assemblyReference = new DefaultAssemblyReference(type.Assembly.FullName);
 				int typeParameterCount;
 				string name = SplitTypeParameterCountFromReflectionName(type.Name, out typeParameterCount);
 				return new GetClassTypeReference(assemblyReference, type.Namespace, name, typeParameterCount);
@@ -203,7 +203,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		/// For looking up closed, assembly qualified type names, the root type resolve context for the compilation
 		/// is sufficient.
 		/// When looking up a type name that isn't assembly qualified, the type reference will look in
-		/// <see cref="ITypeResolveContext.CurrentAssembly"/> first, and if the type is not found there,
+		/// <see cref="ITypeResolveContext.CurrentModule"/> first, and if the type is not found there,
 		/// it will look in all other assemblies of the compilation.
 		/// </remarks>
 		/// <seealso cref="FullTypeName(string)"/>
@@ -347,7 +347,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		
 		static ITypeReference CreateGetClassTypeReference(string assemblyName, string typeName, int tpc)
 		{
-			IAssemblyReference assemblyReference;
+			IModuleReference assemblyReference;
 			if (assemblyName != null) {
 				assemblyReference = new DefaultAssemblyReference(assemblyName);
 			} else {

ICSharpCode.Decompiler/TypeSystem/SimpleTypeResolveContext.cs

@@ -26,7 +26,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 	public class SimpleTypeResolveContext : ITypeResolveContext
 	{
 		readonly ICompilation compilation;
-		readonly IAssembly currentAssembly;
+		readonly IModule currentModule;
 		readonly ITypeDefinition currentTypeDefinition;
 		readonly IMember currentMember;
 		
@@ -37,12 +37,12 @@ namespace ICSharpCode.Decompiler.TypeSystem
 			this.compilation = compilation;
 		}
 		
-		public SimpleTypeResolveContext(IAssembly assembly)
+		public SimpleTypeResolveContext(IModule module)
 		{
-			if (assembly == null)
-				throw new ArgumentNullException("assembly");
-			this.compilation = assembly.Compilation;
-			this.currentAssembly = assembly;
+			if (module == null)
+				throw new ArgumentNullException(nameof(module));
+			this.compilation = module.Compilation;
+			this.currentModule = module;
 		}
 		
 		public SimpleTypeResolveContext(IEntity entity)
@@ -50,15 +50,15 @@ namespace ICSharpCode.Decompiler.TypeSystem
 			if (entity == null)
 				throw new ArgumentNullException("entity");
 			this.compilation = entity.Compilation;
-			this.currentAssembly = entity.ParentAssembly;
+			this.currentModule = entity.ParentModule;
 			this.currentTypeDefinition = (entity as ITypeDefinition) ?? entity.DeclaringTypeDefinition;
 			this.currentMember = entity as IMember;
 		}
 		
-		private SimpleTypeResolveContext(ICompilation compilation, IAssembly currentAssembly, ITypeDefinition currentTypeDefinition, IMember currentMember)
+		private SimpleTypeResolveContext(ICompilation compilation, IModule currentModule, ITypeDefinition currentTypeDefinition, IMember currentMember)
 		{
 			this.compilation = compilation;
-			this.currentAssembly = currentAssembly;
+			this.currentModule = currentModule;
 			this.currentTypeDefinition = currentTypeDefinition;
 			this.currentMember = currentMember;
 		}
@@ -67,8 +67,8 @@ namespace ICSharpCode.Decompiler.TypeSystem
 			get { return compilation; }
 		}
 		
-		public IAssembly CurrentAssembly {
-			get { return currentAssembly; }
+		public IModule CurrentModule {
+			get { return currentModule; }
 		}
 		
 		public ITypeDefinition CurrentTypeDefinition {
@@ -81,12 +81,12 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		
 		public ITypeResolveContext WithCurrentTypeDefinition(ITypeDefinition typeDefinition)
 		{
-			return new SimpleTypeResolveContext(compilation, currentAssembly, typeDefinition, currentMember);
+			return new SimpleTypeResolveContext(compilation, currentModule, typeDefinition, currentMember);
 		}
 		
 		public ITypeResolveContext WithCurrentMember(IMember member)
 		{
-			return new SimpleTypeResolveContext(compilation, currentAssembly, currentTypeDefinition, member);
+			return new SimpleTypeResolveContext(compilation, currentModule, currentTypeDefinition, member);
 		}
 	}
 }

ICSharpCode.Decompiler/TypeSystem/SpecializingDecompilerTypeSystem.cs

@@ -51,6 +51,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		}
 
 		public Metadata.PEFile ModuleDefinition => context.ModuleDefinition;
+		public MetadataModule MainModule => context.MainModule;
 
 		public TypeParameterSubstitution Substitution {
 			get { return substitution; }
@@ -97,11 +98,6 @@ namespace ICSharpCode.Decompiler.TypeSystem
 				member = member.Specialize(substitution);
 			return member;
 		}
-
-		public PEFile GetModuleDefinition(IAssembly assembly)
-		{
-			return context.GetModuleDefinition(assembly);
-		}
 		
 		MethodSignature<IType> IDecompilerTypeSystem.DecodeMethodSignature(StandaloneSignatureHandle standaloneSignatureHandle)
 		{

ICSharpCode.Decompiler/TypeSystem/TupleType.cs

@@ -51,7 +51,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		
 		public TupleType(ICompilation compilation, ImmutableArray<IType> elementTypes,
 			ImmutableArray<string> elementNames = default(ImmutableArray<string>),
-			IAssembly valueTupleAssembly = null)
+			IModule valueTupleAssembly = null)
 		{
 			this.Compilation = compilation;
 			this.UnderlyingType = CreateUnderlyingType(compilation, elementTypes, valueTupleAssembly);
@@ -64,7 +64,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 			}
 		}
 
-		static ParameterizedType CreateUnderlyingType(ICompilation compilation, ImmutableArray<IType> elementTypes, IAssembly valueTupleAssembly)
+		static ParameterizedType CreateUnderlyingType(ICompilation compilation, ImmutableArray<IType> elementTypes, IModule valueTupleAssembly)
 		{
 			int remainder = (elementTypes.Length - 1) % (RestPosition - 1) + 1;
 			Debug.Assert(remainder >= 1 && remainder < RestPosition);
@@ -82,7 +82,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 			return type;
 		}
 
-		private static IType FindValueTupleType(ICompilation compilation, IAssembly valueTupleAssembly, int tpc)
+		private static IType FindValueTupleType(ICompilation compilation, IModule valueTupleAssembly, int tpc)
 		{
 			FullTypeName typeName = new TopLevelTypeName("System", "ValueTuple", tpc);
 			if (valueTupleAssembly != null) {
@@ -134,7 +134,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 				return new TupleType(
 					compilation,
 					elementTypes,
-					valueTupleAssembly: type.GetDefinition()?.ParentAssembly
+					valueTupleAssembly: type.GetDefinition()?.ParentModule
 				);
 			} else {
 				return null;
@@ -252,7 +252,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 			}
 			if (newElementTypes != null) {
 				return new TupleType(this.Compilation, newElementTypes.ToImmutableArray(), this.ElementNames,
-					this.GetDefinition()?.ParentAssembly);
+					this.GetDefinition()?.ParentModule);
 			} else {
 				return this;
 			}
@@ -343,7 +343,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		/// </summary>
 		public ImmutableArray<string> ElementNames { get; }
 
-		public IAssemblyReference ValueTupleAssembly { get; }
+		public IModuleReference ValueTupleAssembly { get; }
 
 		public TupleTypeReference(ImmutableArray<ITypeReference> elementTypes)
 		{
@@ -352,7 +352,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 
 		public TupleTypeReference(ImmutableArray<ITypeReference> elementTypes,
 			ImmutableArray<string> elementNames = default(ImmutableArray<string>),
-			IAssemblyReference valueTupleAssembly = null)
+			IModuleReference valueTupleAssembly = null)
 		{
 			this.ValueTupleAssembly = valueTupleAssembly;
 			this.ElementTypes = elementTypes;

ICSharpCode.Decompiler/TypeSystem/TypeProvider.cs

@@ -32,13 +32,13 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		SRM.ISignatureTypeProvider<IType, GenericContext>,
 		SRM.ICustomAttributeTypeProvider<IType>
 	{
-		readonly MetadataAssembly assembly;
+		readonly MetadataModule module;
 		readonly ICompilation compilation;
 
-		public TypeProvider(IAssembly assembly)
+		public TypeProvider(MetadataModule module)
 		{
-			this.assembly = (MetadataAssembly)assembly; // TODO: change parameter type instead of casting
-			this.compilation = assembly.Compilation;
+			this.module = module;
+			this.compilation = module.Compilation;
 		}
 
 		public TypeProvider(ICompilation compilation)
@@ -122,7 +122,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 
 		public IType GetTypeFromDefinition(SRM.MetadataReader reader, SRM.TypeDefinitionHandle handle, byte rawTypeKind)
 		{
-			ITypeDefinition td = assembly?.GetDefinition(handle);
+			ITypeDefinition td = module?.GetDefinition(handle);
 			if (td != null)
 				return td;
 			bool? isReferenceType = IsReferenceType(reader, handle, rawTypeKind);
@@ -131,10 +131,10 @@ namespace ICSharpCode.Decompiler.TypeSystem
 
 		public IType GetTypeFromReference(SRM.MetadataReader reader, SRM.TypeReferenceHandle handle, byte rawTypeKind)
 		{
-			var asmref = handle.GetDeclaringAssembly(reader);
+			var asmref = handle.GetDeclaringModule(reader);
 			bool? isReferenceType = IsReferenceType(reader, handle, rawTypeKind);
-			var gctr = new GetClassTypeReference(handle.GetFullTypeName(reader), handle.GetDeclaringAssembly(reader), isReferenceType);
-			return gctr.Resolve(assembly != null ? new SimpleTypeResolveContext(assembly) : new SimpleTypeResolveContext(compilation));
+			var gctr = new GetClassTypeReference(handle.GetFullTypeName(reader), handle.GetDeclaringModule(reader), isReferenceType);
+			return gctr.Resolve(module != null ? new SimpleTypeResolveContext(module) : new SimpleTypeResolveContext(compilation));
 		}
 
 		public IType GetTypeFromSerializedName(string name)
@@ -143,7 +143,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 				return null;
 			}
 			return ReflectionHelper.ParseReflectionName(name)
-				.Resolve(assembly != null ? new SimpleTypeResolveContext(assembly) : new SimpleTypeResolveContext(compilation));
+				.Resolve(module != null ? new SimpleTypeResolveContext(module) : new SimpleTypeResolveContext(compilation));
 		}
 		
 		public IType GetTypeFromSpecification(SRM.MetadataReader reader, GenericContext genericContext, SRM.TypeSpecificationHandle handle, byte rawTypeKind)

ICSharpCode.Decompiler/TypeSystem/TypeSystemExtensions.cs

@@ -262,7 +262,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		/// </summary>
 		public static IEnumerable<ITypeDefinition> GetAllTypeDefinitions (this ICompilation compilation)
 		{
-			return compilation.Assemblies.SelectMany(a => a.TypeDefinitions);
+			return compilation.Modules.SelectMany(a => a.TypeDefinitions);
 		}
 
 		/// <summary>
@@ -271,7 +271,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		/// </summary>
 		public static IEnumerable<ITypeDefinition> GetTopLevelTypeDefinitions (this ICompilation compilation)
 		{
-			return compilation.Assemblies.SelectMany(a => a.TopLevelTypeDefinitions);
+			return compilation.Modules.SelectMany(a => a.TopLevelTypeDefinitions);
 		}
 		#endregion
 		
@@ -299,14 +299,14 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		/// There can be multiple types with the same full name in a compilation, as a
 		/// full type name is only unique per assembly.
 		/// If there are multiple possible matches, this method will return just one of them.
-		/// When possible, use <see cref="IAssembly.GetTypeDefinition"/> instead to
+		/// When possible, use <see cref="IModule.GetTypeDefinition"/> instead to
 		/// retrieve a type from a specific assembly.
 		/// </remarks>
 		public static IType FindType(this ICompilation compilation, FullTypeName fullTypeName)
 		{
 			if (compilation == null)
 				throw new ArgumentNullException("compilation");
-			foreach (IAssembly asm in compilation.Assemblies) {
+			foreach (IModule asm in compilation.Modules) {
 				ITypeDefinition def = asm.GetTypeDefinition(fullTypeName);
 				if (def != null)
 					return def;
@@ -318,12 +318,12 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		/// Gets the type definition for the specified unresolved type.
 		/// Returns null if the unresolved type does not belong to this assembly.
 		/// </summary>
-		public static ITypeDefinition GetTypeDefinition(this IAssembly assembly, FullTypeName fullTypeName)
+		public static ITypeDefinition GetTypeDefinition(this IModule module, FullTypeName fullTypeName)
 		{
-			if (assembly == null)
+			if (module == null)
 				throw new ArgumentNullException("assembly");
 			TopLevelTypeName topLevelTypeName = fullTypeName.TopLevelTypeName;
-			ITypeDefinition typeDef = assembly.GetTypeDefinition(topLevelTypeName);
+			ITypeDefinition typeDef = module.GetTypeDefinition(topLevelTypeName);
 			if (typeDef == null)
 				return null;
 			int typeParameterCount = topLevelTypeName.TypeParameterCount;
@@ -418,11 +418,11 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		/// Gets the type definition for a top-level type.
 		/// </summary>
 		/// <remarks>This method uses ordinal name comparison, not the compilation's name comparer.</remarks>
-		public static ITypeDefinition GetTypeDefinition(this IAssembly assembly, string namespaceName, string name, int typeParameterCount = 0)
+		public static ITypeDefinition GetTypeDefinition(this IModule module, string namespaceName, string name, int typeParameterCount = 0)
 		{
-			if (assembly == null)
+			if (module == null)
 				throw new ArgumentNullException ("assembly");
-			return assembly.GetTypeDefinition (new TopLevelTypeName (namespaceName, name, typeParameterCount));
+			return module.GetTypeDefinition (new TopLevelTypeName (namespaceName, name, typeParameterCount));
 		}
 		#endregion
 		

ICSharpCode.Decompiler/TypeSystem/VarArgInstanceMethod.cs

@@ -220,8 +220,8 @@ namespace ICSharpCode.Decompiler.TypeSystem
 			get { return baseMethod.DeclaringType; }
 		}
 
-		public IAssembly ParentAssembly {
-			get { return baseMethod.ParentAssembly; }
+		public IModule ParentModule {
+			get { return baseMethod.ParentModule; }
 		}
 
 		public bool IsStatic {

ILSpy.BamlDecompiler/CecilType.cs

@@ -22,7 +22,7 @@ namespace ILSpy.BamlDecompiler
 		public string AssemblyQualifiedName {
 			get {
 				return type.FullName +
-					", " + type.ParentAssembly.FullAssemblyName;
+					", " + type.ParentModule.FullAssemblyName;
 			}
 		}
 		

ILSpy.BamlDecompiler/CecilTypeResolver.cs

@@ -27,7 +27,7 @@ namespace ILSpy.BamlDecompiler
 		
 		public bool IsLocalAssembly(string name)
 		{
-			return MakeShort(name) == compilation.MainAssembly.AssemblyName;
+			return MakeShort(name) == compilation.MainModule.AssemblyName;
 		}
 		
 		string MakeShort(string name)

ILSpy/Analyzers/AnalyzerEntityTreeNode.cs

@@ -40,7 +40,7 @@ namespace ICSharpCode.ILSpy.Analyzers
 		public override bool HandleAssemblyListChanged(ICollection<LoadedAssembly> removedAssemblies, ICollection<LoadedAssembly> addedAssemblies)
 		{
 			foreach (LoadedAssembly asm in removedAssemblies) {
-				if (this.Member.ParentAssembly.PEFile == asm.GetPEFileOrNull())
+				if (this.Member.ParentModule.PEFile == asm.GetPEFileOrNull())
 					return false; // remove this node
 			}
 			this.Children.RemoveAll(

ILSpy/Analyzers/AnalyzerSearchTreeNode.cs

@@ -51,7 +51,7 @@ namespace ICSharpCode.ILSpy.Analyzers
 		protected IEnumerable<AnalyzerTreeNode> FetchChildren(CancellationToken ct)
 		{
 			if (analyzer is IEntityAnalyzer<T> entityAnalyzer) {
-				var module = analyzedEntity.ParentAssembly.PEFile;
+				var module = analyzedEntity.ParentModule.PEFile;
 				var ts = new DecompilerTypeSystem(module, module.GetAssemblyResolver());
 				var context = new AnalyzerContext(ts) {
 					CancellationToken = ct,

ILSpy/Analyzers/Builtin/EventImplementsInterfaceAnalyzer.cs

@@ -34,14 +34,14 @@ namespace ICSharpCode.ILSpy.Analyzers.Builtin
 		public IEnumerable<IEntity> Analyze(IEvent analyzedEntity, ITypeDefinition type, AnalyzerContext context)
 		{
 			var token = analyzedEntity.DeclaringTypeDefinition.MetadataToken;
-			var module = analyzedEntity.DeclaringTypeDefinition.ParentAssembly.PEFile;
+			var module = analyzedEntity.DeclaringTypeDefinition.ParentModule.PEFile;
 			if (!type.GetAllBaseTypeDefinitions()
-				.Any(t => t.MetadataToken == token && t.ParentAssembly.PEFile == module))
+				.Any(t => t.MetadataToken == token && t.ParentModule.PEFile == module))
 				yield break;
 
 			foreach (var @event in type.GetEvents(options: GetMemberOptions.ReturnMemberDefinitions)) {
 				if (InheritanceHelper.GetBaseMembers(@event, true)
-					.Any(m => m.DeclaringTypeDefinition.MetadataToken == token && m.ParentAssembly.PEFile == module))
+					.Any(m => m.DeclaringTypeDefinition.MetadataToken == token && m.ParentModule.PEFile == module))
 					yield return @event;
 			}
 		}

ILSpy/Analyzers/Builtin/EventOverriddenByAnalyzer.cs

@@ -34,14 +34,14 @@ namespace ICSharpCode.ILSpy.Analyzers.Builtin
 		public IEnumerable<IEntity> Analyze(IEvent analyzedEntity, ITypeDefinition type, AnalyzerContext context)
 		{
 			if (!analyzedEntity.DeclaringType.GetAllBaseTypeDefinitions()
-				.Any(t => t.MetadataToken == analyzedEntity.DeclaringTypeDefinition.MetadataToken && t.ParentAssembly.PEFile == type.ParentAssembly.PEFile))
+				.Any(t => t.MetadataToken == analyzedEntity.DeclaringTypeDefinition.MetadataToken && t.ParentModule.PEFile == type.ParentModule.PEFile))
 				yield break;
 
 			foreach (var property in type.Properties) {
 				if (!property.IsOverride) continue;
 				if (InheritanceHelper.GetBaseMembers(property, false)
 					.Any(p => p.MetadataToken == analyzedEntity.MetadataToken &&
-							  p.ParentAssembly.PEFile == analyzedEntity.ParentAssembly.PEFile)) {
+							  p.ParentModule.PEFile == analyzedEntity.ParentModule.PEFile)) {
 					yield return property;
 				}
 			}

ILSpy/Analyzers/Builtin/FieldAccessAnalyzer.cs

@@ -89,7 +89,7 @@ namespace ICSharpCode.ILSpy.Analyzers.Builtin
 					continue;
 
 				found = field.MetadataToken == analyzedField.MetadataToken
-					&& field.ParentAssembly.PEFile == analyzedField.ParentAssembly.PEFile;
+					&& field.ParentModule.PEFile == analyzedField.ParentModule.PEFile;
 			}
 
 			if (found) {

ILSpy/Analyzers/Builtin/MethodImplementsInterfaceAnalyzer.cs

@@ -37,14 +37,14 @@ namespace ICSharpCode.ILSpy.Analyzers.Builtin
 		public IEnumerable<IEntity> Analyze(IMethod analyzedEntity, ITypeDefinition type, AnalyzerContext context)
 		{
 			var token = analyzedEntity.DeclaringTypeDefinition.MetadataToken;
-			var module = analyzedEntity.DeclaringTypeDefinition.ParentAssembly.PEFile;
+			var module = analyzedEntity.DeclaringTypeDefinition.ParentModule.PEFile;
 			if (!type.GetAllBaseTypeDefinitions()
-				.Any(t => t.MetadataToken == token && t.ParentAssembly.PEFile == module))
+				.Any(t => t.MetadataToken == token && t.ParentModule.PEFile == module))
 				yield break;
 
 			foreach (var method in type.GetMethods(options: GetMemberOptions.ReturnMemberDefinitions)) {
 				if (InheritanceHelper.GetBaseMembers(method, true)
-					.Any(m => m.DeclaringTypeDefinition.MetadataToken == token && m.ParentAssembly.PEFile == module))
+					.Any(m => m.DeclaringTypeDefinition.MetadataToken == token && m.ParentModule.PEFile == module))
 					yield return method;
 			}
 		}

ILSpy/Analyzers/Builtin/MethodOverriddenByAnalyzer.cs

@@ -34,14 +34,14 @@ namespace ICSharpCode.ILSpy.Analyzers.Builtin
 		public IEnumerable<IEntity> Analyze(IMethod analyzedEntity, ITypeDefinition type, AnalyzerContext context)
 		{
 			if (!analyzedEntity.DeclaringType.GetAllBaseTypeDefinitions()
-				.Any(t => t.MetadataToken == analyzedEntity.DeclaringTypeDefinition.MetadataToken && t.ParentAssembly.PEFile == type.ParentAssembly.PEFile))
+				.Any(t => t.MetadataToken == analyzedEntity.DeclaringTypeDefinition.MetadataToken && t.ParentModule.PEFile == type.ParentModule.PEFile))
 				yield break;
 
 			foreach (var property in type.Properties) {
 				if (!property.IsOverride) continue;
 				if (InheritanceHelper.GetBaseMembers(property, false)
 					.Any(p => p.MetadataToken == analyzedEntity.MetadataToken &&
-							  p.ParentAssembly.PEFile == analyzedEntity.ParentAssembly.PEFile)) {
+							  p.ParentModule.PEFile == analyzedEntity.ParentModule.PEFile)) {
 					yield return property;
 				}
 			}

ILSpy/Analyzers/Builtin/MethodUsedByAnalyzer.cs

@@ -74,7 +74,7 @@ namespace ICSharpCode.ILSpy.Analyzers.Builtin
 		static bool IsSameMember(IMember analyzedMethod, IMember m)
 		{
 			return m.MetadataToken == analyzedMethod.MetadataToken
-				&& m.ParentAssembly.PEFile == analyzedMethod.ParentAssembly.PEFile;
+				&& m.ParentModule.PEFile == analyzedMethod.ParentModule.PEFile;
 		}
 	}
 }

ILSpy/Analyzers/Builtin/MethodUsesAnalyzer.cs

@@ -48,7 +48,7 @@ namespace ICSharpCode.ILSpy.Analyzers.Builtin
 
 		IEnumerable<IEntity> ScanMethod(IMethod analyzedMethod, MethodDefinitionHandle handle, AnalyzerContext context)
 		{
-			var module = analyzedMethod.ParentAssembly.PEFile;
+			var module = analyzedMethod.ParentModule.PEFile;
 			var md = module.Metadata.GetMethodDefinition(handle);
 			if (!md.HasBody()) yield break;
 

ILSpy/Analyzers/Builtin/MethodVirtualUsedByAnalyzer.cs

@@ -56,7 +56,7 @@ namespace ICSharpCode.ILSpy.Analyzers.Builtin
 							case HandleKind.MethodSpecification:
 							case HandleKind.MemberReference:
 								var m = context.TypeSystem.ResolveAsMember(member)?.MemberDefinition;
-								if (m.MetadataToken == analyzedMethod.MetadataToken && m.ParentAssembly.PEFile == analyzedMethod.ParentAssembly.PEFile) {
+								if (m.MetadataToken == analyzedMethod.MetadataToken && m.ParentModule.PEFile == analyzedMethod.ParentModule.PEFile) {
 									yield return method;
 									yield break;
 								}

ILSpy/Analyzers/Builtin/PropertyImplementsInterfaceAnalyzer.cs

@@ -34,14 +34,14 @@ namespace ICSharpCode.ILSpy.Analyzers.Builtin
 		public IEnumerable<IEntity> Analyze(IProperty analyzedEntity, ITypeDefinition type, AnalyzerContext context)
 		{
 			var token = analyzedEntity.DeclaringTypeDefinition.MetadataToken;
-			var module = analyzedEntity.DeclaringTypeDefinition.ParentAssembly.PEFile;
+			var module = analyzedEntity.DeclaringTypeDefinition.ParentModule.PEFile;
 			if (!type.GetAllBaseTypeDefinitions()
-				.Any(t => t.MetadataToken == token && t.ParentAssembly.PEFile == module))
+				.Any(t => t.MetadataToken == token && t.ParentModule.PEFile == module))
 				yield break;
 
 			foreach (var property in type.GetProperties(options: GetMemberOptions.ReturnMemberDefinitions)) {
 				if (InheritanceHelper.GetBaseMembers(property, true)
-					.Any(m => m.DeclaringTypeDefinition.MetadataToken == token && m.ParentAssembly.PEFile == module))
+					.Any(m => m.DeclaringTypeDefinition.MetadataToken == token && m.ParentModule.PEFile == module))
 					yield return property;
 			}
 		}

ILSpy/Analyzers/Builtin/PropertyOverriddenByAnalyzer.cs

@@ -37,14 +37,14 @@ namespace ICSharpCode.ILSpy.Analyzers.Builtin
 		public IEnumerable<IEntity> Analyze(IProperty analyzedEntity, ITypeDefinition type, AnalyzerContext context)
 		{
 			if (!analyzedEntity.DeclaringType.GetAllBaseTypeDefinitions()
-				.Any(t => t.MetadataToken == analyzedEntity.DeclaringTypeDefinition.MetadataToken && t.ParentAssembly.PEFile == type.ParentAssembly.PEFile))
+				.Any(t => t.MetadataToken == analyzedEntity.DeclaringTypeDefinition.MetadataToken && t.ParentModule.PEFile == type.ParentModule.PEFile))
 				yield break;
 
 			foreach (var property in type.Properties) {
 				if (!property.IsOverride) continue;
 				if (InheritanceHelper.GetBaseMembers(property, false)
 					.Any(p => p.MetadataToken == analyzedEntity.MetadataToken &&
-							  p.ParentAssembly.PEFile == analyzedEntity.ParentAssembly.PEFile)) {
+							  p.ParentModule.PEFile == analyzedEntity.ParentModule.PEFile)) {
 					yield return property;
 				}
 			}

ILSpy/Analyzers/Builtin/TypeExposedByAnalyzer.cs

@@ -40,7 +40,7 @@ namespace ICSharpCode.ILSpy.Analyzers.Builtin
 		{
 			if (analyzedType.Kind == TypeKind.Enum
 				&& type.MetadataToken == analyzedType.MetadataToken
-				&& type.ParentAssembly.PEFile == analyzedType.ParentAssembly.PEFile)
+				&& type.ParentModule.PEFile == analyzedType.ParentModule.PEFile)
 				yield break;
 
 			if (!context.Language.ShowMember(type))

ILSpy/Analyzers/Builtin/TypeInstantiatedByAnalyzer.cs

@@ -57,7 +57,7 @@ namespace ICSharpCode.ILSpy.Analyzers.Builtin
 					continue;
 
 				found = ctor.DeclaringTypeDefinition?.MetadataToken == analyzedEntity.MetadataToken
-					&& ctor.ParentAssembly.PEFile == analyzedEntity.ParentAssembly.PEFile;
+					&& ctor.ParentModule.PEFile == analyzedEntity.ParentModule.PEFile;
 			}
 
 			if (found) {

ILSpy/Analyzers/Builtin/TypeUsedByAnalyzer.cs

@@ -141,7 +141,7 @@ namespace ICSharpCode.ILSpy.Analyzers.Builtin
 
 		public IEnumerable<IEntity> Analyze(ITypeDefinition analyzedEntity, ITypeDefinition type, AnalyzerContext context)
 		{
-			if (analyzedEntity.ParentAssembly.PEFile == type.ParentAssembly.PEFile
+			if (analyzedEntity.ParentModule.PEFile == type.ParentModule.PEFile
 				&& analyzedEntity.MetadataToken == type.MetadataToken)
 				yield break;
 
@@ -185,7 +185,7 @@ namespace ICSharpCode.ILSpy.Analyzers.Builtin
 		public override IType VisitTypeDefinition(ITypeDefinition type)
 		{
 			Found |= typeDefinition.MetadataToken == type.MetadataToken
-				&& typeDefinition.ParentAssembly.PEFile == type.ParentAssembly.PEFile;
+				&& typeDefinition.ParentModule.PEFile == type.ParentModule.PEFile;
 			return base.VisitTypeDefinition(type);
 		}
 	}

ILSpy/Analyzers/ScopedWhereUsedAnalyzer.cs

@@ -35,7 +35,7 @@ namespace ICSharpCode.ILSpy.Analyzers
 	{
 		readonly Language language;
 		readonly IAnalyzer<T> analyzer;
-		readonly IAssembly assemblyScope;
+		readonly IModule assemblyScope;
 		readonly T analyzedEntity;
 		ITypeDefinition typeScope;
 
@@ -47,7 +47,7 @@ namespace ICSharpCode.ILSpy.Analyzers
 			this.language = language ?? throw new ArgumentNullException(nameof(language));
 			this.analyzer = analyzer ?? throw new ArgumentNullException(nameof(analyzer));
 			this.analyzedEntity = analyzedEntity;
-			this.assemblyScope = analyzedEntity.ParentAssembly;
+			this.assemblyScope = analyzedEntity.ParentModule;
 			if (analyzedEntity is ITypeDefinition type) {
 				this.typeScope = type;
 				this.typeAccessibility = type.Accessibility;
@@ -112,7 +112,7 @@ namespace ICSharpCode.ILSpy.Analyzers
 		{
 			var ts = new DecompilerTypeSystem(module, module.GetAssemblyResolver());
 			var context = new AnalyzerContext(ts) { CancellationToken = ct, Language = language };
-			foreach (var type in ts.MainAssembly.TypeDefinitions) {
+			foreach (var type in ts.MainModule.TypeDefinitions) {
 				ct.ThrowIfCancellationRequested();
 				if (type.MetadataToken.IsNil) continue;
 				context.CodeMappingInfo = language.GetCodeMappingInfo(module, type.MetadataToken);

ILSpy/Languages/CSharpLanguage.cs

@@ -131,7 +131,7 @@ namespace ICSharpCode.ILSpy
 
 		public override void DecompileMethod(IMethod method, ITextOutput output, DecompilationOptions options)
 		{
-			PEFile assembly = method.ParentAssembly.PEFile;
+			PEFile assembly = method.ParentModule.PEFile;
 			AddReferenceWarningMessage(assembly, output);
 			WriteCommentLine(output, TypeToString(method.DeclaringType, includeNamespace: true));
 			CSharpDecompiler decompiler = CreateDecompiler(assembly, options);
@@ -198,7 +198,7 @@ namespace ICSharpCode.ILSpy
 
 		public override void DecompileProperty(IProperty property, ITextOutput output, DecompilationOptions options)
 		{
-			PEFile assembly = property.ParentAssembly.PEFile;
+			PEFile assembly = property.ParentModule.PEFile;
 			AddReferenceWarningMessage(assembly, output);
 			CSharpDecompiler decompiler = CreateDecompiler(assembly, options);
 			WriteCommentLine(output, TypeToString(property.DeclaringType, includeNamespace: true));
@@ -207,7 +207,7 @@ namespace ICSharpCode.ILSpy
 
 		public override void DecompileField(IField field, ITextOutput output, DecompilationOptions options)
 		{
-			PEFile assembly = field.ParentAssembly.PEFile;
+			PEFile assembly = field.ParentModule.PEFile;
 			AddReferenceWarningMessage(assembly, output);
 			WriteCommentLine(output, TypeToString(field.DeclaringType, includeNamespace: true));
 			CSharpDecompiler decompiler = CreateDecompiler(assembly, options);
@@ -266,7 +266,7 @@ namespace ICSharpCode.ILSpy
 
 		public override void DecompileEvent(IEvent @event, ITextOutput output, DecompilationOptions options)
 		{
-			PEFile assembly = @event.ParentAssembly.PEFile;
+			PEFile assembly = @event.ParentModule.PEFile;
 			AddReferenceWarningMessage(assembly, output);
 			base.WriteCommentLine(output, TypeToString(@event.DeclaringType, includeNamespace: true));
 			CSharpDecompiler decompiler = CreateDecompiler(assembly, options);
@@ -275,7 +275,7 @@ namespace ICSharpCode.ILSpy
 
 		public override void DecompileType(ITypeDefinition type, ITextOutput output, DecompilationOptions options)
 		{
-			PEFile assembly = type.ParentAssembly.PEFile;
+			PEFile assembly = type.ParentModule.PEFile;
 			AddReferenceWarningMessage(assembly, output);
 			WriteCommentLine(output, TypeToString(type, includeNamespace: true));
 			CSharpDecompiler decompiler = CreateDecompiler(assembly, options);
@@ -331,7 +331,7 @@ namespace ICSharpCode.ILSpy
 				using (options.FullDecompilation ? null : LoadedAssembly.DisableAssemblyLoad()) {
 					IAssemblyResolver assemblyResolver = assembly.GetAssemblyResolver();
 					var typeSystem = new DecompilerTypeSystem(module, assemblyResolver, options.DecompilerSettings);
-					var globalType = typeSystem.MainAssembly.TypeDefinitions.FirstOrDefault();
+					var globalType = typeSystem.MainModule.TypeDefinitions.FirstOrDefault();
 					if (globalType != null) {
 						output.Write("// Global type: ");
 						output.WriteReference(globalType, globalType.FullName);
@@ -556,7 +556,7 @@ namespace ICSharpCode.ILSpy
 
 		public override bool ShowMember(IEntity member)
 		{
-			PEFile assembly = member.ParentAssembly.PEFile;
+			PEFile assembly = member.ParentModule.PEFile;
 			return showAllMembers || !CSharpDecompiler.MemberIsHidden(assembly, member.MetadataToken, new DecompilationOptions().DecompilerSettings);
 		}
 

ILSpy/Languages/ILAstLanguage.cs

@@ -74,7 +74,7 @@ namespace ICSharpCode.ILSpy
 		{
 			base.DecompileMethod(method, output, options);
 			new ReflectionDisassembler(output, options.CancellationToken)
-				.DisassembleMethodHeader(method.ParentAssembly.PEFile, (SRM.MethodDefinitionHandle)method.MetadataToken);
+				.DisassembleMethodHeader(method.ParentModule.PEFile, (SRM.MethodDefinitionHandle)method.MetadataToken);
 			output.WriteLine();
 			output.WriteLine();
 		}
@@ -86,7 +86,7 @@ namespace ICSharpCode.ILSpy
 			public override void DecompileMethod(IMethod method, ITextOutput output, DecompilationOptions options)
 			{
 				base.DecompileMethod(method, output, options);
-				var module = method.ParentAssembly.PEFile;
+				var module = method.ParentModule.PEFile;
 				var methodDef = module.Metadata.GetMethodDefinition((SRM.MethodDefinitionHandle)method.MetadataToken);
 				if (!methodDef.HasBody())
 					return;
@@ -109,7 +109,7 @@ namespace ICSharpCode.ILSpy
 			public override void DecompileMethod(IMethod method, ITextOutput output, DecompilationOptions options)
 			{
 				base.DecompileMethod(method, output, options);
-				var module = method.ParentAssembly.PEFile;
+				var module = method.ParentModule.PEFile;
 				var metadata = module.Metadata;
 				var methodDef = metadata.GetMethodDefinition((SRM.MethodDefinitionHandle)method.MetadataToken);
 				if (!methodDef.HasBody())

ILSpy/Languages/ILLanguage.cs

@@ -63,21 +63,21 @@ namespace ICSharpCode.ILSpy
 		public override void DecompileMethod(IMethod method, ITextOutput output, DecompilationOptions options)
 		{
 			var dis = CreateDisassembler(output, options);
-			dis.AssemblyResolver = method.ParentAssembly.PEFile.GetAssemblyResolver();
-			dis.DisassembleMethod(method.ParentAssembly.PEFile, (MethodDefinitionHandle)method.MetadataToken);
+			dis.AssemblyResolver = method.ParentModule.PEFile.GetAssemblyResolver();
+			dis.DisassembleMethod(method.ParentModule.PEFile, (MethodDefinitionHandle)method.MetadataToken);
 		}
 		
 		public override void DecompileField(IField field, ITextOutput output, DecompilationOptions options)
 		{
 			var dis = CreateDisassembler(output, options);
-			dis.AssemblyResolver = field.ParentAssembly.PEFile.GetAssemblyResolver();
-			dis.DisassembleField(field.ParentAssembly.PEFile, (FieldDefinitionHandle)field.MetadataToken);
+			dis.AssemblyResolver = field.ParentModule.PEFile.GetAssemblyResolver();
+			dis.DisassembleField(field.ParentModule.PEFile, (FieldDefinitionHandle)field.MetadataToken);
 		}
 		
 		public override void DecompileProperty(IProperty property, ITextOutput output, DecompilationOptions options)
 		{
 			var dis = CreateDisassembler(output, options);
-			PEFile module = property.ParentAssembly.PEFile;
+			PEFile module = property.ParentModule.PEFile;
 			dis.AssemblyResolver = module.GetAssemblyResolver();
 			dis.DisassembleProperty(module, (PropertyDefinitionHandle)property.MetadataToken);
 			var pd = module.Metadata.GetPropertyDefinition((PropertyDefinitionHandle)property.MetadataToken);
@@ -100,7 +100,7 @@ namespace ICSharpCode.ILSpy
 		public override void DecompileEvent(IEvent ev, ITextOutput output, DecompilationOptions options)
 		{
 			var dis = CreateDisassembler(output, options);
-			PEFile module = ev.ParentAssembly.PEFile;
+			PEFile module = ev.ParentModule.PEFile;
 			dis.AssemblyResolver = module.GetAssemblyResolver();
 			dis.DisassembleEvent(module, (EventDefinitionHandle)ev.MetadataToken);
 
@@ -127,7 +127,7 @@ namespace ICSharpCode.ILSpy
 		public override void DecompileType(ITypeDefinition type, ITextOutput output, DecompilationOptions options)
 		{
 			var dis = CreateDisassembler(output, options);
-			PEFile module = type.ParentAssembly.PEFile;
+			PEFile module = type.ParentModule.PEFile;
 			dis.AssemblyResolver = module.GetAssemblyResolver();
 			dis.DisassembleType(module, (TypeDefinitionHandle)type.MetadataToken);
 		}
@@ -135,7 +135,7 @@ namespace ICSharpCode.ILSpy
 		public override void DecompileNamespace(string nameSpace, IEnumerable<ITypeDefinition> types, ITextOutput output, DecompilationOptions options)
 		{
 			var dis = CreateDisassembler(output, options);
-			PEFile module = types.FirstOrDefault()?.ParentAssembly.PEFile;
+			PEFile module = types.FirstOrDefault()?.ParentModule.PEFile;
 			dis.AssemblyResolver = module.GetAssemblyResolver();
 			dis.DisassembleNamespace(nameSpace, module, types.Select(t => (TypeDefinitionHandle)t.MetadataToken));
 		}

ILSpy/SearchPane.cs

@@ -222,7 +222,7 @@ namespace ICSharpCode.ILSpy
 							continue;
 						CancellationToken cancellationToken = cts.Token;
 
-						foreach (var type in typeSystem.MainAssembly.TopLevelTypeDefinitions) {
+						foreach (var type in typeSystem.MainModule.TopLevelTypeDefinitions) {
 							cancellationToken.ThrowIfCancellationRequested();
 							searcher.Search(type, language, AddResult);
 						}

ILSpy/SearchStrategies.cs

@@ -321,7 +321,7 @@ namespace ICSharpCode.ILSpy
 		{
 			if (method == null)
 				return false;
-			var module = ((MetadataAssembly)method.ParentAssembly).PEFile;
+			var module = ((MetadataModule)method.ParentModule).PEFile;
 			var m = (SRM.MethodDefinitionHandle)method.MetadataToken;
 			if (m.IsNil)
 				return false;

ILSpy/TextView/DecompilerTextView.cs

@@ -211,9 +211,9 @@ namespace ICSharpCode.ILSpy.TextView
 				XmlDocRenderer renderer = new XmlDocRenderer();
 				renderer.AppendText(MainWindow.Instance.CurrentLanguage.GetTooltip(entity));
 				try {
-					if (entity.ParentAssembly == null || entity.ParentAssembly.PEFile == null)
+					if (entity.ParentModule == null || entity.ParentModule.PEFile == null)
 						return null;
-					var docProvider = XmlDocLoader.LoadDocumentation(entity.ParentAssembly.PEFile);
+					var docProvider = XmlDocLoader.LoadDocumentation(entity.ParentModule.PEFile);
 					if (docProvider != null) {
 						string documentation = docProvider.GetDocumentation(XmlDocKeyProvider.GetKey(entity));
 						if (documentation != null) {
@@ -237,9 +237,9 @@ namespace ICSharpCode.ILSpy.TextView
 				XmlDocRenderer renderer = new XmlDocRenderer();
 				renderer.AppendText(MainWindow.Instance.CurrentLanguage.GetTooltip(resolved));
 				try {
-					if (resolved.ParentAssembly == null || resolved.ParentAssembly.PEFile == null)
+					if (resolved.ParentModule == null || resolved.ParentModule.PEFile == null)
 						return null;
-					var docProvider = XmlDocLoader.LoadDocumentation(resolved.ParentAssembly.PEFile);
+					var docProvider = XmlDocLoader.LoadDocumentation(resolved.ParentModule.PEFile);
 					if (docProvider != null) {
 						string documentation = docProvider.GetDocumentation(XmlDocKeyProvider.GetKey(resolved));
 						if (documentation != null) {

ILSpy/TreeNodes/AssemblyListTreeNode.cs

@@ -177,11 +177,9 @@ namespace ICSharpCode.ILSpy.TreeNodes
 			return null;
 		}
 
-		public AssemblyTreeNode FindAssemblyNode(IAssembly module)
+		public AssemblyTreeNode FindAssemblyNode(IModule module)
 		{
-			if (!(module is MetadataAssembly assembly))
-				return null;
-			return FindAssemblyNode(assembly.PEFile);
+			return FindAssemblyNode(module.PEFile);
 		}
 
 		public AssemblyTreeNode FindAssemblyNode(PEFile module)
@@ -224,7 +222,7 @@ namespace ICSharpCode.ILSpy.TreeNodes
 					return decl.Children.OfType<TypeTreeNode>().FirstOrDefault(t => t.TypeDefinition.MetadataToken == def.MetadataToken && !t.IsHidden);
 				}
 			} else {
-				AssemblyTreeNode asm = FindAssemblyNode(def.ParentAssembly);
+				AssemblyTreeNode asm = FindAssemblyNode(def.ParentModule);
 				if (asm != null) {
 					return asm.FindTypeNode(def);
 				}

ILSpy/TreeNodes/AssemblyTreeNode.cs

@@ -140,7 +140,7 @@ namespace ICSharpCode.ILSpy.TreeNodes
 				return;
 			}
 			typeSystem = LoadedAssembly.GetTypeSystemOrNull();
-			var assembly = (MetadataAssembly)typeSystem.MainAssembly;
+			var assembly = (MetadataModule)typeSystem.MainModule;
 			var metadata = module.Metadata;
 
 			this.Children.Add(new ReferenceFolderTreeNode(module, this));

ILSpy/TreeNodes/BaseTypesEntryNode.cs

@@ -53,7 +53,7 @@ namespace ICSharpCode.ILSpy.TreeNodes
 			var t = typeSystem.ResolveAsType(handle).GetDefinition();
 			if (t != null) {
 				showExpander = t.DirectBaseTypes.Any();
-				var other = t.ParentAssembly.PEFile.GetTypeSystemOrNull();
+				var other = t.ParentModule.PEFile.GetTypeSystemOrNull();
 				Debug.Assert(other != null);
 				t = other.FindType(t.FullTypeName).GetDefinition();
 			} else {
@@ -74,7 +74,7 @@ namespace ICSharpCode.ILSpy.TreeNodes
 		{
 			var t = TryResolve(module, handle, type, false);
 			if (t != null) {
-				BaseTypesTreeNode.AddBaseTypes(this.Children, t.ParentAssembly.PEFile, t);
+				BaseTypesTreeNode.AddBaseTypes(this.Children, t.ParentModule.PEFile, t);
 			}
 		}
 

ILSpy/TreeNodes/DerivedTypesTreeNode.cs

@@ -63,11 +63,11 @@ namespace ICSharpCode.ILSpy.TreeNodes
 		internal static IEnumerable<DerivedTypesEntryNode> FindDerivedTypes(AssemblyList list, ITypeDefinition type,
 			PEFile[] assemblies, CancellationToken cancellationToken)
 		{
-			var definitionMetadata = type.ParentAssembly.PEFile.Metadata;
+			var definitionMetadata = type.ParentModule.PEFile.Metadata;
 			var metadataToken = (SRM.TypeDefinitionHandle)type.MetadataToken;
 			foreach (var module in assemblies) {
 				var metadata = module.Metadata;
-				var assembly = (MetadataAssembly)module.GetTypeSystemOrNull().MainAssembly;
+				var assembly = (MetadataModule)module.GetTypeSystemOrNull().MainModule;
 				foreach (var h in metadata.TypeDefinitions) {
 					cancellationToken.ThrowIfCancellationRequested();
 					var td = metadata.GetTypeDefinition(h);

ILSpy/TypeExtensionMethodsAnalyzer.cs

@@ -25,7 +25,7 @@ namespace ICSharpCode.ILSpy.Analyzers.Builtin
 				var firstParamType = method.Parameters[0].Type.GetDefinition();
 				if (firstParamType != null &&
 					firstParamType.MetadataToken == analyzedType.MetadataToken &&
-					firstParamType.ParentAssembly.PEFile == analyzedType.ParentAssembly.PEFile)
+					firstParamType.ParentModule.PEFile == analyzedType.ParentModule.PEFile)
 					yield return method;
 			}
 		}

TestPlugin/CustomLanguage.cs

@@ -33,7 +33,7 @@ namespace TestPlugin
 		// There are several methods available to override; in this sample, we deal with methods only
 		public override void DecompileMethod(IMethod method, ITextOutput output, DecompilationOptions options)
 		{
-			var module = ((MetadataAssembly)method.ParentAssembly).PEFile;
+			var module = ((MetadataModule)method.ParentModule).PEFile;
 			var methodDef = module.Metadata.GetMethodDefinition((MethodDefinitionHandle)method.MetadataToken);
 			if (methodDef.HasBody()) {
 				var methodBody = module.Reader.GetMethodBody(methodDef.RelativeVirtualAddress);