Implement .NET Framework / .NET Core differences for GetModuleType

src/AsmResolver.DotNet/ModuleDefinition.cs

@@ -304,7 +304,7 @@ public ModuleDefinition(Utf8String? name)
             AssemblyReferences.Add((AssemblyReference)CorLibTypeFactory.CorLibScope);
             MetadataResolver = new DefaultMetadataResolver(new DotNetFrameworkAssemblyResolver());
 
-            TopLevelTypes.Add(new TypeDefinition(null, "<Module>", 0));
+            TopLevelTypes.Add(new TypeDefinition(null, TypeDefinition.ModuleTypeName, 0));
         }
 
         /// <summary>
@@ -325,7 +325,7 @@ public ModuleDefinition(string? name, AssemblyReference corLib)
             OriginalTargetRuntime = DetectTargetRuntime();
             MetadataResolver = new DefaultMetadataResolver(CreateAssemblyResolver(UncachedFileService.Instance));
 
-            TopLevelTypes.Add(new TypeDefinition(null, "<Module>", 0));
+            TopLevelTypes.Add(new TypeDefinition(null, TypeDefinition.ModuleTypeName, 0));
         }
 
         /// <summary>
@@ -915,21 +915,35 @@ public IEnumerable<TypeDefinition> GetAllTypes()
         /// Obtains the global scope type of the .NET module.
         /// </summary>
         /// <returns>The module type.</returns>
-        public TypeDefinition? GetModuleType() => TopLevelTypes.Count > 0 ? TopLevelTypes[0] : null;
+        public TypeDefinition? GetModuleType()
+        {
+            if (TopLevelTypes.Count == 0)
+                return null;
+
+            var firstType = TopLevelTypes[0];
+
+            // Only .NET Framework allows the module type to be renamed to something else.
+            if (!OriginalTargetRuntime.IsNetFramework && !firstType.IsTypeOfUtf8(null, TypeDefinition.ModuleTypeName))
+                return null;
+
+            return firstType;
+        }
 
         /// <summary>
         /// Obtains or creates the global scope type of the .NET module.
         /// </summary>
         /// <returns>The module type.</returns>
         public TypeDefinition GetOrCreateModuleType()
         {
-            if (TopLevelTypes.Count == 0 || TopLevelTypes[0].Name != "<Module>")
+            var moduleType = GetModuleType();
+
+            if (moduleType is null)
             {
-                var moduleType = new TypeDefinition(null, "<Module>", 0);
+                moduleType = new TypeDefinition(null, TypeDefinition.ModuleTypeName, 0);
                 TopLevelTypes.Insert(0, moduleType);
             }
 
-            return TopLevelTypes[0];
+            return moduleType;
         }
 
         /// <summary>

src/AsmResolver.DotNet/Serialized/SerializedModuleDefinition.cs

@@ -336,12 +336,11 @@ private CorLibTypeFactory CreateCorLibTypeFactory()
             // TODO: perhaps check public key tokens.
 
             IResolutionScope? mostRecentCorLib = null;
-            var mostRecentVersion = new Version();
             foreach (var reference in AssemblyReferences)
             {
                 if (reference.Name is not null && KnownCorLibs.KnownCorLibNames.Contains(reference.Name))
                 {
-                    if (mostRecentVersion < reference.Version)
+                    if (mostRecentCorLib is null || reference.Version > mostRecentCorLib.GetAssembly()!.Version)
                         mostRecentCorLib = reference;
                 }
             }

src/AsmResolver.DotNet/TypeDefinition.cs

@@ -25,6 +25,8 @@ public class TypeDefinition :
         IOwnedCollectionElement<ModuleDefinition>,
         IOwnedCollectionElement<TypeDefinition>
     {
+        internal static readonly Utf8String ModuleTypeName = "<Module>";
+
         private readonly LazyVariable<Utf8String?> _namespace;
         private readonly LazyVariable<Utf8String?> _name;
         private readonly LazyVariable<ITypeDefOrRef?> _baseType;
@@ -492,10 +494,11 @@ public bool IsDelegate
         }
 
         /// <summary>
-        /// <c>true</c> if this is the global (aka. &lt;Module&gt;) type, otherwise <c>false</c>.
+        /// <c>true</c> if this is the global (i.e., &lt;Module&gt;) type, otherwise <c>false</c>.
         /// </summary>
         /// <remarks>
-        /// If the global (aka. &lt;Module&gt;) type was not added or does not exist yet in the <see cref="Module"/> will return false.
+        /// If the global (i.e., &lt;Module&gt;) type was not added or does not exist yet in the <see cref="Module"/>,
+        /// this will return <c>false</c>.
         /// </remarks>
         public bool IsModuleType
         {

test/AsmResolver.DotNet.Tests/ModuleDefinitionTest.cs

@@ -412,5 +412,63 @@ public void RewriteSystemPrivateXml()
             using var stream = new MemoryStream();
             module.Write(stream);
         }
+
+        [Fact]
+        public void GetModuleTypeNetFramework()
+        {
+            var module = ModuleDefinition.FromBytes(Properties.Resources.ModuleCctorNetFramework);
+
+            // Module type should exist.
+            var type = module.GetModuleType();
+            Assert.NotNull(type);
+            Assert.Equal("CustomModuleType", type.Name);
+
+            // Creating module type should give us the existing type.
+            Assert.Same(type, module.GetOrCreateModuleType());
+        }
+
+        [Fact]
+        public void GetModuleTypeNet6()
+        {
+            var module = ModuleDefinition.FromBytes(Properties.Resources.ModuleCctorNet6);
+
+            // Module type should exist.
+            var type = module.GetModuleType();
+            Assert.NotNull(type);
+            Assert.Equal("<Module>", type.Name);
+
+            // Creating module type should give us the existing type.
+            Assert.Same(type, module.GetOrCreateModuleType());
+        }
+
+        [Fact]
+        public void GetModuleTypeAbsentNet6()
+        {
+            var module = ModuleDefinition.FromBytes(Properties.Resources.ModuleCctorAbsentNet6);
+
+            // Module type should not exist.
+            var type = module.GetModuleType();
+            Assert.Null(type);
+
+            // Creating should add it to the module.
+            type = module.GetOrCreateModuleType();
+            Assert.NotNull(type);
+            Assert.Same(type, module.GetModuleType());
+        }
+
+        [Fact]
+        public void GetModuleTypeLookalikeNet6()
+        {
+            var module = ModuleDefinition.FromBytes(Properties.Resources.ModuleCctorLookalikeNet6);
+
+            // Module type should not exist.
+            var type = module.GetModuleType();
+            Assert.Null(type);
+
+            // Creating should add it to the module.
+            type = module.GetOrCreateModuleType();
+            Assert.NotNull(type);
+            Assert.Same(type, module.GetModuleType());
+        }
     }
 }

test/AsmResolver.DotNet.Tests/Properties/Resources.resx

@@ -141,4 +141,16 @@
     <data name="MyLibrary_X64" type="System.Resources.ResXFileRef, System.Windows.Forms">
         <value>..\Resources\MyLibrary.x64.dll;System.Byte[], mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
     </data>
+    <data name="ModuleCctorAbsentNet6" type="System.Resources.ResXFileRef, System.Windows.Forms">
+        <value>..\Resources\ModuleCctorAbsentNet6.dll;System.Byte[], mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+    </data>
+    <data name="ModuleCctorLookalikeNet6" type="System.Resources.ResXFileRef, System.Windows.Forms">
+        <value>..\Resources\ModuleCctorLookalikeNet6.dll;System.Byte[], mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+    </data>
+    <data name="ModuleCctorNet6" type="System.Resources.ResXFileRef, System.Windows.Forms">
+        <value>..\Resources\ModuleCctorNet6.dll;System.Byte[], mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+    </data>
+    <data name="ModuleCctorNetFramework" type="System.Resources.ResXFileRef, System.Windows.Forms">
+        <value>..\Resources\ModuleCctorNetFramework.exe;System.Byte[], mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+    </data>
 </root>