#312: Preserve module initializers

ILRepack.IntegrationTests/Scenarios/AnotherClassLibrary/AnotherClassLibrary.csproj

@@ -23,6 +23,9 @@
     <Compile Include="ADummyUserControl.xaml.cs">
       <DependentUpon>ADummyUserControl.xaml</DependentUpon>
     </Compile>
+    <Compile Include="ModuleInitializers\MakeInitialized.cs" />
+    <Compile Include="ModuleInitializers\LibraryModuleInitializer.cs" />
+    <Compile Include="ModuleInitializers\ModuleInitializerAttribute.cs" />
     <Compile Include="WpfWindowStarter.cs" />
   </ItemGroup>
   <ItemGroup>

ILRepack.IntegrationTests/Scenarios/AnotherClassLibrary/ModuleInitializers/LibraryModuleInitializer.cs

@@ -0,0 +1,35 @@
+//
+// Copyright (c) 2025 David Rettenbacher
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//       http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+using System;
+using System.Runtime.CompilerServices;
+
+namespace AnotherClassLibrary.ModuleInitializers
+{
+    public static class LibraryModuleInitializer
+    {
+        [ModuleInitializer]
+        public static void Initialize()
+        {
+            // some "complex" code to prove the ModuleInitializersRepackStep can handle it
+            var shouldInitialize = DateTime.Now > new DateTime(2000, 1, 1);
+            if (shouldInitialize)
+            {
+                MakeInitialized.Initialize();
+            }
+        }
+    }
+}

ILRepack.IntegrationTests/Scenarios/AnotherClassLibrary/ModuleInitializers/MakeInitialized.cs

@@ -0,0 +1,35 @@
+//
+// Copyright (c) 2025 David Rettenbacher
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//       http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+namespace AnotherClassLibrary.ModuleInitializers
+{
+    public class MakeInitialized
+    {
+        public static bool IsInitialized { get; private set; }
+
+        public static int Counter { get;private set; }
+
+        public static void Initialize()
+        {
+            IsInitialized = true;
+
+            Counter = ClassLibrary.ModuleInitializers.MakeInitialized.Counter + 1;
+
+            // force an actual assembly dependency to ClassLibrary
+            ClassLibrary.DummyConverter dummy = new ClassLibrary.DummyConverter();
+        }
+    }
+}

ILRepack.IntegrationTests/Scenarios/AnotherClassLibrary/ModuleInitializers/ModuleInitializerAttribute.cs

@@ -0,0 +1,33 @@
+//
+// Copyright (c) 2025 David Rettenbacher
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//       http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
+
+#pragma warning disable IDE0130 // Namespace does not match folder structure
+namespace System.Runtime.CompilerServices
+#pragma warning restore IDE0130 // Namespace does not match folder structure
+{
+    /// <summary>
+    /// Polyfill for compiler support
+    /// </summary>
+    [ExcludeFromCodeCoverage]
+    [DebuggerNonUserCode]
+    [AttributeUsage(AttributeTargets.Method, Inherited = false)]
+    internal sealed class ModuleInitializerAttribute : Attribute
+    {
+    }
+}

ILRepack.IntegrationTests/Scenarios/ClassLibrary/ClassLibrary.csproj

@@ -42,6 +42,9 @@
       <DependentUpon>DummyUserControl.xaml</DependentUpon>
     </Compile>
     <Compile Include="GenericBasedResourceKey.cs" />
+    <Compile Include="ModuleInitializers\LibraryModuleInitializer.cs" />
+    <Compile Include="ModuleInitializers\MakeInitialized.cs" />
+    <Compile Include="ModuleInitializers\ModuleInitializerAttribute.cs" />
     <Compile Include="Properties\Resources.Designer.cs">
       <AutoGen>True</AutoGen>
       <DesignTime>True</DesignTime>

ILRepack.IntegrationTests/Scenarios/ClassLibrary/ModuleInitializers/LibraryModuleInitializer.cs

@@ -0,0 +1,29 @@
+//
+// Copyright (c) 2025 David Rettenbacher
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//       http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+using System.Runtime.CompilerServices;
+
+namespace ClassLibrary.ModuleInitializers
+{
+    public static class LibraryModuleInitializer
+    {
+        [ModuleInitializer]
+        public static void Initialize()
+        {
+            MakeInitialized.Initialize();
+        }
+    }
+}

ILRepack.IntegrationTests/Scenarios/ClassLibrary/ModuleInitializers/MakeInitialized.cs

@@ -0,0 +1,32 @@
+//
+// Copyright (c) 2025 David Rettenbacher
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//       http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+namespace ClassLibrary.ModuleInitializers
+{
+    public class MakeInitialized
+    {
+        public static bool IsInitialized { get; private set; }
+
+        public static int Counter { get; private set; }
+
+        public static void Initialize()
+        {
+            Counter++;
+
+            IsInitialized = true;
+        }
+    }
+}

ILRepack.IntegrationTests/Scenarios/ClassLibrary/ModuleInitializers/ModuleInitializerAttribute.cs

@@ -0,0 +1,33 @@
+//
+// Copyright (c) 2025 David Rettenbacher
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//       http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
+
+#pragma warning disable IDE0130 // Namespace does not match folder structure
+namespace System.Runtime.CompilerServices
+#pragma warning restore IDE0130 // Namespace does not match folder structure
+{
+    /// <summary>
+    /// Polyfill for compiler support
+    /// </summary>
+    [ExcludeFromCodeCoverage]
+    [DebuggerNonUserCode]
+    [AttributeUsage(AttributeTargets.Method, Inherited = false)]
+    internal sealed class ModuleInitializerAttribute : Attribute
+    {
+    }
+}

ILRepack.IntegrationTests/Scenarios/NestedLibraryUsageInXAML/MainWindow.xaml.cs

@@ -1,4 +1,5 @@
-using System.Windows;
+using System;
+using System.Windows;
 using AnotherClassLibrary;
 
 namespace NestedLibraryUsageInXAML
@@ -13,6 +14,18 @@ public MainWindow()
         private async void MainWindowLoaded(object sender, RoutedEventArgs e)
         {
             await new BclAsyncUsage().GetNumber();
+
+            if (!ClassLibrary.ModuleInitializers.MakeInitialized.IsInitialized &&
+                ClassLibrary.ModuleInitializers.MakeInitialized.Counter == 1)
+                throw new InvalidOperationException($"ModuleInitializer of '{nameof(ClassLibrary.ModuleInitializers.LibraryModuleInitializer)}' was not executed");
+
+            if (!AnotherClassLibrary.ModuleInitializers.MakeInitialized.IsInitialized &&
+                AnotherClassLibrary.ModuleInitializers.MakeInitialized.Counter == 2)
+                throw new InvalidOperationException($"ModuleInitializer of '{nameof(AnotherClassLibrary.ModuleInitializers.LibraryModuleInitializer)}' was not executed or not in right order");
+
+            if (Program.Counter != 3)
+                throw new InvalidOperationException($"ModuleInitializers of '{nameof(Program)}' were not executed or not in right order");
+
             Close();
         }
     }

ILRepack.IntegrationTests/Scenarios/NestedLibraryUsageInXAML/ModuleInitializers/ModuleInitializerAttribute.cs

@@ -0,0 +1,33 @@
+//
+// Copyright (c) 2025 David Rettenbacher
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//       http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
+
+#pragma warning disable IDE0130 // Namespace does not match folder structure
+namespace System.Runtime.CompilerServices
+#pragma warning restore IDE0130 // Namespace does not match folder structure
+{
+    /// <summary>
+    /// Polyfill for compiler support
+    /// </summary>
+    [ExcludeFromCodeCoverage]
+    [DebuggerNonUserCode]
+    [AttributeUsage(AttributeTargets.Method, Inherited = false)]
+    internal sealed class ModuleInitializerAttribute : Attribute
+    {
+    }
+}

ILRepack.IntegrationTests/Scenarios/NestedLibraryUsageInXAML/Program.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Runtime.CompilerServices;
 using System.Windows;
 
 namespace NestedLibraryUsageInXAML
@@ -19,5 +20,20 @@ public static int Main()
                 return 1;
             }
         }
+
+        internal static int Counter { get; private set; }
+
+        [ModuleInitializer]
+        internal static void TheInitializer()
+        {
+            Counter++;
+            Counter *= AnotherClassLibrary.ModuleInitializers.MakeInitialized.Counter;
+        }
+
+        [ModuleInitializer]
+        internal static void TheInitializer2()
+        {
+            Counter++;
+        }
     }
 }

ILRepack.IntegrationTests/Scenarios/NestedLibraryUsageInXAML/Properties/launchSettings.json

@@ -0,0 +1,11 @@
+{
+  "profiles": {
+    "NestedLibraryUsageInXAML": {
+      "commandName": "Project"
+    },
+    "Merged": {
+      "commandName": "Executable",
+      "executablePath": "$(TargetDir)merged\\NestedLibraryUsageInXAML.exe"
+    }
+  }
+}

ILRepack/ILRepack.cs

@@ -419,6 +419,7 @@ private void RepackCore(string tempOutputDirectory)
                 {
                     signingStep,
                     new ReferencesRepackStep(Logger, this, Options),
+                    new ModuleInitializersRepackStep(Logger, this, Options),
                     new TypesRepackStep(Logger, this, _repackImporter, Options),
                     new ILLinkFileMergeStep(Logger, this, Options),
                     new ResourcesRepackStep(Logger, this, Options),