Add public APIs for persisted AssemblyBulder

src/coreclr/System.Private.CoreLib/src/System/Reflection/Emit/RuntimeAssemblyBuilder.cs

@@ -299,5 +299,7 @@ protected override void SetCustomAttributeCore(ConstructorInfo con, ReadOnlySpan
                     binaryAttribute);
             }
         }
+
+        protected override void SaveCore(Stream stream) => throw new NotSupportedException();
     }
 }

src/libraries/System.Private.CoreLib/src/System/Reflection/Emit/AssemblyBuilder.cs

@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
 using System.IO;
 using System.Runtime.CompilerServices;
@@ -32,8 +33,59 @@ public ModuleBuilder DefineDynamicModule(string name)
             return GetDynamicModuleCore(name);
         }
 
+        /// <summary>
+        /// Defines an <see cref="AssemblyBuilder"/> that can be saved to a file or stream.
+        /// </summary>
+        /// <param name="name">The name of the assembly.</param>
+        /// <param name="coreAssembly">The assembly that denotes the "system assembly" that houses the well-known types such as <see cref="object"/></param>
+        /// <param name="assemblyAttributes">A collection that contains the attributes of the assembly.</param>
+        /// <returns>An <see cref="AssemblyBuilder"/> that can be persisted.</returns>
+        /// <exception cref="ArgumentNullException">The <paramref name="name"/> or <paramref name="name.Name"/> or <paramref name="coreAssembly"/> is null.</exception>
+        /// <remarks>Currently the persisted assembly doesn't support running, need to save it and load back to run.</remarks>
+        public static AssemblyBuilder DefinePersistedAssembly(AssemblyName name, Assembly coreAssembly, IEnumerable<CustomAttributeBuilder>? assemblyAttributes = null)
+        {
+            ArgumentNullException.ThrowIfNull(name);
+            ArgumentNullException.ThrowIfNull(coreAssembly);
+
+            Type? assemblyType = Type.GetType("System.Reflection.Emit.AssemblyBuilderImpl, System.Reflection.Emit", throwOnError: true);
+
+            if (assemblyType == null)
+            {
+                throw new TypeLoadException(SR.Format(SR.TypeLoad_TypeNotFound, "System.Reflection.Emit.AssemblyBuilderImpl"));
+            }
+
+            ConstructorInfo con = assemblyType.GetConstructor(BindingFlags.NonPublic | BindingFlags.Instance, [typeof(AssemblyName), typeof(Assembly), typeof(IEnumerable<CustomAttributeBuilder>)])!;
+            return (AssemblyBuilder)con.Invoke([name, coreAssembly, assemblyAttributes]);
+        }
+
         protected abstract ModuleBuilder? GetDynamicModuleCore(string name);
 
+        /// <summary>
+        /// Serializes the assembly to stream.
+        /// </summary>
+        /// <param name="stream">The stream to which the assembly serialized.</param>
+        /// <exception cref="ArgumentNullException"> <paramref name="stream"/> is null </exception>
+        public void Save(Stream stream) => SaveCore(stream);
+
+        /// <summary>
+        /// Saves the assembly to disk.
+        /// </summary>
+        /// <param name="assemblyFileName">The file name of the assembly.</param>
+        /// <exception cref="ArgumentNullException"> <paramref name="assemblyFileName"/> is null </exception>
+        public void Save(string assemblyFileName)
+        {
+            ArgumentNullException.ThrowIfNull(assemblyFileName);
+
+            using var peStream = new FileStream(assemblyFileName, FileMode.Create, FileAccess.Write);
+            SaveCore(peStream);
+        }
+
+        /// <summary>
+        /// When implemented in derived type serializer the assembly to stream.
+        /// </summary>
+        /// <param name="stream">The stream to which the assembly serialized.</param>
+        protected abstract void SaveCore(Stream stream);
+
         public void SetCustomAttribute(ConstructorInfo con, byte[] binaryAttribute)
         {
             ArgumentNullException.ThrowIfNull(con);

src/libraries/System.Reflection.Emit/ref/System.Reflection.Emit.cs

@@ -24,6 +24,7 @@ protected AssemblyBuilder() { }
         public static System.Reflection.Emit.AssemblyBuilder DefineDynamicAssembly(System.Reflection.AssemblyName name, System.Reflection.Emit.AssemblyBuilderAccess access) { throw null; }
         [System.Diagnostics.CodeAnalysis.RequiresDynamicCode("Defining a dynamic assembly requires dynamic code.")]
         public static System.Reflection.Emit.AssemblyBuilder DefineDynamicAssembly(System.Reflection.AssemblyName name, System.Reflection.Emit.AssemblyBuilderAccess access, System.Collections.Generic.IEnumerable<System.Reflection.Emit.CustomAttributeBuilder>? assemblyAttributes) { throw null; }
+        public static System.Reflection.Emit.AssemblyBuilder DefinePersistedAssembly(System.Reflection.AssemblyName name, System.Reflection.Assembly coreAssembly, System.Collections.Generic.IEnumerable<System.Reflection.Emit.CustomAttributeBuilder>? assemblyAttributes = null) { throw null; }
         public System.Reflection.Emit.ModuleBuilder DefineDynamicModule(string name) { throw null; }
         protected abstract System.Reflection.Emit.ModuleBuilder DefineDynamicModuleCore(string name);
         public override bool Equals(object? obj) { throw null; }
@@ -54,6 +55,9 @@ protected AssemblyBuilder() { }
         [System.Diagnostics.CodeAnalysis.RequiresUnreferencedCodeAttribute("Types might be removed by trimming. If the type name is a string literal, consider using Type.GetType instead.")]
         public override System.Type? GetType(string name, bool throwOnError, bool ignoreCase) { throw null; }
         public override bool IsDefined(System.Type attributeType, bool inherit) { throw null; }
+        public void Save(string assemblyFileName) { throw null; }
+        public void Save(System.IO.Stream stream) { throw null; }
+        protected abstract void SaveCore(System.IO.Stream stream);
         public void SetCustomAttribute(System.Reflection.ConstructorInfo con, byte[] binaryAttribute) { }
         public void SetCustomAttribute(System.Reflection.Emit.CustomAttributeBuilder customBuilder) { }
         protected abstract void SetCustomAttributeCore(System.Reflection.ConstructorInfo con, System.ReadOnlySpan<byte> binaryAttribute);

src/libraries/System.Reflection.Emit/src/ILLink/ILLink.Descriptors.LibraryBuild.xml

@@ -1,9 +1,8 @@
 <linker>
   <assembly fullname="System.Reflection.Emit">
     <type fullname="System.Reflection.Emit.AssemblyBuilderImpl">
-      <!-- Internal API used by tests only. -->
-      <method name="DefinePersistedAssembly" />
-      <method name="Save" />
+      <!-- Internal API called through Reflection by another assembly. -->
+      <method name=".ctor" />
     </type>
   </assembly>
 </linker>

src/libraries/System.Reflection.Emit/src/System/Reflection/Emit/AssemblyBuilderImpl.cs

@@ -19,10 +19,8 @@ internal sealed class AssemblyBuilderImpl : AssemblyBuilder
 
         internal List<CustomAttributeWrapper>? _customAttributes;
 
-        internal AssemblyBuilderImpl(AssemblyName name, Assembly coreAssembly, IEnumerable<CustomAttributeBuilder>? assemblyAttributes)
+        internal AssemblyBuilderImpl(AssemblyName name, Assembly coreAssembly, IEnumerable<CustomAttributeBuilder>? assemblyAttributes = null)
         {
-            ArgumentNullException.ThrowIfNull(name);
-
             name = (AssemblyName)name.Clone();
 
             ArgumentException.ThrowIfNullOrEmpty(name.Name, "AssemblyName.Name");
@@ -40,10 +38,6 @@ internal AssemblyBuilderImpl(AssemblyName name, Assembly coreAssembly, IEnumerab
             }
         }
 
-        internal static AssemblyBuilderImpl DefinePersistedAssembly(AssemblyName name, Assembly coreAssembly,
-            IEnumerable<CustomAttributeBuilder>? assemblyAttributes)
-                => new AssemblyBuilderImpl(name, coreAssembly, assemblyAttributes);
-
         private void WritePEImage(Stream peStream, BlobBuilder ilBuilder)
         {
             var peHeaderBuilder = new PEHeaderBuilder(
@@ -63,7 +57,7 @@ private void WritePEImage(Stream peStream, BlobBuilder ilBuilder)
             peBlob.WriteContentTo(peStream);
         }
 
-        internal void Save(Stream stream)
+        protected override void SaveCore(Stream stream)
         {
             ArgumentNullException.ThrowIfNull(stream);
 
@@ -101,14 +95,6 @@ internal void Save(Stream stream)
         private static AssemblyFlags AddContentType(AssemblyFlags flags, AssemblyContentType contentType)
             => (AssemblyFlags)((int)contentType << 9) | flags;
 
-        internal void Save(string assemblyFileName)
-        {
-            ArgumentNullException.ThrowIfNull(assemblyFileName);
-
-            using var peStream = new FileStream(assemblyFileName, FileMode.Create, FileAccess.Write);
-            Save(peStream);
-        }
-
         protected override ModuleBuilder DefineDynamicModuleCore(string name)
         {
             if (_module != null)

src/libraries/System.Reflection.Emit/tests/PersistableAssemblyBuilder/AssemblySaveAssemblyBuilder.cs

@@ -34,7 +34,7 @@ public void AssemblyWithDifferentTypes()
                 aName.CultureInfo = new CultureInfo("en");
                 aName.Flags = AssemblyNameFlags.Retargetable;
 
-                AssemblyBuilder ab = AssemblySaveTools.PopulateAssemblyBuilderAndSaveMethod(aName, null, typeof(string), out MethodInfo saveMethod);
+                AssemblyBuilder ab = AssemblySaveTools.PopulateAssemblyBuilder(aName);
 
                 ab.SetCustomAttribute(new CustomAttributeBuilder(typeof(AssemblyDelaySignAttribute).GetConstructor([typeof(bool)]), [true]));
 
@@ -213,10 +213,12 @@ public void AssemblyWithDifferentTypes()
                 eventb.SetRemoveOnMethod(mbRemove);
                 tbEvents.CreateType();
 
-                saveMethod.Invoke(ab, [file.Path]);
+                ab.Save(file.Path);
 
-                Assembly assemblyFromDisk = AssemblySaveTools.LoadAssemblyFromPath(file.Path);
-                CheckAssembly(assemblyFromDisk);
+                using (MetadataLoadContext mlc = new MetadataLoadContext(new CoreMetadataAssemblyResolver()))
+                {
+                    CheckAssembly(mlc.LoadFromAssemblyPath(file.Path));
+                }
             }
         }
 

src/libraries/System.Reflection.Emit/tests/PersistableAssemblyBuilder/AssemblySaveConstructorBuilderTests.cs

@@ -16,7 +16,7 @@ public void DefineConstructorsTest()
         {
             using (TempFile file = TempFile.Create())
             {
-                AssemblyBuilder ab = AssemblySaveTools.PopulateAssemblyBuilderTypeBuilderAndSaveMethod(out TypeBuilder type, out MethodInfo saveMethod);
+                AssemblyBuilder ab = AssemblySaveTools.PopulateAssemblyBuilderAndTypeBuilder(out TypeBuilder type);
                 ConstructorBuilder constructor = type.DefineDefaultConstructor(MethodAttributes.Public);
                 ConstructorBuilder constructor2 = type.DefineConstructor(MethodAttributes.Public, CallingConventions.Standard, [typeof(int)]);
                 constructor2.DefineParameter(1, ParameterAttributes.None, "parameter1");
@@ -29,7 +29,7 @@ public void DefineConstructorsTest()
                 il.Emit(OpCodes.Stfld, fieldBuilderA);
                 il.Emit(OpCodes.Ret);
                 type.CreateType();
-                saveMethod.Invoke(ab, [file.Path]);
+                ab.Save(file.Path);
 
                 using (MetadataLoadContext mlc = new MetadataLoadContext(new CoreMetadataAssemblyResolver()))
                 {
@@ -52,7 +52,7 @@ public void DefineConstructorsTest()
         [Fact]
         public void DefineDefaultConstructor_WithTypeBuilderParent()
         {
-            AssemblyBuilder ab = AssemblySaveTools.PopulateAssemblyBuilderTypeBuilderAndSaveMethod(out TypeBuilder type, out MethodInfo _);
+            AssemblyBuilder ab = AssemblySaveTools.PopulateAssemblyBuilderAndTypeBuilder(out TypeBuilder type);
             type.CreateType();
             TypeBuilder child = ab.GetDynamicModule("MyModule").DefineType("ChildType", TypeAttributes.Public | TypeAttributes.Class);
             child.SetParent(type);
@@ -70,7 +70,7 @@ public void DefineDefaultConstructor_TypesWithGenericParents()
         {
             using (TempFile file = TempFile.Create())
             {
-                AssemblyBuilder ab = AssemblySaveTools.PopulateAssemblyBuilderTypeBuilderAndSaveMethod(out TypeBuilder type, out MethodInfo saveMethod);
+                AssemblyBuilder ab = AssemblySaveTools.PopulateAssemblyBuilderAndTypeBuilder(out TypeBuilder type);
                 type.DefineGenericParameters("T");
                 ConstructorBuilder constructor = type.DefineConstructor(MethodAttributes.Public, CallingConventions.Standard, Type.EmptyTypes);
                 FieldBuilder field = type.DefineField("TestField", typeof(bool), FieldAttributes.Public | FieldAttributes.Static);
@@ -94,31 +94,34 @@ public void DefineDefaultConstructor_TypesWithGenericParents()
                 type2.SetParent(genericList);
                 type2.DefineDefaultConstructor(MethodAttributes.Public);
                 type2.CreateTypeInfo();
-                saveMethod.Invoke(ab, [file.Path]);
-
-                Assembly assemblyFromDisk = AssemblySaveTools.LoadAssemblyFromPath(file.Path);
-                ConstructorInfo[] ctors = assemblyFromDisk.GetType("MyType").GetConstructors();
-                Assert.Equal(1, ctors.Length);
-                Assert.Empty(ctors[0].GetParameters());
-                Type derivedFromFile = assemblyFromDisk.GetType("Derived");
-                Assert.NotNull(derivedFromFile.GetConstructor(Type.EmptyTypes));
-                Assert.Equal(genericParent.FullName, derivedFromFile.BaseType.FullName);
-                Assert.NotNull(assemblyFromDisk.GetType("Type2").GetConstructor(Type.EmptyTypes));
+                ab.Save(file.Path);
+
+                using (MetadataLoadContext mlc = new MetadataLoadContext(new CoreMetadataAssemblyResolver()))
+                {
+                    Assembly assemblyFromDisk = mlc.LoadFromAssemblyPath(file.Path);
+                    ConstructorInfo[] ctors = assemblyFromDisk.GetType("MyType").GetConstructors();
+                    Assert.Equal(1, ctors.Length);
+                    Assert.Empty(ctors[0].GetParameters());
+                    Type derivedFromFile = assemblyFromDisk.GetType("Derived");
+                    Assert.NotNull(derivedFromFile.GetConstructor(Type.EmptyTypes));
+                    Assert.Equal(genericParent.FullName, derivedFromFile.BaseType.FullName);
+                    Assert.NotNull(assemblyFromDisk.GetType("Type2").GetConstructor(Type.EmptyTypes));
+                }
             }
         }
 
         [Fact]
         public void DefineDefaultConstructor_Interface_ThrowsInvalidOperationException()
         {
-            AssemblyBuilder ab = AssemblySaveTools.PopulateAssemblyBuilderAndSaveMethod(new AssemblyName("MyAssembly"), null, typeof(string), out var _);
+            AssemblyBuilder ab = AssemblySaveTools.PopulateAssemblyBuilder(new AssemblyName("MyAssembly"));
             TypeBuilder type = ab.DefineDynamicModule("MyModule").DefineType("MyType", TypeAttributes.Public | TypeAttributes.Interface | TypeAttributes.Abstract);
             Assert.Throws<InvalidOperationException>(() => type.DefineDefaultConstructor(MethodAttributes.Public));
         }
 
         [Fact]
         public void DefineDefaultConstructor_ThrowsNotSupportedException_IfParentNotCreated()
         {
-            AssemblyBuilder ab = AssemblySaveTools.PopulateAssemblyBuilderTypeBuilderAndSaveMethod(out TypeBuilder type, out MethodInfo _);
+            AssemblyBuilder ab = AssemblySaveTools.PopulateAssemblyBuilderAndTypeBuilder(out TypeBuilder type);
             TypeBuilder  child = ab.GetDynamicModule("MyModule").DefineType("MyType", TypeAttributes.Public);
             child.SetParent(type);
             Assert.Throws<NotSupportedException>(() => child.DefineDefaultConstructor(MethodAttributes.Public));
@@ -127,14 +130,14 @@ public void DefineDefaultConstructor_ThrowsNotSupportedException_IfParentNotCrea
         [Fact]
         public void DefineDefaultConstructor_StaticVirtual_ThrowsArgumentException()
         {
-            AssemblySaveTools.PopulateAssemblyBuilderTypeBuilderAndSaveMethod(out TypeBuilder type, out MethodInfo saveMethod);
+            AssemblySaveTools.PopulateAssemblyBuilderAndTypeBuilder(out TypeBuilder type);
             AssertExtensions.Throws<ArgumentException>(null, () => type.DefineDefaultConstructor(MethodAttributes.Virtual | MethodAttributes.Static));
         }
 
         [Fact]
         public void DefineDefaultConstructor_ParentNoDefaultConstructor_ThrowsNotSupportedException()
         {
-            AssemblyBuilder ab = AssemblySaveTools.PopulateAssemblyBuilderTypeBuilderAndSaveMethod(out TypeBuilder type, out MethodInfo _);
+            AssemblyBuilder ab = AssemblySaveTools.PopulateAssemblyBuilderAndTypeBuilder(out TypeBuilder type);
             FieldBuilder field = type.DefineField("TestField", typeof(int), FieldAttributes.Family);
 
             ConstructorBuilder constructor = type.DefineConstructor(MethodAttributes.Public, CallingConventions.HasThis, new[] { typeof(int) });
@@ -157,7 +160,7 @@ public void DefineDefaultConstructor_ParentNoDefaultConstructor_ThrowsNotSupport
         [InlineData(MethodAttributes.PrivateScope)]
         public void DefineDefaultConstructor_ParentPrivateDefaultConstructor_ThrowsNotSupportedException(MethodAttributes attributes)
         {
-            AssemblySaveTools.PopulateAssemblyBuilderTypeBuilderAndSaveMethod(out TypeBuilder baseType, out MethodInfo _);
+            AssemblySaveTools.PopulateAssemblyBuilderAndTypeBuilder(out TypeBuilder baseType);
             ConstructorBuilder constructor = baseType.DefineConstructor(attributes, CallingConventions.HasThis, new[] { typeof(int) });
             constructor.GetILGenerator().Emit(OpCodes.Ret);
 
@@ -169,7 +172,7 @@ public void DefineDefaultConstructor_ParentPrivateDefaultConstructor_ThrowsNotSu
         [Fact]
         public void GetConstructor_DeclaringTypeOfConstructorGenericTypeDefinition()
         {
-            AssemblySaveTools.PopulateAssemblyBuilderTypeBuilderAndSaveMethod(out TypeBuilder type, out MethodInfo _);
+            AssemblySaveTools.PopulateAssemblyBuilderAndTypeBuilder(out TypeBuilder type);
             type.DefineGenericParameters("T");
 
             ConstructorBuilder ctor = type.DefineDefaultConstructor(MethodAttributes.PrivateScope | MethodAttributes.Public | MethodAttributes.HideBySig | MethodAttributes.SpecialName);
@@ -180,7 +183,7 @@ public void GetConstructor_DeclaringTypeOfConstructorGenericTypeDefinition()
         [Fact]
         public void TypeBuilder_GetConstructorWorks()
         {
-            AssemblySaveTools.PopulateAssemblyBuilderTypeBuilderAndSaveMethod(out TypeBuilder type, out MethodInfo _);
+            AssemblySaveTools.PopulateAssemblyBuilderAndTypeBuilder(out TypeBuilder type);
             type.DefineGenericParameters("T");
 
             ConstructorBuilder ctor = type.DefineDefaultConstructor(MethodAttributes.Public | MethodAttributes.HideBySig | MethodAttributes.RTSpecialName);
@@ -194,7 +197,7 @@ public void TypeBuilder_GetConstructorWorks()
         [Fact]
         public void GetConstructor_DeclaringTypeOfConstructorNotGenericTypeDefinitionOfType_ThrowsArgumentException()
         {
-            AssemblySaveTools.PopulateAssemblyBuilderTypeBuilderAndSaveMethod(out TypeBuilder type1, out MethodInfo _);
+            AssemblySaveTools.PopulateAssemblyBuilderAndTypeBuilder(out TypeBuilder type1);
             type1.DefineGenericParameters("T");
 
             TypeBuilder type2 = ((ModuleBuilder)type1.Module).DefineType("TestType2", TypeAttributes.Class | TypeAttributes.Public);
@@ -210,7 +213,7 @@ public void GetConstructor_DeclaringTypeOfConstructorNotGenericTypeDefinitionOfT
         [Fact]
         public void GetConstructor_TypeNotGeneric_ThrowsArgumentException()
         {
-            AssemblySaveTools.PopulateAssemblyBuilderTypeBuilderAndSaveMethod(out TypeBuilder type, out MethodInfo _);
+            AssemblySaveTools.PopulateAssemblyBuilderAndTypeBuilder(out TypeBuilder type);
 
             ConstructorBuilder ctor = type.DefineDefaultConstructor(MethodAttributes.Public);