Fix Array.Initialize for value types with default constructors in NativeAOT

src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/UsageBasedMetadataManager.cs

@@ -311,6 +311,22 @@ protected override void GetMetadataDependenciesDueToReflectability(ref Dependenc
                 }
             }
 
+            if (type.IsArray)
+            {
+                // Array.Initialize needs the default constructor of the element type to be reflectable
+                // for value types with a public parameterless constructor.
+                TypeDesc elementType = ((ArrayType)type).ParameterType;
+                if (elementType.IsValueType)
+                {
+                    MethodDesc defaultConstructor = elementType.GetDefaultConstructor();
+                    if (defaultConstructor is not null && !IsReflectionBlocked(defaultConstructor))
+                    {
+                        dependencies ??= new DependencyList();
+                        dependencies.Add(factory.ReflectedMethod(defaultConstructor.GetCanonMethodTarget(CanonicalFormKind.Specific)), "Array.Initialize needs default constructor");
+                    }
+                }
+            }
+
             MetadataType mdType = type as MetadataType;
             ModuleDesc module = mdType?.Module;
             if (module != null && !_rootEntireAssembliesExaminedModules.Contains(module))

src/tests/nativeaot/SmokeTests/Reflection/Reflection.cs

@@ -99,6 +99,7 @@ private static int Main()
         TestGenericAttributesOnEnum.Run();
         TestLdtokenWithSignaturesDifferingInModifiers.Run();
         TestActivatingThingsInSignature.Run();
+        TestArrayInitialize.Run();
         TestDelegateInvokeFromEvent.Run();
 
         return 100;
@@ -3004,6 +3005,37 @@ public struct MyStruct;
         public struct MyArrayElementStruct;
     }
 
+    class TestArrayInitialize
+    {
+        static int s_constructorCallCount = 0;
+
+        public struct ValueTypeWithConstructor
+        {
+            public ValueTypeWithConstructor()
+            {
+                s_constructorCallCount++;
+            }
+        }
+
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        static Array AllocateArray() => new ValueTypeWithConstructor[3];
+
+        public static void Run()
+        {
+            Console.WriteLine(nameof(TestArrayInitialize));
+
+            s_constructorCallCount = 0;
+
+            // Create an array and call Initialize
+            var array = AllocateArray();
+            array.Initialize();
+
+            // Verify that the constructor was called for each element
+            if (s_constructorCallCount != 3)
+                throw new Exception($"Expected constructor to be called 3 times, but was called {s_constructorCallCount} times");
+        }
+    }
+
     class TestDelegateInvokeFromEvent
     {
         class MyClass