From f408cb40e289919bca355e5da01aba71305df2ed Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C5=82=20Petryka?=
 <35800402+MichalPetryka@users.noreply.github.com>
Date: Wed, 28 Feb 2024 20:36:33 +0100
Subject: [PATCH] Copy the NativeAOT AllocateTypeAssociatedMemory to Mono

Found in #99019
---
 .../Runtime/CompilerServices/RuntimeHelpers.Mono.cs       | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/mono/System.Private.CoreLib/src/System/Runtime/CompilerServices/RuntimeHelpers.Mono.cs b/src/mono/System.Private.CoreLib/src/System/Runtime/CompilerServices/RuntimeHelpers.Mono.cs
index 391bfaec6a2a46..030a24a0d3ec05 100644
--- a/src/mono/System.Private.CoreLib/src/System/Runtime/CompilerServices/RuntimeHelpers.Mono.cs
+++ b/src/mono/System.Private.CoreLib/src/System/Runtime/CompilerServices/RuntimeHelpers.Mono.cs
@@ -139,7 +139,13 @@ public static void RunModuleConstructor(ModuleHandle module)
 
         public static IntPtr AllocateTypeAssociatedMemory(Type type, int size)
         {
-            throw new PlatformNotSupportedException();
+            if (type is not RuntimeType)
+                throw new ArgumentException(SR.Arg_MustBeType, nameof(type));
+
+            ArgumentOutOfRangeException.ThrowIfNegative(size);
+
+            // We don't support unloading; the memory will never be freed.
+            return (IntPtr)NativeMemory.AllocZeroed((uint)size);
         }
 
         [Intrinsic]