From 3e129b297749b9d8554a619e1ecc9827b6de3d37 Mon Sep 17 00:00:00 2001
From: PhilippNaused <philipp.naused@t-online.de>
Date: Thu, 12 Feb 2026 20:53:07 +0100
Subject: [PATCH 1/2] Add MethodImplAttributes.Async flag

---
 src/DotNet/MethodDef.cs            | 8 ++++++++
 src/DotNet/MethodImplAttributes.cs | 2 ++
 2 files changed, 10 insertions(+)

diff --git a/src/DotNet/MethodDef.cs b/src/DotNet/MethodDef.cs
index 1411eb1ae..6fe8a88b9 100644
--- a/src/DotNet/MethodDef.cs
+++ b/src/DotNet/MethodDef.cs
@@ -853,6 +853,14 @@ public bool IsAggressiveOptimization {
 		public bool HasSecurityMitigations {
 			get => ((MethodImplAttributes)implAttributes & MethodImplAttributes.SecurityMitigations) != 0;
 			set => ModifyImplAttributes(value, MethodImplAttributes.SecurityMitigations);
+		}
+
+		/// <summary>
+		/// Gets/sets the <see cref="MethodImplAttributes.Async"/> bit
+		/// </summary>
+		public bool IsAsync {
+			get => ((MethodImplAttributes)implAttributes & MethodImplAttributes.Async) != 0;
+			set => ModifyImplAttributes(value, MethodImplAttributes.Async);
 		}
 
 		/// <summary>
diff --git a/src/DotNet/MethodImplAttributes.cs b/src/DotNet/MethodImplAttributes.cs
index b1d3b3a48..eaedf3ccd 100644
--- a/src/DotNet/MethodImplAttributes.cs
+++ b/src/DotNet/MethodImplAttributes.cs
@@ -46,5 +46,7 @@ public enum MethodImplAttributes : ushort {
 		AggressiveOptimization	= 0x0200,
 		/// <summary>The JIT compiler should look for security mitigation attributes, such as the user-defined System.Runtime.CompilerServices.SecurityMitigationsAttribute. If found, the JIT compiler applies any related security mitigations. Available starting with .NET Framework 4.8.</summary>
 		SecurityMitigations		= 0x0400,
+		/// <summary>Method requires async state machine rewrite. Available starting with .NET 11.0.</summary>
+		Async					= 0x2000,
 	}
 }

From 98d43d7404bf512b2d233440ac60b92481978e83 Mon Sep 17 00:00:00 2001
From: PhilippNaused <philipp.naused@t-online.de>
Date: Mon, 1 Jun 2026 08:34:10 +0200
Subject: [PATCH 2/2] Add remarks to MethodDef.HasReturnType

---
 src/DotNet/MethodDef.cs | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/DotNet/MethodDef.cs b/src/DotNet/MethodDef.cs
index 6fe8a88b9..1821508e7 100644
--- a/src/DotNet/MethodDef.cs
+++ b/src/DotNet/MethodDef.cs
@@ -498,6 +498,12 @@ public TypeSig ReturnType {
 		/// <summary>
 		/// <c>true</c> if the method returns a value (i.e., return type is not <see cref="System.Void"/>)
 		/// </summary>
+		/// <remarks>
+		/// <see cref="MethodImplAttributes.Async"/> methods also do not have matching return type conventions as sync methods.
+		/// For sync methods, the stack should contain a value convertible to the stated return type before the <see cref="OpCodes.Ret"/> instruction.
+		/// For async methods, the stack should be empty in the case of <c>Task</c> or <c>ValueTask</c>, or the type argument in the case of <c>Task&lt;T&gt;</c> or <c>ValueTask&lt;T&gt;</c>.
+		/// <seealso href="https://github.com/dotnet/runtime/blob/main/docs/design/specs/runtime-async.md"/>
+		/// </remarks>
 		public bool HasReturnType => ReturnType.RemovePinnedAndModifiers().GetElementType() != ElementType.Void;
 
 		/// <summary>
@@ -853,8 +859,8 @@ public bool IsAggressiveOptimization {
 		public bool HasSecurityMitigations {
 			get => ((MethodImplAttributes)implAttributes & MethodImplAttributes.SecurityMitigations) != 0;
 			set => ModifyImplAttributes(value, MethodImplAttributes.SecurityMitigations);
-		}
-
+		}
+
 		/// <summary>
 		/// Gets/sets the <see cref="MethodImplAttributes.Async"/> bit
 		/// </summary>