Add support for .NET 5 custom calling conventions.

ICSharpCode.Decompiler.Tests/TestCases/ILPretty/CallIndirect.cs

@@ -5,4 +5,19 @@ internal class CallIndirect
 	{
 		((delegate* unmanaged[Stdcall]<int, void>)f)(42);
 	}
-}
+
+	private unsafe void UnmanagedDefaultCall(IntPtr f)
+	{
+		((delegate* unmanaged<int, void>)f)(42);
+	}
+
+	private unsafe void CustomCall(IntPtr f)
+	{
+		((delegate* unmanaged[Custom]<int, void>)f)(42);
+	}
+
+	private unsafe void MultipleCustomCall(IntPtr f)
+	{
+		((delegate* unmanaged[SuppressGCTransition, Custom]<int, void>)f)(42);
+	}
+}

ICSharpCode.Decompiler.Tests/TestCases/ILPretty/CallIndirect.il

@@ -23,6 +23,45 @@
         ret
     } // end of method Example::Test
 
+    .method private hidebysig 
+        instance void UnmanagedDefaultCall (
+            native int f
+        ) cil managed 
+    {
+        .maxstack 8
+
+        ldc.i4.s 42
+        ldarg.1
+        calli unmanaged void(int32)
+        ret
+    } // end of method Example::Test
+    
+    .method private hidebysig 
+        instance void CustomCall (
+            native int f
+        ) cil managed 
+    {
+        .maxstack 8
+
+        ldc.i4.s 42
+        ldarg.1
+        calli unmanaged void modreq([System.Private.CoreLib] System.Runtime.CompilerServices.CallConvCustom)(int32)
+        ret
+    } // end of method Example::Test
+    
+    .method private hidebysig 
+        instance void MultipleCustomCall (
+            native int f
+        ) cil managed 
+    {
+        .maxstack 8
+
+        ldc.i4.s 42
+        ldarg.1
+        calli unmanaged void modreq([System.Private.CoreLib] System.Runtime.CompilerServices.CallConvCustom) modreq([System.Private.CoreLib] System.Runtime.CompilerServices.CallConvSuppressGCTransition) (int32)
+        ret
+    } // end of method Example::Test
+
     .method public hidebysig specialname rtspecialname 
         instance void .ctor () cil managed 
     {

ICSharpCode.Decompiler/CSharp/ExpressionBuilder.cs

@@ -18,6 +18,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Collections.Immutable;
 using System.Diagnostics;
 using System.Linq;
 using System.Reflection.Metadata;
@@ -3948,7 +3949,8 @@ namespace ICSharpCode.Decompiler.CSharp
 			// C# 9 function pointer
 			var ftp = new FunctionPointerType(
 				typeSystem.MainModule,
-				SignatureCallingConvention.Default, // TODO
+				// TODO: calling convention
+				SignatureCallingConvention.Default, ImmutableArray.Create<IType>(),
 				inst.Method.ReturnType, inst.Method.ReturnTypeIsRefReadOnly,
 				inst.Method.Parameters.SelectImmutableArray(p => p.Type),
 				inst.Method.Parameters.SelectImmutableArray(p => p.ReferenceKind)

ICSharpCode.Decompiler/CSharp/OutputVisitor/CSharpOutputVisitor.cs

@@ -2605,12 +2605,15 @@ namespace ICSharpCode.Decompiler.CSharp.OutputVisitor
 			StartNode(functionPointerType);
 			WriteKeyword(Roles.DelegateKeyword);
 			WriteToken(FunctionPointerAstType.PointerRole);
-			if (!functionPointerType.CallingConvention.IsNull)
+			if (functionPointerType.HasUnmanagedCallingConvention)
 			{
 				Space();
 				WriteKeyword("unmanaged");
+			}
+			if (functionPointerType.CallingConventions.Any())
+			{
 				WriteToken(Roles.LBracket);
-				functionPointerType.CallingConvention.AcceptVisitor(this);
+				WriteCommaSeparatedList(functionPointerType.CallingConventions);
 				WriteToken(Roles.RBracket);
 			}
 			WriteToken(Roles.LChevron);

ICSharpCode.Decompiler/CSharp/Syntax/FunctionPointerAstType.cs

@@ -36,13 +36,10 @@ namespace ICSharpCode.Decompiler.CSharp.Syntax
 		public static readonly TokenRole PointerRole = new TokenRole("*");
 		public static readonly Role<AstType> CallingConventionRole = new Role<AstType>("CallConv", AstType.Null);
 
-		public AstType CallingConvention {
-			get {
-				return GetChildByRole(CallingConventionRole);
-			}
-			set {
-				SetChildByRole(CallingConventionRole, value);
-			}
+		public bool HasUnmanagedCallingConvention { get; set; }
+
+		public AstNodeCollection<AstType> CallingConventions {
+			get { return GetChildrenByRole(CallingConventionRole); }
 		}
 
 		public AstNodeCollection<ParameterDeclaration> Parameters {
@@ -72,7 +69,7 @@ namespace ICSharpCode.Decompiler.CSharp.Syntax
 		protected internal override bool DoMatch(AstNode other, PatternMatching.Match match)
 		{
 			return other is FunctionPointerAstType o
-				&& this.CallingConvention.DoMatch(o.CallingConvention, match)
+				&& this.CallingConventions.DoMatch(o.CallingConventions, match)
 				&& this.Parameters.DoMatch(o.Parameters, match)
 				&& this.ReturnType.DoMatch(o.ReturnType, match);
 		}

ICSharpCode.Decompiler/CSharp/Syntax/TypeSystemAstBuilder.cs

@@ -309,11 +309,14 @@ namespace ICSharpCode.Decompiler.CSharp.Syntax
 			else if (type is FunctionPointerType fpt)
 			{
 				var astType = new FunctionPointerAstType();
-				if (fpt.CallingConvention != System.Reflection.Metadata.SignatureCallingConvention.Default)
+				if (fpt.CallingConvention == System.Reflection.Metadata.SignatureCallingConvention.Unmanaged)
+				{
+					astType.HasUnmanagedCallingConvention = true;
+				}
+				else if (fpt.CallingConvention != System.Reflection.Metadata.SignatureCallingConvention.Default)
 				{
 					string callconvName = fpt.CallingConvention switch
 					{
-						System.Reflection.Metadata.SignatureCallingConvention.Default => "",
 						System.Reflection.Metadata.SignatureCallingConvention.CDecl => "Cdecl",
 						System.Reflection.Metadata.SignatureCallingConvention.StdCall => "Stdcall",
 						System.Reflection.Metadata.SignatureCallingConvention.ThisCall => "Thiscall",
@@ -321,7 +324,25 @@ namespace ICSharpCode.Decompiler.CSharp.Syntax
 						System.Reflection.Metadata.SignatureCallingConvention.VarArgs => "Varargs",
 						_ => fpt.CallingConvention.ToString()
 					};
-					astType.CallingConvention = new PrimitiveType(callconvName);
+					astType.HasUnmanagedCallingConvention = true;
+					astType.CallingConventions.Add(new PrimitiveType(callconvName));
+				}
+				foreach (var customCallConv in fpt.CustomCallingConventions)
+				{
+					AstType callConvSyntax;
+					if (customCallConv.Name.StartsWith("CallConv", StringComparison.Ordinal) && customCallConv.Name.Length > 8)
+					{
+						callConvSyntax = new PrimitiveType(customCallConv.Name.Substring(8));
+						if (AddResolveResultAnnotations)
+						{
+							callConvSyntax.AddAnnotation(new TypeResolveResult(customCallConv));
+						}
+					}
+					else
+					{
+						callConvSyntax = ConvertType(customCallConv);
+					}
+					astType.CallingConventions.Add(callConvSyntax);
 				}
 				for (int i = 0; i < fpt.ParameterTypes.Length; i++)
 				{

ICSharpCode.Decompiler/SRMExtensions.cs

@@ -586,6 +586,7 @@ namespace ICSharpCode.Decompiler
 				SignatureCallingConvention.ThisCall => "unmanaged thiscall",
 				SignatureCallingConvention.FastCall => "unmanaged fastcall",
 				SignatureCallingConvention.VarArgs => "vararg",
+				SignatureCallingConvention.Unmanaged => "unmanaged",
 				_ => callConv.ToString().ToLowerInvariant()
 			};
 		}

ICSharpCode.Decompiler/TypeSystem/FunctionPointerType.cs

@@ -33,10 +33,24 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		{
 			IType returnType = signature.ReturnType;
 			bool returnIsRefReadOnly = false;
-			if (returnType is ModifiedType modReturn && modReturn.Modifier.IsKnownType(KnownAttribute.In))
+			var customCallConvs = ImmutableArray.CreateBuilder<IType>();
+			while (returnType is ModifiedType modReturn)
 			{
-				returnType = modReturn.ElementType;
-				returnIsRefReadOnly = true;
+				if (modReturn.Modifier.IsKnownType(KnownAttribute.In))
+				{
+					returnType = modReturn.ElementType;
+					returnIsRefReadOnly = true;
+				}
+				else if (modReturn.Modifier.Name.StartsWith("CallConv", StringComparison.Ordinal)
+					&& modReturn.Modifier.Namespace == "System.Runtime.CompilerServices")
+				{
+					returnType = modReturn.ElementType;
+					customCallConvs.Add(modReturn.Modifier);
+				}
+				else
+				{
+					break;
+				}
 			}
 			var parameterTypes = ImmutableArray.CreateBuilder<IType>(signature.ParameterTypes.Length);
 			var parameterReferenceKinds = ImmutableArray.CreateBuilder<ReferenceKind>(signature.ParameterTypes.Length);
@@ -70,24 +84,27 @@ namespace ICSharpCode.Decompiler.TypeSystem
 				parameterReferenceKinds.Add(kind);
 			}
 			return new FunctionPointerType(
-				module, signature.Header.CallingConvention,
+				module, signature.Header.CallingConvention, customCallConvs.ToImmutable(),
 				returnType, returnIsRefReadOnly,
 				parameterTypes.MoveToImmutable(), parameterReferenceKinds.MoveToImmutable());
 		}
 
 		private readonly MetadataModule module;
 		public readonly SignatureCallingConvention CallingConvention;
+		public readonly ImmutableArray<IType> CustomCallingConventions;
 		public readonly IType ReturnType;
 		public readonly bool ReturnIsRefReadOnly;
 		public readonly ImmutableArray<IType> ParameterTypes;
 		public readonly ImmutableArray<ReferenceKind> ParameterReferenceKinds;
 
-		public FunctionPointerType(MetadataModule module, SignatureCallingConvention callingConvention,
+		public FunctionPointerType(MetadataModule module,
+			SignatureCallingConvention callingConvention, ImmutableArray<IType> customCallingConventions,
 			IType returnType, bool returnIsRefReadOnly,
 			ImmutableArray<IType> parameterTypes, ImmutableArray<ReferenceKind> parameterReferenceKinds)
 		{
 			this.module = module;
 			this.CallingConvention = callingConvention;
+			this.CustomCallingConventions = customCallingConventions;
 			this.ReturnType = returnType;
 			this.ReturnIsRefReadOnly = returnIsRefReadOnly;
 			this.ParameterTypes = parameterTypes;
@@ -146,7 +163,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 				return this;
 			else
 				return new FunctionPointerType(
-					module, CallingConvention,
+					module, CallingConvention, CustomCallingConventions,
 					r, ReturnIsRefReadOnly,
 					pt != null ? pt.ToImmutableArray() : ParameterTypes,
 					ParameterReferenceKinds);
@@ -156,6 +173,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		{
 			return other is FunctionPointerType fpt
 				&& CallingConvention == fpt.CallingConvention
+				&& CustomCallingConventions.SequenceEqual(fpt.CustomCallingConventions)
 				&& ReturnType.Equals(fpt.ReturnType)
 				&& ReturnIsRefReadOnly == fpt.ReturnIsRefReadOnly
 				&& ParameterTypes.SequenceEqual(fpt.ParameterTypes)
@@ -166,7 +184,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		{
 			unchecked
 			{
-				int hash = ReturnType.GetHashCode();
+				int hash = ReturnType.GetHashCode() ^ CallingConvention.GetHashCode();
 				foreach (var (p, k) in ParameterTypes.Zip(ParameterReferenceKinds))
 				{
 					hash ^= p.GetHashCode() ^ k.GetHashCode();
@@ -178,8 +196,10 @@ namespace ICSharpCode.Decompiler.TypeSystem
 
 		internal IType WithSignature(IType returnType, ImmutableArray<IType> parameterTypes)
 		{
-			return new FunctionPointerType(this.module, this.CallingConvention, returnType,
-				this.ReturnIsRefReadOnly, parameterTypes, this.ParameterReferenceKinds);
+			return new FunctionPointerType(this.module,
+				this.CallingConvention, this.CustomCallingConventions,
+				returnType, this.ReturnIsRefReadOnly,
+				parameterTypes, this.ParameterReferenceKinds);
 		}
 	}
 }