ComInterfaceGenerator produces invalid C# for `partial` interface methods.

[jtschuster]

Looks like we just copy the partial modifier from user code when we shouldn't

Code:

[GeneratedComInterface]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
[Guid(IID)]
internal partial interface ICalculator
{
 int Add(int a, int b);
 public partial int Subtract(int a, int b) => 0;
 public partial int Subtract(int a, int b);
 public const string IID = "c67121c6-cf26-431f-adc7-d12fe2448841";
}

generated:

// <auto-generated />
#pragma warning disable CS0612, CS0618
file unsafe class InterfaceInformation : global::System.Runtime.InteropServices.Marshalling.IIUnknownInterfaceType
{
 public static global::System.Guid Iid { get; } = new(new global::System.ReadOnlySpan<byte>(new byte[] { 198, 33, 113, 198, 38, 207, 31, 67, 173, 199, 209, 47, 226, 68, 136, 65 }));

 private static void** _vtable;
 public static void** ManagedVirtualMethodTable => _vtable != null ? _vtable : (_vtable = InterfaceImplementation.CreateManagedVirtualFunctionTable());
}

[global::System.Runtime.InteropServices.DynamicInterfaceCastableImplementationAttribute]
file unsafe partial interface InterfaceImplementation : global::Tutorial.ICalculator
{
 [global::System.CodeDom.Compiler.GeneratedCodeAttribute("Microsoft.Interop.ComInterfaceGenerator", "8.0.8.41904")]
 [global::System.Runtime.CompilerServices.SkipLocalsInitAttribute]
 int global::Tutorial.ICalculator.Add(int a, int b)
 {
 var(__this, __vtable_native) = ((global::System.Runtime.InteropServices.Marshalling.IUnmanagedVirtualMethodTableProvider)this).GetVirtualMethodTableInfoForKey(typeof(global::Tutorial.ICalculator));
 int __retVal;
 int __invokeRetVal;
 {
 __invokeRetVal = ((delegate* unmanaged[MemberFunction]<void*, int, int, int*, int> )__vtable_native[3])(__this, a, b, &__retVal);
 }

 // NotifyForSuccessfulInvoke - Keep alive any managed objects that need to stay alive across the call.
 global::System.Runtime.InteropServices.Marshal.ThrowExceptionForHR(__invokeRetVal);
 global::System.GC.KeepAlive(this);
 return __retVal;
 }

 [global::System.CodeDom.Compiler.GeneratedCodeAttribute("Microsoft.Interop.ComInterfaceGenerator", "8.0.8.41904")]
 [global::System.Runtime.CompilerServices.SkipLocalsInitAttribute]
 partial int global::Tutorial.ICalculator.Subtract(int a, int b)
 {
 var(__this, __vtable_native) = ((global::System.Runtime.InteropServices.Marshalling.IUnmanagedVirtualMethodTableProvider)this).GetVirtualMethodTableInfoForKey(typeof(global::Tutorial.ICalculator));
 int __retVal;
 int __invokeRetVal;
 {
 __invokeRetVal = ((delegate* unmanaged[MemberFunction]<void*, int, int, int*, int> )__vtable_native[4])(__this, a, b, &__retVal);
 }

 // NotifyForSuccessfulInvoke - Keep alive any managed objects that need to stay alive across the call.
 global::System.Runtime.InteropServices.Marshal.ThrowExceptionForHR(__invokeRetVal);
 global::System.GC.KeepAlive(this);
 return __retVal;
 }
}

file unsafe partial interface InterfaceImplementation
{
 [global::System.Runtime.InteropServices.UnmanagedCallersOnlyAttribute(CallConvs = new[] { typeof(global::System.Runtime.CompilerServices.CallConvMemberFunction) })]
 internal static int ABI_Add(global::System.Runtime.InteropServices.ComWrappers.ComInterfaceDispatch* __this_native, int a, int b, int* __invokeRetValUnmanaged__param)
 {
 global::Tutorial.ICalculator @this = default;
 ref int __invokeRetValUnmanaged = ref *__invokeRetValUnmanaged__param;
 int __invokeRetVal = default;
 int __retVal = default;
 try
 {
 // Unmarshal - Convert native data to managed data.
 @this = global::System.Runtime.InteropServices.ComWrappers.ComInterfaceDispatch.GetInstance<global::Tutorial.ICalculator>(__this_native);
 __invokeRetVal = @this.Add(a, b);
 // NotifyForSuccessfulInvoke - Keep alive any managed objects that need to stay alive across the call.
 __retVal = 0; // S_OK
 // Marshal - Convert managed data to native data.
 __invokeRetValUnmanaged = __invokeRetVal;
 }
 catch (global::System.Exception __exception)
 {
 __retVal = global::System.Runtime.InteropServices.Marshalling.ExceptionAsHResultMarshaller<int>.ConvertToUnmanaged(__exception);
 }

 return __retVal;
 }

 [global::System.Runtime.InteropServices.UnmanagedCallersOnlyAttribute(CallConvs = new[] { typeof(global::System.Runtime.CompilerServices.CallConvMemberFunction) })]
 internal static int ABI_Subtract(global::System.Runtime.InteropServices.ComWrappers.ComInterfaceDispatch* __this_native, int a, int b, int* __invokeRetValUnmanaged__param)
 {
 global::Tutorial.ICalculator @this = default;
 ref int __invokeRetValUnmanaged = ref *__invokeRetValUnmanaged__param;
 int __invokeRetVal = default;
 int __retVal = default;
 try
 {
 // Unmarshal - Convert native data to managed data.
 @this = global::System.Runtime.InteropServices.ComWrappers.ComInterfaceDispatch.GetInstance<global::Tutorial.ICalculator>(__this_native);
 __invokeRetVal = @this.Subtract(a, b);
 // NotifyForSuccessfulInvoke - Keep alive any managed objects that need to stay alive across the call.
 __retVal = 0; // S_OK
 // Marshal - Convert managed data to native data.
 __invokeRetValUnmanaged = __invokeRetVal;
 }
 catch (global::System.Exception __exception)
 {
 __retVal = global::System.Runtime.InteropServices.Marshalling.ExceptionAsHResultMarshaller<int>.ConvertToUnmanaged(__exception);
 }

 return __retVal;
 }
}

file unsafe partial interface InterfaceImplementation
{
 internal static void** CreateManagedVirtualFunctionTable()
 {
 void** vtable = (void**)global::System.Runtime.CompilerServices.RuntimeHelpers.AllocateTypeAssociatedMemory(typeof(global::Tutorial.ICalculator), sizeof(void*) * 5);
 {
 nint v0, v1, v2;
 global::System.Runtime.InteropServices.ComWrappers.GetIUnknownImpl(out v0, out v1, out v2);
 vtable[0] = (void*)v0;
 vtable[1] = (void*)v1;
 vtable[2] = (void*)v2;
 }

 {
 vtable[3] = (void*)(delegate* unmanaged[MemberFunction]<global::System.Runtime.InteropServices.ComWrappers.ComInterfaceDispatch*, int, int, int*, int> )&ABI_Add;
 vtable[4] = (void*)(delegate* unmanaged[MemberFunction]<global::System.Runtime.InteropServices.ComWrappers.ComInterfaceDispatch*, int, int, int*, int> )&ABI_Subtract;
 }

 return vtable;
 }
}

namespace Tutorial
{
 [global::System.Runtime.InteropServices.Marshalling.IUnknownDerivedAttribute<InterfaceInformation, InterfaceImplementation>]
 internal partial interface ICalculator
 {
 }
}

namespace Tutorial
{
 internal partial interface ICalculator
 {
 }
}

Error:

Microsoft.Interop.ComInterfaceGenerator\ICalculator.cs(33,46): error CS0759: No defining declaration found for implementing declaration of partial method 'InterfaceImplementation.Subtract(int, int)'

Microsoft.Interop.ComInterfaceGenerator\ICalculator.cs(33,46): error CS0754: A partial method may not explicitly implement an interface method

Microsoft.Interop.ComInterfaceGenerator\ICalculator.cs(33,46): error CS0539: 'InterfaceImplementation.Subtract(int, int)' in explicit interface declaration is not found among members of the interface that can be implemented

Microsoft.Interop.ComInterfaceGenerator\ICalculator.cs(33,46): error CS8796: Partial method 'InterfaceImplementation.Subtract(int, int)' must have accessibility modifiers because it has a non-void return type. 

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Issue Details

---

Looks like we just copy the partial modifier from user code when we shouldn't

Code:

[GeneratedComInterface]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
[Guid(IID)]
internal partial interface ICalculator
{
 int Add(int a, int b);
 public partial int Subtract(int a, int b) => 0;
 public partial int Subtract(int a, int b);
 public const string IID = "c67121c6-cf26-431f-adc7-d12fe2448841";
}

generated:

// <auto-generated />
#pragma warning disable CS0612, CS0618
file unsafe class InterfaceInformation : global::System.Runtime.InteropServices.Marshalling.IIUnknownInterfaceType
{
 public static global::System.Guid Iid { get; } = new(new global::System.ReadOnlySpan<byte>(new byte[] { 198, 33, 113, 198, 38, 207, 31, 67, 173, 199, 209, 47, 226, 68, 136, 65 }));

 private static void** _vtable;
 public static void** ManagedVirtualMethodTable => _vtable != null ? _vtable : (_vtable = InterfaceImplementation.CreateManagedVirtualFunctionTable());
}

[global::System.Runtime.InteropServices.DynamicInterfaceCastableImplementationAttribute]
file unsafe partial interface InterfaceImplementation : global::Tutorial.ICalculator
{
 [global::System.CodeDom.Compiler.GeneratedCodeAttribute("Microsoft.Interop.ComInterfaceGenerator", "8.0.8.41904")]
 [global::System.Runtime.CompilerServices.SkipLocalsInitAttribute]
 int global::Tutorial.ICalculator.Add(int a, int b)
 {
 var(__this, __vtable_native) = ((global::System.Runtime.InteropServices.Marshalling.IUnmanagedVirtualMethodTableProvider)this).GetVirtualMethodTableInfoForKey(typeof(global::Tutorial.ICalculator));
 int __retVal;
 int __invokeRetVal;
 {
 __invokeRetVal = ((delegate* unmanaged[MemberFunction]<void*, int, int, int*, int> )__vtable_native[3])(__this, a, b, &__retVal);
 }

 // NotifyForSuccessfulInvoke - Keep alive any managed objects that need to stay alive across the call.
 global::System.Runtime.InteropServices.Marshal.ThrowExceptionForHR(__invokeRetVal);
 global::System.GC.KeepAlive(this);
 return __retVal;
 }

 [global::System.CodeDom.Compiler.GeneratedCodeAttribute("Microsoft.Interop.ComInterfaceGenerator", "8.0.8.41904")]
 [global::System.Runtime.CompilerServices.SkipLocalsInitAttribute]
 partial int global::Tutorial.ICalculator.Subtract(int a, int b)
 {
 var(__this, __vtable_native) = ((global::System.Runtime.InteropServices.Marshalling.IUnmanagedVirtualMethodTableProvider)this).GetVirtualMethodTableInfoForKey(typeof(global::Tutorial.ICalculator));
 int __retVal;
 int __invokeRetVal;
 {
 __invokeRetVal = ((delegate* unmanaged[MemberFunction]<void*, int, int, int*, int> )__vtable_native[4])(__this, a, b, &__retVal);
 }

 // NotifyForSuccessfulInvoke - Keep alive any managed objects that need to stay alive across the call.
 global::System.Runtime.InteropServices.Marshal.ThrowExceptionForHR(__invokeRetVal);
 global::System.GC.KeepAlive(this);
 return __retVal;
 }
}

file unsafe partial interface InterfaceImplementation
{
 [global::System.Runtime.InteropServices.UnmanagedCallersOnlyAttribute(CallConvs = new[] { typeof(global::System.Runtime.CompilerServices.CallConvMemberFunction) })]
 internal static int ABI_Add(global::System.Runtime.InteropServices.ComWrappers.ComInterfaceDispatch* __this_native, int a, int b, int* __invokeRetValUnmanaged__param)
 {
 global::Tutorial.ICalculator @this = default;
 ref int __invokeRetValUnmanaged = ref *__invokeRetValUnmanaged__param;
 int __invokeRetVal = default;
 int __retVal = default;
 try
 {
 // Unmarshal - Convert native data to managed data.
 @this = global::System.Runtime.InteropServices.ComWrappers.ComInterfaceDispatch.GetInstance<global::Tutorial.ICalculator>(__this_native);
 __invokeRetVal = @this.Add(a, b);
 // NotifyForSuccessfulInvoke - Keep alive any managed objects that need to stay alive across the call.
 __retVal = 0; // S_OK
 // Marshal - Convert managed data to native data.
 __invokeRetValUnmanaged = __invokeRetVal;
 }
 catch (global::System.Exception __exception)
 {
 __retVal = global::System.Runtime.InteropServices.Marshalling.ExceptionAsHResultMarshaller<int>.ConvertToUnmanaged(__exception);
 }

 return __retVal;
 }

 [global::System.Runtime.InteropServices.UnmanagedCallersOnlyAttribute(CallConvs = new[] { typeof(global::System.Runtime.CompilerServices.CallConvMemberFunction) })]
 internal static int ABI_Subtract(global::System.Runtime.InteropServices.ComWrappers.ComInterfaceDispatch* __this_native, int a, int b, int* __invokeRetValUnmanaged__param)
 {
 global::Tutorial.ICalculator @this = default;
 ref int __invokeRetValUnmanaged = ref *__invokeRetValUnmanaged__param;
 int __invokeRetVal = default;
 int __retVal = default;
 try
 {
 // Unmarshal - Convert native data to managed data.
 @this = global::System.Runtime.InteropServices.ComWrappers.ComInterfaceDispatch.GetInstance<global::Tutorial.ICalculator>(__this_native);
 __invokeRetVal = @this.Subtract(a, b);
 // NotifyForSuccessfulInvoke - Keep alive any managed objects that need to stay alive across the call.
 __retVal = 0; // S_OK
 // Marshal - Convert managed data to native data.
 __invokeRetValUnmanaged = __invokeRetVal;
 }
 catch (global::System.Exception __exception)
 {
 __retVal = global::System.Runtime.InteropServices.Marshalling.ExceptionAsHResultMarshaller<int>.ConvertToUnmanaged(__exception);
 }

 return __retVal;
 }
}

file unsafe partial interface InterfaceImplementation
{
 internal static void** CreateManagedVirtualFunctionTable()
 {
 void** vtable = (void**)global::System.Runtime.CompilerServices.RuntimeHelpers.AllocateTypeAssociatedMemory(typeof(global::Tutorial.ICalculator), sizeof(void*) * 5);
 {
 nint v0, v1, v2;
 global::System.Runtime.InteropServices.ComWrappers.GetIUnknownImpl(out v0, out v1, out v2);
 vtable[0] = (void*)v0;
 vtable[1] = (void*)v1;
 vtable[2] = (void*)v2;
 }

 {
 vtable[3] = (void*)(delegate* unmanaged[MemberFunction]<global::System.Runtime.InteropServices.ComWrappers.ComInterfaceDispatch*, int, int, int*, int> )&ABI_Add;
 vtable[4] = (void*)(delegate* unmanaged[MemberFunction]<global::System.Runtime.InteropServices.ComWrappers.ComInterfaceDispatch*, int, int, int*, int> )&ABI_Subtract;
 }

 return vtable;
 }
}

namespace Tutorial
{
 [global::System.Runtime.InteropServices.Marshalling.IUnknownDerivedAttribute<InterfaceInformation, InterfaceImplementation>]
 internal partial interface ICalculator
 {
 }
}

namespace Tutorial
{
 internal partial interface ICalculator
 {
 }
}

Error:

Microsoft.Interop.ComInterfaceGenerator\ICalculator.cs(33,46): error CS0759: No defining declaration found for implementing declaration of partial method 'InterfaceImplementation.Subtract(int, int)'

Microsoft.Interop.ComInterfaceGenerator\ICalculator.cs(33,46): error CS0754: A partial method may not explicitly implement an interface method

Microsoft.Interop.ComInterfaceGenerator\ICalculator.cs(33,46): error CS0539: 'InterfaceImplementation.Subtract(int, int)' in explicit interface declaration is not found among members of the interface that can be implemented

Microsoft.Interop.ComInterfaceGenerator\ICalculator.cs(33,46): error CS8796: Partial method 'InterfaceImplementation.Subtract(int, int)' must have accessibility modifiers because it has a non-void return type. 

Author:	jtschuster
Assignees:	-
Labels:	area-System.Runtime.InteropServices, source-generator
Milestone:	9.0.0