Ignore AssociatedSourceType on UnmanagedCallersOnly in CoreCLR

src/coreclr/vm/callconvbuilder.cpp

@@ -550,7 +550,7 @@ bool CallConv::TryGetCallingConventionFromUnmanagedCallersOnly(_In_ MethodDesc*
 
     // UnmanagedCallersOnly each
     // have optional named arguments.
-    CaNamedArg namedArgs[2];
+    CaNamedArg namedArgs[3];
 
     // For the UnmanagedCallersOnly scenario.
     CaType caCallConvs;
@@ -563,6 +563,9 @@ bool CallConv::TryGetCallingConventionFromUnmanagedCallersOnly(_In_ MethodDesc*
     CaTypeCtor caEntryPoint(SERIALIZATION_TYPE_STRING);
     namedArgs[1].Init("EntryPoint", SERIALIZATION_TYPE_STRING, caEntryPoint);
 
+    CaTypeCtor caAssociatedSourceType(SERIALIZATION_TYPE_TYPE);
+    namedArgs[2].Init("AssociatedSourceType", SERIALIZATION_TYPE_TYPE, caAssociatedSourceType);
+
     InlineFactory<SArray<CaValue>, 4> caValueArrayFactory;
     Assembly* assembly = pMD->GetLoaderModule()->GetAssembly();
     IfFailThrow(CustomAttribute::ParseArgumentValues(

src/mono/mono/metadata/marshal.c

@@ -3474,17 +3474,18 @@ mono_marshal_set_callconv_from_unmanaged_callers_only_attribute (MonoMethod *met
 	}
 
 	if (attr != NULL) {
-		MonoDecodeCustomAttr *decoded_args = mono_reflection_create_custom_attr_data_args_noalloc (mono_defaults.corlib, attr->ctor, attr->data, attr->data_size, error);
+		MonoDecodeCustomAttr *decoded_args = mono_reflection_create_custom_attr_data_args_noalloc (m_class_get_image (method->klass), attr->ctor, attr->data, attr->data_size, error);
 		mono_error_assert_ok (error);
 		for (int i = 0; i < decoded_args->named_args_num; ++i) {
 			if (decoded_args->named_args_info [i].field && !strcmp (decoded_args->named_args_info [i].field->name, "CallConvs")) {
-				g_assertf(decoded_args->named_args_info [i].field->type->type == MONO_TYPE_SZARRAY, "UnmanagedCallersOnlyAttribute parameter %s must be an array, specified for method %s", decoded_args->named_args_info [i].field->name, method->name);
+				g_assertf (decoded_args->named_args_info [i].field->type->type == MONO_TYPE_SZARRAY, "Expected UnmanagedCallersOnlyAttribute field %s to be SZARRAY type, specified for method %s. This indicates a malformed attribute or incorrect usage pattern.", decoded_args->named_args_info [i].field->name, method->name);
 				MonoCustomAttrValueArray *calling_conventions = decoded_args->named_args[i]->value.array;
 				if (calling_conventions->len > 0) {
 					if (calling_conventions->len > 1)
-						g_warning ("Multiple calling conventions are not supported for UnmanagedCallersOnlyAttribute parameter %s, specified for method %s. Only the first calling convention will be taken into account", decoded_args->named_args_info [i].field->name, method->name);
+						g_warning ("Multiple calling conventions are not supported for UnmanagedCallersOnlyAttribute field %s, specified for method %s. Only the first calling convention will be taken into account", decoded_args->named_args_info [i].field->name, method->name);
 					// TODO: Support multiple conventions?
-					MonoType* calling_convention = (MonoType*)calling_conventions->values[0].value.primitive;
+					// System.Type values are stored in the primitive union member by load_cattr_value_noalloc.
+					MonoType *calling_convention = (MonoType*)calling_conventions->values[0].value.primitive;
 					mono_marshal_set_signature_callconv_from_attribute (csig, calling_convention, error);
 				}
 			}

src/tests/Interop/UnmanagedCallersOnlyBasic/UnmanagedCallersOnlyBasicTest.cs

@@ -45,6 +45,12 @@ public static int ManagedDoubleCallback(int n)
         return DoubleImpl(n);
     }
 
+    [UnmanagedCallersOnly(AssociatedSourceType = typeof(UnmanagedCallersOnlyBasicTest))]
+    public static int ManagedDoubleCallback_AssociatedSourceType(int n)
+    {
+        return DoubleImpl(n);
+    }
+
     [ActiveIssue("https://github.com/dotnet/runtime/issues/64127", typeof(PlatformDetection), nameof(PlatformDetection.PlatformDoesNotSupportNativeTestAssets))]
     [ActiveIssue("Needs coreclr build", typeof(PlatformDetection), nameof(PlatformDetection.IsMonoFULLAOT))]
     [ActiveIssue("needs triage", TestPlatforms.Android)]
@@ -60,7 +66,21 @@ public static void TestUnmanagedCallersOnlyValid()
         Assert.Equal(expected, UnmanagedCallersOnlyDll.CallManagedProc((IntPtr)(delegate* unmanaged<int, int>)&ManagedDoubleCallback, n));
     }
 
-   [UnmanagedCallersOnly(CallConvs = [typeof(CallConvStdcall)])]
+    [ActiveIssue("https://github.com/dotnet/runtime/issues/64127", typeof(PlatformDetection), nameof(PlatformDetection.PlatformDoesNotSupportNativeTestAssets))]
+    [ActiveIssue("Needs coreclr build", typeof(PlatformDetection), nameof(PlatformDetection.IsMonoFULLAOT))]
+    [ActiveIssue("needs triage", TestPlatforms.Android)]
+    [ActiveIssue("needs triage", TestPlatforms.iOS | TestPlatforms.tvOS | TestPlatforms.MacCatalyst)]
+    [Fact]
+    public static void TestUnmanagedCallersOnlyValid_AssociatedSourceType()
+    {
+        Console.WriteLine($"Running {nameof(TestUnmanagedCallersOnlyValid_AssociatedSourceType)}...");
+
+        int n = 12345;
+        int expected = DoubleImpl(n);
+        Assert.Equal(expected, ((delegate* unmanaged<int, int>)&ManagedDoubleCallback_AssociatedSourceType)(n));
+    }
+
+    [UnmanagedCallersOnly(CallConvs = [typeof(CallConvStdcall)])]
     public static int ManagedDoubleCallback_Stdcall(int n)
     {
         return DoubleImpl(n);