MarshalingPInvokeScanner doesn't see [DisableRuntimeMarshalling] attributes in any assembly except System.Runtime.dll

[rolfbjarne]

The MarshalingPInvokeScanner task doesn't see [DisableRuntimeMarshalling] attributes defined in any assembly except System.Runtime.dll (where the attribute is defined).

The problem is that this code:

runtime/src/tasks/MonoTargetsTasks/MarshalingPInvokeScanner/MarshalingPInvokeScanner.cs

Lines 116 to 131 in 035d268

	foreach (CustomAttributeHandle attrHandle in mdtReader.CustomAttributes)
	{
	CustomAttribute attr = mdtReader.GetCustomAttribute(attrHandle);
	if (attr.Constructor.Kind == HandleKind.MethodDefinition)
	{
	MethodDefinitionHandle mdh = (MethodDefinitionHandle)attr.Constructor;
	MethodDefinition md = mdtReader.GetMethodDefinition(mdh);
	TypeDefinitionHandle tdh = md.GetDeclaringType();
	TypeDefinition td = mdtReader.GetTypeDefinition(tdh);
	if (mdtReader.GetString(td.Namespace) == "System.Runtime.CompilerServices" &&
	mdtReader.GetString(td.Name) == "DisableRuntimeMarshallingAttribute")
	return false;
	}
	}

does not take into account that the attribute's constructor will be a MethodReference when referencing a constructor defined in another assembly.

Repro:

• Clone https://github.com/rolfbjarne/marshalling-scanner (including submodules)
• Run make disable-runtime-marshalling-attribute

This happens:

[...]
Assembly /Users/rolf/test/dotnet/marshalling-scanner/disable-runtime-marshalling-attribute/bin/Debug/net9.0/disable-runtime-marshalling-attribute.dll requires marshal-ilgen for method .Class1:DoSomething (first pass).
❌ Failed, because some assemblies are incompatible
make: *** [disable-runtime-marshalling-attribute] Error 1