I am calling MethodCall.invoke and attempting to invoke an inaccessible method (the method is declared to be package private) on an object.
If I were using reflection, I could do theMethod.setAccessible(true) and then access checks would be disabled.
As a hack, I know that MethodDescription inherits from ByteCodeElement which defines isAccessibleTo(TypeDescription). I overrode that to return true just to see what would happen. Unsurprisingly, I get an IllegalAccessError at method invocation time. This also happens if I override isVisibleTo(TypeDescription).
I know that the magic of setAccessible(true) is achieved partially by subclassing MagicAccessorImpl. I also know this is in the jdk.internal.reflect package which is not exported by default and which cannot be exported if you're using --release with javac, which I am.
Anyway it occurred to me that ByteBuddy may have some facility for performing the same kind of unchecked bytecode work that MethodAccessorGenerator does.
How can I achieve this with ByteBuddy?
This is not possible as you cannot legally express it in Byte Code. I'd also recommend against using the magic accessor as this does no longer work in future Java versions where this is solved using MethodHandles. You can resolve a method handle and invoke it from a generated class.