[GROOVY-10568] MissingMethodException using method-pointer operator in superclass

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 4.0.1
• Fix Version/s: 5.0.0-alpha-1
• Component/s: Compiler, Static compilation
• Assignee: Eric Milles
• Reporter: Christopher Smith
• Created: 05/Apr/22 15:15
• Updated: 23/Aug/23 09:11
• Resolved: 14/Jul/23 19:05

Description

I'm working on teasing out the minimal effect here, but this is my setup:

• Base service interface B.
• Core concrete implementation BImpl implements B. This implementation includes a private method Table<T> getOrCreateTable(TableKey<T>) and a Caffeine cache defined as Caffeine.newBuilder().build(this.&getOrCreateTable).

This worked fine. However, in a particular project, I want to extend B. For Reasons™, the extensions are implementable just fine as default methods, so I have

interface E extends B {
  default <R extends Record> Table<R> tableForRecord(R record) {
    this.stuff(r)
  }
}

Because of Groovy internals, this is implemented as a trait. I now have

class EImpl extends BImpl implements E {
  EImpl(DynamoDbClient c) {
    super(c)
  }
}

Instantiating EImpl now fails with a MissingMethodException inside ScriptBytecodeAdapter.unwrap(ScriptBytecodeAdapter.java:72):

groovy.lang.MissingMethodException: No signature of method: com.example.EImpl.getOrCreateTable() is applicable for argument types: (com.example.BImpl$TableKey) values: [com.example.BImpl$TableKey(flow_preference, software.amazon.awssdk.enhanced.dynamodb.mapper.BeanTableSchema@427946b9)]

I think what's happening is that since the Groovy compiler doesn't support real method closures, it's delegating the implementation duties of .& to a reflection routine that is tripping on either the private super method or the private type; I'm inclined to guess the method since the functionality works correctly with a single type. Changing the access modifier on B.getOrCreateTable(TableKey) to protected seems to fix it, but the base class should be able to access its own private members.

Issue Links

• is related to: GROOVY-2433 Closure in base class unable to call private methods when invoked from derived class
• is related to: GROOVY-5051 'this' uses in a superclass is treated as subclass, preventing acces to private members