dylanhz opened a new pull request, #27787:
URL: https://github.com/apache/flink/pull/27787
## What is the purpose of the change
Fix a bug where UDF type inference throws "Argument name conflict" when a
method (e.g. eval, accumulate) contains a lambda expression that captures its
own parameters.
The ASM-based `ParameterExtractor` in `ExtractionUtils` matched target
methods only by bytecode descriptor, ignoring the method name. When a lambda
captures parameters of the enclosing `eval` method, the Java compiler generates
a `lambda$eval$N` synthetic static method with the same descriptor. The
`ParameterExtractor` visits both the real `eval` and the synthetic method,
causing the lambda's local variable names (starting at slot 0) to overwrite the
instance method's parameter entries (where slot 0 is `this`) in the shared
`TreeMap`, producing duplicate names and triggering the validation error.
## Brief change log
- Store `methodName` in `ParameterExtractor` (`method.getName()` for
methods, `"<init>"` for constructors)
- Match on both `name.equals(methodName) &&
descriptor.equals(methodDescriptor)` in `visitMethod` to avoid visiting lambda
synthetic methods
## Verifying this change
This change added tests and can be verified as follows:
- Added a unit test in `ExtractionUtilsTest` that directly verifies
`extractExecutableNames` returns correct parameter names for a method
containing a lambda that captures its own parameters
- Added an integration test in `TypeInferenceExtractorTest` that verifies
end-to-end type inference succeeds for a `ScalarFunction` with lambda capture
## Does this pull request potentially affect one of the following parts:
- Dependencies (does it add or upgrade a dependency): no
- The public API, i.e., is any changed class annotated with
`@Public(Evolving)`: no
- The serializers: no
- The runtime per-record code paths (performance sensitive): no
- Anything that affects deployment or recovery: JobManager (and its
components), Checkpointing, Kubernetes/Yarn, ZooKeeper: no
- The S3 file system connector: no
## Documentation
- Does this pull request introduce a new feature? no
- If yes, how is the feature documented? not applicable
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