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[Python]Fix type inference for closures in lambdas - #36080

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[Python]Fix type inference for closures in lambdas#36080
Suvrat1629 wants to merge 1 commit into
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Suvrat1629:closure_type

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@Suvrat1629 Suvrat1629 commented Sep 7, 2025

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Please add a meaningful description for your change here

Fixes #28420
Fixes type inference bug in load_closure where captured variables in inner lambdas (closures) were incorrectly inferred as type instead of their actual type (e.g., int).Updates load_closure in apache_beam/typehints/opcodes.py to use inferred types from the inference state context, with fallback to typehints.Any.

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@github-actions github-actions Bot added the python label Sep 7, 2025
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Summary of Changes

Hello @Suvrat1629, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a critical type inference bug within Apache Beam's Python SDK, specifically concerning how types are determined for variables captured by closures in lambda functions. The change ensures that the type hinting system accurately identifies and propagates the correct types for these variables, improving the reliability of type analysis within the framework.

Highlights

  • Closure Type Inference: Resolves a bug in load_closure where captured variables within inner lambdas (closures) were not correctly inferring their specific types, leading to incorrect type assignments.
  • Enhanced Type Resolution: Updates the load_closure function to prioritize inferred types from the inference state context, ensuring more precise type propagation, with typehints.Any as a robust fallback.
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Checks are failing. Will not request review until checks are succeeding. If you'd like to override that behavior, comment assign set of reviewers

@stankiewicz

stankiewicz commented Sep 25, 2025

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please review logs:

TrivialInferenceTest.testDictComprehension __________________
[gw1] linux -- Python 3.10.17 /runner/_work/beam/beam/sdks/python/test-suites/tox/py310/build/srcs/sdks/python/target/.tox-py310/py310/bin/python

self = <apache_beam.typehints.trivial_inference_test.TrivialInferenceTest testMethod=testDictComprehension>

    def testDictComprehension(self):
      fields = []
      expected_type = typehints.Dict[typehints.Any, typehints.Any]
>     self.assertReturnType(
          expected_type, lambda row: {f: row[f] for f in fields}, [typehints.Any])

apache_beam/typehints/trivial_inference_test.py:357: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
apache_beam/typehints/trivial_inference_test.py:38: in assertReturnType
    trivial_inference.infer_return_type(f, inputs, debug=True, depth=depth))
target/.tox-py310/py310/lib/python3.10/site-packages/apache_beam/yaml/yaml_provider.py:554: in infer_return_type
    return original_infer_return_type(fn, *args, **kwargs)
target/.tox-py310/py310/lib/python3.10/site-packages/apache_beam/typehints/trivial_inference.py:297: in infer_return_type
    return infer_return_type_func(c, input_types, debug, depth)
target/.tox-py310/py310/lib/python3.10/site-packages/apache_beam/typehints/trivial_inference.py:626: in infer_return_type_func
    simple_ops[opname](state, arg)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

state = Stack: [Any] Vars: [Any], arg = 0

    def load_closure(state, arg):
      # The arg is no longer offset by len(covar_names) as of 3.11
      # See https://docs.python.org/3/library/dis.html#opcode-LOAD_CLOSURE
      if (sys.version_info.major, sys.version_info.minor) >= (3, 11):
        arg -= len(state.co.co_varnames)
      state.stack.append(state.closure_type(arg))
      closure_idx = arg
>     inferred_type = state.closure_type[closure_idx] if hasattr(state, 'closure_types') else state.get_inferred_type_for_closure(closure_idx)
E     AttributeError: 'FrameState' object has no attribute 'get_inferred_type_for_closure'

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This pull request has been marked as stale due to 60 days of inactivity. It will be closed in 1 week if no further activity occurs. If you think that’s incorrect or this pull request requires a review, please simply write any comment. If closed, you can revive the PR at any time and @mention a reviewer or discuss it on the dev@beam.apache.org list. Thank you for your contributions.

@github-actions github-actions Bot added the stale label Nov 24, 2025
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github-actions Bot commented Dec 1, 2025

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This pull request has been closed due to lack of activity. If you think that is incorrect, or the pull request requires review, you can revive the PR at any time.

@github-actions github-actions Bot closed this Dec 1, 2025
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[Bug]: Type inference failure with closure creation.

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