Update Trivial Inference for Python 3.15

[jrmccluskey]

Updates the trivial inference state machine for Python 3.15 opcodes. Tested locally; will not be exercised on-repo until 3.15 support is added outright.

Part of #40249

[github-actions]

📋 Review Summary

This PR updates the bytecode-based trivial type inference state machine (opcodes.py and trivial_inference.py) to accommodate Python 3.15 bytecode changes. It properly handles the new two-slot iterator stack representation (GET_ITER, FOR_ITER, POP_ITER, END_SEND), the expanded LOAD_COMMON_CONSTANT opcode, and generator expression call patterns where GET_ITER moved inside the generator code object.

🔍 General Feedback

• The changes are well-isolated with sys.version_info checks, ensuring full backwards compatibility with existing Python versions.
• Stack-relative adjustments and constant table lookups are handled cleanly with clear inline documentation explaining the CPython 3.15 runtime mechanics.

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[github-actions]

Assigning reviewers:

R: @damccorm for label python.
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[codecov]

Codecov Report

❌ Patch coverage is 35.00000% with 13 lines in your changes missing coverage. Please review.
✅ Project coverage is 79.92%. Comparing base (76f6e6d) to head (2319e42).
⚠️ Report is 164 commits behind head on master.

Files with missing lines	Patch %	Lines
sdks/python/apache_beam/typehints/opcodes.py	27.27%	8 Missing ⚠️
.../python/apache_beam/typehints/trivial_inference.py	44.44%	5 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             master   #40578       +/-   ##
=============================================
+ Coverage     56.16%   79.92%   +23.75%     
=============================================
  Files          1124      488      -636     
  Lines        178336    82362    -95974     
  Branches       1489        0     -1489     
=============================================
- Hits         100170    65831    -34339     
+ Misses        75645    16531    -59114     
+ Partials       2521        0     -2521     

Flag	Coverage Δ
go	?
java	?
python	79.92% <35.00%> (+0.37%)	⬆️

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[damccorm]

Generally LGTM, but had one question

[damccorm]

Is this called anywhere?

[jrmccluskey]

It doesn't have a direct call but will be used when the typehint tests run on 3.15. The functions defined in opcodes.py get imported in infer_return_type_func() and placed into a dictionary, then invoked through that dict entry rather than calling the function directly. This is the general convention for any operation that doesn't do more complex behavior like modifying the program counter

[damccorm]

Got it, thanks