Fix optional input positions in converter

[the0cp]

Summary

• Preserve empty input positions when a later optional ONNX input is supplied
• Allow the converter to consume normalized None placeholders
• Add generic argument-partitioning tests
• Add a Resize conversion and ONNX Runtime regression test

Fixes #2007

[Copilot]

Pull request overview

Fixes a converter/argument-partitioning bug where omitted optional ONNX inputs were dropped, causing later optional inputs (e.g., Resize(..., sizes=...)) to shift into the wrong input positions and produce invalid models for ONNX Runtime.

Changes:

• Preserve “holes” for omitted optional inputs when a later input is provided (positional or keyword) during argument partitioning.
• Update the converter to accept normalized None placeholders (in addition to parsed ast.Constant(None)) for optional inputs.
• Add targeted unit tests and an ONNX Runtime regression test for Resize(..., sizes=...) ensuring required empty inputs are preserved.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
onnxscript/_internal/param_manipulation.py	Tracks omitted optional inputs and inserts None placeholders only when needed to preserve later input positions.
onnxscript/_internal/param_manipulation_test.py	Adds parameterized tests covering preserved optional input positions (including explicit None).
onnxscript/_internal/converter.py	Allows _translate_opt_expr to handle None placeholders introduced by normalization.
onnxscript/_internal/converter_test.py	Adds an ONNX Runtime regression test validating Resize inputs include the required empty slots.

[codecov]

Codecov Report

❌ Patch coverage is 93.93939% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 72.66%. Comparing base (00de62e) to head (c6a0c8f).

Files with missing lines	Patch %	Lines
onnxscript/_internal/converter_test.py	88.88%	1 Missing ⚠️
onnxscript/_internal/param_manipulation.py	92.85%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2961      +/-   ##
==========================================
+ Coverage   72.64%   72.66%   +0.01%     
==========================================
  Files         265      265              
  Lines       32192    32221      +29     
  Branches     3038     3041       +3     
==========================================
+ Hits        23385    23412      +27     
- Misses       7776     7777       +1     
- Partials     1031     1032       +1     

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[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated no new comments.