Fix optional input positions in converter

[Theodore Cooper (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 94.73684% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 72.65%. Comparing base (a00b0e0) to head (48a8476).

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   72.63%   72.65%   +0.02%     
==========================================
  Files         265      265              
  Lines       32208    32242      +34     
  Branches     3042     3045       +3     
==========================================
+ Hits        23395    23427      +32     
- Misses       7779     7780       +1     
- Partials     1034     1035       +1     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

[Copilot]

Pull request overview

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

[Theodore Cooper (the0cp)]

Hi Justin Chu (@justinchuby), could you please review this PR or point me to the right maintainer? Thanks!

[Theodore Cooper (the0cp)]

The only failing jobs are the three Torch nightly jobs. These appear unrelated to this PR.

[Justin Chu (justinchuby)]

G. Ramalingam (@gramalingam)

[Copilot]

Pull request overview

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