Add custom operator names to the script decorator

[ilia-sokolov]

Summary

• add a keyword-only op_type argument to @script
• apply the custom name consistently to the ONNX callable, signature, IR graph, FunctionProto, and nested call nodes
• preserve the original Python function name for introspection
• track called functions by their full ONNX identifier (domain, name, overload) and report conflicting definitions instead of silently dropping one

Why

Python function names do not always match the operator name required by an existing runtime or interoperability contract. This enables:

@script(op_type="MY_NEW_NAME_OP")
def custom_op(x):
    ...

while keeping custom_op.__name__ == "custom_op".

Validation

• python -m pytest onnxscript/_internal/main_test.py onnxscript/_internal/values_test.py onnxscript/_internal/builder_test.py -q
• 102 tests and 6 subtests passed
• git diff --check

Fixes #1985

[Copilot]

Pull request overview

Adds support for specifying a custom ONNX operator name (op_type) when using the @script decorator, while preserving the original Python function name for introspection. This enables defining ONNX functions that must match externally required operator names without renaming the Python symbol.

Changes:

• Added keyword-only op_type: str | None to @script, with validation for type and non-empty strings.
• Applied op_type consistently by setting the IR function name and IR graph name prior to constructing the OnnxFunction.
• Updated nested-function collection/deduplication to key by full ONNX identifier and raise on conflicting definitions; added comprehensive tests for the new behavior.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
onnxscript/_internal/main.py	Adds op_type to @script and applies it to the generated IR before wrapping as an OnnxFunction.
onnxscript/_internal/main_test.py	Adds tests covering custom operator naming, identifier conflict behavior, and input validation.
onnxscript/_internal/irbuilder.py	Changes called-function tracking to use full operator identifiers and to error on conflicting definitions.

[codecov]

Codecov Report

❌ Patch coverage is 84.16667% with 19 lines in your changes missing coverage. Please review.
✅ Project coverage is 72.67%. Comparing base (9ef0aac) to head (f7d14d7).

Files with missing lines	Patch %	Lines
onnxscript/_internal/main_test.py	81.90%	18 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2977      +/-   ##
==========================================
+ Coverage   72.63%   72.67%   +0.03%     
==========================================
  Files         265      266       +1     
  Lines       32204    32320     +116     
  Branches     3041     3048       +7     
==========================================
+ Hits        23391    23488      +97     
- Misses       7779     7797      +18     
- Partials     1034     1035       +1     

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated no new comments.