[Akshay Sonawane (apsonawane)]

This pull request improves how tensor element types are handled in the ONNX Runtime Rust bindings. It introduces more robust error handling for unsupported and undefined tensor element types, replacing previous unchecked conversions with a safe and explicit conversion mechanism. The most important changes are:

Error Handling Improvements:

• Added a new OrtError::UnsupportedTensorElementType(i64) variant to represent unsupported tensor types, and updated the UndefinedTensorElementType error message for clarity.

Type Conversion and Safety:

• Implemented TryFrom<sys::ONNXTensorElementDataType> for TensorElementDataType, returning descriptive errors for undefined or unsupported types instead of using unsafe transmute.
• Updated code in dangerous module to use the new try_from conversion for tensor element types, eliminating unsafe casting and ensuring errors are handled explicitly.

Testing:

• Added unit tests to verify that supported types convert successfully, undefined types return the correct error, and unsupported types are properly rejected.

Code Cleanliness:

• Added necessary imports for TryFrom in session.rs to support the new conversion logic.

[Copilot]

Pull request overview

This PR hardens tensor element type handling in the ONNX Runtime Rust bindings by replacing an unchecked transmute with an explicit fallible conversion that reports undefined/unsupported types via OrtError.

Changes:

• Added OrtError::UnsupportedTensorElementType(i64) to represent tensor element types not supported by the Rust binding.
• Implemented TryFrom<sys::ONNXTensorElementDataType> for TensorElementDataType and updated session IO inspection to use it instead of transmute.
• Added unit tests for supported, undefined, and unsupported tensor element type conversions.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
rust/onnxruntime/src/session.rs	Switches session IO type extraction to use TensorElementDataType::try_from(...) instead of transmute.
rust/onnxruntime/src/lib.rs	Adds TryFrom conversion logic for TensorElementDataType plus unit tests.
rust/onnxruntime/src/error.rs	Introduces a new OrtError variant for unsupported tensor element types.

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