cuda.core: accept ProgramOptions(name=None)

[aryanputta]

Description

Closes #2516.

ProgramOptions.name is annotated str | None and documented as name : str, optional, but __post_init__ called .encode() on it unconditionally, so ProgramOptions(name=None) raised AttributeError: 'NoneType' object has no attribute 'encode'.

name was the only field in __post_init__ whose None case was unhandled. arch already normalizes two lines below:

if self.arch is None:
    self.arch = f"sm_{Device().arch}"

This applies the same treatment to name, so the annotation and the implementation agree.

Behavior

options._name is what reaches nvrtcCreateProgram via <const char*>options._name. After this change name=None produces b"default_program", byte-for-byte identical to what default construction produces today:

construction	name	_name
ProgramOptions()	"default_program"	b"default_program"
ProgramOptions(name=None)	"default_program"	b"default_program"
ProgramOptions(name="mine")	"mine"	b"mine"

No existing construction changes. The only path affected is the one that previously raised before reaching any CUDA call, so nothing can be depending on the old behavior.

Testing

Added test_program_options_name_accepts_none, parametrized over None and an explicit name, asserting both name and the encoded _name. It passes arch="sm_90" explicitly so it introduces no device query of its own.

The None path had no coverage before this: every ProgramOptions(name=...) in cuda_core/tests/test_program.py passed a string.

Scope is deliberately limited to the None contract. A non-str name still raises AttributeError rather than a typed error; that is a separate question from the annotation mismatch this fixes, and I did not want to bundle it.

Checklist

• New or existing tests cover these changes
• The documentation is up to date with these changes
• Release note added to cuda_core/docs/source/release/1.2.0-notes.rst

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