[Refactor] Adjustments to moe_comm_method selection process

[Pr0Wh1teGivee]

What this PR does / why we need it?

Fix issues mentioned in #2791

1. Use Enum instead of string.
2. Avoid setting a new property to forward_context in AscendFusedMoE.forward().

Does this PR introduce any user-facing change?

No

How was this patch tested?

E2E & UT

• vLLM version: v0.10.2
• vLLM main: vllm-project/vllm@4f02b77

[github-actions]

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[gemini-code-assist]

Code Review

This pull request refactors the Mixture-of-Experts (MoE) communication method selection to use an Enum instead of raw strings, which is a great improvement for code clarity and type safety. The changes are mostly consistent with this goal. However, I've identified a few critical issues, including typos in Enum member access and an incorrect import, which would lead to runtime errors. Please address these issues to ensure the refactoring is robust.

[gemini-code-assist]

There is a typo in the MoECommImpl enum member name. It should be ALLTOALL instead of AllTOAll. This will cause an AttributeError at runtime.

Suggested change

	if moe_comm_method_type in {MoECommImpl.AllTOAll, MoECommImpl.MC2}:
	if moe_comm_method_type in {MoECommImpl.ALLTOALL, MoECommImpl.MC2}:

[gemini-code-assist]

There is a typo in the MoECommImpl enum member name. It should be ALLTOALL instead of AllTOAll. This will cause an AttributeError at runtime.

Suggested change

	if moe_comm_method_type in {MoECommImpl.AllTOAll, MoECommImpl.MC2}:
	if moe_comm_method_type in {MoECommImpl.ALLTOALL, MoECommImpl.MC2}:

[gemini-code-assist]

The MoECommImpl enum is being imported from vllm_ascend.ascend_config, but it is defined in vllm_ascend.ascend_forward_context. This will cause an ImportError at runtime. Please correct the import statement. For better code style, you could also combine this with the existing import from vllm_ascend.ascend_forward_context on the next line.

Suggested change

	from vllm_ascend.ascend_config import (MoECommImpl,
	get_ascend_config)
	from vllm_ascend.ascend_config import get_ascend_config
	from vllm_ascend.ascend_forward_context import MoECommImpl

[github-actions]

This pull request has conflicts, please resolve those before we can evaluate the pull request.

[github-actions]

This pull request has conflicts, please resolve those before we can evaluate the pull request.