No changes needed - answered question about nightly rustfmt usage

[Copilot]

This was a question from the PR author about using nightly rustfmt with a stable toolchain.

Answer Provided

RUSTC_BOOTSTRAP=1 enables unstable features for rustc but not for rustfmt. Stable rustfmt always rejects unstable features regardless of environment variables.

To use the unstable features in rustfmt.toml:

# Install nightly rustfmt
rustup toolchain install nightly --component rustfmt

# Run formatting with nightly
cargo +nightly fmt

Suggested Follow-up

Update these to use cargo +nightly fmt:

• .pre-commit-config.yaml line 13
• .github/workflows/ci.yml line 243

No code changes were made as this was an informational question only.

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[Itsusinn]

@copilot Use rustup component add rustfmt --toolchain nightly & cargo +nightly fmt

move cargo fmt as a standalone job named prepare，which compile relies on