Update Nightly rustc #4

	name: Update Nightly rustc
	on:
	schedule:
	- cron: "0 0 * * *" # runs daily at 00:00
	workflow_dispatch: # allows manual triggering
	jobs:
	format:
	name: Update nightly rustc
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v4
	- uses: dtolnay/rust-toolchain@nightly
	- name: Update rust.yml to use latest nightly
	run: \|
	set -x
	# Not every night has a nightly, so extract the date from whatever
	# version of the compiler dtolnay/rust-toolchain gives us.
	NIGHTLY_DATE=$(rustc +nightly --verbose --version \| sed -ne 's/^commit-date: //p')
	# Update the nightly version in the reference file.
	echo "nightly-${NIGHTLY_DATE}" > .github/nightly-version
	echo "nightly_date=${NIGHTLY_DATE}" >> $GITHUB_ENV
	# Some days there is no new nightly. In this case don't make an empty PR.
	if ! git diff --exit-code > /dev/null; then
	echo "Updated nightly. Opening PR."
	echo "changes_made=true" >> $GITHUB_ENV
	else
	echo "Attempted to update nightly but the latest-nightly date did not change. Not opening any PR."
	echo "changes_made=false" >> $GITHUB_ENV
	fi
	- name: Create Pull Request
	if: env.changes_made == 'true'
	uses: peter-evans/create-pull-request@v6
	with:
	author: Update Nightly Rustc Bot <[email protected]>
	title: Automated daily update to rustc (to nightly-${{ env.nightly_date }})
	body: \|
	Automated update to Github CI workflow `rust.yml` by [create-pull-request](https://github.com/peter-evans/create-pull-request) GitHub action
	commit-message: Automated update to Github CI to rustc nightly-${{ env.nightly_date }}

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