Add OptionalBackend wrapper #511

	name: CI

	on:
	pull_request:
	branches: [main]
	push:
	branches: [main]

	jobs:
	build:
	runs-on: ubuntu-latest
	strategy:
	matrix:
	target:
	- x86_64-unknown-linux-gnu
	- thumbv7em-none-eabi

	steps:
	- name: Checkout repository
	uses: actions/checkout@v2

	- name: Install Rust toolchain
	run: \|
	rustup show
	rustup target add ${{ matrix.target }}

	- name: Install build dependencies
	run: >
	sudo apt-get update -y -qq &&
	sudo apt-get install -y -qq llvm libc6-dev-i386 libclang-dev

	- uses: fiam/arm-none-eabi-gcc@v1
	with:
	release: "9-2020-q2"

	- name: Build
	run: cargo build --workspace --target ${{ matrix.target }}

	- name: Check all targets without default features
	run: cargo check --workspace --all-targets --no-default-features
	if: matrix.target == 'x86_64-unknown-linux-gnu'

	- name: Check all targets with default features
	run: cargo check --workspace --all-targets
	if: matrix.target == 'x86_64-unknown-linux-gnu'

	- name: Check all features and targets
	run: cargo check --workspace --all-features --all-targets
	if: matrix.target == 'x86_64-unknown-linux-gnu'

	- name: Run tests
	run: cargo test --features serde-extensions,virt
	if: matrix.target == 'x86_64-unknown-linux-gnu'

	- name: Check formatting
	run: cargo fmt --all -- --check
	if: matrix.target == 'x86_64-unknown-linux-gnu'

	- name: Check clippy lints
	run: make clippy
	if: matrix.target == 'x86_64-unknown-linux-gnu'

	- name: Check documentation
	run: RUSTDOCFLAGS="-D warnings" cargo doc --no-deps --features serde-extensions,virt
	if: matrix.target == 'x86_64-unknown-linux-gnu'

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