no_std: add `no_std` crate level attribute #340

	on: [push, pull_request]

	name: Rust CI

	jobs:
	check:
	name: Check
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v2
	- uses: actions-rs/toolchain@v1
	with:
	profile: minimal
	toolchain: stable
	override: true
	- uses: Swatinem/rust-cache@v1
	- uses: actions-rs/cargo@v1
	with:
	command: check

	test:
	name: Test Suite
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v2
	- uses: actions-rs/toolchain@v1
	with:
	profile: minimal
	toolchain: stable
	override: true
	- uses: Swatinem/rust-cache@v1
	- uses: actions-rs/cargo@v1
	with:
	command: test
	args: --features r1cs

	fmt:
	name: Rustfmt
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v2
	- uses: actions-rs/toolchain@v1
	with:
	profile: minimal
	toolchain: stable
	override: true
	- uses: Swatinem/rust-cache@v1
	- run: rustup component add rustfmt
	- uses: actions-rs/cargo@v1
	with:
	command: fmt
	args: --all -- --check

	no-std:
	name: no-std compatibility check
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v2
	- uses: actions-rs/toolchain@v1
	with:
	profile: minimal
	toolchain: stable
	override: true
	- run: cargo install --locked cargo-nono
	- run: cargo nono check --no-default-features

	# clippy:
	# name: Clippy
	# runs-on: ubuntu-latest
	# steps:
	# - uses: actions/checkout@v2
	# - uses: actions-rs/toolchain@v1
	# with:
	# profile: minimal
	# toolchain: stable
	# override: true
	# - uses: Swatinem/rust-cache@v1
	# - run: rustup component add clippy
	# - uses: actions-rs/cargo@v1
	# with:
	# command: clippy
	# args: -- -D warnings

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