improve some derive diagnostics #23

	name: CI
	on: [push, pull_request]

	env:
	CARGO_TERM_COLOR: always
	RUST_BACKTRACE: 1

	jobs:
	rust:
	name: Test
	strategy:
	matrix:
	rust:
	- stable
	- 1.58
	include:
	- rust: stable
	extra_components: rustfmt
	extra_test_args: -p static-xml-derive
	runs-on: ubuntu-20.04
	steps:
	- name: Checkout
	uses: actions/checkout@v2
	- name: Cache
	uses: actions/cache@v2
	with:
	path: \|
	~/.cargo/registry
	~/.cargo/git
	target
	key: ${{ matrix.rust }}-cargo-${{ hashFiles('**/Cargo.lock') }}
	- name: Install Rust
	uses: actions-rs/toolchain@v1
	with:
	profile: minimal
	toolchain: ${{ matrix.rust }}
	override: true
	components: ${{ matrix.extra_components }}
	- name: Test
	run: cargo test --all-features -p static-xml -p test-suite ${{ matrix.extra_test_args }}
	- name: Check formatting
	if: matrix.rust == 'stable'
	run: cargo fmt -- --check
	license:
	name: Check copyright/license headers
	runs-on: ubuntu-20.04
	steps:
	- name: Checkout
	uses: actions/checkout@v2
	- run: find . -type f -print0 \| xargs -0 .github/workflows/check-license.py

Provide feedback