Add basic continuous integration script

.github/workflows/ci.yml

@@ -0,0 +1,24 @@
+name: CI
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
+
+# Cancel old workflows for PRs (only the most recent workflow can run).
+concurrency:
+  group: ci-${{ github.ref }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+
+# Avoid workflow-level permissions, instead use job-level permissions.
+permissions: {}
+
+jobs:
+  ubuntu:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - run: ./ci.sh

ci.sh

@@ -0,0 +1,30 @@
+#!/bin/sh
+set -ex
+
+has_target() {
+  rustup target list --installed | grep -q "$1"
+}
+ensure_target() {
+  has_target "$1" || rustup target add "$1"
+}
+cargo_check() {
+  cargo check "$@"
+  # TODO: Uncomment once clippy lints are fixed.
+  # cargo clippy "$@" -- --deny=warnings
+}
+cargo_test() {
+  cargo_check --all-targets "$@"
+  cargo test "$@"
+}
+
+cargo_test --features=alloc,experimental-derive
+
+ensure_target thumbv7em-none-eabi
+cargo_check --target=thumbv7em-none-eabi --no-default-features
+cargo_check --target=thumbv7em-none-eabi --features=alloc,experimental-derive
+
+# TODO: Uncomment once formatting is correct.
+# cargo fmt -- --check
+
+# TODO: Uncomment once documentation lints are fixed.
+# env RUSTDOCFLAGS='--cfg=docsrs --deny=warnings' cargo doc --no-deps