Check that we compile on solaris

This also adds infrastructure to make it easier to add more check targets in
the future.

.github/workflows/test.yml

@@ -1,4 +1,4 @@
-name: test
+name: All Tests and Builds
 
 on:
   push:
@@ -116,3 +116,19 @@ jobs:
         env:
           RUST_VERSION: stable
           WASM: wasm_simple
+
+  cross-targets:
+    strategy:
+      matrix:
+        target:
+          - x86_64-sun-solaris
+
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Install cross
+        run: bash ci/install-cross.sh
+
+      - name: Build static library
+        run: cross check --target ${{ matrix.target }}

ci/install-cross.sh

@@ -0,0 +1,43 @@
+#!/usr/bin/env bash
+
+set -euxo pipefail
+
+main() {
+    local target=
+    if [[ "$(os)" == "ubuntu-latest" || "$(os)" == Linux ]]; then
+        target=x86_64-unknown-linux-musl
+        # shellcheck disable=SC2209
+        sort=sort
+    else
+        target=x86_64-apple-darwin
+        sort=gsort
+    fi
+
+    # This fetches latest stable release
+    local tag
+    tag=$(git ls-remote --tags --refs --exit-code https://github.com/rust-embedded/cross \
+              | cut -d/ -f3 \
+              | grep -E '^v[0.1.0-9.]+$' \
+              | $sort --version-sort \
+              | tail -n1)
+
+    curl -LSfs https://japaric.github.io/trust/install.sh | \
+        sh -s -- \
+           --force \
+           --git rust-embedded/cross \
+           --tag "$tag" \
+           --target $target
+
+    cross --version
+}
+
+# get an os name, either github's pre-set one or the result of uname
+os() {
+    if [ -n "${OS_NAME:-}" ]; then
+        echo "$OS_NAME"
+        return
+    fi
+    uname
+}
+
+main