Add ensure_no_std build to CI

.github/workflows/rust.yml

@@ -63,7 +63,7 @@ jobs:
     name: Run Lints
     runs-on: ubuntu-22.04
     steps:
-    - name: Install Rust 1.69.0
+    - name: Install Rust
       uses: dtolnay/rust-toolchain@1.69.0
       with:
           components: rustfmt, clippy
@@ -114,7 +114,7 @@ jobs:
     name: Make sure all builds work
     runs-on: ubuntu-22.04
     steps:
-    - name: Install Rust 1.69.0
+    - name: Install Rust
       uses: dtolnay/rust-toolchain@1.69.0
     - name: Set up cargo cache
       uses: Swatinem/rust-cache@v2
@@ -158,6 +158,27 @@ jobs:
       run: cargo check-all-features --workspace --all-targets
 
 
+  # NOTE: the term "smoke test" comes from electronics design: the minimal
+  # expectations anyone has in their device is to not catch fire on boot.
+  smoke-no-std:
+    name: Make sure no-std works
+    runs-on: ubuntu-22.04
+    steps:
+    - name: Install Rust
+      uses: dtolnay/rust-toolchain@1.69.0
+      with:
+        targets: wasm32-unknown-unknown
+    - name: Set up cargo cache
+      uses: Swatinem/rust-cache@v2
+    - name: Checkout
+      uses: actions/checkout@v3
+
+    - name: Check
+      run: |
+        cd ensure_no_std
+        cargo build --release
+        cargo build --release -F alloc
+
   tests:
     needs: build-programs
     strategy:
@@ -168,7 +189,7 @@ jobs:
     name: Run tests
     runs-on: ubuntu-22.04
     steps:
-    - name: Install Rust 1.69.0
+    - name: Install Rust
       uses: dtolnay/rust-toolchain@1.69.0
       with:
           components: llvm-tools-preview
@@ -237,7 +258,7 @@ jobs:
     name: Build release binary for comparisons
     runs-on: ubuntu-22.04
     steps:
-    - name: Install Rust 1.69.0
+    - name: Install Rust
       uses: dtolnay/rust-toolchain@1.69.0
     - name: Set up cargo cache
       uses: Swatinem/rust-cache@v2