Check on CI whether library compiles for no_std

.github/workflows/ci.yml

@@ -97,6 +97,17 @@ jobs:
     - run: RUSTFLAGS=-Dwarnings cargo check --target x86_64-unknown-linux-gnu --package smoldot-light --locked --no-default-features --features std --features wasmtime
     - run: RUSTFLAGS=-Dwarnings cargo check --target i686-unknown-linux-gnu --package smoldot-light --locked --no-default-features --features std --features wasmtime
 
+  check-no-std:
+    runs-on: ubuntu-latest
+    container:
+      image: rust:1.72
+    steps:
+    - uses: actions/checkout@v4
+    - run: rustup target add thumbv7m-none-eabi
+    - uses: Swatinem/rust-cache@v2
+    # We use `thumbv7m-none-eabi` as this target seems to generally work fine and doesn't support `std`. Many targets unfortunately have Rust/LLVM bugs preventing compilation.
+    - run: RUSTFLAGS=-Dwarnings cargo build --package smoldot --locked --no-default-features --target=thumbv7m-none-eabi
+
   fuzzing-binaries-compile:
     runs-on: ubuntu-latest
     container:
@@ -206,7 +217,7 @@ jobs:
   all-ci:
     # This dummy job depends on all the mandatory checks. It succeeds if and only if CI is
     # considered successful.
-    needs: [test-64bits, test-32bits, wasm-node-check, check-features, fuzzing-binaries-compile, check-rustdoc-links, fmt, clippy, cargo-deny, cargo-spellcheck, wasm-node-versions-match]
+    needs: [test-64bits, test-32bits, wasm-node-check, check-features, check-no-std, fuzzing-binaries-compile, check-rustdoc-links, fmt, clippy, cargo-deny, cargo-spellcheck, wasm-node-versions-match]
     runs-on: ubuntu-latest
     steps:
      - run: echo Success