Fix Windows backend import condition to match cfg_if! logic (#137)

* Fix Windows backend import condition to match cfg_if! logic

When running under Miri on Windows, the cfg_if! block in backends/mod.rs selects the fallback backend (because miri is checked first), but the conditional import at line 178 was only checking #[cfg(windows)], causing a compilation error when the windows module wasn't compiled.

This fix ensures the import condition matches the cfg_if! logic by using #[cfg(all(windows, not(miri)))] instead of #[cfg(windows)], so the windows backend is only imported when it's actually compiled.

Fixes compilation error: could not find 'windows' in 'backends'

* Add Miri testing to CI workflow

Adds a new miri-test job that runs Miri tests on Ubuntu, Windows, and macOS for both stacker and psm manifests. This will help catch conditional compilation issues like the one fixed in the previous commit.

* Limit Miri tests to stacker crate only

The psm crate has test compilation issues unrelated to this fix. Focus Miri testing on the main stacker crate where the cfg condition fix applies.

* Skip heavy recursion tests under Miri

Deep recursion tests are too slow under Miri's interpreter. These tests are skipped under Miri while still validating that the code compiles correctly (which was the main goal - catching the cfg condition mismatch).

* Update Miri test conditions in smoke.rs

Modified the deep test to include Miri in the target architecture check, allowing for better handling of recursion limits under Miri. This change ensures that the test is appropriately limited when running in the Miri environment, addressing performance concerns.

Author: TKorr

.github/workflows/test.yml

@@ -397,3 +397,25 @@ jobs:
           echo "${{ runner.tool_cache }}/wasmtime-v24.0.0-x86_64-linux" >> $GITHUB_PATH
           echo "CARGO_TARGET_WASM32_WASIP1_RUNNER=wasmtime run --" >> $GITHUB_ENV
       - run: cargo test --target wasm32-wasip1 --all -- --nocapture
+
+  miri-test:
+    name: Test stacker with Miri on ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, windows-latest, macos-latest]
+    timeout-minutes: 10
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install Rust nightly with Miri
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: nightly
+          profile: minimal
+          components: miri
+          default: true
+      - name: Setup Miri
+        run: cargo miri setup
+      - name: Test with Miri
+        run: cargo miri test -- --nocapture

src/lib.rs

@@ -169,12 +169,12 @@ psm_stack_manipulation! {
     }
 
     no {
-        #[cfg(not(windows))]
+        #[cfg(not(all(windows, not(miri))))]
         fn _grow(stack_size: usize, callback: &mut dyn FnMut()) {
             let _ = stack_size;
             callback();
         }
-        #[cfg(windows)]
+        #[cfg(all(windows, not(miri)))]
         use backends::windows::_grow;
     }
 }

tests/simple.rs

@@ -18,6 +18,7 @@ fn recurse(n: usize) {
 }
 
 #[test]
+#[cfg_attr(miri, ignore)] // Too slow under Miri's interpreter
 fn foo() {
     let limit = if cfg!(target_arch = "wasm32") {
         2000

tests/smoke.rs

@@ -21,7 +21,7 @@ fn deep() {
         }
     }
 
-    let limit = if cfg!(target_arch = "wasm32") {
+    let limit = if cfg!(target_arch = "wasm32") || cfg!(miri) {
         2000
     } else {
         256 * 1024
@@ -31,6 +31,7 @@ fn deep() {
 
 #[test]
 #[cfg_attr(target_arch = "wasm32", ignore)]
+#[cfg_attr(miri, ignore)] // Too slow under Miri's interpreter
 fn panic() {
     fn foo(n: usize, s: &mut [u8]) {
         __stacker_black_box(s.as_ptr());