Add a miri run to the test suite + fix a few smaller things

.github/workflows/ci.yml

@@ -92,11 +92,36 @@ jobs:
       - name: Run basic tests
         run: cargo test
 
-      - name: Run concurrent tests and benchmarks
+      - name: Run concurrent tests
         # FIXME: macOS runners are too overloaded for concurrent testing
         if: runner.os != 'macOS'
-        run: cargo test --release -- --ignored --nocapture --test-threads=1
+        run: cargo test --release -- --ignored --test-threads=1
+
+
+  # Run the tests in Miri for more thorough runtime checks
+  #
+  # Since Miri is an abstract machine and this crate contains no OS-specific
+  # code, testing on one single OS is sufficient. Per Miri documentation, Linux
+  # gets the highest-quality support, so that's our obvious pick.
+  miri:
+    # Only run on "pull_request" event for external PRs. This is to avoid
+    # duplicate builds for PRs created from internal branches.
+    if: github.event_name == 'push' || github.event.pull_request.head.repo.full_name != github.repository || github.event_name == 'schedule'
+
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout sources
+        uses: actions/checkout@v4
+
+      - name: Set up toolchain
+        uses: actions-rust-lang/setup-rust-toolchain@v1
+        with:
+          components: miri,rust-src
+          toolchain: nightly
 
+      - name: Run tests
+        run: cargo +nightly miri test --features=miri -- --include-ignored
 
   # Check compatibility with newer Rust/deps versions (scheduled CI)
   #
@@ -134,4 +159,4 @@ jobs:
       - name: Run concurrent tests and benchmarks
         # FIXME: macOS runners are too overloaded for concurrent testing
         if: runner.os != 'macOS'
-        run: cargo test --release -- --ignored --nocapture --test-threads=1
+        run: cargo test --release -- --ignored --test-threads=1

Cargo.toml

@@ -26,6 +26,11 @@ rust-version = "1.70"
 [badges]
 maintenance = { status = "passively-maintained" }
 
+[features]
+# Adjust the test configuration (e.g. reduce problem sizes) so the tests can run
+# under Miri within a reasonable time budget.
+miri = []
+
 [dependencies]
 crossbeam-utils = { version = "0.8.11", default-features = false }
 

src/lib.rs

@@ -763,7 +763,10 @@ mod tests {
     fn contended_concurrent_read_write() {
         // We will stress the infrastructure by performing this many writes
         // as a reader continuously reads the latest value
+        #[cfg(not(feature = "miri"))]
         const TEST_WRITE_COUNT: usize = 100_000_000;
+        #[cfg(feature = "miri")]
+        const TEST_WRITE_COUNT: usize = 3_000;
 
         // This is the buffer that our reader and writer will share
         let buf = TripleBuffer::new(&RaceCell::new(0));
@@ -809,7 +812,10 @@ mod tests {
     fn uncontended_concurrent_read_write() {
         // We will stress the infrastructure by performing this many writes
         // as a reader continuously reads the latest value
+        #[cfg(not(feature = "miri"))]
         const TEST_WRITE_COUNT: usize = 625;
+        #[cfg(feature = "miri")]
+        const TEST_WRITE_COUNT: usize = 200;
 
         // This is the buffer that our reader and writer will share
         let buf = TripleBuffer::new(&RaceCell::new(0));
@@ -852,7 +858,10 @@ mod tests {
     fn concurrent_bidirectional_exchange() {
         // We will stress the infrastructure by performing this many writes
         // as a reader continuously reads the latest value
+        #[cfg(not(feature = "miri"))]
         const TEST_WRITE_COUNT: usize = 100_000_000;
+        #[cfg(feature = "miri")]
+        const TEST_WRITE_COUNT: usize = 3_000;
 
         // This is the buffer that our reader and writer will share
         let buf = TripleBuffer::new(&RaceCell::new(0));
@@ -898,7 +907,7 @@ mod tests {
     /// Range check for triple buffer indexes
     #[allow(unused_comparisons)]
     fn index_in_range(idx: BufferIndex) -> bool {
-        (idx >= 0) & (idx <= 2)
+        (0..=2).contains(&idx)
     }
 
     /// Get a pointer to the target of some reference (e.g. an &, an Arc...)