Test the try_op feature with a custom cfg

Author: keithw

.github/actions/install-rust/action.yml

@@ -40,7 +40,7 @@ runs:
         EOF
 
         # Deny warnings on CI to keep our code warning-free as it lands in-tree.
-        echo RUSTFLAGS="-D warnings" >> "$GITHUB_ENV"
+        echo RUSTFLAGS="-D warnings $RUSTFLAGS" >> "$GITHUB_ENV"
 
     - run: rustup target add wasm32-wasip2
       if: inputs.toolchain != 'msrv'

.github/workflows/main.yml

@@ -132,6 +132,12 @@ jobs:
             rust: stable
             env:
               RUST_BACKTRACE: 1
+          # test the 'try_op' feature
+          - os: ubuntu-latest
+            rust: stable
+            env:
+              RUSTFLAGS: --cfg=debug_check_try_op
+            flags: -F wasmparser/try-op
     env: ${{ matrix.env || fromJSON('{}') }}
     steps:
     - uses: actions/checkout@v6
@@ -155,7 +161,6 @@ jobs:
     - run: cargo test -p wasm-smith --features wasmparser
     - run: cargo test -p wasm-smith --features component-model
     - run: cargo test --locked -p wasmparser --features try-op
-    - run: cargo test --locked -F wasmparser/try-op
 
   test_capi:
     name: Test the C API

Cargo.toml

@@ -66,7 +66,7 @@ rust-2024-incompatible-pat = 'warn'
 missing-unsafe-on-extern = 'warn'
 unsafe-op-in-unsafe-fn = 'warn'
 
-unexpected_cfgs = { level = 'warn', check-cfg = ['cfg(fuzzing)'] }
+unexpected_cfgs = { level = 'warn', check-cfg = ['cfg(fuzzing)', 'cfg(debug_check_try_op)'] }
 
 [workspace.lints.clippy]
 # The default set of lints in Clippy is viewed as "too noisy" right now so

crates/wasmparser/src/validator/func.rs

@@ -122,9 +122,9 @@ impl<T: WasmModuleResources> FuncValidator<T> {
             reader.set_features(self.validator.features);
         }
         while !reader.eof() {
-            // In a debug build, verify that `rollback` successfully returns the
+            // In a `debug_check_try_op` build, verify that `rollback` successfully returns the
             // validator to its previous state after each (valid or invalid) operator.
-            #[cfg(all(debug_assertions, feature = "try-op"))]
+            #[cfg(all(debug_check_try_op, feature = "try-op"))]
             {
                 let snapshot = self.validator.clone();
                 let op = reader.peek_operator(&self.visitor(reader.original_position()))?;