bindgen config

Author: aborgna-q

.github/workflows/python-wheels.yml

@@ -41,6 +41,8 @@ env:
   EMSDK_VERSION: "4.0.9"
   # hugrverse-env target used to fetch the pre-built tket-c-api WebAssembly library.
   HUGRVERSE_WASM_TARGET: "emscripten_4_0_9_wasm32"
+  # Rust nightly version used to build the WebAssembly wheels.
+  RUST_NIGHTLY_VERSION: "nightly-2026-08-20"
 
 jobs:
   # Check if the tag matches the package name,
@@ -276,12 +278,12 @@ jobs:
       - name: Install nightly Rust toolchain
         uses: dtolnay/rust-toolchain@master
         with:
-          toolchain: "nightly"
+          toolchain: ${{ env.RUST_NIGHTLY_VERSION }}
       - name: Add required rust targets and components
         run: |
-          rustup override set nightly
+          rustup override set ${{ env.RUST_NIGHTLY_VERSION }}
           rustup target add wasm32-unknown-emscripten
-          rustup component add rust-src --toolchain nightly-x86_64-unknown-linux-gnu
+          rustup component add rust-src --toolchain ${{ env.RUST_NIGHTLY_VERSION }}
       - name: Install Node.js for emsdk
         uses: actions/setup-node@v6
         with:

tket1-passes/build.rs

@@ -96,9 +96,18 @@ fn main() {
         println!("cargo:rustc-link-lib=stdc++");
     }
 
-    // Generate bindings using bindgen
-    let bindings = bindgen::Builder::default()
-        .header(header_path.to_str().unwrap())
+    // Generate bindings using bindgen. The C API only contains opaque pointers
+    // and target-independent scalar types, so parsing it for the host produces
+    // bindings that are also valid for Emscripten. This avoids libclang
+    // dropping function declarations when using its Emscripten target.
+    let mut bindings_builder = bindgen::Builder::default().header(header_path.to_str().unwrap());
+    if target == Some(SupportedPlatform::Emscripten) {
+        println!("cargo:rerun-if-env-changed=HOST");
+        let host = env::var("HOST").expect("Cargo should set HOST for build scripts");
+        bindings_builder = bindings_builder.clang_arg(format!("--target={host}"));
+    }
+
+    let bindings = bindings_builder
         .generate()
         .expect("Unable to generate bindings");