Support Emscripten with Wasm EH

iex-rs · Jan 24, 2025 · 4f1dd6f · 4f1dd6f
1 parent 9f875d4
commit 4f1dd6f
Show file tree

Hide file tree

Showing 3 changed files with 14 additions and 8 deletions.
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
@@ -107,12 +107,17 @@ jobs:
         run: cargo install cross --git https://github.com/cross-rs/cross
       - name: Test with panic backend (debug)
         run: LITHIUM_BACKEND=panic cross test --target $target
+      - name: Test with Itanium backend (debug)
+        run: RUSTFLAGS="-Z emscripten_wasm_eh" LITHIUM_BACKEND=itanium cross test --target $target -Z build-std
       - name: Test with Emscripten backend (debug)
         run: LITHIUM_BACKEND=emscripten cross test --target $target
       - name: Test with std thread locals (debug)
         run: LITHIUM_THREAD_LOCAL=std cross test --target $target
       - name: Test with panic backend (release)
         run: LITHIUM_BACKEND=panic cross test --target $target --release
+      # XXX: https://github.com/rust-lang/rust/issues/132416
+      # - name: Test with Itanium backend (release)
+      #   run: RUSTFLAGS="-Z emscripten_wasm_eh" LITHIUM_BACKEND=itanium cross test --target $target --release -Z build-std
       - name: Test with Emscripten backend (release)
         run: LITHIUM_BACKEND=emscripten cross test --target $target --release
       - name: Test with std thread locals (release)

diff --git a/build.rs b/build.rs
@@ -45,7 +45,7 @@ fn main() {
     println!("cargo::rerun-if-env-changed=LITHIUM_BACKEND");
     if let Ok(backend) = std::env::var("LITHIUM_BACKEND") {
         println!("cargo::rustc-cfg=backend=\"{backend}\"");
-    } else if is_nightly && cfg("target_os") == "emscripten" {
+    } else if is_nightly && cfg("target_os") == "emscripten" && !has_cfg("emscripten_wasm_eh") {
         println!("cargo::rustc-cfg=backend=\"emscripten\"");
     } else if is_nightly
         && (has_cfg("unix")

diff --git a/src/lib.rs b/src/lib.rs
@@ -32,13 +32,14 @@
 //!
 //! On nightly Rust, Lithium uses a custom mechanism on the following targets:
 //!
-//! |Target             |Implementation|Performance                                  |
-//! |-------------------|--------------|---------------------------------------------|
-//! |Linux, macOS       |Itanium EH ABI|2.5x faster than panics                      |
-//! |Windows (MSVC ABI) |SEH           |1.5x faster than panics                      |
-//! |Windows (GNU ABI)  |Itanium EH ABI|2.5x faster than panics, but slower than MSVC|
-//! |Emscripten         |C++ exceptions|2x faster than panics                        |
-//! |WASI               |Itanium EH ABI|2.5x faster than panics                      |
+//! |Target             |Implementation |Performance                                  |
+//! |-------------------|---------------|---------------------------------------------|
+//! |Linux, macOS       |Itanium EH ABI |2.5x faster than panics                      |
+//! |Windows (MSVC ABI) |SEH            |1.5x faster than panics                      |
+//! |Windows (GNU ABI)  |Itanium EH ABI |2.5x faster than panics, but slower than MSVC|
+//! |Emscripten (old EH)|C++ exceptions |2x faster than panics                        |
+//! |Emscripten (new EH)|Wasm exceptions|2.5x faster than panics                      |
+//! |WASI               |Itanium EH ABI |2.5x faster than panics                      |
 //!
 //! Lithium strives to support all targets that Rust panics support. If Lithium does not work
 //! correctly on such a target, please [open an issue](https://github.com/iex-rs/lithium/issues/).