Dotnet Uses Legacy Wasm Exceptions.

wasm/dotnet/build.sh

@@ -10,7 +10,7 @@
 # Finally `sudo dotnet workload install wasm-tools` (without sudo for a user
 # installation of dotnet, e.g., with option B above).
 
-rm -r ./build-interp ./build-aot build.log
+rm -r src/dotnet/bin src/dotnet/obj ./build-interp ./build-aot build.log
 
 touch build.log
 BUILD_LOG="$(realpath build.log)"
@@ -27,10 +27,25 @@ printf '%s\n' 'import.meta.url ??= "";' | cat - ./src/dotnet/bin/Release/net9.0/
 echo "Copying symbol maps..." | tee -a "$BUILD_LOG"
 cp ./src/dotnet/obj/Release/net9.0/wasm/for-publish/dotnet.native.js.symbols ./build-interp/wwwroot/_framework/
 
+# Net9 and Net10 use Emscripten version 3.1.56, which emits legacy EH, see https://github.com/WebKit/JetStream/pull/188
+# FIXME: Update toolchain to Net11 once available, then remove this wasm-opt call.
+for wasmFile in $(find "./build-interp" -type f -name "*.wasm");
+do
+    wasm-opt "$wasmFile" --translate-to-exnref --enable-bulk-memory --enable-exception-handling --enable-simd --enable-reference-types --enable-multivalue -o "$wasmFile"
+done
+
+
 echo "Building aot..." | tee -a "$BUILD_LOG"
 dotnet publish -o ./build-aot ./src/dotnet/dotnet.csproj -p:RunAOTCompilation=true
 
 # Workaround for `jsc` CLI
 printf '%s\n' 'import.meta.url ??= "";' | cat - ./build-aot/wwwroot/_framework/dotnet.js > temp.js && mv temp.js ./build-aot/wwwroot/_framework/dotnet.js
 echo "Copying symbol maps..." | tee -a "$BUILD_LOG"
 cp ./src/dotnet/obj/Release/net9.0/wasm/for-publish/dotnet.native.js.symbols ./build-aot/wwwroot/_framework/
+
+# Net9 and Net10 use Emscripten version 3.1.56, which emits legacy EH, see https://github.com/WebKit/JetStream/pull/188
+# FIXME: Update toolchain to Net11 once available, then remove this wasm-opt call.
+for wasmFile in $(find "./build-aot" -type f -name "*.wasm");
+do
+    wasm-opt "$wasmFile" --translate-to-exnref --enable-bulk-memory --enable-exception-handling --enable-simd --enable-reference-types --enable-multivalue -o "$wasmFile"
+done