pyodide · hoodmane · Feb 27, 2025 · Jan 13, 2025 · Jan 13, 2025 · Jan 13, 2025
diff --git a/Makefile.envs b/Makefile.envs
@@ -5,10 +5,12 @@ export PYODIDE_ABI_VERSION ?= 2025_0
 
 export PYTHON_ARCHIVE_SHA256=73ac8fe780227bf371add8373c3079f42a0dc62deff8d612cd15a618082ab623
 
+export RUST_TOOLCHAIN ?= nightly-2025-01-15
+export RUST_EMSCRIPTEN_TARGET_URL ?= http://pyodide-cache.s3-website-us-east-1.amazonaws.com/rustc-emscripten-target/${RUST_TOOLCHAIN}.tar.bz2
 # I'm not really sure what this explicit -Z link-native-libraries=yes is for,
 # `rustc -Z help` shows that `link-native-libraries=yes` is the default. But it
 # seems to be necessary...
-export RUSTFLAGS = -C link-arg=-sSIDE_MODULE=2 -Z link-native-libraries=yes
+export RUSTFLAGS = -C link-arg=-sSIDE_MODULE=2 -Z link-native-libraries=yes -Z emscripten-wasm-eh
 
 # URL to the prebuilt packages
 export PYODIDE_PREBUILT_PACKAGES_BASE=https://github.com/pyodide/pyodide-recipes/releases/download/20250114
@@ -129,6 +131,8 @@ export CFLAGS_BASE=\
 	$(OPTFLAGS) \
 	$(DBGFLAGS) \
 	-fPIC \
+	-fwasm-exceptions \
+	-sSUPPORT_LONGJMP \
 	$(EXTRA_CFLAGS)
 
 
@@ -138,7 +142,9 @@ export LDFLAGS_BASE=\
 	$(DBG_LDFLAGS) \
 	-L$(CPYTHONROOT)/installs/python-$(PYVERSION)/lib/ \
 	-s WASM_BIGINT \
-	$(EXTRA_LDFLAGS)
+	-fwasm-exceptions \
+	-sSUPPORT_LONGJMP \
+	$(EXTRA_LDFLAGS) \
 
 export CXXFLAGS_BASE=
 
@@ -148,7 +154,6 @@ export MAIN_MODULE_LDFLAGS= $(LDFLAGS_BASE) \
 	-s LZ4=1 \
 	-s EXPORT_NAME="'_createPyodideModule'" \
 	-s EXPORT_EXCEPTION_HANDLING_HELPERS \
-	-s EXCEPTION_CATCHING_ALLOWED=['we only want to allow exception handling in side modules'] \
 	-sEXPORTED_RUNTIME_METHODS='wasmTable,ERRNO_CODES' \
 	-s USE_ZLIB \
 	-s USE_BZIP2 \
@@ -234,14 +239,15 @@ EXPORTS=_main \
    ,__PyTraceback_Add \
    ,_PyUnicode_Data \
    ,_PyUnicode_New \
+   ,_emscripten_stack_get_current \
    ,_Py_Version \
 
 
 ifeq ($(DISABLE_DYLINK), 1)
 	export MAIN_MODULE_LDFLAGS= $(LDFLAGS_BASE) \
 		-s MODULARIZE=1 \
 		-s EXPORT_NAME="'_createPyodideModule'" \
-		-sEXPORTED_RUNTIME_METHODS='wasmTable,ERRNO_CODES,FS,ENV,stringToNewUTF8,addFunction' \
+		-sEXPORTED_RUNTIME_METHODS='wasmTable,ERRNO_CODES,FS,ENV,stringToNewUTF8,addFunction,stackSave,stackRestore' \
 		-s LZ4=1 \
 		-s USE_ZLIB \
 		-s USE_BZIP2 \
@@ -273,7 +279,6 @@ export MAIN_MODULE_CFLAGS= $(CFLAGS_BASE) \
 	-mreference-types \
 	-I$(PYTHONINCLUDE) \
 	-I$(PYTHONINCLUDE)/.. \
-	-s EXCEPTION_CATCHING_ALLOWED=['we only want to allow exception handling in side modules']
 
 .output_vars:
 	set
diff --git a/docs/project/changelog.md b/docs/project/changelog.md
@@ -18,6 +18,8 @@ myst:
 
 - ABI break: Upgraded Emscripten to 3.1.63 {pr}`5343` {pr}`5350` {pr}`5357`
   {pr}`5334` {pr}`5363`
+- ABI break: Switched to using WebAssembly exception handling for C++ errors,
+  Rust panics, and setjmp/longjmp. {pr}`5320`
 - Added `jiter` 0.8.2 {pr}`5388`
 
 ### Packages

diff --git a/packages/RobotRaconteur/meta.yaml b/packages/RobotRaconteur/meta.yaml
@@ -17,8 +17,8 @@ requirements:
     - numpy
 
 build:
-  cxxflags: -fexceptions -fPIC -DBOOST_SP_DISABLE_THREADS=1 -O2
-  ldflags: -fexceptions
+  cxxflags: -fwasm-exceptions -fPIC -DBOOST_SP_DISABLE_THREADS=1 -O2
+  ldflags: -fwasm-exceptions
   script: |
     export INSTALL_DIR=${WASM_LIBRARY_DIR}
 
@@ -28,7 +28,7 @@ build:
     -DNUMPY_INCLUDE_DIR=$HOSTINSTALLDIR/lib/python$PYMAJOR.$PYMINOR/site-packages/numpy/_core/include/ \
     -DPYTHON3_INCLUDE_DIR=$PYTHONINCLUDE -DPYTHON3_EXECUTABLE=python$PYMAJOR.$PYMINOR \
     -DPYTHON3_LIBRARY=$HOSTINSTALLDIR/lib/python$PYMAJOR.$PYMINOR.a \
-    -DCMAKE_CXX_FLAGS="-fPIC -fexceptions -DBOOST_AP_DISABLE_THREADS=1 -O2 -DBOOST_BIND_GLOBAL_PLACEHOLDERS=1" \
+    -DCMAKE_CXX_FLAGS="-fPIC -fwasm-exceptions -DBOOST_AP_DISABLE_THREADS=1 -O2 -DBOOST_BIND_GLOBAL_PLACEHOLDERS=1" \
     -DBoost_INCLUDE_DIR=$WASM_LIBRARY_DIR/include -DBoost_LIBRARY_DIR=$WASM_LIBRARY_DIR/lib \
     -DBoost_DATE_TIME_LIBRARY_RELEASE=$WASM_LIBRARY_DIR/lib/libboost_date_time.a \
     -DBoost_DATE_TIME_LIBRARY_DEBUG=$WASM_LIBRARY_DIR/lib/libboost_date_time.a \
@@ -52,7 +52,7 @@ build:
     -DCMAKE_VERBOSE_MAKEFILE=ON \
      .
     emmake make -j ${PYODIDE_JOBS:-3}
-    emcc ${SIDE_MODULE_LDFLAGS} -fexceptions out/lib/libRobotRaconteurCore.a \
+    emcc ${SIDE_MODULE_LDFLAGS} -fwasm-exceptions out/lib/libRobotRaconteurCore.a \
       out/Python3/RobotRaconteur/_RobotRaconteurPython.a \
       $WASM_LIBRARY_DIR/lib/libboost_chrono.a \
       $WASM_LIBRARY_DIR/lib/libboost_date_time.a \

diff --git a/packages/boost-cpp/meta.yaml b/packages/boost-cpp/meta.yaml
@@ -22,8 +22,8 @@ build:
     ./b2 variant=release toolset=clang-emscripten link=static threading=single \
       --with-date_time --with-filesystem \
       --with-system --with-regex --with-chrono --with-random --with-program_options --disable-icu \
-      cxxflags="$SIDE_MODULE_CXXFLAGS -fexceptions -DBOOST_SP_DISABLE_THREADS=1" \
-      cflags="$SIDE_MODULE_CFLAGS -fexceptions -DBOOST_SP_DISABLE_THREADS=1" \
+      cxxflags="$SIDE_MODULE_CXXFLAGS -fwasm-exceptions -DBOOST_SP_DISABLE_THREADS=1" \
+      cflags="$SIDE_MODULE_CFLAGS -fwasm-exceptions -DBOOST_SP_DISABLE_THREADS=1" \
       linkflags="-fpic $SIDE_MODULE_LDFLAGS" \
       --layout=system -j"${PYODIDE_JOBS:-3}" --prefix=${INSTALL_DIR} \
       install

diff --git a/packages/casadi/meta.yaml b/packages/casadi/meta.yaml
@@ -14,11 +14,11 @@ requirements:
 build:
   exports: requested
   cflags: |
-    -fexceptions -frtti
+    -fwasm-exceptions -frtti
   cxxflags: |
-    -fexceptions -frtti
+    -fwasm-exceptions -frtti
   ldflags: |
-    -fexceptions
+    -fwasm-exceptions
 about:
   home: http://casadi.org
   PyPI: https://pypi.org/project/casadi

diff --git a/packages/coolprop/meta.yaml b/packages/coolprop/meta.yaml
@@ -16,9 +16,9 @@ source:
       - ./pyproject.toml
 
 build:
-  cflags: -fexceptions
-  cxxflags: -fexceptions
-  ldflags: -fexceptions
+  cflags: -fwasm-exceptions
+  cxxflags: -fwasm-exceptions
+  ldflags: -fwasm-exceptions
 
 requirements:
   run:

diff --git a/packages/cpp-exceptions-test/meta.yaml b/packages/cpp-exceptions-test/meta.yaml
@@ -11,9 +11,9 @@ source:
 build:
   type: shared_library
   script: |
-    em++ ${SIDE_MODULE_CFLAGS} -fexceptions -I${PYTHONINCLUDE} -flto -fno-lto -std=c++20 -c throw.cpp -o throw.o
-    em++ ${SIDE_MODULE_CFLAGS} -fexceptions -I${PYTHONINCLUDE} -flto -fno-lto -std=c++20 -c catch.cpp -o catch.o -mreference-types
-    em++ ${SIDE_MODULE_LDFLAGS} -fexceptions  -o ${DISTDIR}/cpp-exceptions-test-throw.so throw.o
-    em++ ${SIDE_MODULE_LDFLAGS} -fexceptions  -o ${DISTDIR}/cpp-exceptions-test-catch.so catch.o
+    em++ ${SIDE_MODULE_CFLAGS} -fwasm-exceptions -I${PYTHONINCLUDE} -flto -fno-lto -std=c++20 -c throw.cpp -o throw.o
+    em++ ${SIDE_MODULE_CFLAGS} -fwasm-exceptions -I${PYTHONINCLUDE} -flto -fno-lto -std=c++20 -c catch.cpp -o catch.o -mreference-types
+    em++ ${SIDE_MODULE_LDFLAGS} -fwasm-exceptions -sSIDE_MODULE=1 -o ${DISTDIR}/cpp-exceptions-test-throw.so throw.o
+    em++ ${SIDE_MODULE_LDFLAGS} -fwasm-exceptions  -sSIDE_MODULE=1 ${DISTDIR}/cpp-exceptions-test-throw.so -o ${DISTDIR}/cpp-exceptions-test-catch.so catch.o
 about:
   license: MPL-2.0
diff --git a/packages/cpp-exceptions-test2/meta.yaml b/packages/cpp-exceptions-test2/meta.yaml
@@ -7,7 +7,7 @@ package:
 source:
   path: src
 build:
-  cxxflags: -fexceptions
-  ldflags: -fexceptions
+  cxxflags: -fwasm-exceptions
+  ldflags: -fwasm-exceptions
 about:
   license: MPL-2.0
diff --git a/packages/gdal/meta.yaml b/packages/gdal/meta.yaml
@@ -26,7 +26,7 @@ build:
 
     embuilder build zlib --pic
     embuilder build libjpeg --pic
-    embuilder build libpng --pic
+    embuilder build libpng-wasm-sjlj --pic
     embuilder build sqlite3 --pic
 
     mkdir -p build
@@ -62,7 +62,7 @@ build:
       \
       -DGDAL_USE_PNG=ON \
       -DPNG_PNG_INCLUDE_DIR=$EMSCRIPTEN_INCLUDE \
-      -DPNG_LIBRARY_RELEASE=$EMSCRIPTEN_LIB/libpng.a \
+      -DPNG_LIBRARY_RELEASE=$EMSCRIPTEN_LIB/libpng-wasm-sjlj.a \
       \
       -DGDAL_USE_JPEG=ON \
       -DJPEG_INCLUDE_DIR=$EMSCRIPTEN_INCLUDE \
@@ -79,7 +79,8 @@ build:
       -DGDAL_USE_JSONC_INTERNAL=ON \
       -DGDAL_USE_PCRE2=OFF \
       -DBUILD_TESTING=OFF \
-      -DBUILD_PYTHON_BINDINGS=OFF
+      -DBUILD_PYTHON_BINDINGS=OFF \
+      -DCMAKE_VERBOSE_MAKEFILE=ON
 
 
     # Note:

diff --git a/packages/glpk/meta.yaml b/packages/glpk/meta.yaml
@@ -11,7 +11,7 @@ source:
 build:
   type: static_library
   script: |
-    CFLAGS="-fPIC" emconfigure ./configure \
+    CFLAGS="-fPIC -sSUPPORT_LONGJMP=wasm" LDFLAGS="-sSUPPORT_LONGJMP=wasm" emconfigure ./configure \
       --prefix=${WASM_LIBRARY_DIR} \
       --disable-dependency-tracking \
       --disable-shared \

diff --git a/packages/matplotlib/meta.yaml b/packages/matplotlib/meta.yaml
@@ -25,13 +25,13 @@ build:
     -s USE_FREETYPE=1
     -s USE_LIBPNG=1
     -s USE_ZLIB=1
-    -fexceptions
+    -fwasm-exceptions
     -fno-lto
   cxxflags: |
     -std=c++14
-    -fexceptions
+    -fwasm-exceptions
   ldflags: |
-    -fexceptions
+    -fwasm-exceptions
   script: export SETUPTOOLS_SCM_PRETEND_VERSION=$PKG_VERSION
   post: |
     rm -rf matplotlib/backends/qt_editor

diff --git a/packages/opencv-python/meta.yaml b/packages/opencv-python/meta.yaml
@@ -39,7 +39,7 @@ build:
   ldflags: |
     -ljpeg
     -lz
-    -lpng
+    -lpng-wasm-sjlj
   # Note on CMAKE_ARGS:
   #   CMake args are adopted from OpenCV.js (https://github.com/opencv/opencv/blob/4.x/platforms/js/build_js.py)
   #   But we support more modules than OpenCV.js.

diff --git a/packages/ppl/meta.yaml b/packages/ppl/meta.yaml
@@ -20,8 +20,8 @@ build:
     emconfigure ./configure \
         CFLAGS="-fPIC -Wno-reserved-identifier -Wno-reserved-macro-identifier" \
         CPPFLAGS="-I${WASM_LIBRARY_DIR}/include" \
-        CXXFLAGS="-std=c++11 -fPIC -Wno-reserved-identifier -Wno-zero-as-null-pointer-constant -Wno-double-promotion -Wno-unsafe-buffer-usage -Wno-extra-semi-stmt -Wno-shadow -Wno-implicit-fallthrough -Wno-deprecated-literal-operator -Wno-suggest-override -Wno-suggest-destructor-override -Wno-deprecated-copy-with-user-provided-dtor -Wno-deprecated-copy-with-user-provided-copy -Wno-unused-template -Wno-comma -Wno-unreachable-code-return -Wno-deprecated-declarations -Wno-unreachable-code-break -Wno-format-nonliteral -Wno-missing-variable-declarations -Wno-missing-prototypes -Wno-weak-vtables -Wno-old-style-cast -Wno-header-hygiene -Wno-undef" \
-        LDFLAGS="-L${WASM_LIBRARY_DIR}/lib" \
+        CXXFLAGS="-fwasm-exceptions -std=c++11 -fPIC -Wno-reserved-identifier -Wno-zero-as-null-pointer-constant -Wno-double-promotion -Wno-unsafe-buffer-usage -Wno-extra-semi-stmt -Wno-shadow -Wno-implicit-fallthrough -Wno-deprecated-literal-operator -Wno-suggest-override -Wno-suggest-destructor-override -Wno-deprecated-copy-with-user-provided-dtor -Wno-deprecated-copy-with-user-provided-copy -Wno-unused-template -Wno-comma -Wno-unreachable-code-return -Wno-deprecated-declarations -Wno-unreachable-code-break -Wno-format-nonliteral -Wno-missing-variable-declarations -Wno-missing-prototypes -Wno-weak-vtables -Wno-old-style-cast -Wno-header-hygiene -Wno-undef" \
+        LDFLAGS="-L${WASM_LIBRARY_DIR}/lib -fwasm-exceptions -sSUPPORT_LONGJMP" \
         --disable-dependency-tracking \
         --enable-coefficients=mpz --disable-fpmath \
         --enable-interfaces=c,c++ \

diff --git a/packages/pygame-ce/meta.yaml b/packages/pygame-ce/meta.yaml
@@ -68,13 +68,13 @@ build:
       ${SIDE_MODULE_LDFLAGS} \
       -fPIC \
       -lSDL2 \
-      -lSDL2_image-bmp-gif-jpg-png \
+      -lSDL2_image-bmp-gif-jpg-png-wasm-sjlj \
       -lSDL2_ttf \
       -lSDL2_mixer_mid-mod-mpg-ogg \
       -lSDL2_gfx \
-      -lfreetype \
+      -lfreetype-wasm-sjlj \
       -lharfbuzz \
-      -lpng \
+      -lpng-wasm-sjlj \
       -ljpeg \
       -lgif \
       -lvorbis \
@@ -84,6 +84,7 @@ build:
       -lhtml5 \
       ${STATIC_OBJS} \
       ${SHARED_LIBS} \
+      -sSUPPORT_LONGJMP=wasm \
       -o pygame_static.so
 
     # Remove duplicated static.so module

diff --git a/packages/rust-panic-test/meta.yaml b/packages/rust-panic-test/meta.yaml
@@ -3,10 +3,6 @@ package:
   version: "1.0"
 source:
   path: src
-build:
-  script: |
-    rustup toolchain install ${RUST_TOOLCHAIN} && rustup default ${RUST_TOOLCHAIN}
-    rustup target add wasm32-unknown-emscripten --toolchain ${RUST_TOOLCHAIN}
 requirements:
   executable:
     - rustup

diff --git a/packages/scipy/meta.yaml b/packages/scipy/meta.yaml
@@ -54,12 +54,12 @@ build:
     -DUNDERSCORE_G77
     -fvisibility=default
   cxxflags: |
-    -fexceptions
+    -fwasm-exceptions
     -fvisibility=default
   ldflags: |
     -L$(NUMPY_LIB)/core/lib/
     -L$(NUMPY_LIB)/random/lib/
-    -fexceptions
+    -fwasm-exceptions
 
   # Exclude tests via Meson's install tags functionality.
   unvendor-tests: true

diff --git a/packages/shapely/meta.yaml b/packages/shapely/meta.yaml
@@ -11,9 +11,9 @@ build:
   script: |
     export GEOS_CONFIG=${WASM_LIBRARY_DIR}/bin/geos-config
   cxxflags: |
-    -fexceptions
+    -fwasm-exceptions
   ldflags: |
-    -fexceptions
+    -fwasm-exceptions
 requirements:
   run:
     - numpy

diff --git a/pyodide-build b/pyodide-build
diff --git a/pyproject.toml b/pyproject.toml
@@ -146,9 +146,6 @@ markers = [
 
 [tool._pyodide]
 
-[tool.pyodide.build]
-rust_toolchain = "nightly-2025-01-15"
-
 [tool.codespell]
 ignore-words = 'tools/codespell_ignore_words.txt'
 skip = 'benchmark/benchmarks/pystone_benchmarks/pystone.py,src/js/package-lock.json,tools/codespell_ignore_words.txt'
diff --git a/src/core/error_handling.ts b/src/core/error_handling.ts
@@ -42,7 +42,13 @@ function ensureCaughtObjectIsError(e: any): Error {
 
 class CppException extends Error {
   ty: string;
-  constructor(ty: string, msg: string | undefined, ptr: number) {
+  constructor(
+    ty: string,
+    msg: string | undefined,
+    e: any /* WebAssembly.Exception */,
+  ) {
+    // @ts-ignore
+    const ptr = Module.getCppExceptionThrownObjectFromWebAssemblyException(e);
     if (!msg) {
       msg = `The exception is an object of type ${ty} at address ${ptr} which does not inherit from std::exception`;
     }
@@ -56,19 +62,10 @@ Object.defineProperty(CppException.prototype, "name", {
   },
 });
 
-// As a fallback for when Wasm EH is not available, use an empty function.
-// The fallback ensures instanceof always returns false.
-const wasmException = (WebAssembly as any).Exception || function () {};
-const isWasmException = (e: any) => e instanceof wasmException;
+const WasmException = (WebAssembly as any).Exception;
+const isWasmException = (e: any) => e instanceof WasmException;
 
 function convertCppException(e: any) {
-  if (isWasmException(e)) {
-    if (e.is(Module.jsWrapperTag)) {
-      e = e.getArg(Module.jsWrapperTag, 0);
-    } else {
-      return e;
-    }
-  }
   let [ty, msg]: [string, string] = Module.getExceptionMessage(e);
   return new CppException(ty, msg, e);
 }
+4 −2		pyodide_build/common.py
+4 −1		pyodide_build/config.py
+1 −0		pyodide_build/pypabuild.py
+12 −3		pyodide_build/pywasmcross.py
+35 −10		pyodide_build/recipe/graph_builder.py
+1 −1		pyproject.toml