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Emscripten: An LLVM-to-WebAssembly Compiler
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Undefined symbol `_emscripten_memcpy_js` when linking rust code with -lc -Oz #22742

Open hoodmane opened 1 month ago

hoodmane commented 1 month ago

You need rust and the emscripten target installed. rustup target add wasm32-unknown-emscripten installs the emscripten target if you use rustup.

echo "fn main(){}" > a.rs
rustc -Copt-level=z a.rs -o a.js --target=wasm32-unknown-emscripten

Fails with:

          error: undefined symbol: _emscripten_memcpy_js (referenced by root reference (e.g. compiled C/C++ code))
          warning: To disable errors for undefined symbols use `-sERROR_ON_UNDEFINED_SYMBOLS=0`
          warning: __emscripten_memcpy_js may need to be added to EXPORTED_FUNCTIONS if it arrives from a system library
          Error: Aborting compilation due to previous errors
          emcc: error: '/home/rchatham/Documents/programming/emsdk/node/18.20.3_64bit/bin/node /home/rchatham/Documents/programming/emsdk/upstream/emscripten/src/compiler.mjs /tmp/tmpogw1glcz.json' failed (returned 1)

If we minimize the failing emcc link command, it looks like:

emcc -o a.js -Oz -lc \
a.a.<some-hash>-cgu.0.rcgu.o \
a.<some-hash>.rcgu.o \
.../lib/rustlib/wasm32-unknown-emscripten/lib/libstd-1d3ccab4f7990fa9.rlib \
.../lib/rustlib/wasm32-unknown-emscripten/lib/libpanic_abort-bb30bbb88530dc79.rlib \
.../lib/rustlib/wasm32-unknown-emscripten/lib/liballoc-6b694a8bc75de25c.rlib \
.../lib/rustlib/wasm32-unknown-emscripten/lib/libcore-99daaba8bfbbfe7e.rlib \

If I remove either -Oz or -lc then it succeeds. If I pass EMCC_DEBUG=1 and look at the contents of tmpogw1glcz.json it looks like:

Details { "ABORTING_MALLOC": true, "ABORT_ON_WASM_EXCEPTIONS": false, "AGGRESSIVE_VARIABLE_ELIMINATION": 0, "ALIASING_FUNCTION_POINTERS": 0, "ALLOW_BLOCKING_ON_MAIN_THREAD": true, "ALLOW_MEMORY_GROWTH": false, "ALLOW_TABLE_GROWTH": false, "ALLOW_UNIMPLEMENTED_SYSCALLS": true, "ALL_INCOMING_MODULE_JS_API": [ "ENVIRONMENT", "GL_MAX_TEXTURE_IMAGE_UNITS", "SDL_canPlayWithWebAudio", "SDL_numSimultaneouslyQueuedBuffers", "INITIAL_MEMORY", "wasmMemory", "arguments", "buffer", "canvas", "doNotCaptureKeyboard", "dynamicLibraries", "elementPointerLock", "extraStackTrace", "forcedAspectRatio", "instantiateWasm", "keyboardListeningElement", "freePreloadedMediaOnUse", "loadSplitModule", "locateFile", "logReadFiles", "mainScriptUrlOrBlob", "mem", "monitorRunDependencies", "noExitRuntime", "noInitialRun", "onAbort", "onCustomMessage", "onExit", "onFree", "onFullScreen", "onMalloc", "onRealloc", "onRuntimeInitialized", "postMainLoop", "postRun", "preInit", "preMainLoop", "preRun", "preinitializedWebGLContext", "preloadPlugins", "print", "printErr", "setStatus", "statusMessage", "stderr", "stdin", "stdout", "thisProgram", "wasm", "wasmBinary", "websocket", "fetchSettings" ], "ASAN_SHADOW_SIZE": -1, "ASM_JS": 1, "ASM_PRIMITIVE_VARS": [], "ASSERTIONS": 0, "ASYNCIFY": 0, "ASYNCIFY_ADD": [], "ASYNCIFY_ADVISE": false, "ASYNCIFY_BLACKLIST": [], "ASYNCIFY_DEBUG": 0, "ASYNCIFY_EXPORTS": [], "ASYNCIFY_IGNORE_INDIRECT": false, "ASYNCIFY_IMPORTS": [], "ASYNCIFY_IMPORTS_EXCEPT_JS_LIBS": [], "ASYNCIFY_LAZY_LOAD_CODE": false, "ASYNCIFY_ONLY": [], "ASYNCIFY_PROPAGATE_ADD": true, "ASYNCIFY_REMOVE": [], "ASYNCIFY_STACK_SIZE": 4096, "ASYNCIFY_WHITELIST": [], "AUDIO_WORKLET": 0, "AUDIO_WORKLET_FILE": "", "AUTODEBUG": false, "AUTOLOAD_DYLIBS": true, "AUTO_ARCHIVE_INDEXES": 0, "AUTO_JS_LIBRARIES": true, "AUTO_NATIVE_LIBRARIES": true, "BINARYEN": 1, "BINARYEN_ASYNC_COMPILATION": true, "BINARYEN_EXTRA_PASSES": "", "BINARYEN_FEATURES": [ "--mvp-features", "--enable-multivalue", "--enable-mutable-globals", "--enable-reference-types", "--enable-sign-ext" ], "BINARYEN_IGNORE_IMPLICIT_TRAPS": false, "BINARYEN_MEM_MAX": 2147483648, "BINARYEN_METHOD": "native-wasm", "BINARYEN_PASSES": "", "BINARYEN_SCRIPTS": "", "BINARYEN_TRAP_MODE": -1, "BOOTSTRAPPING_STRUCT_INFO": false, "BUILD_AS_SHARED_LIB": 0, "BUILD_AS_WORKER": false, "BULK_MEMORY": false, "CAN_ADDRESS_2GB": false, "CASE_INSENSITIVE_FS": false, "CHECK_NULL_WRITES": true, "CLOSURE_WARNINGS": "quiet", "DEAD_FUNCTIONS": [], "DEBUG_LEVEL": 0, "DECLARE_ASM_MODULE_EXPORTS": true, "DEFAULT_LIBRARY_FUNCS_TO_INCLUDE": [ "$ExitStatus", "$callRuntimeCallbacks", "$getValue", "$noExitRuntime", "$setValue", "$stackRestore", "$stackSave", "__cxa_find_matching_catch_2", "__cxa_find_matching_catch_4", "__resumeException", "__syscall_getcwd", "_abort_js", "_emscripten_memcpy_js", "emscripten_resize_heap", "environ_get", "environ_sizes_get", "fd_write", "llvm_eh_typeid_for", "$exitJS", "$handleException", "$stringToUTF8OnStack", "$getWasmTableEntry" ], "DEFAULT_PTHREAD_STACK_SIZE": 0, "DEFAULT_TO_CXX": true, "DEMANGLE_SUPPORT": false, "DETERMINISTIC": false, "DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR": true, "DISABLE_EXCEPTION_CATCHING": 1, "DISABLE_EXCEPTION_THROWING": false, "DOUBLE_MODE": 0, "DYLINK_DEBUG": 0, "DYNAMIC_EXECUTION": 1, "DYNCALLS": false, "ELIMINATE_DUPLICATE_FUNCTIONS": 0, "ELIMINATE_DUPLICATE_FUNCTIONS_DUMP_EQUIVALENT_FUNCTIONS": 0, "ELIMINATE_DUPLICATE_FUNCTIONS_PASSES": 5, "EMBIND": false, "EMBIND_AOT": false, "EMBIND_STD_STRING_IS_UTF8": true, "EMITTING_JS": 1, "EMIT_EMSCRIPTEN_LICENSE": false, "EMIT_EMSCRIPTEN_METADATA": 0, "EMIT_NAME_SECTION": false, "EMIT_PRODUCERS_SECTION": false, "EMIT_SYMBOL_MAP": false, "EMIT_TSD": false, "EMSCRIPTEN_TRACING": false, "EMSCRIPTEN_VERSION": "3.1.68", "EMULATE_FUNCTION_POINTER_CASTS": false, "ENVIRONMENT": "web,webview,worker,node", "ENVIRONMENT_MAY_BE_NODE": true, "ENVIRONMENT_MAY_BE_SHELL": false, "ENVIRONMENT_MAY_BE_WEB": true, "ENVIRONMENT_MAY_BE_WEBVIEW": true, "ENVIRONMENT_MAY_BE_WORKER": true, "ERROR_ON_MISSING_LIBRARIES": 1, "ERROR_ON_UNDEFINED_SYMBOLS": true, "ERROR_ON_WASM_CHANGES_AFTER_LINK": false, "EVAL_CTORS": 0, "EXCEPTION_CATCHING_ALLOWED": [], "EXCEPTION_CATCHING_WHITELIST": [], "EXCEPTION_DEBUG": false, "EXCEPTION_STACK_TRACES": false, "EXIT_RUNTIME": false, "EXPECT_MAIN": true, "EXPORTED_FUNCTIONS": [ "_memory", "___indirect_function_table", "_main" ], "EXPORTED_RUNTIME_METHODS": [ "HEAPF32", "HEAPF64", "HEAP_DATA_VIEW", "HEAP8", "HEAPU8", "HEAP16", "HEAPU16", "HEAP32", "HEAPU32", "HEAP64", "HEAPU64" ], "EXPORT_ALL": false, "EXPORT_BINDINGS": 0, "EXPORT_ES6": false, "EXPORT_EXCEPTION_HANDLING_HELPERS": false, "EXPORT_FUNCTION_TABLES": 0, "EXPORT_IF_DEFINED": [ "__start_em_asm", "__stop_em_asm", "__start_em_lib_deps", "__stop_em_lib_deps", "__start_em_js", "__stop_em_js", "main", "__main_argc_argv" ], "EXPORT_KEEPALIVE": true, "EXPORT_NAME": "Module", "EXTRA_EXPORTED_RUNTIME_METHODS": [], "FAST_UNROLLED_MEMCPY_AND_MEMSET": 0, "FETCH": false, "FETCH_DEBUG": false, "FETCH_SUPPORT_INDEXEDDB": true, "FILESYSTEM": true, "FINALIZE_ASM_JS": 0, "FORCE_ALIGNED_MEMORY": 0, "FORCE_FILESYSTEM": false, "FS_DEBUG": false, "FULL_ES2": false, "FULL_ES3": false, "FUNCTION_POINTER_ALIGNMENT": 2, "GENERATE_DWARF": false, "GENERATE_SOURCE_MAP": false, "GLOBAL_BASE": 1024, "GL_ASSERTIONS": false, "GL_DEBUG": false, "GL_DISABLE_HALF_FLOAT_EXTENSION_IF_BROKEN": false, "GL_EMULATE_GLES_VERSION_STRING_FORMAT": true, "GL_ENABLE_GET_PROC_ADDRESS": true, "GL_EXPLICIT_UNIFORM_BINDING": false, "GL_EXPLICIT_UNIFORM_LOCATION": false, "GL_EXTENSIONS_IN_PREFIXED_FORMAT": true, "GL_FFP_ONLY": false, "GL_MAX_TEMP_BUFFER_SIZE": 2097152, "GL_POOL_TEMP_BUFFERS": true, "GL_PREINITIALIZED_CONTEXT": false, "GL_SUPPORT_AUTOMATIC_ENABLE_EXTENSIONS": true, "GL_SUPPORT_EXPLICIT_SWAP_CONTROL": false, "GL_SUPPORT_SIMPLE_ENABLE_EXTENSIONS": true, "GL_TESTING": false, "GL_TRACK_ERRORS": true, "GL_UNSAFE_OPTS": true, "GL_WORKAROUND_SAFARI_GETCONTEXT_BUG": true, "HAS_MAIN": true, "HAVE_EM_ASM": false, "HEADLESS": false, "HEAP_BASE": 0, "HTML5_SUPPORT_DEFERRING_USER_SENSITIVE_REQUESTS": true, "IGNORE_CLOSURE_COMPILER_ERRORS": false, "IGNORE_MISSING_MAIN": true, "IMPORTED_MEMORY": false, "INCLUDE_FULL_LIBRARY": false, "INCLUDE_WEBGL1_FALLBACK": true, "INCOMING_MODULE_JS_API": [ "ENVIRONMENT", "GL_MAX_TEXTURE_IMAGE_UNITS", "SDL_canPlayWithWebAudio", "SDL_numSimultaneouslyQueuedBuffers", "INITIAL_MEMORY", "wasmMemory", "arguments", "buffer", "canvas", "doNotCaptureKeyboard", "dynamicLibraries", "elementPointerLock", "extraStackTrace", "forcedAspectRatio", "instantiateWasm", "keyboardListeningElement", "freePreloadedMediaOnUse", "loadSplitModule", "locateFile", "logReadFiles", "mainScriptUrlOrBlob", "mem", "monitorRunDependencies", "noExitRuntime", "noInitialRun", "onAbort", "onCustomMessage", "onExit", "onFree", "onFullScreen", "onMalloc", "onRealloc", "onRuntimeInitialized", "postMainLoop", "postRun", "preInit", "preMainLoop", "preRun", "preinitializedWebGLContext", "preloadPlugins", "print", "printErr", "setStatus", "statusMessage", "stderr", "stdin", "stdout", "thisProgram", "wasm", "wasmBinary", "websocket" ], "INITIAL_HEAP": 16777216, "INITIAL_MEMORY": -1, "INITIAL_TABLE": -1, "INLINING_LIMIT": false, "INVOKE_RUN": true, "JSPI": 0, "JSPI_EXPORTS": [], "JSPI_IMPORTS": [], "JS_LIBRARIES": [ "library_pthread_stub.js" ], "JS_MATH": false, "LEGACY_GL_EMULATION": false, "LEGACY_RUNTIME": false, "LEGACY_SETTINGS": [ "BINARYEN", "TOTAL_STACK", "BINARYEN_ASYNC_COMPILATION", "UNALIGNED_MEMORY", "FORCE_ALIGNED_MEMORY", "PGO", "QUANTUM_SIZE", "FUNCTION_POINTER_ALIGNMENT", "RESERVED_FUNCTION_POINTERS", "BUILD_AS_SHARED_LIB", "SAFE_SPLIT_MEMORY", "SPLIT_MEMORY", "BINARYEN_METHOD", "BINARYEN_TRAP_MODE", "PRECISE_I64_MATH", "MEMFS_APPEND_TO_TYPED_ARRAYS", "ERROR_ON_MISSING_LIBRARIES", "EMITTING_JS", "SKIP_STACK_IN_SMALL", "SAFE_STACK", "MEMORY_GROWTH_STEP", "ELIMINATE_DUPLICATE_FUNCTIONS", "ELIMINATE_DUPLICATE_FUNCTIONS_DUMP_EQUIVALENT_FUNCTIONS", "ELIMINATE_DUPLICATE_FUNCTIONS_PASSES", "WASM_OBJECT_FILES", "TOTAL_MEMORY", "WASM_MEM_MAX", "BINARYEN_MEM_MAX", "BINARYEN_PASSES", "SWAPPABLE_ASM_MODULE", "ASM_JS", "FINALIZE_ASM_JS", "ASYNCIFY_WHITELIST", "ASYNCIFY_BLACKLIST", "EXCEPTION_CATCHING_WHITELIST", "SEPARATE_ASM", "SEPARATE_ASM_MODULE_NAME", "FAST_UNROLLED_MEMCPY_AND_MEMSET", "DOUBLE_MODE", "PRECISE_F32", "ALIASING_FUNCTION_POINTERS", "AGGRESSIVE_VARIABLE_ELIMINATION", "SIMPLIFY_IFS", "DEAD_FUNCTIONS", "WASM_BACKEND", "EXPORT_BINDINGS", "RUNNING_JS_OPTS", "EXPORT_FUNCTION_TABLES", "BINARYEN_SCRIPTS", "WARN_UNALIGNED", "ASM_PRIMITIVE_VARS", "WORKAROUND_IOS_9_RIGHT_SHIFT_BUG", "RUNTIME_FUNCS_TO_IMPORT", "LIBRARY_DEPS_TO_AUTOEXPORT", "EMIT_EMSCRIPTEN_METADATA", "SHELL_FILE", "LLD_REPORT_UNDEFINED", "MEM_INIT_METHOD", "USE_PTHREADS", "USES_DYNAMIC_ALLOC", "REVERSE_DEPS", "RUNTIME_LOGGING", "MIN_EDGE_VERSION", "MIN_IE_VERSION", "WORKAROUND_OLD_WEBGL_UNIFORM_UPLOAD_IGNORED_OFFSET_BUG", "AUTO_ARCHIVE_INDEXES" ], "LEGACY_VM_SUPPORT": false, "LEGALIZE_JS_FFI": true, "LIBRARY_DEBUG": false, "LIBRARY_DEPS_TO_AUTOEXPORT": [], "LINKABLE": false, "LINK_AS_CXX": true, "LLD_REPORT_UNDEFINED": 1, "LOAD_SOURCE_MAP": false, "LTO": 0, "LZ4": false, "MAIN_MODULE": 0, "MAIN_READS_PARAMS": true, "MALLOC": "dlmalloc", "MAXIMUM_MEMORY": 2147483648, "MAX_WEBGL_VERSION": 1, "MAYBE_CLOSURE_COMPILER": false, "MAYBE_WASM2JS": false, "MEMFS_APPEND_TO_TYPED_ARRAYS": 1, "MEMORY64": 0, "MEMORYPROFILER": false, "MEMORY_GROWTH_GEOMETRIC_CAP": 100663296, "MEMORY_GROWTH_GEOMETRIC_STEP": 0.2, "MEMORY_GROWTH_LINEAR_STEP": -1, "MEMORY_GROWTH_STEP": -1, "MEM_INIT_METHOD": 0, "MINIFICATION_MAP": "", "MINIFY_HTML": true, "MINIFY_WASM_EXPORT_NAMES": true, "MINIFY_WASM_IMPORTED_MODULES": 1, "MINIFY_WASM_IMPORTS_AND_EXPORTS": 1, "MINIFY_WHITESPACE": true, "MINIMAL_RUNTIME": 0, "MINIMAL_RUNTIME_STREAMING_WASM_COMPILATION": false, "MINIMAL_RUNTIME_STREAMING_WASM_INSTANTIATION": false, "MIN_CHROME_VERSION": 85, "MIN_EDGE_VERSION": 2147483647, "MIN_FIREFOX_VERSION": 79, "MIN_IE_VERSION": 2147483647, "MIN_NODE_VERSION": 160000, "MIN_SAFARI_VERSION": 140100, "MIN_WEBGL_VERSION": 1, "MODULARIZE": false, "NODEJS_CATCH_EXIT": false, "NODEJS_CATCH_REJECTION": 0, "NODERAWFS": false, "NODE_CODE_CACHING": false, "OFFSCREENCANVASES_TO_PTHREAD": "#canvas", "OFFSCREENCANVAS_SUPPORT": false, "OFFSCREEN_FRAMEBUFFER": false, "OFFSCREEN_FRAMEBUFFER_FORBID_VAO_PATH": false, "OPENAL_DEBUG": false, "OPT_LEVEL": 2, "PGO": 0, "POLYFILL": true, "POLYFILL_OLD_MATH_FUNCTIONS": 0, "POST_JS_FILES": [], "PRECISE_F32": 0, "PRECISE_I64_MATH": 1, "PRE_JS_FILES": [], "PRINTF_LONG_DOUBLE": false, "PROXY_POSIX_SOCKETS": false, "PROXY_TO_PTHREAD": false, "PROXY_TO_WORKER": false, "PROXY_TO_WORKER_FILENAME": "", "PTHREADS": false, "PTHREADS_DEBUG": false, "PTHREADS_PROFILING": false, "PTHREAD_POOL_DELAY_LOAD": false, "PTHREAD_POOL_SIZE": 0, "PTHREAD_POOL_SIZE_STRICT": 1, "PURE_WASI": false, "QUANTUM_SIZE": 4, "RELOCATABLE": false, "REQUIRED_EXPORTS": [ "_emscripten_stack_alloc", "__get_temp_ret", "__set_temp_ret", "__wasm_call_ctors", "emscripten_stack_get_current", "_emscripten_stack_restore" ], "RESERVED_FUNCTION_POINTERS": false, "RETAIN_COMPILER_SETTINGS": false, "REVERSE_DEPS": "auto", "RUNNING_JS_OPTS": 0, "RUNTIME_DEBUG": false, "RUNTIME_FUNCS_TO_IMPORT": [], "RUNTIME_LINKED_LIBS": [], "RUNTIME_LOGGING": false, "SAFE_HEAP": 0, "SAFE_HEAP_LOG": false, "SAFE_SPLIT_MEMORY": 0, "SAFE_STACK": 0, "SDL2_IMAGE_FORMATS": [], "SDL2_MIXER_FORMATS": [ "ogg" ], "SEPARATE_ASM": 0, "SEPARATE_ASM_MODULE_NAME": "", "SEPARATE_DWARF": false, "SEPARATE_DWARF_URL": "", "SHARED_MEMORY": false, "SHELL_FILE": "", "SHRINK_LEVEL": 2, "SIDE_MODULE": 0, "SIDE_MODULE_EXPORTS": [], "SIGNATURE_CONVERSIONS": [], "SIMPLIFY_IFS": 1, "SINGLE_FILE": false, "SKIP_STACK_IN_SMALL": 0, "SMALL_XHR_CHUNKS": false, "SOCKET_DEBUG": false, "SOCKET_WEBRTC": false, "SOURCE_MAP_BASE": "", "SPLIT_MEMORY": 0, "SPLIT_MODULE": false, "STACK_FIRST": false, "STACK_HIGH": 0, "STACK_LOW": 0, "STACK_OVERFLOW_CHECK": 0, "STACK_SIZE": 65536, "STANDALONE_WASM": false, "STB_IMAGE": false, "STRICT": false, "STRICT_JS": false, "SUPPORTS_GLOBALTHIS": true, "SUPPORTS_PROMISE_ANY": true, "SUPPORT_BASE64_EMBEDDING": false, "SUPPORT_BIG_ENDIAN": false, "SUPPORT_ERRNO": true, "SUPPORT_LONGJMP": "emscripten", "SWAPPABLE_ASM_MODULE": 0, "SYSCALLS_REQUIRE_FILESYSTEM": true, "SYSCALL_DEBUG": false, "TABLE_BASE": 1, "TARGET_BASENAME": "a", "TARGET_JS_NAME": "a.js", "TEXTDECODER": 1, "TOTAL_MEMORY": -1, "TOTAL_STACK": 65536, "TRACE_WEBGL_CALLS": false, "TRANSPILE": false, "TRUSTED_TYPES": false, "UBSAN_RUNTIME": 0, "UNALIGNED_MEMORY": 0, "USER_EXPORTS": [], "USES_DYNAMIC_ALLOC": 1, "USE_ASAN": false, "USE_BOOST_HEADERS": false, "USE_BULLET": false, "USE_BZIP2": false, "USE_CLOSURE_COMPILER": false, "USE_COCOS2D": 0, "USE_ES6_IMPORT_META": true, "USE_FREETYPE": false, "USE_GIFLIB": false, "USE_GLFW": 0, "USE_HARFBUZZ": false, "USE_ICU": false, "USE_LIBJPEG": false, "USE_LIBPNG": false, "USE_LSAN": false, "USE_MODPLUG": false, "USE_MPG123": false, "USE_OFFSET_CONVERTER": false, "USE_OGG": false, "USE_PTHREADS": 0, "USE_READY_PROMISE": true, "USE_REGAL": false, "USE_RTTI": true, "USE_SDL": 0, "USE_SDL_GFX": 0, "USE_SDL_IMAGE": 1, "USE_SDL_MIXER": 1, "USE_SDL_NET": 1, "USE_SDL_TTF": 1, "USE_SQLITE3": false, "USE_VORBIS": false, "USE_WEBGL2": false, "USE_WEBGPU": false, "USE_ZLIB": false, "VERBOSE": false, "WARN_DEPRECATED": true, "WARN_ON_UNDEFINED_SYMBOLS": true, "WARN_UNALIGNED": 0, "WASI_MODULE_NAME": "wasi_snapshot_preview1", "WASM": 1, "WASM2JS": false, "WASMFS": false, "WASM_ASYNC_COMPILATION": true, "WASM_BACKEND": -1, "WASM_BIGINT": false, "WASM_BINARY_FILE": "a.wasm", "WASM_EXCEPTIONS": false, "WASM_EXNREF": false, "WASM_EXPORTS": [ "memory", "__wasm_call_ctors", "main", "__indirect_function_table", "malloc", "htonl", "htons", "ntohs", "_emscripten_tempret_set", "_emscripten_stack_restore", "_emscripten_stack_alloc", "emscripten_stack_get_current", "__cxa_can_catch" ], "WASM_GLOBAL_EXPORTS": [], "WASM_MEM_MAX": 2147483648, "WASM_OBJECT_FILES": 0, "WASM_WORKERS": 0, "WASM_WORKER_FILE": "", "WEAK_IMPORTS": [], "WEBAUDIO_DEBUG": 0, "WEBGL2_BACKWARDS_COMPATIBILITY_EMULATION": false, "WEBGL_USE_GARBAGE_FREE_APIS": false, "WEBSOCKET_DEBUG": false, "WEBSOCKET_SUBPROTOCOL": "binary", "WEBSOCKET_URL": "ws:#", "WORKAROUND_IOS_9_RIGHT_SHIFT_BUG": 0, "WORKAROUND_OLD_WEBGL_UNIFORM_UPLOAD_IGNORED_OFFSET_BUG": 0 }

If I delete _emscripten_memcpy_js from DEFAULT_LIBRARY_FUNCS_TO_INCLUDE then compiler.mjs succeeds.

Version of emscripten/emsdk:

emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 3.1.68 (ceee49d2ecdab36a3feb85a684f8e5a453dde910)
clang version 20.0.0git (https:/github.com/llvm/llvm-project 5cc64bf60bc04b9315de3c679eb753de4d554a8a)
Target: wasm32-unknown-emscripten
Thread model: posix
sbc100 commented 1 month ago

_emscripten_memcpy_js is just a normal JS library function. I lives here: https://github.com/emscripten-core/emscripten/blob/1dfe990c558b259b8c9561e34de80d351919359c/src/library.js#L409-L439

Does your version of library JS also contains this symbol?

hoodmane commented 1 month ago

Yeah library.js has _emscripten_memcpy_js. I am using stock emscripten 3.1.68 installed with emsdk. The following is a full reproduction:

git clone https://github.com/emscripten-core/emsdk.git
./emsdk/emsdk install 3.1.68
./emsdk/emsdk activate 3.1.68
source ./emsdk/emsdk_env.sh
# install rustup
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y
source $HOME/.cargo/env
rustup target add wasm32-unknown-emscripten
echo "fn main(){}" > a.rs
rustc -Copt-level=z a.rs -o a.js --target=wasm32-unknown-emscripten
hoodmane commented 1 month ago

I've attached the output from --reproduce=repro.tar repro.tar.gz

hoodmane commented 1 month ago

This also happens with -lc -sWASM_BIGINT.