undefined symbol: eglGetProcAddress even with -lEGL flag #14335

kjlubick · 2021-06-01T12:50:38Z

Here's a small repro case of an issue I'm seeing on a WASM build of Skia.

#include <emscripten.h>
#include <emscripten/bind.h>

#include <string>

#include <EGL/egl.h>

using namespace emscripten;

EMSCRIPTEN_BINDINGS(my_module) {

  function("doTheThing", optional_override([](std::string name)-> void {
    auto p = eglGetProcAddress(name.c_str());
    printf("%s - %p\n", name.c_str(), p);
  }), allow_raw_pointers());
}

When I compile with

source $EMSDK/emsdk_env.sh
EMCXX=`which em++`

EMCC_DEBUG=1 ${EMCXX} \
  --bind \
  --no-entry \
  ./bindings.cpp \
  -lEGL -lGL \
  -s STRICT=1 \
  -s WASM=1 \
  -s USE_WEBGL2=1 \
  -o out.js

I see the following output and error:

emcc:WARNING: invocation: /home/user_name/emsdk/upstream/emscripten/em++.py --bind --no-entry ./bindings.cpp -lEGL -lGL -s STRICT=1 -s WASM=1 -s USE_WEBGL2=1 -o out.js  (in /home/user_name/repro-egl)
shared:DEBUG: successfully executed /home/user_name/emsdk/upstream/bin/clang --version
cache:DEBUG: PID 57486 acquiring multiprocess file lock to Emscripten cache at /home/user_name/emsdk/upstream/emscripten/cache
tools.filelock:DEBUG: Attempting to acquire lock 140181672808944 on /home/user_name/emsdk/upstream/emscripten/cache/cache.lock
tools.filelock:DEBUG: Lock 140181672808944 acquired on /home/user_name/emsdk/upstream/emscripten/cache/cache.lock
cache:DEBUG: done
shared:DEBUG: sanity file up-to-date but check forced: /home/user_name/emsdk/upstream/emscripten/cache/sanity.txt
shared:DEBUG: successfully executed /home/user_name/emsdk/node/14.15.5_64bit/bin/node --version
shared:DEBUG: successfully executed /home/user_name/emsdk/upstream/bin/llc --version
shared:INFO: (Emscripten: Running sanity checks)
shared:DEBUG: successfully executed /home/user_name/emsdk/node/14.15.5_64bit/bin/node -e console.log("hello")
profiler:DEBUG: block "sanity compiler_engine" took 0.05 seconds
profiler:DEBUG: block "sanity LLVM" took 0.00 seconds
tools.filelock:DEBUG: Attempting to release lock 140181672808944 on /home/user_name/emsdk/upstream/emscripten/cache/cache.lock
tools.filelock:DEBUG: Lock 140181672808944 released on /home/user_name/emsdk/upstream/emscripten/cache/cache.lock
cache:DEBUG: PID 57486 released multiprocess file lock to Emscripten cache at /home/user_name/emsdk/upstream/emscripten/cache
profiler:DEBUG: block "sanity" took 0.11 seconds
profiler:DEBUG: block "parse arguments and setup" took 0.00 seconds
profiler:DEBUG: block "ensure_sysroot" took 0.00 seconds
emcc:DEBUG: compiling source file: ./bindings.cpp
shared:DEBUG: successfully executed /home/user_name/emsdk/upstream/bin/clang++ -target wasm32-unknown-emscripten -fignore-exceptions -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr -D__EMSCRIPTEN_major__=2 -D__EMSCRIPTEN_minor__=0 -D__EMSCRIPTEN_tiny__=20 -D_LIBCPP_ABI_VERSION=2 -Dunix -D__unix -D__unix__ -Werror=implicit-function-declaration -Xclang -iwithsysroot/include/SDL --sysroot=/home/user_name/emsdk/upstream/emscripten/cache/sysroot -Xclang -iwithsysroot/include/compat ./bindings.cpp -c -o /tmp/emscripten_temp/bindings_0.o
profiler:DEBUG: block "compile inputs" took 0.72 seconds
emcc:DEBUG: looking for library "EGL"
building:DEBUG: Mapping library `EGL` to JS libraries: ['library_egl.js']
emcc:DEBUG: looking for library "GL"
building:DEBUG: Mapping library `GL` to JS libraries: ['library_webgl.js', 'library_html5_webgl.js']
profiler:DEBUG: block "calc linker inputs" took 0.00 seconds
shared:DEBUG: executed /home/user_name/emsdk/upstream/bin/llvm-nm /tmp/emscripten_temp/bindings_0.o
profiler:DEBUG: block "llvm_nm_multiple" took 0.02 seconds
system_libs:DEBUG: adding dependency on free due to deps-info on _embind_register_function
system_libs:DEBUG: adding dependency on malloc due to deps-info on eglGetProcAddress
system_libs:DEBUG: forcing stdlibs: {'libembind'}
system_libs:DEBUG: including libembind (libembind-rtti.a)
system_libs:DEBUG: including libc (libc.a)
system_libs:DEBUG: including libcompiler_rt (libcompiler_rt.a)
system_libs:DEBUG: including libc++ (libc++-noexcept.a)
system_libs:DEBUG: including libc++abi (libc++abi-noexcept.a)
system_libs:DEBUG: including libmalloc (libdlmalloc.a)
system_libs:DEBUG: including libc_rt_wasm (libc_rt_wasm.a)
system_libs:DEBUG: including libsockets (libsockets.a)
profiler:DEBUG: block "calculate system libraries" took 0.02 seconds
emcc:DEBUG: linking: ['/tmp/emscripten_temp/bindings_0.o', '-L/home/user_name/emsdk/upstream/emscripten/cache/sysroot/lib/wasm32-emscripten', '--whole-archive', '/home/user_name/emsdk/upstream/emscripten/cache/sysroot/lib/wasm32-emscripten/libembind-rtti.a', '--no-whole-archive', '/home/user_name/emsdk/upstream/emscripten/cache/sysroot/lib/wasm32-emscripten/libc.a', '/home/user_name/emsdk/upstream/emscripten/cache/sysroot/lib/wasm32-emscripten/libcompiler_rt.a', '/home/user_name/emsdk/upstream/emscripten/cache/sysroot/lib/wasm32-emscripten/libc++-noexcept.a', '/home/user_name/emsdk/upstream/emscripten/cache/sysroot/lib/wasm32-emscripten/libc++abi-noexcept.a', '/home/user_name/emsdk/upstream/emscripten/cache/sysroot/lib/wasm32-emscripten/libdlmalloc.a', '/home/user_name/emsdk/upstream/emscripten/cache/sysroot/lib/wasm32-emscripten/libc_rt_wasm.a', '/home/user_name/emsdk/upstream/emscripten/cache/sysroot/lib/wasm32-emscripten/libsockets.a']
shared:DEBUG: successfully executed /home/user_name/emsdk/upstream/bin/wasm-ld -o out.wasm /tmp/emscripten_temp/bindings_0.o -L/home/user_name/emsdk/upstream/emscripten/cache/sysroot/lib/wasm32-emscripten --whole-archive /home/user_name/emsdk/upstream/emscripten/cache/sysroot/lib/wasm32-emscripten/libembind-rtti.a --no-whole-archive /home/user_name/emsdk/upstream/emscripten/cache/sysroot/lib/wasm32-emscripten/libc.a /home/user_name/emsdk/upstream/emscripten/cache/sysroot/lib/wasm32-emscripten/libcompiler_rt.a /home/user_name/emsdk/upstream/emscripten/cache/sysroot/lib/wasm32-emscripten/libc++-noexcept.a /home/user_name/emsdk/upstream/emscripten/cache/sysroot/lib/wasm32-emscripten/libc++abi-noexcept.a /home/user_name/emsdk/upstream/emscripten/cache/sysroot/lib/wasm32-emscripten/libdlmalloc.a /home/user_name/emsdk/upstream/emscripten/cache/sysroot/lib/wasm32-emscripten/libc_rt_wasm.a /home/user_name/emsdk/upstream/emscripten/cache/sysroot/lib/wasm32-emscripten/libsockets.a --fatal-warnings -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr --allow-undefined --strip-debug --export emscripten_stack_get_end --export emscripten_stack_get_free --export emscripten_stack_init --export stackSave --export stackRestore --export stackAlloc --export __wasm_call_ctors --export fflush --export __errno_location --export malloc --export free --export-table --export-if-defined __start_em_asm --export-if-defined __stop_em_asm -z stack-size=5242880 --initial-memory=16777216 --no-entry --max-memory=16777216 --global-base=1024
profiler:DEBUG: block "link" took 0.03 seconds
emcc:DEBUG: emscript
building:DEBUG: saving debug copy /tmp/emscripten_temp/emcc-0-base.wasm
shared:DEBUG: successfully executed /home/user_name/emsdk/upstream/bin/wasm-opt --version
shared:DEBUG: successfully executed /home/user_name/emsdk/upstream/bin/wasm-emscripten-finalize --minimize-wasm-changes --dyncalls-i64 out.wasm -o out.wasm --detect-features
building:DEBUG: saving debug copy /tmp/emscripten_temp/emcc-1-wasm-emscripten-finalize.wasm
building:DEBUG: saving debug copy /tmp/emscripten_temp/emcc-2-post_finalize.wasm
emscripten:DEBUG: Metadata parsed: {'asmConsts': {},
'declares': ['_embind_register_function',
            'eglGetProcAddress',
            '_embind_register_void',
            '_embind_register_bool',
            '_embind_register_std_string',
            '_embind_register_std_wstring',
            '_embind_register_emval',
            '_embind_register_integer',
            '_embind_register_float',
            '_embind_register_memory_view',
            'abort',
            'fd_write',
            'emscripten_resize_heap',
            'emscripten_memcpy_big',
            'setTempRet0',
            '_embind_register_bigint'],
'emJsFuncs': {},
'exports': ['__wasm_call_ctors',
           '__getTypeName',
           '__embind_register_native_and_builtin_types',
           '__errno_location',
           'malloc',
           'fflush',
           'stackSave',
           'stackRestore',
           'stackAlloc',
           'emscripten_stack_init',
           'emscripten_stack_get_free',
           'emscripten_stack_get_end',
           'free',
           'dynCall_jiji'],
'features': [],
'globalImports': [],
'invokeFuncs': [],
'mainReadsParams': 0,
'namedGlobals': {},
'staticBump': 0,
'tableSize': 28}
emscripten:DEBUG: very limited syscalls (fd_write) so disabling full filesystem support
emscripten:DEBUG: emscript: js compiler glue
error: undefined symbol: eglGetProcAddress (referenced by top-level compiled C/C++ code)
warning: Link with `-s LLD_REPORT_UNDEFINED` to get more information on undefined symbols
warning: To disable errors for undefined symbols use `-s ERROR_ON_UNDEFINED_SYMBOLS=0`
warning: _eglGetProcAddress may need to be added to EXPORTED_FUNCTIONS if it arrives from a system library
Error: Aborting compilation due to previous errors
em++: error: '/home/user_name/emsdk/node/14.15.5_64bit/bin/node /home/user_name/emsdk/upstream/emscripten/src/compiler.js /tmp/emscripten_temp/tmpvp_okyyt.txt' failed (1)
profiler:DEBUG: block "emscript" took 0.28 seconds
profiler:DEBUG: block "post_link" took 0.28 seconds
not cleaning up temp files since in debug-save mode, see them in /tmp/emscripten_temp
not cleaning up temp files since in debug-save mode, see them in /tmp/emscripten_temp
tools.filelock:DEBUG: Attempting to release lock 140181672812496 on /tmp/emscripten_temp/emscripten.lock
tools.filelock:DEBUG: Lock 140181672812496 released on /tmp/emscripten_temp/emscripten.lock

This had previously been working in emsdk 2.0.10 and I noticed it when updating to 2.0.20

Interesting note from the logs: system_libs:DEBUG: adding dependency on malloc due to deps-info on eglGetProcAddress. I don't see any addition of system/lib/gl/libprocaddr.c which now has the implementation after #13524 right?

The text was updated successfully, but these errors were encountered:

kjlubick · 2021-06-01T12:58:07Z

The issue persists even after running emcc --clear-cache

sbc100 · 2021-06-01T15:53:33Z

Smaller test case:

$ cat test.cc 
#include <EGL/egl.h>

int main() {
    return (int)eglGetProcAddress("foo");
}
$ em++ test.cc -lEGL -lGL -s STRICT=1 
error: undefined symbol: eglGetProcAddress (referenced by top-level compiled C/C++ code)

Problem goes away without -s STRICT.. so is somehow related to strict mode.

sbc100 · 2021-06-01T15:58:05Z

strict mode defaults a bunch of settings and the one that causes this issue is -s AUTO_NATIVE_LIBRARIES=0. This is because our GL library is called libgl.a (lowercase) so, while we work on a fix there are two workarounds you can try:

Add -s AUTO_NATIVE_LIBRARIES (which will prevent strict mode from turning it off)
Add -lgl (as opposed to -lGL) to pick up our actual gl library

This also happens to fix an old bug (#10171) where we would look on the file system for `libGL.a` before looking in `map_to_js_libs`. Fixes: #10171 Fixes: #14335

sbc100 · 2021-06-01T18:06:56Z

Fix is in #14337. Workarounds above should help until that change rolls into a release.

When calling `map_to_js_libs('GL')` we were mapping this to the JS libraries, and not also including the native `libgl` library. Normally this doesn't matter since `libgl` is normally included by default but not when `AUTO_NATIVE_LIBRARIES=0` is used. This also happens to fix an old bug (#10171) where we would look on the file system for `libGL.a` before looking in `map_to_js_libs`. Fixes: #10171 Fixes: #14335

When calling `map_to_js_libs('GL')` we were mapping this to the JS libraries, and not also including the native `libgl` library. Normally this doesn't matter since `libgl` is included by default, but not when `AUTO_NATIVE_LIBRARIES=0` is used. This also happens to fix an old bug (#10171) where we would look on the file system for `libGL.a` before looking in `map_to_js_libs`. Fixes: #10171 Fixes: #14335

emscripten-core/emscripten#14335

sbc100 added a commit that referenced this issue Jun 1, 2021

Fix for -lGL + AUTO_NATIVE_LIBRARIES=0

dcb5a80

This also happens to fix an old bug (#10171) where we would look on the file system for `libGL.a` before looking in `map_to_js_libs`. Fixes: #10171 Fixes: #14335

sbc100 mentioned this issue Jun 1, 2021

Fix for -lGL + AUTO_NATIVE_LIBRARIES=0 #14337

Merged

sbc100 closed this as completed in #14337 Jun 7, 2021

Usnul added a commit to Usnul/xatlas-web that referenced this issue May 8, 2025

Following recommendation to resolve compile issue

98f1d28

emscripten-core/emscripten#14335

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undefined symbol: eglGetProcAddress even with -lEGL flag #14335

undefined symbol: eglGetProcAddress even with -lEGL flag #14335

kjlubick commented Jun 1, 2021

kjlubick commented Jun 1, 2021

sbc100 commented Jun 1, 2021

sbc100 commented Jun 1, 2021

sbc100 commented Jun 1, 2021

undefined symbol: eglGetProcAddress even with -lEGL flag #14335

undefined symbol: eglGetProcAddress even with -lEGL flag #14335

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kjlubick commented Jun 1, 2021

kjlubick commented Jun 1, 2021

sbc100 commented Jun 1, 2021

sbc100 commented Jun 1, 2021

sbc100 commented Jun 1, 2021