# Trying to build latest swipl repo and getting wasm-ld error undefined symbol: PL\_dlsym **URL:** \ **Category:** General\ **Created:** [October 15, 2024, 9:58pm UTC](https://swi-prolog.discourse.group/t/trying-to-build-latest-swipl-repo-and-getting-wasm-ld-error-undefined-symbol-pl-dlsym/8538 "2024-10-15T21:58:10Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![32bitmicro](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/32bitmicro/32/6832_2.png) [@32bitmicro](https://swi-prolog.discourse.group/u/32bitmicro)\ **Post date:** [October 15, 2024, 9:58pm UTC](https://swi-prolog.discourse.group/t/trying-to-build-latest-swipl-repo-and-getting-wasm-ld-error-undefined-symbol-pl-dlsym/8538/1 "2024-10-15T21:58:10Z")
Hi, I am trying to build swi-prolog from swipl repo for wasm32 but I am getting this error: `wasm-ld: error: src/libswipl.a(pl-alloc.c.o): undefined symbol: PL_dlsym` I am using ubuntu 22.04 and emcc 3.1.69. Any help would be appreciated. ---
**Author:** ![jan](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/jan/32/4_2.png) [@jan](https://swi-prolog.discourse.group/u/jan)\ **Post date:** [October 16, 2024, 8:10am UTC](https://swi-prolog.discourse.group/t/trying-to-build-latest-swipl-repo-and-getting-wasm-ld-error-undefined-symbol-pl-dlsym/8538/2 "2024-10-16T08:10:01Z")
Just upgraded emcc to 3.1.69 and rebuild. Works fine. That is, using the current development git and the following to configure: ```prolog WASM_HOME=$HOME/wasm source $WASM_HOME/emsdk/emsdk_env.sh TOOLCHAIN=$EMSDK/upstream/emscripten/cmake/Modules/Platform/Emscripten.cmake [-f $TOOLCHAIN] || echo "Could not find emscripten toolchain" LDFLAGS="-s STACK_SIZE=1048576" \ cmake -DCMAKE_TOOLCHAIN_FILE=$TOOLCHAIN \ -DCMAKE_BUILD_TYPE=Release \ -DCMAKE_FIND_ROOT_PATH=$HOME/wasm \ -DUSE_GMP=OFF \ -DINSTALL_DOCUMENTATION=OFF \ -G Ninja .. $@ ``` In `$HOME/wasm` are the builds of the dependencies (zlib is needed, pcre2 is there as well, but this is not required for building). ---
**Author:** ![32bitmicro](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/32bitmicro/32/6832_2.png) [@32bitmicro](https://swi-prolog.discourse.group/u/32bitmicro)\ **Post date:** [October 16, 2024, 7:58pm UTC](https://swi-prolog.discourse.group/t/trying-to-build-latest-swipl-repo-and-getting-wasm-ld-error-undefined-symbol-pl-dlsym/8538/3 "2024-10-16T19:58:25Z")
hi Jan, Thank you for your quick reply. I tested build using your configuration and got the same result. Then I have tested with npm-swipl-wasm and it builds OK on my machine. Based on the Dockerfile I have made a build script to replicate build steps from the command line. Well, result is exactly the same as before when building either swipl-devel of swipl see below. Now I am at loss because docker build is also based on ubuntu 22.04. Here is a log from build ```prolog [189/600] Building C object src/CMakeFiles/swiplobjs.dir/pl-rsort.c.o /prolog/build-wasm/swipl-devel/src/pl-rsort.c:110:31: warning: incompatible pointer types passing 'struct sort_r_data *' to parameter of type 'int (*)(const void *, const void *, void *)' [-Wincompatible-pointer-types] 110 | qsort_r(base, nel, width, &tmp, &sort_r_arg_swap); | ^~~~ /home/pawel/sda4/home/pawel/src/Emscripten/emsdk/upstream/emscripten/cache/sysroot/include/stdlib.h:151:45: note: passing argument to parameter here 151 | void qsort_r (void *, size_t, size_t, int (*)(const void *, const void *, void *), void *); | ^ 1 warning generated. [571/600] Linking C executable src/swipl.js FAILED: src/swipl.js : && /home/pawel/sda4/home/pawel/src/Emscripten/emsdk/upstream/emscripten/emcc -O3 -DNDEBUG -s NODERAWFS=1 -s EXIT_RUNTIME=1 -s WASM_BIGINT=1 -s ALLOW_MEMORY_GROWTH=1 -s STACK_SIZE=1048576 -s STACK_OVERFLOW_CHECK=1 src/CMakeFiles/swipl.dir/pl-main.c.o -o src/swipl.js src/libswipl.a -lm -lrt packages/clib/memfile.a packages/clib/files.a packages/clib/uri.a packages/clib/readutil.a packages/clib/prolog_stream.a packages/clib/md54pl.a packages/clib/crypt.a packages/clib/hashstream.a packages/clib/sha4pl.a packages/http/json.a packages/http/http_stream.a packages/semweb/turtle.a packages/semweb/ntriples.a packages/pcre/pcre4pl.a /prolog/build-wasm/wasm/lib/libpcre2-8.a packages/sgml/sgml2pl.a packages/nlp/double_metaphone.a packages/nlp/porter_stem.a packages/nlp/isub.a packages/nlp/snowball.a packages/nlp/libstemmer_c/liblibstemmer.a packages/zlib/zlib4pl.a /prolog/build-wasm/wasm/lib/libz.a && : wasm-ld: error: src/libswipl.a(pl-alloc.c.o): undefined symbol: PL_dlsym wasm-ld: error: src/libswipl.a(pl-alloc.c.o): undefined symbol: PL_dlsym wasm-ld: error: src/libswipl.a(pl-alloc.c.o): undefined symbol: PL_dlsym wasm-ld: error: src/libswipl.a(pl-alloc.c.o): undefined symbol: PL_dlsym wasm-ld: error: src/libswipl.a(pl-alloc.c.o): undefined symbol: PL_dlsym wasm-ld: error: src/libswipl.a(pl-alloc.c.o): undefined symbol: PL_dlsym wasm-ld: error: src/libswipl.a(pl-alloc.c.o): undefined symbol: PL_dlsym wasm-ld: error: src/libswipl.a(pl-alloc.c.o): undefined symbol: PL_dlsym ``` ---
**Author:** ![jan](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/jan/32/4_2.png) [@jan](https://swi-prolog.discourse.group/u/jan)\ **Post date:** [October 16, 2024, 8:34pm UTC](https://swi-prolog.discourse.group/t/trying-to-build-latest-swipl-repo-and-getting-wasm-ld-error-undefined-symbol-pl-dlsym/8538/4 "2024-10-16T20:34:00Z")
I have no clue. Possibly something is wrong with your emsdk installation, possibly something in the environment that breaks the cmake configuration, … Hard to say. ---
**Author:** ![32bitmicro](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/32bitmicro/32/6832_2.png) [@32bitmicro](https://swi-prolog.discourse.group/u/32bitmicro)\ **Post date:** [October 20, 2024, 11:11pm UTC](https://swi-prolog.discourse.group/t/trying-to-build-latest-swipl-repo-and-getting-wasm-ld-error-undefined-symbol-pl-dlsym/8538/5 "2024-10-20T23:11:26Z")
Thank you!