Trying to build latest swipl repo and getting wasm-ld error undefined symbol: PL_dlsym

General
1

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.

2

Just upgraded emcc to 3.1.69 and rebuild. Works fine. That is, using the current development git and the following to configure:

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).

3

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

[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
4

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.

5

Thank you!