Duplicate symbols when compiling for wasm with emscripten

[almahmoud]

I did this

Trying to compile curl from source for WASM via emscripten, with the final goal of compiling RCurl R package for WebR. This can be reproduced in the ghcr.io/r-wasm/webr:main container, which provides emscripten configured for wasm compilation. Concretely within the container (i.e. docker run --rm -it ghcr.io/r-wasm/webr:main bash)

cd /root
git clone https://github.com/curl/curl 
apt update
apt install -y vim autoconf automake libtool
cd /root/curl
autoreconf -i
mkdir -p /manual/curl
emconfigure ./configure --prefix=/manual/curl --without-ssl
emmake make V=1

The above creates the libcurl.so file, but errors out with a bunch of duplicate symbols

wasm-ld: error: duplicate symbol: curlx_ultous
>>> defined in ../lib/warnless.o
>>> defined in ../lib/.libs/libcurl.so

wasm-ld: error: duplicate symbol: curlx_strtoofft
>>> defined in ../lib/strtoofft.o
>>> defined in ../lib/.libs/libcurl.so

A gist with the full emmake V=1 log can be found in this gist

Fwiw, I do not have much experience with emscripten, or compilation in general, so I apologize in advance if I am doing something obviously wrong

I expected the following

Success

curl/libcurl version

master branch source, and 8.6.0

operating system

Linux aefe9808b6b4 5.15.0-89-generic #99-Ubuntu SMP Mon Oct 30 20:42:41 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux

[dfandrich]

The logs show a link that's pulling in both libcurl.so and some of the object files that are already contained in libcurl.so, like base64.o and nonblock.o. I don't know why emscripten is doing that, but I suspect it's trying to outsmart autoconf somehow. You could try adding --disable-shared or --disable-symbol-hiding to see if changes its behaviour. You might want to look at the WASIX build at https://curl.se/download.html as they're compiling curl against wasm already.

[bagder]

This sounds like a not-curl problem. We don't provide those build scripts - the ones we do provide don't have this problem...

[almahmoud]

Thank you for the input, and sorry for the noise. I'll close it as I agree it's only tangentially related to the repository, and I'll come back with a solution to the closed issue if I find one, in case it can help anyone else searching in the future.

[notsilverhoft]

Hey guys, lil late to the party, but credit to @dfandrich I was able to get it to work with
emconfigure ./configure --without-ssl --prefix=/workspaces/WasmFlash/curl/build --disable-shared --disable-symbol-hiding

I am aware that some of this makes no sense, as the file paths are my own, and the whole SSL thing, but the --disable-shared and --disable-symbol-hiding flags worked when combined.