Cannot build cdylib for wasm32-unknown-emscripten

[dalcde]

Create an empty file test.rs and run

rustc -C link-args='-s SIDE_MODULE' --target wasm32-unknown-emscripten --crate-type cdylib test.rs

It gives the error

error: linking with `emcc` failed: exit code: 1
  |
  = note: "emcc" "-s" "DISABLE_EXCEPTION_CATCHING=0" "-L" "/home/$USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-emscripten/lib" "-L" "/home/$USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-emscripten/lib/self-contained" "test.test.3a1fbbbh-cgu.0.rcgu.o" "-o" "test.wasm" "-s" "EXPORTED_FUNCTIONS=[\"_rust_eh_personality\"]" "test.2h4nzeicjcod1ad3.rcgu.o" "-O0" "--memory-init-file" "0" "-g0" "-s" "DEFAULT_LIBRARY_FUNCS_TO_INCLUDE=[]" "-L" "/home/$USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-emscripten/lib" "/home/$USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-emscripten/lib/libstd-d69e7237ec2ec907.rlib" "/home/$USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-emscripten/lib/libpanic_unwind-cf6146279e321a86.rlib" "/home/$USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-emscripten/lib/librustc_demangle-30de99a0feadb118.rlib" "/home/$USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-emscripten/lib/libhashbrown-744fdda8cec61518.rlib" "/home/$USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-emscripten/lib/librustc_std_workspace_alloc-1bd061abaa6299ee.rlib" "/home/$USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-emscripten/lib/libunwind-790ede63273b678e.rlib" "/home/$USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-emscripten/lib/libcfg_if-33e32972cf91da62.rlib" "/home/$USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-emscripten/lib/liblibc-455b1f1bdddd2493.rlib" "/home/$USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-emscripten/lib/liballoc-38821dae73c49cdd.rlib" "/home/$USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-emscripten/lib/librustc_std_workspace_core-f752c0f2f8e113a2.rlib" "/home/$USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-emscripten/lib/libcore-79c24dc82f9ff182.rlib" "/home/$USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-emscripten/lib/libcompiler_builtins-da221c4cef139dc0.rlib" "-l" "c" "-s" "SIDE_MODULE" "-s" "ERROR_ON_UNDEFINED_SYMBOLS=1" "-s" "ASSERTIONS=1" "-s" "ABORTING_MALLOC=0" "-Wl,--fatal-warnings"
  = note: wasm-ld: error: unknown file type: lib.rmeta
          emcc: error: '/opt/emscripten-llvm/bin/wasm-ld -o test.wasm --whole-archive -L/home/$USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-emscripten/lib -L/home/$USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-emscripten/lib/self-contained test.test.3a1fbbbh-cgu.0.rcgu.o -L/usr/lib/emscripten/system/local/lib -L/usr/lib/emscripten/system/lib test.2h4nzeicjcod1ad3.rcgu.o -L/home/$USER/.emscripten_cache/wasm-pic -L/home/$USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-emscripten/lib /home/$USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-emscripten/lib/libstd-d69e7237ec2ec907.rlib /home/$USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-emscripten/lib/libpanic_unwind-cf6146279e321a86.rlib /home/$USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-emscripten/lib/librustc_demangle-30de99a0feadb118.rlib /home/$USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-emscripten/lib/libhashbrown-744fdda8cec61518.rlib /home/$USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-emscripten/lib/librustc_std_workspace_alloc-1bd061abaa6299ee.rlib /home/$USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-emscripten/lib/libunwind-790ede63273b678e.rlib /home/$USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-emscripten/lib/libcfg_if-33e32972cf91da62.rlib /home/$USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-emscripten/lib/liblibc-455b1f1bdddd2493.rlib /home/$USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-emscripten/lib/liballoc-38821dae73c49cdd.rlib /home/$USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-emscripten/lib/librustc_std_workspace_core-f752c0f2f8e113a2.rlib /home/$USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-emscripten/lib/libcore-79c24dc82f9ff182.rlib /home/$USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-emscripten/lib/libcompiler_builtins-da221c4cef139dc0.rlib /home/$USER/.emscripten_cache/wasm-pic/libc.a --fatal-warnings --no-whole-archive -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-cxx-exceptions -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr --allow-undefined --import-memory --strip-debug --no-gc-sections --export-dynamic --export-all --experimental-pic -shared' failed (1)

[hoodmane]

As an update, the solution to this is to use -sSIDE_MODULE=2. If you also want everything to be exported, you could try -sSIDE_MODULE=2 -sEXPORT_ALL.