emstrip strips out the `dylink.0` section

[ryanking13]

I am not sure if this is an intentional behavior or not, but reporting for visibility.

I noticed that emstrip recently started to strip out the dylink.0 section from the WASM binary, breaking modules built with -sSIDE_MODULE flag set.

This started to happen since Emscripten 5.0.1, and wasn't the case before 5.0.0

Version of emscripten/emsdk:

emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 5.0.3 (285c424dfa9e83b03cf8490c65ceadb7c45f28eb)
clang version 23.0.0git (https:/github.com/llvm/llvm-project e5927fecf8a6ce89e1a4eac5b828e7d42676452a)

Failing command line in full:

// lib.c
int add(int a, int b) { return a + b; }

emcc -o "lib.wasm" -shared -sSIDE_MODULE=1 lib.c

echo "before:"; llvm-objdump -h "lib.wasm" | grep -i dylink || echo "dylink.0 missing"

cp "lib.wasm" "lib.stripped.wasm"
emstrip "lib.stripped.wasm"

echo "after:"; llvm-objdump -h "lib.stripped.wasm" | grep -i dylink || echo "dylink.0 missing"

[ryanking13]

Looks like this is the related llvm change: llvm/llvm-project#180246

[hoodmane]

Seems like we should make a pr adjusting strip to retain dylink.0

[sbc100]

Yes, that seems reasonable. I guess it should be possible to strip that section, but it probably should never happen by default.