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Emscripten dynamic linking and libc #98155

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hoodmane opened this issue Jun 16, 2022 · 2 comments
Closed

Emscripten dynamic linking and libc #98155

hoodmane opened this issue Jun 16, 2022 · 2 comments
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A-linkage Area: linking into static, shared libraries and binaries C-bug Category: This is a bug. O-emscripten Target: 50% off wasm32-unknown-musl. the savings come out of stdio.h, but hey, you get SDL! O-wasm Target: WASM (WebAssembly), http://webassembly.org/ T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.

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@hoodmane
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When dynamically linking Emscripten modules, Rust passes -lc to Emscripten. This causes wasm-ld: error: unable to find library -lc-debug. I see that -lc is coming via EmLinker.link_dylib. If I make link_dylib into a no-op this fixes the problem, though maybe that has other bad side effects. I am not sure how to filter out libraries that shouldn't be statically linked into a dynamic library. But it would be great to fix this. I am currently using an emcc linker wrapper that deletes the -lc argument.

@sbc100
xref emscripten-core/emscripten#17191
@hoodmane
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For a reproduction:

touch lib.rs
rustc lib.rs -C link-arg=-sSIDE_MODULE=2 --target wasm32-unknown-emscripten --crate-type cdylib

using tip of tree emcc and nightly rust.

@hoodmane hoodmane mentioned this issue Jun 20, 2022
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@jyn514 jyn514 added A-linkage Area: linking into static, shared libraries and binaries T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. O-wasm Target: WASM (WebAssembly), http://webassembly.org/ C-bug Category: This is a bug. labels Apr 10, 2023
@workingjubilee workingjubilee added the O-emscripten Target: 50% off wasm32-unknown-musl. the savings come out of stdio.h, but hey, you get SDL! label Oct 11, 2024
@hoodmane
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Closed because the Emscripten issue that causes this problem seems to have been resolved.

hoodmane added a commit to hoodmane/libc that referenced this issue Nov 1, 2024
@hoodmane
Don't pass -lc to Emscripten, it breaks
66e3665 
See:
emscripten-core/emscripten#22742
emscripten-core/emscripten#16680
rust-lang/rust#98155
rust-lang/rust#98303
rust-lang/rust#131885
@hoodmane hoodmane mentioned this issue Nov 1, 2024
Merged
tgross35 pushed a commit to tgross35/rust-libc that referenced this issue Nov 6, 2024
@hoodmane @tgross35
Don't pass -lc to Emscripten, it breaks
31d430b 
See:
emscripten-core/emscripten#22742
emscripten-core/emscripten#16680
rust-lang/rust#98155
rust-lang/rust#98303
rust-lang/rust#131885

(backport <rust-lang#4002>)
(cherry picked from commit 66e3665)
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A-linkage Area: linking into static, shared libraries and binaries C-bug Category: This is a bug. O-emscripten Target: 50% off wasm32-unknown-musl. the savings come out of stdio.h, but hey, you get SDL! O-wasm Target: WASM (WebAssembly), http://webassembly.org/ T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.
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Emscripten: Drop -lc the emcc driver will add it when it is needed hoodmane/rust
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@hoodmane @jyn514 @workingjubilee