Stream: rust-toolchain

Topic: rust 1.91.0 cross-crate symbol import bugs

view this post on Zulip Alex Crichton (Nov 01 2025 at 23:02):

Wanted to give a heads up if anyone sees unusual behavior for wasm binaries compiled with Rust 1.91. Paul opened https://github.com/rust-lang/rust/issues/148347 which is a link-error which isn't so bad but yowl also saw issues in wit-bindgen at #wit-bindgen > PR help please which looks like the same issue. The affected behavior can range from linker errors to unusual runtime behavior so mostly just wanted to give a heads up to try to head off any weird debugging sessions hopefully.

I think this should be fixed in https://github.com/rust-lang/rust/pull/148363 and I'll ask for a beta-backport on that, but I suspect a stable backport may be unlikely so affected crates may want to pin to 1.90 for now

Wasm Linker "module mismatch for symbol" Regression in 1.91.0 · Issue #148347 · rust-lang/rust
Additional notes and repro cases: https://github.com/posborne/rustc-1.91.0-wasm-linkage-bug-repro With the Rust 1.91.0 stable update, it appears that a regression has been introduced which causes l...
Fix `wasm_import_module` attribute cross-crate by alexcrichton · Pull Request #148363 · rust-lang/rust
This commit fixes an accidental regression from #144678 where wasm targets would now accidentally use the wrong import module map for a symbol causing a symbol to skip mangling. This can result in ...

Last updated: Dec 06 2025 at 05:03 UTC