v0 mangling breaks hot-patching

[fasterthanlime]

Today's nightly (nightly-2025-11-21) has switched to v0 mangling by default, see the announcement.

I like getting in trouble so I switched to it today, and noticed that it breaks hot-patching because the wbindgen workaround you have relies on the the C++ like mangled form.

My proposed fix is to rely on the rustc-demangle crate instead.

I'm working on a PR, I'll submit it as soon as I can.

Also it might be time to poke the wbindgen folks about wasm-bindgen/wasm-bindgen#4494

[fasterthanlime]

There are other v0-related issues in wasm-bindgen, so my fix might not be good enough:

cf. wasm-bindgen/wasm-bindgen#4820
cf. rust-lang/rustc-demangle#86

[fasterthanlime]

see #5006 (comment) — I think the ball is in rustc-demangle's court right now (then wasm-bindgen (then yours)).

[qouteall]

Current workaround: In .cargo/config.toml add

[build]
rustflags = [
    "-Zunstable-options",
    "-Csymbol-mangling-version=legacy",
]