Not sound to use lifetimes in function signatures

[attente]

Seems like wasm-bindgen prohibits the use of lifetime specifiers in certain places where the compiler requires them. I have a test repo here: https://github.com/attente/wasm-bindgen-lifetime-issue

Building it, the error is:

[nix-shell:~/wasm-bindgen-lifetime-issue]$ cargo build --release --target=wasm32-unknown-unknown
   Compiling wasm-bindgen-lifetime-issue v0.1.0 (/home/william/wasm-bindgen-lifetime-issue)
error: it is currently not sound to use lifetimes in function signatures
  --> src/lib.rs:10:31
   |
10 |     pub fn f() -> Result<(), &'static str> {
   |                               ^^^^^^^

error: aborting due to previous error

error: Could not compile `wasm-bindgen-lifetime-issue`.

To learn more, run the command again with --verbose.

Unfortunately if I remove the 'static lifetime specifier, then the compiler will complain:

[nix-shell:~/wasm-bindgen-lifetime-issue]$ cargo build --release --target=wasm32-unknown-unknown
   Compiling wasm-bindgen-lifetime-issue v0.1.0 (/home/william/wasm-bindgen-lifetime-issue)
error[E0106]: missing lifetime specifier
  --> src/lib.rs:10:30
   |
10 |     pub fn f() -> Result<(), &str> {
   |                              ^ help: consider giving it a 'static lifetime: `&'static`
   |
   = help: this function's return type contains a borrowed value, but there is no value for it to be borrowed from

error: aborting due to previous error

For more information about this error, try `rustc --explain E0106`.
error: Could not compile `wasm-bindgen-lifetime-issue`.

To learn more, run the command again with --verbose.

Is there any workaround for this issue?

[alexcrichton]

Thanks for the report! This is one I don't think we've given a ton of thought to just yet, but I suspect that with some work we could get 'static working as it doesn't run into the same issues as an arbitrary 'a. Would a String work for you use case for now though?

[attente]

Thanks for the feedback! What I ended up doing instead is changing my Error type from &'static str to i32, with numeric error codes. I'm sure it must be non-trivial to add lifetime support to wasm-bindgen.

[takkuumi]

@attente i am agree this. when i learn rust, the rust-book tell me how important about the lifetime. so i learned the lifetime . but when i use rust to write a WebAssembly program, wasm-bindgen tell me i cant do this. Am i wrong? 😭

[anymost]

The same issue I encountered. I suspect that wasm-bindgen do not support static lifetime yet either.

[anymost]

So, I want to know When this bug will be fixed. Thanks a lot.

[oHaiyang]

same probleme here, I'm passing a js cloure to wasm, the complier tells me to add 'static lifetime parameter to the rust function signature, but wasm-bindgen forbids it.