WASI cdylib output

[nhynes]

Currently wasm32-wasi does not support the cdylib output type, which is unfortunate because this means that only Rust programs can consume programs that target wasi (through the rlib output).

As a motivating example, consider a database wrapper Wasm module. One might want to write it safely in Rust and use it from another Wasm module loaded at runtime. The database wrapper would want to use WASI syscalls to access the database process. This is not yet possible because Rust WASI modules cannot be made into cdylibs.

It looks like all that would need to be done to support this feature is to not link crt1 when compiling to cdylib. This would amount to creating a target that looks like wasm32-unknown-unknown except with wasi sys.

[mikevoronov]

Also stumbled with such problem, are there any news?

[jonas-schievink]

Why is this not possible? Is there some design work that needs to be done before it can be implemented, or why is this an RFCs issue?

[nhynes]

It was moved from rust-lang/rust#61243 as it wasn't clear what the procedure for this kind of change is. The implementation should be straightforward, though.