Duplicate imports

[maximebedard]

Hi! I have a setup where I'm embedding quickjs (with wasi support) and pre-initializing as such:

#[export_name = "wizer.initialize"]
pub extern "C" fn init() {
    let bytes = std::fs::read("./foo.js");
    unsafe {
        Ctx::new().compile(&bytes, "foo.js");
        // ...
    }
}

Turns out I'm having duplicate imports when introspecting the WASM module:

$ wasm2wat out.wasm | grep 'fd_write' | head -n 2
  (import "wasi_snapshot_preview1" "fd_write" (func $_ZN4wasi13lib_generated22wasi_snapshot_preview18fd_write17h33e34a8685c72169E (type 30)))
  (import "wasi_snapshot_preview1" "fd_write" (func $__wasi_fd_write (type 30)))

This seems to be tripping the following assertion https://github.com/bytecodealliance/wizer/blob/main/src/parse.rs#L268.

I'd be happy to open a PR, I'm just unsure what the expectation is in such case. Any idea?

[fitzgen]

Duplicate imports are disallowed by module linking. I'd expect that the module would be rejected before making it that far. So that's a little funny. The root issue here is that your module has duplicate imports, though. That will eventually be fixed in https://bugs.llvm.org/show_bug.cgi?id=50938. In the meantime, you can run wasm-opt -O to deduplicate the imports.

[maximebedard]

Amazing, thanks for the link and the tip, I'll try it out with wasm-opt -0. I seemed to have had success when compiling in release mode (which effectively skips this assertion).