Cannot use function name "encrypt"

[SaritNike]

If I take the example hello.wit from the README and just change the name of the function from hello to encrypt and do the same in app.py, I get a linker error:

thread '' (19152) panicked at C:\Users\runneradmin.cargo\git\checkouts\wasm-tools-83155cefafadb9f3\e2bb0a2\crates\wit-component\src\linking.rs:237:9: one or more duplicate items detected when collecting into set or map

app.py:

import wit_world

class WitWorld(wit_world.WitWorld):
    def encrypt(self) -> str:
        return "Hello, World!"

hello.wit:

package example:hello;
world hello {
  export encrypt: func() -> string;
}

When I change the function name to anything else (e.g. xencrypt) it works. When I write the guest-code directly in Rust, there is no issue with the function name encrypt. Is it a reserved keyword?

[dicej]

Hi @SaritNike; thanks for reporting this.

My first guess is that it's conflicting with the POSIX function of the same name, causing a conflict with the encrypt function exported by libc.so. I'll take a closer look to see if that's the case and, if so, what can be done.

[dicej]

Yeah, looks like this is due to a name conflict with libc.so. You'd get the same result if you named your function e.g. sin, cos, isupper, etc.

componentize-py (and also other bindings generators like the ones in wit-bindgen) use a mangling scheme to name component model exports so they can be recognized by wit-component. Unfortunately, top level function names aren't mangled at all in that scheme, which makes conflicts likely when linking with other .so files. There's a new scheme being proposed which will mangle those names and thereby avoid conflicts, but work on that has stalled somewhat (e.g. it doesn't support any concurrency features) so it's not ready for general use yet.

In the meantime, I'd recommend either moving your exported function into a WIT interface (which will force the exported symbol names to be <interface name>#<function name>) or choose a name that doesn't clash with libc.so's exports.

[SaritNike]

@dicej thank you for your quick help! I guess this issue can be closed.