Description
Hello! I am trying to call Swift from Rust, but having a heck of a time getting anything but the most trivial example to work.
In all of the examples below, I have edited src/main.rs and swift-library/Sources/swift-library/swift_library.swift in the rust-binary-calls-swift-package example.
If I try to return an option, like so:
#[swift_bridge::bridge]
mod ffi {
extern "Swift" {
fn opt() -> Option<usize>;
}
}func opt() -> Optional<UInt> {
Optional.none
}I get the following error:
/Users/paho/git/swift-bridge/examples/rust-binary-calls-swift-package/swift-library/Sources/swift-library/generated/rust-calls-swift/rust-calls-swift.swift:3:31: error: cannot convert return expression of type '__private__OptionUsize' to return type 'UInt'
as well as some warnings about dangling pointers. Looking at the generated code, the generated function is returning a plain UInt:
@_cdecl("__swift_bridge__$opt")
func __swift_bridge__opt () -> UInt {
{ let val = opt(); return __private__OptionUsize(val: val ?? 123, is_some: val != nil); }()
}
If I try to pass a String from Rust to Swift:
#[swift_bridge::bridge]
mod ffi {
extern "Swift" {
fn string(str: String);
}
}func string(str: RustString) {}Then I get dangling pointer warnings still, and this error:
/Users/paho/git/swift-bridge/examples/rust-binary-calls-swift-package/swift-library/Sources/swift-library/generated/rust-calls-swift/rust-calls-swift.swift:2:37: error: cannot find type 'GenericIntoRustString' in scope
func __swift_bridge__string (_ str: GenericIntoRustString) {
^~~~~~~~~~~~~~~~~~~~~
Finally, if I try to pass in a Vec (replace String with Vec<usize> and RustString with RustVec<UInt> in the previous example), I get this error:
/Users/paho/git/swift-bridge/examples/rust-binary-calls-swift-package/swift-library/Sources/swift-library/generated/rust-calls-swift/rust-calls-swift.swift:3:30: error: cannot convert value of type 'RustVec<UInt>' to expected argument type 'UnsafeMutableRawPointer'
vector(vec: RustVec(ptr: vec)) ^
I must be doing something simple wrong, but I can't for the life of me figure out what it is, and I would appreciate any help.