OtaK / uniffi-custom-bug

UniFFI Bug Repro

Bug

UniFFI tends to create duplicate declarations for custom types that use the new bytes UDL type AND appear in function parameters.

In example for kotlin the types that are emitted are both ByteArray (correct) and List<UByte> (incorrect) - same goes for Swift's Data / [UInt8], Python's bytes / typing.List[int].)

This leads me to think that the issue is not in the bindings generation but above that, probably in type disambiguation.

Steps to repro

$ cargo build --release
$ cargo run --features uniffi/cli --bin uniffi-bindgen -- generate --language kotlin --out-dir ./bindings/kt --library target/release/libuniffi_custom_bug.so
$ cargo run --features uniffi/cli --bin uniffi-bindgen -- generate --language python --out-dir ./bindings/python --library target/release/libuniffi_custom_bug.so
$ cargo run --features uniffi/cli --bin uniffi-bindgen -- generate --language swift --out-dir ./bindings/swift --library target/release/libuniffi_custom_bug.so

Then check the bindings folder for faulty types declarations (search for CustomType).

Examples of double declarations

Kotlin

// ./bindings/kit/uniffi/UniffiCustomBug/UniffiCustomBug.kt:477

/**
 * Typealias from the type name used in the UDL file to the builtin type.  This
 * is needed because the UDL type name is used in function/method signatures.
 * It's also what we have an external type that references a custom type.
 */
public typealias CustomType = ByteArray
public typealias FfiConverterTypeCustomType = FfiConverterByteArray

/**
 * Typealias from the type name used in the UDL file to the builtin type.  This
 * is needed because the UDL type name is used in function/method signatures.
 * It's also what we have an external type that references a custom type.
 */
public typealias CustomType = List<UByte>
public typealias FfiConverterTypeCustomType = FfiConverterSequenceUByte

Swift

// ./bindings/swift/UniffiCustomBug.swift:349


/**
 * Typealias from the type name used in the UDL file to the builtin type.  This
 * is needed because the UDL type name is used in function/method signatures.
 */
public typealias CustomType = Data
public struct FfiConverterTypeCustomType: FfiConverter {
    public static func read(from buf: inout (data: Data, offset: Data.Index)) throws -> CustomType {
        return try FfiConverterData.read(from: &buf)
    }

    public static func write(_ value: CustomType, into buf: inout [UInt8]) {
        return FfiConverterData.write(value, into: &buf)
    }

    public static func lift(_ value: RustBuffer) throws -> CustomType {
        return try FfiConverterData.lift(value)
    }

    public static func lower(_ value: CustomType) -> RustBuffer {
        return FfiConverterData.lower(value)
    }
}


/**
 * Typealias from the type name used in the UDL file to the builtin type.  This
 * is needed because the UDL type name is used in function/method signatures.
 */
public typealias CustomType = [UInt8]
public struct FfiConverterTypeCustomType: FfiConverter {
    public static func read(from buf: inout (data: Data, offset: Data.Index)) throws -> CustomType {
        return try FfiConverterSequenceUInt8.read(from: &buf)
    }

    public static func write(_ value: CustomType, into buf: inout [UInt8]) {
        return FfiConverterSequenceUInt8.write(value, into: &buf)
    }

    public static func lift(_ value: RustBuffer) throws -> CustomType {
        return try FfiConverterSequenceUInt8.lift(value)
    }

    public static func lower(_ value: CustomType) -> RustBuffer {
        return FfiConverterSequenceUInt8.lower(value)
    }
}

Python

# ./bindings/python/UniffiCustomBug.py:621


# Type alias
CustomType = bytes

class FfiConverterTypeCustomType:
    @staticmethod
    def write(value, buf):
        FfiConverterBytes.write(value, buf)

    @staticmethod
    def read(buf):
        return FfiConverterBytes.read(buf)

    @staticmethod
    def lift(value):
        return FfiConverterBytes.lift(value)

    @staticmethod
    def lower(value):
        return FfiConverterBytes.lower(value)


# Type alias
CustomType = typing.List[int]

class FfiConverterTypeCustomType:
    @staticmethod
    def write(value, buf):
        FfiConverterSequenceUInt8.write(value, buf)

    @staticmethod
    def read(buf):
        return FfiConverterSequenceUInt8.read(buf)

    @staticmethod
    def lift(value):
        return FfiConverterSequenceUInt8.lift(value)

    @staticmethod
    def lower(value):
        return FfiConverterSequenceUInt8.lower(value)