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Description
Description
AsyncIteratorProtocol has inconsistence behavior with protocol witness table. which cause Runtime crash.
Sometime EXC_BAD_ACCESS
Reproduction
declare own AsyncIteratorProtocol
public protocol TypedAsyncIteratorProtocol<Element, Failure> {
associatedtype Element
associatedtype Failure: Error
@inlinable
mutating func next(isolation actor: isolated (any Actor)?) async throws(Failure) -> Element?
}
public protocol TypedAsyncSequence<Element, Failure> {
associatedtype Element where AsyncIterator.Element == Element
associatedtype Failure:Error where Failure == AsyncIterator.Failure
associatedtype AsyncIterator:TypedAsyncIteratorProtocol
func makeAsyncIterator() -> AsyncIterator
}
// this do cause runtime crash
func boom<T:AsyncSequence>(base:T) async throws where T.AsyncIterator:TypedAsyncIteratorProtocol{
var iter = base.makeAsyncIterator()
while let value = try await iter.next(isolation: nil) {
}
}
// this does not cause runtime crash
func noBoom<T:AsyncSequence&TypedAsyncSequence>(base:T) async where T.AsyncIterator:TypedAsyncIteratorProtocol{
var iter = base.makeAsyncIterator()
do {
while let value = try await iter.next(isolation: nil) {
}
} catch {
}
}
extension AsyncStream.Iterator: TypedAsyncIteratorProtocol {
@_implements(TypedAsyncIteratorProtocol, next(isolation:))
mutating public func tetraNext(isolation actor: isolated (any Actor)?) async throws(Never) -> Self.Element? {
return await next()
}
}
extension AsyncStream: TypedAsyncSequence {
}
func test() async throws {
// no crash and do compile
try await noBoom(base: AsyncStream<Int>{
$0.yield(0)
$0.finish()
})
// runtime crash and do compile
try await boom(base: AsyncStream<Int>{
$0.yield(0)
$0.finish()
})
}Stack dump
#0 0x00000001adde4c40 in swift_getAssociatedTypeWitness ()
#1 0x000000010373620c in boom<τ_0_0>(base:) ()
#2 0x00000001037357b4 in TetraTests.testExample() at /Users/bagbyeong-gwan/IDE/XcodeWorkSpace/Tetra/Tests/TetraTests/TetraTests.swift:34
#10 0x0000000103706364 in partial apply for specialized thunk for @escaping @isolated(any) @callee_guaranteed @Sendable @async () -> (@out τ_0_0) ()
Expected behavior
Not crash in runtime and should run normally.
Environment
Xcode 16.0 beta swift 6
Additional information
No response