Generic type parameter pack combining operation crash #78191
Labels
bug
A deviation from expected or documented behavior. Also: expected but undesirable behavior.
compiler
The Swift compiler itself
crash
Bug: A crash, i.e., an abnormal termination of software
generic constraints
Feature → generics: generic constraints
generics
Feature: generic declarations and types
IRGen
LLVM IR generation
parameter packs
Feature → generics: Parameter packs
swift 6.0
tuples
Feature: tuples
types
Feature: types
Comments
stephencelis
added
bug
|
This reduction displays that you simply cannot refer to another parameter pack in an instance method: extension S {
func ƒ<each A, each B>(
_ b: S<(repeat each B)>
) where T == (repeat each A) {
_ = b.t // compiler crash
}
}Fortunately, you can still have the equivalently-functional API, as this is not a problem with static methods. @Test func chain() {
let boxes = (
Box(1, "2"),
Box(3.0, "4", 5)
)
#expect(
Box.chain(boxes.0, boxes.1).value == (1, "2", 3, "4", 5)
)
}
@Test func zip() {
let boxes = (
Box(0, "1"),
Box("0", 1)
)
let value = Box.zip(boxes.0, boxes.1).value
#expect(value.0 == (0, "0"))
#expect(value.1 == ("1", 1))
}public extension Box {
init<each Element>(_ element: repeat each Element)
where Value == (repeat each Element) {
self.value = (repeat each element)
}
static func chain<each Element0, each Element1>(
_ box0: Box<(repeat each Element0)>,
_ box1: Box<(repeat each Element1)>
) -> Self
where Value == (repeat each Element0, repeat each Element1) {
.init(
value: MyLibrary.chain((repeat each box0.value), (repeat each box1.value))
)
}
static func zip<each Element0, each Element1>(
_ box0: Box<(repeat each Element0)>,
_ box1: Box<(repeat each Element1)>
) -> Self
where Value == (repeat (each Element0, each Element1)) {
.init(
value: MyLibrary.zip((repeat each box0.value), (repeat each box1.value))
)
}
}// You can't extend tuples so these are global in whatever module "MyLibrary" actually is.
// E.g. https://github.com/Catterwaul/Tuplay
/// Concatenate 2 tuples into one.
@inlinable public func chain<
each Element0,
each Element1
>(
_ element0: (repeat each Element0),
_ element1: (repeat each Element1)
) -> (
repeat each Element0,
repeat each Element1
) {
( repeat each element0,
repeat each element1
)
}
/// A tuple of pairs built out of two underlying tuples.
///
/// - Note: Unlike `zip` for sequences, these two tuples are required to have the same count.
@_documentation(visibility: private) // DocC can't cope with this signature.
@inlinable public func zip<each Element0, each Element1>(
_ element0: (repeat each Element0),
_ element1: (repeat each Element1)
) -> (repeat (each Element0, each Element1)) {
(repeat (each element0, each element1))
}I saw your post here. You can copy my information there if you want but I won't ever go back there. |
|
@JessyCatterwaul Thanks for sharing a potential workaround! Hopefully the underlying bug will be fixed soon. |
AnthonyLatsis
added
generics
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Description
I tried to extend a generic type with a parameter pack combining operation, but the compiler crashes.
Reproduction
Stack dump
Expected behavior
I expect the code to compile and not crash.
Environment
swift-driver version: 1.115.1 Apple Swift version 6.0.3 (swiftlang-6.0.3.1.10 clang-1600.0.30.1)
Target: arm64-apple-macosx15.0
Additional information
No response
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