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Added Hashable conformance to Async(Throwing)Stream.Continuation #79457

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Merged
merged 3 commits into from
Apr 16, 2025
Merged

Added Hashable conformance to Async(Throwing)Stream.Continuation #79457

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1b2e031
Added Hashable conformance to Async(Throwing)Stream.Continuation
nickolas-pohilets Feb 18, 2025
d8cbaeb
Added explicit availability attribute for each protocol requirement
nickolas-pohilets Apr 13, 2025
90cac69
Use concrete SwiftStdlib version
nickolas-pohilets Apr 14, 2025
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Added explicit availability attribute for each protocol requirement 
To fix failing test/api-digester/stability-concurrency-abi.test
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@nickolas-pohilets
nickolas-pohilets committed Apr 13, 2025
commit d8cbaebbd48cc0327f44dd8c6126750768437a3b
6 changes: 6 additions & 0 deletions stdlib/public/Concurrency/AsyncStream.swift
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Expand Up @@ -477,9 +477,15 @@ extension AsyncStream.Continuation.YieldResult: Sendable where Element: Sendable

@available(SwiftStdlib 9999, *)
extension AsyncStream.Continuation: Hashable {
@available(SwiftStdlib 9999, *)
public func hash(into hasher: inout Hasher) {
return hasher.combine(ObjectIdentifier(storage))
}
@available(SwiftStdlib 9999, *)
public var hashValue: Int {
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Why that, isn't the hash function enough?

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@nickolas-pohilets nickolas-pohilets Apr 14, 2025 •
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Apparently no. If omitted it gets synthesised as expected, but then test complains that it does not have availability annotations. I'm not sure if this is expected or a bug in code gen of the Hashable conformance.

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Is this expected @lorentey ?

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This definitely is a bug! Conformances with availability are a relatively recent development, and evidently we have not yet tried to combine them with synthesized requirements. The expected behavior is that the synthesized requirement would match the availability of the conformance itself.

It feels like this might be a good candidate for a starter task in compiler development.

(The hashValue as implemented matches the synthesized one; when the compiler issue is resolved, then it can simply be deleted to have it be replaced with the implicit default.)

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Oh hang on -- can you tell me what test is failing?

The compiler itself seems fine with it; this compiles with no diagnostic:

@available(macOS 11, *)
public struct Foo {
  public var value: Int
}
@available(macOS 12, *)
extension Foo: Hashable {
  @available(macOS 12, *)
  public func hash(into hasher: inout Hasher) {
    hasher.combine(value)
  }
}

The generated .swiftinterface indeed doesn't set availability directly on the synthesized members (== and hashValue), but they still inherit that from the extension's own context:

import Swift
import _Concurrency
import _StringProcessing
import _SwiftConcurrencyShims
@available(macOS 11, *)
public struct Foo {
  public var value: Swift.Int
}
@available(macOS 12, *)
extension foo.Foo : Swift.Hashable {
  @available(macOS 12, *)
  public func hash(into hasher: inout Swift.Hasher)
  public static func == (a: foo.Foo, b: foo.Foo) -> Swift.Bool
  public var hashValue: Swift.Int {
    get
  }
}

This sounds like it might actually be due to an overzealous test that attempts to analyze the interface. (If my diagnosis is correct, then the choice is between seeing if the test can be adjusted, or changing the compiler to generate the extra @available attributes anyway.)

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The failing test was test/api-digester/stability-concurrency-abi.test

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I see, that makes sense.

return _hashValue(for: self)
}
@available(SwiftStdlib 9999, *)
public static func == (lhs: Self, rhs: Self) -> Bool {
return lhs.storage === rhs.storage
}
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6 changes: 6 additions & 0 deletions stdlib/public/Concurrency/AsyncThrowingStream.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -523,9 +523,15 @@ extension AsyncThrowingStream.Continuation.YieldResult: Sendable where Element:

@available(SwiftStdlib 9999, *)
extension AsyncThrowingStream.Continuation: Hashable {
@available(SwiftStdlib 9999, *)
public func hash(into hasher: inout Hasher) {
return hasher.combine(ObjectIdentifier(storage))
}
@available(SwiftStdlib 9999, *)
public var hashValue: Int {
return _hashValue(for: self)
}
@available(SwiftStdlib 9999, *)
public static func == (lhs: Self, rhs: Self) -> Bool {
return lhs.storage === rhs.storage
}
Expand Down