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[SR-7229] Unexpected ambiguity error #49777

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nevil opened this issue Mar 19, 2018 · 7 comments
Closed

[SR-7229] Unexpected ambiguity error #49777

nevil opened this issue Mar 19, 2018 · 7 comments
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@nevil
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bug A deviation from expected or documented behavior. Also: expected but undesirable behavior. compiler The Swift compiler in itself regression swift 4.2 type checker Area → compiler: Semantic analysis

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@nevil
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nevil commented Mar 19, 2018

Previous ID SR-7229
Radar rdar://problem/38641996
Original Reporter @nevil
Type Bug
Status Closed
Resolution Done
Environment

swift-DEVELOPMENT-SNAPSHOT-2018-03-17-a.xctoolchain

iOS SDK from Xcode 9.2:
Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS.sdk

Additional Detail from JIRA
Votes 0
Component/s Compiler
Labels Bug, 4.2Regression, TypeChecker
Assignee @nevil
Priority Medium

md5: 8600a956a0c0a5ab22f49113a8df937b

relates to:

  • SR-7235 "nearly matches optional requirement" warning for correct function signature from protocol UICollectionViewDelegate

Issue Description:

The below code generates an unexpected error:

Error:

bug.swift:22:17: error: ambiguous use of 'convert(_:to:)'
        let p = sender.convert(sender.bounds, to: collectionView)

//

import UIKit

class ACollectionViewDelegate: NSObject, UICollectionViewDelegate {
    var collectionView: UICollectionView! { return UICollectionView() }

    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 0
    }

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        return UICollectionViewCell()
    }

    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
    }
}

final class Reproducer: ACollectionViewDelegate {
    @objc private func buttonAction(_ sender: UIButton) {
        let p = sender.convert(sender.bounds, to: collectionView)
    }
}

Builds fine with Swift from Xcode 9.2 (Apple Swift version 4.0.3 (swiftlang-900.0.74.1 clang-900.0.39.2)) but fails with swift-DEVELOPMENT-SNAPSHOT-2018-03-17-a.xctoolchain.

Full invocation and output:

Apple Swift version 4.2-dev (LLVM cef3fe6d75, Clang bdc970d89c, Swift 931d06d1cc)
Target: arm64-apple-ios10.0
/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2018-03-17-a.xctoolchain/usr/bin/swift -frontend -c -primary-file bug.swift -target arm64-apple-ios10.0 -Xllvm -aarch64-use-tbi -enable-objc-interop -sdk /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS.sdk -color-diagnostics -module-name bug -o bug.o
bug.swift:12:10: warning: instance method 'collectionView(_:cellForItemAt:)' nearly matches optional requirement 'collectionView(_:canFocusItemAt:)' of protocol 'UICollectionViewDelegate'
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
         ^
bug.swift:12:10: note: candidate has non-matching type '(UICollectionView, IndexPath) -> UICollectionViewCell'
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
         ^
bug.swift:12:10: note: move 'collectionView(_:cellForItemAt:)' to an extension to silence this warning
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
         ^
bug.swift:12:10: note: make 'collectionView(_:cellForItemAt:)' private to silence this warning
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
         ^
    private
UIKit.UICollectionViewDelegate:63:26: note: requirement 'collectionView(_:canFocusItemAt:)' declared here
    optional public func collectionView(_ collectionView: UICollectionView, canFocusItemAt indexPath: IndexPath) -> Bool
                         ^
bug.swift:22:17: error: ambiguous use of 'convert(_:to:)'
        let p = sender.convert(sender.bounds, to: collectionView)
                ^
UIKit.UIView:61:15: note: found this candidate
    open func convert(_ rect: CGRect, to coordinateSpace: UICoordinateSpace) -> CGRect
              ^
UIKit.UIView:26:15: note: found this candidate
    open func convert(_ rect: CGRect, to view: UIView?) -> CGRect
              ^
@nevil
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nevil commented Mar 19, 2018

The error goes away if I cast the collectionView property from "UICollectionView!" to a UICollectionView:

+        let p = sender.convert(sender.bounds, to: collectionView as UICollectionView)

or if I remove one of the UICollectionViewDelegate methods from ACollectionViewDelegate.

@belkadan
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cc @rudkx for the convert(_:to:) one and @DougGregor for the "nearly matches" one.

@belkadan
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Actually, can you split out one of these into a separate bug? They're not related.

@nevil
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nevil commented Mar 19, 2018

Thanks @belkadan!

I created SR-7235 for the warning.
It was a lazy "drive-by" comment that I should have created a separate ticket for in the first place...

@belkadan
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Thanks, so this is about the issue with the IUO UICollectionView.

@swift-ci create

@rudkx
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rudkx commented Apr 12, 2018

Resolved by #15881

@nevil
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nevil commented Apr 13, 2018

Confirmed fixed in swift-DEVELOPMENT-SNAPSHOT-2018-04-12-a.xctoolchain

Thanks!

@swift-ci swift-ci transferred this issue from apple/swift-issues Apr 25, 2022
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@nevil nevil

Labels
bug A deviation from expected or documented behavior. Also: expected but undesirable behavior. compiler The Swift compiler in itself regression swift 4.2 type checker Area → compiler: Semantic analysis
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@nevil @rudkx @belkadan @AnthonyLatsis