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[SR-1595] Chained subsequence operations confuse the compiler #44204

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natecook1000 opened this issue May 23, 2016 · 1 comment
Closed

[SR-1595] Chained subsequence operations confuse the compiler #44204

natecook1000 opened this issue May 23, 2016 · 1 comment
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bug A deviation from expected or documented behavior. Also: expected but undesirable behavior. compiler The Swift compiler in itself standard library Area: Standard library umbrella type checker Area → compiler: Semantic analysis

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@natecook1000
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Previous ID SR-1595
Radar None
Original Reporter @natecook1000
Type Bug
Status Resolved
Resolution Duplicate
Additional Detail from JIRA
Votes 0
Component/s Compiler, Standard Library
Labels Bug, TypeChecker
Assignee None
Priority Medium

md5: 1622ec52e01ecd9f6cd4ebb2fe338b4c

duplicates:

  • SR-851 Result of dropFirst differs between 2.1.1 and 2.2

Issue Description:

If I chain collection operations that produce subsequences, the compiler finds ambiguous ways of resolving the methods.

(swift) let x = Array(1...10)
// x : Array<Int> = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
(swift) x.dropFirst(2).prefix(5)
<REPL Input>:1:1: error: ambiguous use of 'dropFirst'
x.dropFirst(2).prefix(5)
^
Swift.Collection:39:17: note: found this candidate
    public func dropFirst(_ n: Int) -> Self.SubSequence
                ^
Swift.Sequence:20:17: note: found this candidate
    public func dropFirst(_ n: Int) -> AnySequence<Self.Iterator.Element>
                ^

If I break the calls up into separate assignments, there's no such trouble.

(swift) let y = x.dropFirst(2)
// y : ArraySlice<Int> = ArraySlice([3, 4, 5, 6, 7, 8, 9, 10])
(swift) y.prefix(5)
// r0 : ArraySlice<Int> = ArraySlice([3, 4, 5, 6, 7])
@moiseev
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Mannequin

moiseev mannequin commented May 24, 2016

Duplicate of https://bugs.swift.org/browse/SR-851

@swift-ci swift-ci transferred this issue from apple/swift-issues Apr 25, 2022
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Labels
bug A deviation from expected or documented behavior. Also: expected but undesirable behavior. compiler The Swift compiler in itself standard library Area: Standard library umbrella type checker Area → compiler: Semantic analysis
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@natecook1000