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[SR-2493] Escaping and Type-aliases don't work together #45098

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swift-ci opened this issue Aug 26, 2016 · 2 comments
Closed

[SR-2493] Escaping and Type-aliases don't work together #45098

swift-ci opened this issue Aug 26, 2016 · 2 comments
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@swift-ci
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@swift-ci swift-ci commented Aug 26, 2016

Previous ID SR-2493
Radar None
Original Reporter chriseidhof (JIRA User)
Type Bug
Status Resolved
Resolution Duplicate
Additional Detail from JIRA
Votes 0
Component/s
Labels Bug
Assignee None
Priority Medium

md5: de270f0eb69ba2760e8b414045a431b4

duplicates:

Issue Description:

I created a typealias for a sort descriptor:

typealias SortDescriptor<A> = (A, A) -> Bool

Now, when I try to create function that takes a sort descriptor and inverts it, the parameter should be marked as escaping, however, the compiler doesn't detect that, and worse, disallows it:

func invert<A>(_ x: SortDescriptor<A>) -> SortDescriptor<A> {
return { l, r in !x(l, r)
}

If I define the same function without the typealias, all is well:

// Exact same function, but now it needs to be marked as escaping... (which is correct)
func invert2<A>(_ x: @escaping (A,A) -> Bool) -> (A,A) -> Bool {
return { l, r in !x(l, r)
}

I can, however, call the first function just fine:

let gte: SortDescriptor<Int> = invert(<)

@swift-ci
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@swift-ci swift-ci commented Aug 26, 2016

Comment by Chris Eidhof (JIRA)

Sorry about the messed up code samples, I have no clue how to convince JIRA to display it preformatted... The triple braces somehow disappear

@swift-ci
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@swift-ci swift-ci commented Aug 26, 2016

Comment by Chris Eidhof (JIRA)

Btw, the generics are not the issue here, it's the same when you have a non-generic typealias, e.g. (Int,Int) -> Bool.

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