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[SR-11507] Type inference breaks using flatMap in ternary operator #53908

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swift-ci opened this issue Sep 23, 2019 · 1 comment
Open

[SR-11507] Type inference breaks using flatMap in ternary operator #53908

swift-ci opened this issue Sep 23, 2019 · 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 type checker Area → compiler: Semantic analysis

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@swift-ci
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Previous ID SR-11507
Radar None
Original Reporter eimantas (JIRA User)
Type Bug
Environment

macOS 10.14.6
Xcode 11.0

Additional Detail from JIRA
Votes 0
Component/s Compiler
Labels Bug, TypeChecker
Assignee None
Priority Medium

md5: ce3bf80ddd36708fbf03ea71d8edf9af

Issue Description:

Using following code I would expect to get identical output from print statements. However it differs:

let maybeDouble: CGFloat? = 5.0

let trueFlag = true

let flatDouble = maybeDouble.flatMap({ $0 }) ?? 0

let d = trueFlag ? flatDouble ?? 0 : 0
let e = trueFlag ? (maybeDouble.flatMap({ $0 }) ?? 0) : 0

print(d) // prints "5.0"
print(e) // prints "Optional(5.0)"

Being explicit helps too:

let f: CGFloat = trueFlag ? (maybeDouble.flatMap({ $0 }) ?? 0) : 0
print(f) // prints "5.0"
@belkadan
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@xedin, I think we have an older dup of this?

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