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[SR-7884] Overload resolution picks optional variant even when value is not optional #50419

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slavapestov opened this issue Jun 5, 2018 · 7 comments
Closed

[SR-7884] Overload resolution picks optional variant even when value is not optional #50419

slavapestov opened this issue Jun 5, 2018 · 7 comments
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@slavapestov
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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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@slavapestov
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Previous ID SR-7884
Radar rdar://problem/40819547
Original Reporter @slavapestov
Type Bug
Status Resolved
Resolution Done
Additional Detail from JIRA
Votes 0
Component/s Compiler
Labels Bug, 4.2Regression, TypeChecker
Assignee @slavapestov
Priority Medium

md5: 039128c33d520a4d60fb1f4f65a98c4e

is duplicated by:

  • SR-7964 Overloading a method with an optional parameter chooses wrong overload
  • SR-7899 [4.2 regression] type checker chooses different type than it used to

Issue Description:

I'm not sure if this is intended behavior or not:

func f<T>(x: T) {
  print("not optional")
}

func f<T>(x: T?) {
  print("optional")
}


let x: String = "hi"

f(x: x) // calls optional variant

In Swift 4.1, we used to pick the non optional variant.

Reported by amseddi (JIRA User) in WWDC labs
@slavapestov
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@rudkx Any ideas?

@slavapestov
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@swift-ci create

@rudkx
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rudkx commented Jun 6, 2018

This was broken by #14499. I'm looking at fixing it.

@xedin
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xedin commented Jun 7, 2018

@rudkx I think we need to remove that optimization because it's unsound, and we can't make these local choices until we have full solutions.

@rudkx
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rudkx commented Jun 7, 2018

My plan is to back it out for now. I don't know if there is any safe way to do this since we are not actually taking into account the scoring that would happen due to optional injection, function conversion, etc.

I am collecting test cases to add to the test suite.

@xedin
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xedin commented Jun 7, 2018

Yes, I agree, that's what I meant exactly...

@rudkx
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rudkx commented Jun 8, 2018

This is merged to master: 7601d50

and swift-4.2-branch: 02150f1

@swift-ci swift-ci transferred this issue from apple/swift-issues Apr 25, 2022
This issue was closed.
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@slavapestov slavapestov

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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@xedin @slavapestov @rudkx @AnthonyLatsis