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[SR-2657] error: '(f: () -> ())' is not convertible to '(f: () -> ())' #45262

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lilyball mannequin opened this issue Sep 15, 2016 · 6 comments
Closed

[SR-2657] error: '(f: () -> ())' is not convertible to '(f: () -> ())' #45262

lilyball mannequin opened this issue Sep 15, 2016 · 6 comments
Labels
bug A deviation from expected or documented behavior. Also: expected but undesirable behavior. compiler The Swift compiler in itself diagnostics QoI Bug: Diagnostics Quality of Implementation type checker Area → compiler: Semantic analysis

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@lilyball
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Mannequin

lilyball mannequin commented Sep 15, 2016

Previous ID SR-2657
Radar None
Original Reporter @lilyball
Type Bug
Status Resolved
Resolution Done
Environment

Apple Swift version 3.0 (swiftlang-800.0.46.2 clang-800.0.38)

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

md5: 7a65e12153c1ff4a9c591acc187417a4

relates to:

  • SR-4014 Can't Call Overloaded Method Within Another Overloaded Method

Issue Description:

The following code produces a bad error:

private class Block<T> {
    let f: T
    init(f: T) { self.f = f }
}

func foo(block: () -> ()) {
    let b = Block<()->()>(f: block)
}

The error it produces is

unnamed.swift:7:26: error: '(f: () -> ())' is not convertible to '(f: () -> ())'
    let b = Block<()->()>(f: block)
                         ^~~~~~~~~~

If I change the code to say Block<()->()>.init(f: block) I get a much better error:

unnamed.swift:7:35: error: passing non-escaping parameter 'block' to function expecting an @escaping closure
    let b = Block<()->()>.init(f: block)
                                  ^

The original code should be producing this error as well.
@lilyball
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Mannequin Author

lilyball mannequin commented Sep 15, 2016

Similarly if I say

func foo(block: () -> ()) {
    let b: Block<()->()> = Block(f: block)
}

I get another unhelpful error:

unnamed.swift:7:28: error: cannot convert value of type 'Block<() -> ()>' to specified type 'Block<() -> ()>'
    let b: Block<()->()> = Block(f: block)
                           ^~~~~~~~~~~~~~~

@belkadan
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cc @milseman

@milseman
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Mannequin

milseman mannequin commented Sep 23, 2016

This is a distinct problem, and not fixed by #4905

@CodaFi
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CodaFi commented Jan 1, 2017

I have a partial solution that tackles the meat of this SR, but diagnosing the invalid type ascription is going to be gnarly and involve special-casing our escaping diagnostics to look into bound generic types.

@milseman
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milseman mannequin commented Jun 12, 2017

It's unlikely that I'll be able to address this any time soon. @rudkx, are you or Pavel able to hold onto this? Alternatively, CodaFi (JIRA User)?

@slavapestov
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4.2 and master:

e.swift:7:30: error: passing non-escaping parameter 'block' to function expecting an @escaping closure
    let b = Block<()->()>(f: block)
                             ^
e.swift:6:10: note: parameter 'block' is implicitly non-escaping
func foo(block: () -> ()) {
         ^
                @escaping

@swift-ci swift-ci transferred this issue from apple/swift-issues Apr 25, 2022
This issue was closed.
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Labels
bug A deviation from expected or documented behavior. Also: expected but undesirable behavior. compiler The Swift compiler in itself diagnostics QoI Bug: Diagnostics Quality of Implementation type checker Area → compiler: Semantic analysis
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@slavapestov @belkadan @CodaFi