TyperState crash: search for extension method in implicit scope #18687
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m8nmueller
added
itype:bug
itype:crash
stat:needs triage
|
replacing the argument to resume results in another strange error: trait SuspendSupport:
type Suspension[-T, +R]
extension [T, R](s: Suspension[T, R])
def resume(arg: T): R
def suspend[T, R](body: Suspension[T, R] => R): T
trait Async(using val support: SuspendSupport)
private class YZ(using ac: Async):
private def test =
Some(()).getOrElse:
ac.support.suspend[scala.util.Try[Unit], Unit](k =>
k.resume(??? : scala.util.Failure[Nothing])
)-- [E007] Type Mismatch Error: test.scala:17:8 ---------------------------------
17 | k.resume(??? : scala.util.Failure[Nothing])
| ^
|Found: (k : YZ.this.ac.support.Suspension[util.Try[Unit], Unit])
|Required: ?{ resume: ? }
|Note that implicit extension methods cannot be applied because they are ambiguous;
|both YZ.this.ac.support and YZ.this.ac.support provide an extension method `resume` on (k : YZ.this.ac.support.Suspension[util.Try[Unit], Unit])
|
| longer explanation available when compiling with `-explain`
1 error found |
|
importing the extension explicitly avoids the crash, as there is no longer "implicit extension method" search: trait SuspendSupport:
type Suspension[-T, +R]
extension [T, R](s: Suspension[T, R])
def resume(arg: T): R
def suspend[T, R](body: Suspension[T, R] => R): T
trait Async(using val support: SuspendSupport)
private class YZ(using ac: Async):
import ac.support.resume
private def test =
Some(()).getOrElse:
ac.support.suspend[scala.util.Try[Unit], Unit](k =>
k.resume(scala.util.Failure(Exception()))
) |
bishabosha
added
area:extension-methods
and removed
stat:needs triage
bishabosha
changed the title
bishabosha
added
the
regression
|
This is also a regression from error to crash between 3.0.2 and 3.1.0 (fixing the usage of fewer braces) - however as it was always an error I think perhaps this isn't as serious as standard regression |
bishabosha
removed
the
regression
Note that this error (instead of the crash) can also be produced by unwrapping this code block outside of getOrElse. |
|
Likely duplicate of #16326 but will keep both open while I dig deeper. |
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Compiler version
3.3.1
Minimized code
Output (click arrow to expand)
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