Skip to content

Commit

Permalink
Backport "Bring back ambiguity filter when we report an implicit not …
Browse files Browse the repository at this point in the history
…found error" to LTS (#21103)

Backports #20368 to the LTS branch.

PR submitted by the release tooling.
[skip ci]
  • Loading branch information
WojciechMazur authored Jul 6, 2024
2 parents f3bc211 + 1ee9297 commit 6ff12a3
Show file tree
Hide file tree
Showing 2 changed files with 36 additions and 1 deletion.
9 changes: 8 additions & 1 deletion compiler/src/dotty/tools/dotc/typer/Typer.scala
Original file line number Diff line number Diff line change
Expand Up @@ -3810,7 +3810,14 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
* `SearchFailureType`.
*/
def issueErrors(fun: Tree, args: List[Tree]): Tree =
def firstFailure = args.tpes.find(_.isInstanceOf[SearchFailureType]).getOrElse(NoType)
// Prefer other errors over ambiguities. If nested in outer searches a missing
// implicit can be healed by simply dropping this alternative and trying something
// else. But an ambiguity is sticky and propagates outwards. If we have both
// a missing implicit on one argument and an ambiguity on another the whole
// branch should be classified as a missing implicit.
val firstNonAmbiguous = args.tpes.find(tp => tp.isError && !tp.isInstanceOf[AmbiguousImplicits])
def firstError = args.tpes.find(_.isInstanceOf[SearchFailureType]).getOrElse(NoType)
def firstFailure = firstNonAmbiguous.getOrElse(firstError)
val errorType =
firstFailure match
case tp: AmbiguousImplicits =>
Expand Down
28 changes: 28 additions & 0 deletions tests/pos/i20344.scala
Original file line number Diff line number Diff line change
@@ -0,0 +1,28 @@
trait Monad[F[_]] extends Invariant[F]

trait Invariant[F[_]]
object Invariant:
implicit def catsInstancesForList: Monad[List] = ???
implicit def catsInstancesForVector: Monad[Vector] = ???

trait Shrink[T]
object Shrink extends ShrinkLowPriorityImplicits:
trait Buildable[T,C]
implicit def shrinkContainer[C[_],T](implicit v: C[T] => Traversable[T], s: Shrink[T], b: Buildable[T,C[T]]): Shrink[C[T]] = ???
trait ShrinkLowPriorityImplicits:
implicit def shrinkAny[T]: Shrink[T] = ???

trait Distribution[F[_], -P, X] extends (P => F[X])
type GenBeta[A, B, X] = [F[_]] =>> Distribution[F, Beta.Params[A, B], X]
type Beta[R] = [F[_]] =>> GenBeta[R, R, R][F]

object Beta:
trait Params[+A, +B]
trait BetaInstances:
given schrodingerRandomBetaForDouble[F[_]: Monad]: Beta[Double][F] = ???

object all extends BetaInstances

@main def Test =
import all.given
summon[Shrink[Beta.Params[Double, Double]]]

0 comments on commit 6ff12a3

Please sign in to comment.