diff options
| -rw-r--r-- | src/compiler/scala/tools/nsc/typechecker/Implicits.scala | 42 | ||||
| -rw-r--r-- | test/pending/pos/t8460.scala | 25 |
2 files changed, 49 insertions, 18 deletions
diff --git a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala index 1a38fcf3a4..a777f483e5 100644 --- a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala +++ b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala @@ -833,19 +833,26 @@ trait Implicits { * so that if there is a best candidate it can still be selected. */ object DivergentImplicitRecovery { - // symbol of the implicit that caused the divergence. - // Initially null, will be saved on first diverging expansion. - private var implicitSym: Symbol = _ - private var countdown: Int = 1 - - def sym: Symbol = implicitSym - def apply(search: SearchResult, i: ImplicitInfo): SearchResult = - if (search.isDivergent && countdown > 0) { - countdown -= 1 - implicitSym = i.sym - log(s"discarding divergent implicit $implicitSym during implicit search") + private var divergentError: Option[DivergentImplicitTypeError] = None + + private def saveDivergent(err: DivergentImplicitTypeError) { + if (divergentError.isEmpty) divergentError = Some(err) + } + + def issueSavedDivergentError() { + divergentError foreach (err => context.issue(err)) + } + + def apply(search: SearchResult, i: ImplicitInfo, errors: Seq[AbsTypeError]): SearchResult = { + if (search.isDivergent && divergentError.isEmpty) { + // Divergence triggered by `i` at this level of the implicit serach. We haven't + // seen divergence so far, we won't issue this error just yet, and instead temporarily + // treat `i` as a failed candidate. + saveDivergent(DivergentImplicitTypeError(tree, pt, i.sym)) + log(s"discarding divergent implicit ${i.sym} during implicit search") SearchFailure } else search + } } /** Sorted list of eligible implicits. @@ -871,7 +878,9 @@ trait Implicits { @tailrec private def rankImplicits(pending: Infos, acc: Infos): Infos = pending match { case Nil => acc case i :: is => - DivergentImplicitRecovery(typedImplicit(i, ptChecked = true, isLocalToCallsite), i) match { + val typedImplicitResult = typedImplicit(i, ptChecked = true, isLocalToCallsite) + val recoveredResult = DivergentImplicitRecovery(typedImplicitResult, i, context.errors) + recoveredResult match { case sr if sr.isDivergent => Nil case sr if sr.isFailure => @@ -921,12 +930,9 @@ trait Implicits { } if (best.isFailure) { - /* If there is no winner, and we witnessed and caught divergence, - * now we can throw it for the error message. - */ - if (DivergentImplicitRecovery.sym != null) { - DivergingImplicitExpansionError(tree, pt, DivergentImplicitRecovery.sym)(context) - } + // If there is no winner, and we witnessed and recorded a divergence error, + // our recovery attempt has failed, so we must now issue it. + DivergentImplicitRecovery.issueSavedDivergentError() if (invalidImplicits.nonEmpty) setAddendum(pos, () => diff --git a/test/pending/pos/t8460.scala b/test/pending/pos/t8460.scala new file mode 100644 index 0000000000..10d2ed432c --- /dev/null +++ b/test/pending/pos/t8460.scala @@ -0,0 +1,25 @@ +object tan extends UFunc { + implicit def ImplDouble: Impl[Double, Double] = ??? +} + +trait UFunc { + trait TC[+A] + type Impl[V, VR] = UFunc.UImpl[this.type, V, VR] +} + +object UFunc { + class UImpl[A, B, C] + implicit def implicitDoubleUTag[Tag, V, VR](implicit conv: V=>Double, impl: UImpl[Tag, Double, VR]):UImpl[Tag, V, VR] = ??? + +} + +object Test { + implicitly[tan.Impl[Double, Double]] + // we should discard the one and only divergent implicit (`implicitDoubleUTag`) + // This is done under `scalac-hash v2.10.4 test.scala`, but not under + // `scalac-hash v2.10.4 -Xdivergence211 test.scala` + // + // This seems to be because the companion implicits contain redundant entries + // + +} |