SI-8894 dealias when looking at tuple components

Classic bait-and-switch: `isTupleType` dealiases, but `typeArgs` does not.
When deciding with `isTupleType`, process using `tupleComponents`.
Similar for other combos. We should really enforce this using extractors,
and only decouple when performance is actually impacted.

2 files changed, 2 insertions, 2 deletions

diff --git a/src/compiler/scala/tools/nsc/transform/patmat/MatchAnalysis.scala b/src/compiler/scala/tools/nsc/transform/patmat/MatchAnalysis.scala
index a8852a3ff3..21e90b1d78 100644
--- a/src/compiler/scala/tools/nsc/transform/patmat/MatchAnalysis.scala
+++ b/src/compiler/scala/tools/nsc/transform/patmat/MatchAnalysis.scala
@@ -172,7 +172,6 @@ trait TreeAndTypeAnalysis extends Debugging {
     // a type is "uncheckable" (for exhaustivity) if we don't statically know its subtypes (i.e., it's unsealed)
     // we consider tuple types with at least one component of a checkable type as a checkable type
     def uncheckableType(tp: Type): Boolean = {
-      def tupleComponents(tp: Type) = tp.normalize.typeArgs
       val checkable = (
            (isTupleType(tp) && tupleComponents(tp).exists(tp => !uncheckableType(tp)))
         || enumerateSubtypes(tp).nonEmpty)
diff --git a/src/reflect/scala/reflect/internal/Definitions.scala b/src/reflect/scala/reflect/internal/Definitions.scala
index 57a17693ad..70375d974c 100644
--- a/src/reflect/scala/reflect/internal/Definitions.scala
+++ b/src/reflect/scala/reflect/internal/Definitions.scala
@@ -653,6 +653,7 @@ trait Definitions extends api.StandardDefinitions {
     // tends to change the course of events by forcing types.
     def isFunctionType(tp: Type)       = isFunctionTypeDirect(tp.dealiasWiden)
     def isTupleType(tp: Type)          = isTupleTypeDirect(tp.dealiasWiden)
+    def tupleComponents(tp: Type)      = tp.dealiasWiden.typeArgs
 
     lazy val ProductRootClass: ClassSymbol = requiredClass[scala.Product]
       def Product_productArity          = getMemberMethod(ProductRootClass, nme.productArity)
@@ -837,7 +838,7 @@ trait Definitions extends api.StandardDefinitions {
     def typeOfMemberNamedApply(tp: Type) = typeArgOfBaseTypeOr(tp, SeqClass)(resultOfMatchingMethod(tp, nme.apply)(IntTpe))
     def typeOfMemberNamedDrop(tp: Type)  = typeArgOfBaseTypeOr(tp, SeqClass)(resultOfMatchingMethod(tp, nme.drop)(IntTpe))
     def typesOfSelectors(tp: Type)       =
-      if (isTupleType(tp)) tp.typeArgs
+      if (isTupleType(tp)) tupleComponents(tp)
       else getterMemberTypes(tp, productSelectors(tp))
 
     // SI-8128 Still using the type argument of the base type at Seq/Option if this is an old-style (2.10 compatible)