Small cleanups to pattern matcher

While investigating https://github.com/scala/scala-dev/issues/251

2 files changed, 19 insertions, 15 deletions

diff --git a/src/compiler/scala/tools/nsc/transform/patmat/MatchOptimization.scala b/src/compiler/scala/tools/nsc/transform/patmat/MatchOptimization.scala
index cca8d2dbb8..f827043094 100644
--- a/src/compiler/scala/tools/nsc/transform/patmat/MatchOptimization.scala
+++ b/src/compiler/scala/tools/nsc/transform/patmat/MatchOptimization.scala
@@ -116,8 +116,8 @@ trait MatchOptimization extends MatchTreeMaking with MatchAnalysis {
               case _ =>
             }
 
-            debug.patmat("sharedPrefix: "+ sharedPrefix)
-            debug.patmat("suffix: "+ sharedPrefix)
+            debug.patmat(s"sharedPrefix: $sharedPrefix")
+            debug.patmat(s"suffix: $suffix")
             // if the shared prefix contains interesting conditions (!= True)
             // and the last of such interesting shared conditions reuses another treemaker's test
             // replace the whole sharedPrefix by a ReusingCondTreeMaker
diff --git a/src/compiler/scala/tools/nsc/transform/patmat/MatchTranslation.scala b/src/compiler/scala/tools/nsc/transform/patmat/MatchTranslation.scala
index a2afb76b0e..bf3bc6b26e 100644
--- a/src/compiler/scala/tools/nsc/transform/patmat/MatchTranslation.scala
+++ b/src/compiler/scala/tools/nsc/transform/patmat/MatchTranslation.scala
@@ -110,25 +110,29 @@ trait MatchTranslation {
 
       // example check: List[Int] <:< ::[Int]
       private def extractorStep(): TranslationStep = {
-        def paramType = extractor.aligner.wholeType
         import extractor.treeMaker
-        // chain a type-testing extractor before the actual extractor call
-        // it tests the type, checks the outer pointer and casts to the expected type
-        // TODO: the outer check is mandated by the spec for case classes, but we do it for user-defined unapplies as well [SPEC]
-        // (the prefix of the argument passed to the unapply must equal the prefix of the type of the binder)
-        lazy val typeTest = TypeTestTreeMaker(binder, binder, paramType, paramType)(pos, extractorArgTypeTest = true)
-        // check whether typetest implies binder is not null,
-        // even though the eventual null check will be on typeTest.nextBinder
-        // it'll be equal to binder casted to paramType anyway (and the type test is on binder)
-        def extraction: TreeMaker = treeMaker(typeTest.nextBinder, typeTest impliesBinderNonNull binder, pos)
 
         // paramType = the type expected by the unapply
         // TODO: paramType may contain unbound type params (run/t2800, run/t3530)
-        val makers = (
+        val makers = {
+          val paramType = extractor.aligner.wholeType
           // Statically conforms to paramType
           if (this ensureConformsTo paramType) treeMaker(binder, false, pos) :: Nil
-          else typeTest :: extraction :: Nil
-        )
+          else {
+            // chain a type-testing extractor before the actual extractor call
+            // it tests the type, checks the outer pointer and casts to the expected type
+            // TODO: the outer check is mandated by the spec for case classes, but we do it for user-defined unapplies as well [SPEC]
+            // (the prefix of the argument passed to the unapply must equal the prefix of the type of the binder)
+            val typeTest = TypeTestTreeMaker(binder, binder, paramType, paramType)(pos, extractorArgTypeTest = true)
+            val binderKnownNonNull = typeTest impliesBinderNonNull binder
+
+            // check whether typetest implies binder is not null,
+            // even though the eventual null check will be on typeTest.nextBinder
+            // it'll be equal to binder casted to paramType anyway (and the type test is on binder)
+            typeTest :: treeMaker(typeTest.nextBinder, binderKnownNonNull, pos) :: Nil
+          }
+        }
+
         step(makers: _*)(extractor.subBoundTrees: _*)
       }