Fix it-never-happened performance regression.

Diligent reviewer observed that a hot spot was possibly
being made hotter. Reviewer's suggested remedy was a
spectacular bust, but studious observation revealed the news
lash that expensive methods are expensive and we should
avoid calling them if we can.

Put short-circuit test back in front of unapply call.
Now the time spent in unapply is within a few percent.

1 files changed, 4 insertions, 3 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
index 29d4c8423b..5b11adf127 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
@@ -573,15 +573,16 @@ trait Implicits {
       )
 
       def fail(reason: String): SearchResult = failure(itree, reason)
+      def fallback = typed1(itree, EXPRmode, wildPt)
       try {
-        val itree1 = pt match {
-          case Function1(arg1, arg2) if isView =>
+        val itree1 = if (!isView) fallback else pt match {
+          case Function1(arg1, arg2) =>
             typed1(
               atPos(itree.pos)(Apply(itree, List(Ident("<argument>") setType approximate(arg1)))),
               EXPRmode,
               approximate(arg2)
             )
-          case _ => typed1(itree, EXPRmode, wildPt)
+          case _ => fallback
         }
         if (context.hasErrors) {
           log("implicit adapt failed: " + context.errBuffer.head.errMsg)