Inline Typer.isMonoContext

retronym · retronym · commit 99a8ba24c5cd · 2017-04-29T10:15:03.000+10:00
Contrary to the comment, it wasn't capturing the the context var
at typer initialization, which would not have been correct anyway.

The inlining here is motivated by avoiding allocation of lambda in
every Typer. Even when we're using this value in eta expansion,
SilentResult.filter will actually be inlined to avoid the need for a
lambda at all.
diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -316,10 +316,6 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
       _checkDead
     }
 
-    // for use with silent type checking to when we can't have results with undetermined type params
-    // note that this captures the context var
-    val isMonoContext = (_: Any) => context.undetparams.isEmpty
-
     def dropExistential(tp: Type): Type = tp match {
       case ExistentialType(tparams, tpe) =>
         new SubstWildcardMap(tparams).apply(tp)
@@ -3034,7 +3030,11 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
               // We're looking for a method (as indicated by FUNmode in the silent typed below),
               // so let's make sure our expected type is a MethodType
               val methArgs = NoSymbol.newSyntheticValueParams(argpts map { case NoType => WildcardType case tp => tp })
-              silent(_.typed(meth, mode.forFunMode, MethodType(methArgs, respt))) filter (isMonoContext) map { methTyped =>
+
+              val result = silent(_.typed(meth, mode.forFunMode, MethodType(methArgs, respt)))
+              // we can't have results with undetermined type params
+              val resultMono = result filter (_ => context.undetparams.isEmpty)
+              resultMono map { methTyped =>
                 // if context.undetparams is not empty, the method was polymorphic,
                 // so we need the missing arguments to infer its type. See #871
                 val funPt = normalize(methTyped.tpe) baseType FunctionClass(numVparams)
