print infix

Index: src/compiler/scala/tools/nsc/typechecker/TypeDiagnostics.scala
===================================================================
--- src/compiler/scala/tools/nsc/typechecker/TypeDiagnostics.scala      (revision 22206)
+++ src/compiler/scala/tools/nsc/typechecker/TypeDiagnostics.scala      (working copy)
@@ -218,6 +218,8 @@
               modifyName(x)("scala." + _)
             else if (x.isTypeParameterOrSkolem)
               explainName(x)
+            else if (x.nameString.forall(!_.isLetterOrDigit) && !isAlreadyAltered(x)) // symbol-only names are normally printed without prefixes
+              modifyName(x)(_ => " " + x.fullName)
           }
         }
       }
Index: src/compiler/scala/tools/nsc/symtab/Types.scala
===================================================================
--- src/compiler/scala/tools/nsc/symtab/Types.scala     (revision 22206)
+++ src/compiler/scala/tools/nsc/symtab/Types.scala     (working copy)
@@ -1826,6 +1826,8 @@
           return normalize.typeArgs.init.mkString("(", ", ", ")") + " => " + normalize.typeArgs.last
         if (isTupleType(this))
           return normalize.typeArgs.mkString("(", ", ", if (normalize.typeArgs.length == 1) ",)" else ")")
+        if (normalize.typeArgs.length == 2 && (sym.nameString.forall(c => !c.isLetterOrDigit) || sym.nameString.startsWith(" ") ))
+          return normalize.typeArgs.mkString("(", " " + sym.nameString.trim + " ", ")")
         if (sym.isAliasType && (prefixChain exists (_.termSymbol hasFlag SYNTHETIC))) {
           val normed = normalize;
           if (normed ne this) return normed.toString