A little cleanup along the Any to AnyRef trail.

Followup to 35316be and d3f879a.

 - Remove obsolete comments and replace them with a test.
 - Don't emit error addendum unless we know we're dealing
   with a value class.

3 files changed, 1 insertions, 12 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala b/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala
index b7195b0349..80bb487d2e 100644
--- a/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala
@@ -106,7 +106,7 @@ trait ContextErrors {
       else
         s"$name extends Any, not AnyRef"
     )
-    if (isPrimitiveValueType(found)) "" else "\n" +
+    if (isPrimitiveValueType(found) || isTrivialTopType(tp)) "" else "\n" +
        s"""|Note that $what.
            |Such types can participate in value classes, but instances
            |cannot appear in singleton types or in reference comparisons.""".stripMargin
diff --git a/src/library/scala/runtime/StringAdd.scala b/src/library/scala/runtime/StringAdd.scala
index 4693b0bf44..f074b5407e 100644
--- a/src/library/scala/runtime/StringAdd.scala
+++ b/src/library/scala/runtime/StringAdd.scala
@@ -10,10 +10,5 @@ package scala.runtime
 
 /** A wrapper class that adds string concatenation `+` to any value */
 final class StringAdd(val self: Any) extends AnyVal {
-  // Note: The implicit conversion from Any to StringAdd is one of two
-  // implicit conversions from Any to AnyRef in Predef. It is important to have at least
-  // two such conversions, so that silent conversions from value types to AnyRef
-  // are avoided. If StringFormat should become a value class, another
-  // implicit conversion from Any to AnyRef has to be introduced in Predef
   def +(other: String) = String.valueOf(self) + other
 }
diff --git a/src/library/scala/runtime/StringFormat.scala b/src/library/scala/runtime/StringFormat.scala
index 1f5feec9e1..7d34e82812 100644
--- a/src/library/scala/runtime/StringFormat.scala
+++ b/src/library/scala/runtime/StringFormat.scala
@@ -11,12 +11,6 @@ package scala.runtime
 /** A wrapper class that adds a `formatted` operation to any value
  */
 final class StringFormat(val self: Any) extends AnyVal {
-  // Note: The implicit conversion from Any to StringFormat is one of two
-  // implicit conversions from Any to AnyRef in Predef. It is important to have at least
-  // two such conversions, so that silent conversions from value types to AnyRef
-  // are avoided. If StringFormat should become a value class, another
-  // implicit conversion from Any to AnyRef has to be introduced in Predef
-
   /** Returns string formatted according to given `format` string.
    *  Format strings are as for `String.format`
    *  (@see java.lang.String.format).