No warn when discarding r.f(): r.type

The paradigm is `def add(x: X): Unit = listBuffer += x`.

The value that is discarded is not new information.

Also cleans up the recent tweaks to help messaging.

Adds newlines in case they ask for multiple helps.

1 files changed, 7 insertions, 2 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index d8183ea8df..7d48c548a1 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -1060,8 +1060,13 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
           @inline def tpdPos(transformed: Tree) = typedPos(tree.pos, mode, pt)(transformed)
           @inline def tpd(transformed: Tree)    = typed(transformed, mode, pt)
 
-          @inline def warnValueDiscard(): Unit =
-            if (!isPastTyper && settings.warnValueDiscard) context.warning(tree.pos, "discarded non-Unit value")
+          @inline def warnValueDiscard(): Unit = if (!isPastTyper && settings.warnValueDiscard) {
+            def isThisTypeResult = (tree, tree.tpe) match {
+              case (Apply(Select(receiver, _), _), SingleType(_, sym)) => sym == receiver.symbol
+              case _ => false
+            }
+            if (!isThisTypeResult) context.warning(tree.pos, "discarded non-Unit value")
+          }
           @inline def warnNumericWiden(): Unit =
             if (!isPastTyper && settings.warnNumericWiden) context.warning(tree.pos, "implicit numeric widening")