8 files changed, 79 insertions, 10 deletions
diff --git a/test/files/neg/macro-invalidret.check b/test/files/neg/macro-invalidret.check
index ebdc8ec7da..a4d4fc6f34 100644
--- a/test/files/neg/macro-invalidret.check
+++ b/test/files/neg/macro-invalidret.check
@@ -27,7 +27,7 @@ java.lang.NullPointerException
 Macros_Test_2.scala:15: error: macro implementation is missing
   foo4
   ^
-Macros_Test_2.scala:17: warning: a pure expression does nothing in statement position; you may be omitting necessary parentheses
+Macros_Test_2.scala:17: warning: a pure expression does nothing in statement position; multiline expressions may require enclosing parentheses
   foo6
   ^
 two warnings found
diff --git a/test/files/neg/scopes.check b/test/files/neg/scopes.check
index f8e8c3758a..2db9678185 100644
--- a/test/files/neg/scopes.check
+++ b/test/files/neg/scopes.check
@@ -7,7 +7,7 @@ scopes.scala:5: error: x is already defined as value x
 scopes.scala:8: error: y is already defined as value y
     val y: Float = .0f
         ^
-scopes.scala:6: warning: a pure expression does nothing in statement position; you may be omitting necessary parentheses
+scopes.scala:6: warning: a pure expression does nothing in statement position; multiline expressions may require enclosing parentheses
   {
   ^
 scopes.scala:11: error: x is already defined as value x
diff --git a/test/files/neg/stmt-expr-discard.check b/test/files/neg/stmt-expr-discard.check
index 1207e6da50..4a80765365 100644
--- a/test/files/neg/stmt-expr-discard.check
+++ b/test/files/neg/stmt-expr-discard.check
@@ -1,7 +1,7 @@
-stmt-expr-discard.scala:3: warning: a pure expression does nothing in statement position; you may be omitting necessary parentheses
+stmt-expr-discard.scala:3: warning: a pure expression does nothing in statement position; multiline expressions may require enclosing parentheses
     + 2
     ^
-stmt-expr-discard.scala:4: warning: a pure expression does nothing in statement position; you may be omitting necessary parentheses
+stmt-expr-discard.scala:4: warning: a pure expression does nothing in statement position; multiline expressions may require enclosing parentheses
     - 4
       ^
 error: No warnings can be incurred under -Xfatal-warnings.
diff --git a/test/files/neg/t1181.check b/test/files/neg/t1181.check
index 13b73d5381..a9c102853d 100644
--- a/test/files/neg/t1181.check
+++ b/test/files/neg/t1181.check
@@ -1,10 +1,10 @@
-t1181.scala:8: warning: a pure expression does nothing in statement position; you may be omitting necessary parentheses
-     case (Nil, Nil) => map
-                        ^
 t1181.scala:9: error: type mismatch;
  found   : scala.collection.immutable.Map[Symbol,Symbol]
  required: Symbol
      _ => buildMap(map.updated(keyList.head, valueList.head), keyList.tail, valueList.tail)
                   ^
+t1181.scala:8: warning: a pure expression does nothing in statement position; multiline expressions might require enclosing parentheses
+     case (Nil, Nil) => map
+                        ^
 one warning found
 one error found
diff --git a/test/files/neg/t9847.check b/test/files/neg/t9847.check
new file mode 100644
index 0000000000..e55109b3ef
--- /dev/null
+++ b/test/files/neg/t9847.check
@@ -0,0 +1,45 @@
+t9847.scala:4: warning: discarded non-Unit value
+  def f(): Unit = 42
+                  ^
+t9847.scala:4: warning: a pure expression does nothing in statement position
+  def f(): Unit = 42
+                  ^
+t9847.scala:5: warning: discarded non-Unit value
+  def g = (42: Unit)
+           ^
+t9847.scala:5: warning: a pure expression does nothing in statement position
+  def g = (42: Unit)
+           ^
+t9847.scala:7: warning: a pure expression does nothing in statement position; multiline expressions might require enclosing parentheses
+    1
+    ^
+t9847.scala:12: warning: discarded non-Unit value
+  + 1
+  ^
+t9847.scala:12: warning: a pure expression does nothing in statement position
+  + 1
+  ^
+t9847.scala:11: warning: a pure expression does nothing in statement position; multiline expressions might require enclosing parentheses
+    1
+    ^
+t9847.scala:12: warning: multiline expressions might require enclosing parentheses; a value can be silently discarded when Unit is expected
+  + 1
+  ^
+t9847.scala:16: warning: discarded non-Unit value
+    x + 1
+      ^
+t9847.scala:19: warning: discarded non-Unit value
+  def j(): Unit = x + 1
+                    ^
+t9847.scala:21: warning: a pure expression does nothing in statement position; multiline expressions may require enclosing parentheses
+  class C { 42 }
+            ^
+t9847.scala:22: warning: a pure expression does nothing in statement position; multiline expressions may require enclosing parentheses
+  class D { 42 ; 17 }
+            ^
+t9847.scala:22: warning: a pure expression does nothing in statement position; multiline expressions may require enclosing parentheses
+  class D { 42 ; 17 }
+                 ^
+error: No warnings can be incurred under -Xfatal-warnings.
+14 warnings found
+one error found
diff --git a/test/files/neg/t9847.flags b/test/files/neg/t9847.flags
new file mode 100644
index 0000000000..065e3ca61e
--- /dev/null
+++ b/test/files/neg/t9847.flags
@@ -0,0 +1 @@
+-Xfatal-warnings -Ywarn-value-discard
diff --git a/test/files/neg/t9847.scala b/test/files/neg/t9847.scala
new file mode 100644
index 0000000000..51c16d815f
--- /dev/null
+++ b/test/files/neg/t9847.scala
@@ -0,0 +1,23 @@
+
+trait T {
+
+  def f(): Unit = 42
+  def g = (42: Unit)
+  def h = {
+    1
+  + 1
+  }
+  def hh(): Unit = {
+    1
+  + 1
+  }
+  def i(): Unit = {
+    val x = 1
+    x + 1
+  }
+  def x = 42
+  def j(): Unit = x + 1
+
+  class C { 42 }
+  class D { 42 ; 17 }
+}
diff --git a/test/files/neg/unit-returns-value.check b/test/files/neg/unit-returns-value.check
index f30a506ebe..7ebfbfde29 100644
--- a/test/files/neg/unit-returns-value.check
+++ b/test/files/neg/unit-returns-value.check
@@ -1,13 +1,13 @@
-unit-returns-value.scala:4: warning: a pure expression does nothing in statement position; you may be omitting necessary parentheses
+unit-returns-value.scala:4: warning: a pure expression does nothing in statement position
     if (b) return 5
                   ^
 unit-returns-value.scala:4: warning: enclosing method f has result type Unit: return value discarded
     if (b) return 5
            ^
-unit-returns-value.scala:22: warning: a pure expression does nothing in statement position; you may be omitting necessary parentheses
+unit-returns-value.scala:22: warning: a pure expression does nothing in statement position; multiline expressions might require enclosing parentheses
     i1 // warn
     ^
-unit-returns-value.scala:23: warning: a pure expression does nothing in statement position; you may be omitting necessary parentheses
+unit-returns-value.scala:23: warning: a pure expression does nothing in statement position; multiline expressions might require enclosing parentheses
     i2 // warn
     ^
 error: No warnings can be incurred under -Xfatal-warnings.