SI-9847 Nuance pure expr statement warning

Clarify the current warning, which means that an expression
split over multiple lines may not be parsed as naively expected.

When typing a block, attempt minor nuance. For instance, a
single expression is not in need of parens. Try to avoid
duplicate warnings for expressions that were adapted away
from result position.

1 files changed, 8 insertions, 2 deletions

diff --git a/test/files/run/t3488.check b/test/files/run/t3488.check
index 314dfc7838..75b2c3b07f 100644
--- a/test/files/run/t3488.check
+++ b/test/files/run/t3488.check
@@ -1,7 +1,13 @@
-t3488.scala:4: warning: a pure expression does nothing in statement position; you may be omitting necessary parentheses
+t3488.scala:4: warning: a pure expression does nothing in statement position
   println(foo { val List(_*)=List(0); 1 } ())
                                       ^
-t3488.scala:5: warning: a pure expression does nothing in statement position; you may be omitting necessary parentheses
+t3488.scala:4: warning: multiline expressions might require enclosing parentheses; a value can be silently discarded when Unit is expected
+  println(foo { val List(_*)=List(0); 1 } ())
+                                      ^
+t3488.scala:5: warning: a pure expression does nothing in statement position
+  println(foo { val List(_*)=List(0); 1 } (1))
+                                      ^
+t3488.scala:5: warning: multiline expressions might require enclosing parentheses; a value can be silently discarded when Unit is expected
   println(foo { val List(_*)=List(0); 1 } (1))
                                       ^
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