Mention type of unused value and mitigation

scala · Jul 27, 2022 · 2918434 · 2918434
1 parent 68080c2
commit 2918434
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Showing 2 changed files with 12 additions and 12 deletions.
diff --git a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
@@ -1788,7 +1788,6 @@ abstract class RefChecks extends Transform {
       )
       // begin checkInterestingResultInStatement
       settings.warnNonUnitStatement.value && checkInterestingShapes(t) && {
-        val msg = "unused value"
         val where = t match {
           case Block(_, res) => res
           case If(_, thenpart, Literal(Constant(()))) =>
@@ -1798,6 +1797,7 @@ abstract class RefChecks extends Transform {
             }
           case _ => t
         }
+        def msg = s"unused value of type ${where.tpe} (add `: Unit` to discard silently)"
         refchecksWarning(where.pos, msg, WarningCategory.OtherPureStatement)
         true
       }

diff --git a/test/files/neg/nonunit-statement.check b/test/files/neg/nonunit-statement.check
@@ -1,37 +1,37 @@
-nonunit-statement.scala:13: warning: unused value
+nonunit-statement.scala:13: warning: unused value of type scala.concurrent.Future[Int] (add `: Unit` to discard silently)
     improved              // warn
     ^
-nonunit-statement.scala:20: warning: unused value
+nonunit-statement.scala:20: warning: unused value of type String (add `: Unit` to discard silently)
     new E().toString      // warn
             ^
-nonunit-statement.scala:26: warning: unused value
+nonunit-statement.scala:26: warning: unused value of type scala.concurrent.Future[Int] (add `: Unit` to discard silently)
   Future(42)              // warn
         ^
-nonunit-statement.scala:30: warning: unused value
+nonunit-statement.scala:30: warning: unused value of type K (add `: Unit` to discard silently)
   copy()                  // warn
       ^
-nonunit-statement.scala:37: warning: unused value
+nonunit-statement.scala:37: warning: unused value of type List[Int] (add `: Unit` to discard silently)
   27 +: xs                // warn
      ^
 nonunit-statement.scala:44: warning: a pure expression does nothing in statement position; multiline expressions may require enclosing parentheses
   null                    // warn for purity
   ^
-nonunit-statement.scala:79: warning: unused value
+nonunit-statement.scala:79: warning: unused value of type Int (add `: Unit` to discard silently)
       g   // warn block statement
       ^
-nonunit-statement.scala:86: warning: unused value
+nonunit-statement.scala:86: warning: unused value of type Int (add `: Unit` to discard silently)
       g   // warn
       ^
-nonunit-statement.scala:84: warning: unused value
+nonunit-statement.scala:84: warning: unused value of type Int (add `: Unit` to discard silently)
       g   // warn
       ^
-nonunit-statement.scala:96: warning: unused value
+nonunit-statement.scala:96: warning: unused value of type Int (add `: Unit` to discard silently)
     if (b) {          // warn, at least one branch looks interesting
     ^
-nonunit-statement.scala:116: warning: unused value
+nonunit-statement.scala:116: warning: unused value of type scala.collection.mutable.LinkedHashSet[A] (add `: Unit` to discard silently)
     set += a     // warn because cannot know whether the `set` was supposed to be consumed or assigned
         ^
-nonunit-statement.scala:146: warning: unused value
+nonunit-statement.scala:146: warning: unused value of type String (add `: Unit` to discard silently)
     while (it.hasNext) it.next()  // warn
                               ^
 error: No warnings can be incurred under -Werror.