Fix test output

Author: AnotherMedo

compiler/src/dotty/tools/dotc/reporting/messages.scala

@@ -3150,4 +3150,4 @@ class UnstableInlineAccessor(accessed: Symbol, accessorTree: tpd.Tree)(using Con
 class VolatileOnVal()(using Context)
 extends SyntaxMsg(VolatileOnValID):
   protected def msg(using Context): String = "values cannot be volatile"
-  protected def explain(using Context): String = ""
+  protected def explain(using Context): String = ""

tests/warn/i19416.check

@@ -0,0 +1,4 @@
+-- [E193] Syntax Warning: tests\warn\i19416.scala:2:18 -----------------------------------------------------------------
+2 |    @volatile val x: Int = ??? //warn
+  |                  ^
+  |                  values cannot be volatile