SI-5675 Discard duplicate feature warnings at a position

When -feature has not been enabled, we were double counting
identical feature warnings that were emitted at the same position.
Normal error reporting only reports the first time a warning
appears at a position; feature warning counter incrementing
should behave the same way.

@hubertp: Fixed .check files that were broken in the original commit.

1 files changed, 3 insertions, 3 deletions

diff --git a/src/compiler/scala/tools/nsc/Global.scala b/src/compiler/scala/tools/nsc/Global.scala
index 757ac94dbd..116684c161 100644
--- a/src/compiler/scala/tools/nsc/Global.scala
+++ b/src/compiler/scala/tools/nsc/Global.scala
@@ -1193,13 +1193,13 @@ class Global(var currentSettings: Settings, var reporter: Reporter)
 
   /** Collects for certain classes of warnings during this run. */
   class ConditionalWarning(what: String, option: Settings#BooleanSetting) {
-    val warnings = new mutable.ListBuffer[(Position, String)]
+    val warnings = mutable.LinkedHashMap[Position, String]()
     def warn(pos: Position, msg: String) =
       if (option.value) reporter.warning(pos, msg)
-      else warnings += ((pos, msg))
+      else if (!(warnings contains pos)) warnings += ((pos, msg))
     def summarize() =
       if (option.isDefault && warnings.nonEmpty)
-        reporter.warning(NoPosition, "there were %d %s warnings; re-run with %s for details".format(warnings.size, what, option.name))
+        reporter.warning(NoPosition, "there were %d %s warning(s); re-run with %s for details".format(warnings.size, what, option.name))
   }
 
   def newUnitParser(code: String)      = new syntaxAnalyzer.UnitParser(newCompilationUnit(code))