Easy suppression of deprecated paren syntax warning

src/compiler/scala/tools/nsc/Reporting.scala

@@ -333,7 +333,7 @@ object Reporting {
         .toLowerCase
     }
 
-    def includes(o: WarningCategory): Boolean = this eq o
+    def includes(msg: Message): Boolean = this eq msg.category
     def summaryCategory: WarningCategory = this
   }
 
@@ -354,7 +354,7 @@ object Reporting {
     object JavaSource extends WarningCategory; add(JavaSource)
 
     sealed trait Other extends WarningCategory { override def summaryCategory: WarningCategory = Other }
-    object Other extends Other { override def includes(o: WarningCategory): Boolean = o.isInstanceOf[Other] }; add(Other)
+    object Other extends Other { override def includes(msg: Message): Boolean = msg.category.isInstanceOf[Other] }; add(Other)
     object OtherShadowing extends Other; add(OtherShadowing)
     object OtherPureStatement extends Other; add(OtherPureStatement)
     object OtherMigration extends Other; add(OtherMigration)
@@ -365,15 +365,15 @@ object Reporting {
     object OtherImplicitType extends Other; add(OtherImplicitType)
 
     sealed trait WFlag extends WarningCategory { override def summaryCategory: WarningCategory = WFlag }
-    object WFlag extends WFlag { override def includes(o: WarningCategory): Boolean = o.isInstanceOf[WFlag] }; add(WFlag)
+    object WFlag extends WFlag { override def includes(msg: Message): Boolean = msg.category.isInstanceOf[WFlag] }; add(WFlag)
     object WFlagDeadCode extends WFlag; add(WFlagDeadCode)
     object WFlagExtraImplicit extends WFlag; add(WFlagExtraImplicit)
     object WFlagNumericWiden extends WFlag; add(WFlagNumericWiden)
     object WFlagSelfImplicit extends WFlag; add(WFlagSelfImplicit)
     object WFlagValueDiscard extends WFlag; add(WFlagValueDiscard)
 
     sealed trait Unused extends WarningCategory { override def summaryCategory: WarningCategory = Unused }
-    object Unused extends Unused { override def includes(o: WarningCategory): Boolean = o.isInstanceOf[Unused] }; add(Unused)
+    object Unused extends Unused { override def includes(msg: Message): Boolean = msg.category.isInstanceOf[Unused] }; add(Unused)
     object UnusedImports extends Unused; add(UnusedImports)
     object UnusedPatVars extends Unused; add(UnusedPatVars)
     object UnusedPrivates extends Unused; add(UnusedPrivates)
@@ -382,7 +382,7 @@ object Reporting {
     object UnusedNowarn extends Unused; add(UnusedNowarn)
 
     sealed trait Lint extends WarningCategory { override def summaryCategory: WarningCategory = Lint }
-    object Lint extends Lint { override def includes(o: WarningCategory): Boolean = o.isInstanceOf[Lint] }; add(Lint)
+    object Lint extends Lint { override def includes(msg: Message): Boolean = msg.category.isInstanceOf[Lint] }; add(Lint)
     object LintAdaptedArgs extends Lint; add(LintAdaptedArgs)
     object LintNullaryUnit extends Lint; add(LintNullaryUnit)
     object LintInaccessible extends Lint; add(LintInaccessible)
@@ -410,14 +410,18 @@ object Reporting {
     object LintPerformance extends Lint; add(LintPerformance)
 
     sealed trait Feature extends WarningCategory { override def summaryCategory: WarningCategory = Feature }
-    object Feature extends Feature { override def includes(o: WarningCategory): Boolean = o.isInstanceOf[Feature] }; add(Feature)
+    object Feature extends Feature { override def includes(msg: Message): Boolean = msg.category.isInstanceOf[Feature] }; add(Feature)
     object FeatureDynamics extends Feature; add(FeatureDynamics)
     object FeatureExistentials extends Feature; add(FeatureExistentials)
     object FeatureHigherKinds extends Feature; add(FeatureHigherKinds)
     object FeatureImplicitConversions extends Feature; add(FeatureImplicitConversions)
     object FeaturePostfixOps extends Feature; add(FeaturePostfixOps)
     object FeatureReflectiveCalls extends Feature; add(FeatureReflectiveCalls)
     object FeatureMacros extends Feature; add(FeatureMacros)
+
+    object FunctionParens extends WarningCategory {
+      override def includes(msg: Message): Boolean = (msg.category eq Deprecation) && msg.msg.startsWith("parentheses are required around the parameter of a lambda")
+    }; add(FunctionParens)
   }
 
   sealed trait Version {
@@ -492,7 +496,7 @@ object Reporting {
     }
 
     final case class Category(cat: WarningCategory) extends MessageFilter {
-      def matches(message: Message): Boolean = cat.includes(message.category)
+      def matches(message: Message): Boolean = cat.includes(message)
     }
 
     final case class MessagePattern(pattern: Regex) extends MessageFilter {

src/compiler/scala/tools/nsc/ast/parser/Parsers.scala

@@ -783,7 +783,7 @@ self =>
         if (currentRun.isScala3)
           syntaxError(tree.pos.point, msg)
         else
-          deprecationWarning(tree.pos.point, msg, "2.13.11")
+          deprecationWarning(tree.pos.point, s"$msg (silence with -Wconf:cat=function-parens:s)", "2.13.11")
         List(convertToParam(tree))
       case _ => List(convertToParam(tree))
     }

test/files/neg/parens-for-params.check

@@ -1,4 +1,4 @@
-parens-for-params.scala:5: warning: parentheses are required around the parameter of a lambda
+parens-for-params.scala:5: warning: parentheses are required around the parameter of a lambda (silence with -Wconf:cat=function-parens:s)
     x: Int => x * 2
      ^
 error: No warnings can be incurred under -Werror.

test/files/pos/parens-for-params-silent.scala

@@ -0,0 +1,10 @@
+// scalac: -Werror -Xlint -Wconf:cat=function-parens:s
+
+class C {
+  def f = {
+    x: Int => x * 2
+  }
+  def g = {
+    (x: Int) => x * 2
+  }
+}