Enable stricter pattern binding warnings by default

compiler/src/dotty/tools/backend/jvm/BCodeBodyBuilder.scala

@@ -359,7 +359,7 @@ trait BCodeBodyBuilder extends BCodeSkelBuilder {
             // but I was able to derrive it by reading
             // AbstractValidatingLambdaMetafactory.validateMetafactoryArgs
 
-            val DesugaredSelect(prefix, _) = fun
+            val DesugaredSelect(prefix, _) = fun: @unchecked
             genLoad(prefix)
           }
 
@@ -725,7 +725,7 @@ trait BCodeBodyBuilder extends BCodeSkelBuilder {
       lineNumber(app)
       app match {
         case Apply(_, args) if app.symbol eq defn.newArrayMethod =>
-          val List(elemClaz, Literal(c: Constant), ArrayValue(_, dims)) = args
+          val List(elemClaz, Literal(c: Constant), ArrayValue(_, dims)) = args: @unchecked
 
           generatedType = toTypeKind(c.typeValue)
           mkArrayConstructorCall(generatedType.asArrayBType, app, dims)
@@ -802,7 +802,7 @@ trait BCodeBodyBuilder extends BCodeSkelBuilder {
             if (invokeStyle.hasInstance) genLoadQualifier(fun)
             genLoadArguments(args, paramTKs(app))
 
-            val DesugaredSelect(qual, name) = fun // fun is a Select, also checked in genLoadQualifier
+            val DesugaredSelect(qual, name) = fun: @unchecked // fun is a Select, also checked in genLoadQualifier
             val isArrayClone = name == nme.clone_ && qual.tpe.widen.isInstanceOf[JavaArrayType]
             if (isArrayClone) {
               // Special-case Array.clone, introduced in 36ef60e. The goal is to generate this call
@@ -845,7 +845,7 @@ trait BCodeBodyBuilder extends BCodeSkelBuilder {
     } // end of genApply()
 
     private def genArrayValue(av: tpd.JavaSeqLiteral): BType = {
-      val ArrayValue(tpt, elems) = av
+      val ArrayValue(tpt, elems) = av: @unchecked
 
       lineNumber(av)
       genArray(elems, tpt)
@@ -1530,7 +1530,7 @@ trait BCodeBodyBuilder extends BCodeSkelBuilder {
           import ScalaPrimitivesOps.{ ZNOT, ZAND, ZOR, EQ }
 
           // lhs and rhs of test
-          lazy val DesugaredSelect(lhs, _) = fun
+          lazy val DesugaredSelect(lhs, _) = fun: @unchecked
           val rhs = if (args.isEmpty) tpd.EmptyTree else args.head // args.isEmpty only for ZNOT
 
           def genZandOrZor(and: Boolean): Unit = {

compiler/src/dotty/tools/backend/jvm/BCodeHelpers.scala

@@ -151,7 +151,7 @@ trait BCodeHelpers extends BCodeIdiomatic with BytecodeWriters {
     // sorting ensures nested classes are listed after their enclosing class thus satisfying the Eclipse Java compiler
     for (nestedClass <- allNestedClasses.sortBy(_.internalName.toString)) {
       // Extract the innerClassEntry - we know it exists, enclosingNestedClassesChain only returns nested classes.
-      val Some(e) = nestedClass.innerClassAttributeEntry
+      val Some(e) = nestedClass.innerClassAttributeEntry: @unchecked
       jclass.visitInnerClass(e.name, e.outerName, e.innerName, e.flags)
     }
   }

compiler/src/dotty/tools/backend/jvm/BCodeSkelBuilder.scala

@@ -689,7 +689,7 @@ trait BCodeSkelBuilder extends BCodeHelpers {
       val origSym = dd.symbol.asTerm
       val newSym = makeStatifiedDefSymbol(origSym, origSym.name)
       tpd.DefDef(newSym, { paramRefss =>
-        val selfParamRef :: regularParamRefs = paramRefss.head
+        val selfParamRef :: regularParamRefs = paramRefss.head: @unchecked
         val enclosingClass = origSym.owner.asClass
         new TreeTypeMap(
           typeMap = _.substThis(enclosingClass, selfParamRef.symbol.termRef)

compiler/src/dotty/tools/backend/sjs/JSCodeGen.scala

@@ -1025,7 +1025,7 @@ class JSCodeGen()(using genCtx: Context) {
      */
 
     val (primaryTree :: Nil, secondaryTrees) =
-      constructorTrees.partition(_.symbol.isPrimaryConstructor)
+      constructorTrees.partition(_.symbol.isPrimaryConstructor): @unchecked
 
     val primaryCtor = genPrimaryJSClassCtor(primaryTree)
     val secondaryCtors = secondaryTrees.map(genSecondaryJSClassCtor(_))
@@ -1106,7 +1106,7 @@ class JSCodeGen()(using genCtx: Context) {
 
   private def genPrimaryJSClassCtor(dd: DefDef): PrimaryJSCtor = {
     val sym = dd.symbol
-    val Block(stats, _) = dd.rhs
+    val Block(stats, _) = dd.rhs: @unchecked
     assert(sym.isPrimaryConstructor, s"called with non-primary ctor: $sym")
 
     var jsSuperCall: Option[js.JSSuperConstructorCall] = None
@@ -1179,7 +1179,7 @@ class JSCodeGen()(using genCtx: Context) {
 
     assert(thisCall.isDefined,
         i"could not find the this() call in secondary JS constructor at ${dd.sourcePos}:\n${stats.map(_.show).mkString("\n")}")
-    val Some((targetCtor, ctorArgs)) = thisCall
+    val Some((targetCtor, ctorArgs)) = thisCall: @unchecked
 
     new SplitSecondaryJSCtor(sym, genParamsAndInfo(sym, dd.paramss),
         beforeThisCall.result(), targetCtor, ctorArgs, afterThisCall.result())
@@ -2139,7 +2139,7 @@ class JSCodeGen()(using genCtx: Context) {
    */
   private def genSuperCall(tree: Apply, isStat: Boolean): js.Tree = {
     implicit val pos = tree.span
-    val Apply(fun @ Select(sup @ Super(qual, _), _), args) = tree
+    val Apply(fun @ Select(sup @ Super(qual, _), _), args) = tree: @unchecked
     val sym = fun.symbol
 
     if (sym == defn.Any_getClass) {
@@ -2180,7 +2180,7 @@ class JSCodeGen()(using genCtx: Context) {
   private def genApplyNew(tree: Apply): js.Tree = {
     implicit val pos: SourcePosition = tree.sourcePos
 
-    val Apply(fun @ Select(New(tpt), nme.CONSTRUCTOR), args) = tree
+    val Apply(fun @ Select(New(tpt), nme.CONSTRUCTOR), args) = tree: @unchecked
     val ctor = fun.symbol
     val tpe = tpt.tpe
 
@@ -2229,7 +2229,7 @@ class JSCodeGen()(using genCtx: Context) {
     acquireContextualJSClassValue { jsClassValue =>
       implicit val pos: Position = tree.span
 
-      val Apply(fun @ Select(New(tpt), _), args) = tree
+      val Apply(fun @ Select(New(tpt), _), args) = tree: @unchecked
       val cls = tpt.tpe.typeSymbol
       val ctor = fun.symbol
 
@@ -2898,7 +2898,7 @@ class JSCodeGen()(using genCtx: Context) {
 
     implicit val pos = tree.span
 
-    val Apply(fun, args) = tree
+    val Apply(fun, args) = tree: @unchecked
     val arrayObj = qualifierOf(fun)
 
     val genArray = genExpr(arrayObj)
@@ -3167,7 +3167,7 @@ class JSCodeGen()(using genCtx: Context) {
   private def genJSSuperCall(tree: Apply, isStat: Boolean): js.Tree = {
     acquireContextualJSClassValue { explicitJSSuperClassValue =>
       implicit val pos = tree.span
-      val Apply(fun @ Select(sup @ Super(qual, _), _), args) = tree
+      val Apply(fun @ Select(sup @ Super(qual, _), _), args) = tree: @unchecked
       val sym = fun.symbol
 
       val genReceiver = genExpr(qual)
@@ -3242,7 +3242,7 @@ class JSCodeGen()(using genCtx: Context) {
   /** Gen JS code for a switch-`Match`, which is translated into an IR `js.Match`. */
   def genMatch(tree: Tree, isStat: Boolean): js.Tree = {
     implicit val pos = tree.span
-    val Match(selector, cases) = tree
+    val Match(selector, cases) = tree: @unchecked
 
     def abortMatch(msg: String): Nothing =
       throw new FatalError(s"$msg in switch-like pattern match at ${tree.span}: $tree")
@@ -3441,7 +3441,7 @@ class JSCodeGen()(using genCtx: Context) {
       val call = if (isStaticCall) {
         genApplyStatic(sym, formalCaptures.map(_.ref) ::: actualParams)
       } else {
-        val thisCaptureRef :: argCaptureRefs = formalCaptures.map(_.ref)
+        val thisCaptureRef :: argCaptureRefs = formalCaptures.map(_.ref): @unchecked
         if (!sym.owner.isNonNativeJSClass || sym.isJSExposed)
           genApplyMethodMaybeStatically(thisCaptureRef, sym, argCaptureRefs ::: actualParams)
         else
@@ -3458,7 +3458,7 @@ class JSCodeGen()(using genCtx: Context) {
     }
 
     if (isThisFunction) {
-      val thisParam :: otherParams = formalParams
+      val thisParam :: otherParams = formalParams: @unchecked
       js.Closure(
           arrow = false,
           formalCaptures,
@@ -3970,7 +3970,7 @@ class JSCodeGen()(using genCtx: Context) {
    */
   private def genReflectiveCall(tree: Apply, isSelectDynamic: Boolean): js.Tree = {
     implicit val pos = tree.span
-    val Apply(fun @ Select(receiver, _), args) = tree
+    val Apply(fun @ Select(receiver, _), args) = tree: @unchecked
 
     val selectedValueTree = js.Apply(js.ApplyFlags.empty, genExpr(receiver),
         js.MethodIdent(selectedValueMethodName), Nil)(jstpe.AnyType)
@@ -4213,7 +4213,7 @@ class JSCodeGen()(using genCtx: Context) {
   private def genCaptureValuesFromFakeNewInstance(tree: Tree): List[js.Tree] = {
     implicit val pos: Position = tree.span
 
-    val Apply(fun @ Select(New(_), _), args) = tree
+    val Apply(fun @ Select(New(_), _), args) = tree: @unchecked
     val sym = fun.symbol
 
     /* We use the same strategy as genActualJSArgs to detect which parameters were
@@ -4539,7 +4539,7 @@ class JSCodeGen()(using genCtx: Context) {
         pathName.split('.').toList
 
       def parseGlobalPath(pathName: String): Global = {
-        val globalRef :: path = parsePath(pathName)
+        val globalRef :: path = parsePath(pathName): @unchecked
         Global(globalRef, path)
       }
 

compiler/src/dotty/tools/backend/sjs/JSExportsGen.scala

@@ -356,7 +356,7 @@ final class JSExportsGen(jsCodeGen: JSCodeGen)(using Context) {
         None
       } else {
         val formalArgsRegistry = new FormalArgsRegistry(1, false)
-        val (List(arg), None) = formalArgsRegistry.genFormalArgs()
+        val (List(arg), None) = formalArgsRegistry.genFormalArgs(): @unchecked
         val body = genOverloadDispatchSameArgc(jsName, formalArgsRegistry,
             setters.map(new ExportedSymbol(_, static)), jstpe.AnyType, None)
         Some((arg, body))

compiler/src/dotty/tools/dotc/ast/Desugar.scala

@@ -405,7 +405,7 @@ object desugar {
 
   /** The expansion of a class definition. See inline comments for what is involved */
   def classDef(cdef: TypeDef)(using Context): Tree = {
-    val impl @ Template(constr0, _, self, _) = cdef.rhs
+    val impl @ Template(constr0, _, self, _) = cdef.rhs: @unchecked
     val className = normalizeName(cdef, impl).asTypeName
     val parents = impl.parents
     val mods = cdef.mods
@@ -695,7 +695,7 @@ object desugar {
             .withMods(companionMods | Synthetic))
         .withSpan(cdef.span).toList
       if (companionDerived.nonEmpty)
-        for (modClsDef @ TypeDef(_, _) <- mdefs)
+        for (case modClsDef @ TypeDef(_, _) <- mdefs)
           modClsDef.putAttachment(DerivingCompanion, impl.srcPos.startPos)
       mdefs
     }
@@ -753,7 +753,7 @@ object desugar {
 
     enumCompanionRef match {
       case ref: TermRefTree => // have the enum import watch the companion object
-        val (modVal: ValDef) :: _ = companions
+        val (modVal: ValDef) :: _ = companions: @unchecked
         ref.watching(modVal)
       case _ =>
     }
@@ -1215,7 +1215,7 @@ object desugar {
 
   /** Expand variable identifier x to x @ _ */
   def patternVar(tree: Tree)(using Context): Bind = {
-    val Ident(name) = unsplice(tree)
+    val Ident(name) = unsplice(tree): @unchecked
     Bind(name, Ident(nme.WILDCARD)).withSpan(tree.span)
   }
 
@@ -1553,7 +1553,7 @@ object desugar {
           Function(derivedValDef(gen.pat, named, tpt, EmptyTree, Modifiers(Param)) :: Nil, body)
         case _ =>
           val matchCheckMode =
-            if (gen.checkMode == GenCheckMode.Check) MatchCheck.IrrefutableGenFrom
+            if (gen.checkMode == GenCheckMode.Check || gen.checkMode == GenCheckMode.CheckAndFilter) MatchCheck.IrrefutableGenFrom
             else MatchCheck.None
           makeCaseLambda(CaseDef(gen.pat, EmptyTree, body) :: Nil, matchCheckMode)
       }
@@ -1640,13 +1640,11 @@ object desugar {
         case IdPattern(_) => true
         case _ => false
 
-      def needsNoFilter(gen: GenFrom): Boolean =
-        if (gen.checkMode == GenCheckMode.FilterAlways) // pattern was prefixed by `case`
-          false
-        else
-          gen.checkMode != GenCheckMode.FilterNow
-          || isVarBinding(gen.pat)
-          || isIrrefutable(gen.pat, gen.expr)
+      def needsNoFilter(gen: GenFrom): Boolean = gen.checkMode match
+        case GenCheckMode.FilterAlways => false  // pattern was prefixed by `case`
+        case GenCheckMode.FilterNow | GenCheckMode.CheckAndFilter => isVarBinding(gen.pat) || isIrrefutable(gen.pat, gen.expr)
+        case GenCheckMode.Check => true
+        case GenCheckMode.Ignore => true
 
       /** rhs.name with a pattern filter on rhs unless `pat` is irrefutable when
        *  matched against `rhs`.
@@ -1656,10 +1654,6 @@ object desugar {
         Select(rhs, name)
       }
 
-      def checkMode(gen: GenFrom) =
-        if (gen.checkMode == GenCheckMode.Check) MatchCheck.IrrefutableGenFrom
-        else MatchCheck.None // refutable paterns were already eliminated in filter step
-
       enums match {
         case (gen: GenFrom) :: Nil =>
           Apply(rhsSelect(gen, mapName), makeLambda(gen, body))

compiler/src/dotty/tools/dotc/ast/MainProxies.scala

@@ -183,7 +183,7 @@ object MainProxies {
         case TypeDef(_, template: Template) =>
           template.body.flatMap((_: Tree) match {
             case dd: DefDef if dd.name.is(DefaultGetterName) && dd.name.firstPart == funSymbol.name =>
-              val DefaultGetterName.NumberedInfo(index) = dd.name.info
+              val DefaultGetterName.NumberedInfo(index) = dd.name.info: @unchecked
               List(index -> dd.symbol)
             case _ => Nil
           }).toMap

compiler/src/dotty/tools/dotc/ast/TreeInfo.scala

@@ -956,7 +956,7 @@ trait TypedTreeInfo extends TreeInfo[Type] { self: Trees.Instance[Type] =>
         Some(tree.args.head)
       else if tree.symbol == defn.QuotedTypeModule_of then
         // quoted.Type.of[<body>](quotes)
-        val TypeApply(_, body :: _) = tree.fun
+        val TypeApply(_, body :: _) = tree.fun: @unchecked
         Some(body)
       else None
   }

compiler/src/dotty/tools/dotc/ast/TreeTypeMap.scala

@@ -156,9 +156,10 @@ class TreeTypeMap(
 
   private def transformAllParamss(paramss: List[ParamClause]): (TreeTypeMap, List[ParamClause]) = paramss match
     case params :: paramss1 =>
-      val (tmap1, params1: ParamClause) = (params: @unchecked) match
+      val (tmap1, params1: ParamClause) = ((params: @unchecked) match
         case ValDefs(vparams) => transformDefs(vparams)
         case TypeDefs(tparams) => transformDefs(tparams)
+      ): @unchecked
       val (tmap2, paramss2) = tmap1.transformAllParamss(paramss1)
       (tmap2, params1 :: paramss2)
     case nil =>

compiler/src/dotty/tools/dotc/ast/tpd.scala

@@ -293,7 +293,7 @@ object tpd extends Trees.Instance[Type] with TypedTreeInfo {
     ta.assignType(untpd.TypeDef(sym.name, TypeTree(sym.info)), sym)
 
   def ClassDef(cls: ClassSymbol, constr: DefDef, body: List[Tree], superArgs: List[Tree] = Nil)(using Context): TypeDef = {
-    val firstParent :: otherParents = cls.info.parents
+    val firstParent :: otherParents = cls.info.parents: @unchecked
     val superRef =
       if (cls.is(Trait)) TypeTree(firstParent)
       else {

compiler/src/dotty/tools/dotc/ast/untpd.scala

@@ -168,7 +168,8 @@ object untpd extends Trees.Instance[Untyped] with UntypedTreeInfo {
   enum GenCheckMode {
     case Ignore       // neither filter nor check since filtering was done before
     case Check        // check that pattern is irrefutable
-    case FilterNow    // filter out non-matching elements since we are not yet in 3.x
+    case CheckAndFilter // both check and filter (transitional period starting with 3.2)
+    case FilterNow    // filter out non-matching elements if we are not in 3.2 or later
     case FilterAlways // filter out non-matching elements since pattern is prefixed by `case`
   }
 

compiler/src/dotty/tools/dotc/config/Feature.scala

@@ -88,10 +88,9 @@ object Feature:
   /** If current source migrates to `version`, issue given warning message
    *  and return `true`, otherwise return `false`.
    */
-  def warnOnMigration(msg: Message, pos: SrcPos,
-      version: SourceVersion)(using Context): Boolean =
+  def warnOnMigration(msg: Message, pos: SrcPos, version: SourceVersion)(using Context): Boolean =
     if sourceVersion.isMigrating && sourceVersion.stable == version
-       || (version == `3.0` || version == `3.1` || version == `3.2`) && migrateTo3
+       || (version == `3.0` || version == `3.1`) && migrateTo3
     then
       report.migrationWarning(msg, pos)
       true

compiler/src/dotty/tools/dotc/config/ScalaSettings.scala

@@ -5,6 +5,7 @@ import scala.language.unsafeNulls
 
 import dotty.tools.dotc.config.PathResolver.Defaults
 import dotty.tools.dotc.config.Settings.{Setting, SettingGroup}
+import dotty.tools.dotc.config.SourceVersion
 import dotty.tools.dotc.core.Contexts._
 import dotty.tools.dotc.rewrites.Rewrites
 import dotty.tools.io.{AbstractFile, Directory, JDK9Reflectors, PlainDirectory}
@@ -31,6 +32,9 @@ object ScalaSettings:
   def supportedScalaReleaseVersions: List[String] =
     ScalaRelease.values.toList.map(_.show)
 
+  def supportedSourceVersions: List[String] =
+    SourceVersion.values.toList.map(_.toString)
+
   def defaultClasspath: String = sys.env.getOrElse("CLASSPATH", ".")
 
   def defaultPageWidth: Int = {
@@ -51,7 +55,7 @@ trait AllScalaSettings extends CommonScalaSettings, PluginSettings, VerboseSetti
   /* Path related settings */
   val semanticdbTarget: Setting[String] = PathSetting("-semanticdb-target", "Specify an alternative output directory for SemanticDB files.", "")
 
-  val source: Setting[String] = ChoiceSetting("-source", "source version", "source version", List("3.0", "3.1", "future", "3.0-migration", "future-migration"), "3.0", aliases = List("--source"))
+  val source: Setting[String] = ChoiceSetting("-source", "source version", "source version", ScalaSettings.supportedSourceVersions, SourceVersion.defaultSourceVersion.toString, aliases = List("--source"))
   val uniqid: Setting[Boolean] = BooleanSetting("-uniqid", "Uniquely tag all identifiers in debugging output.", aliases = List("--unique-id"))
   val rewrite: Setting[Option[Rewrites]] = OptionSetting[Rewrites]("-rewrite", "When used in conjunction with a `...-migration` source version, rewrites sources to migrate to new version.", aliases = List("--rewrite"))
   val fromTasty: Setting[Boolean] = BooleanSetting("-from-tasty", "Compile classes from tasty files. The arguments are .tasty or .jar files.", aliases = List("--from-tasty"))

compiler/src/dotty/tools/dotc/config/Settings.scala

@@ -84,7 +84,7 @@ object Settings:
       }
 
     def tryToSet(state: ArgsSummary): ArgsSummary = {
-      val ArgsSummary(sstate, arg :: args, errors, warnings) = state
+      val ArgsSummary(sstate, arg :: args, errors, warnings) = state: @unchecked
       def update(value: Any, args: List[String]): ArgsSummary =
         var dangers = warnings
         val value1 =