Drop old whitebox macro syntax

compiler/src/dotty/tools/dotc/parsing/Parsers.scala

@@ -36,8 +36,6 @@ object Parsers {
 
   import ast.untpd._
 
-  val AllowOldWhiteboxSyntax = true
-
   case class OpInfo(operand: Tree, operator: Ident, offset: Offset)
 
   class ParensCounters {
@@ -1822,16 +1820,9 @@ object Parsers {
         Nil
     }
 
-    def typedOpt(): Tree = {
-      if (in.token == COLONEOL) in.token = COLON
-      	// a hack to allow
-      	//
-      	//     def f():
-      	//       T
-        //
+    def typedOpt(): Tree =
       if (in.token == COLON) { in.nextToken(); toplevelTyp() }
       else TypeTree().withSpan(Span(in.lastOffset))
-    }
 
     def typeDependingOn(location: Location): Tree =
       if location.inParens then typ()
@@ -3266,7 +3257,7 @@ object Parsers {
       }
     }
 
-    /** DefDef  ::=  DefSig [(‘:’ | ‘<:’) Type] ‘=’ Expr
+    /** DefDef  ::=  DefSig [‘:’ Type] ‘=’ Expr
      *            |  this ParamClause ParamClauses `=' ConstrExpr
      *  DefDcl  ::=  DefSig `:' Type
      *  DefSig  ::=  id [DefTypeParamClause] DefParamClauses
@@ -3342,12 +3333,13 @@ object Parsers {
           case rparamss =>
             leadingVparamss ::: rparamss
         var tpt = fromWithinReturnType {
-          if in.token == SUBTYPE && mods.is(Inline) && AllowOldWhiteboxSyntax then
-            deprecationWarning("`<:` return type will no longer be supported. Use transparent modifier instead.")
-            in.nextToken()
-            mods1 = addMod(mods1, Mod.Transparent())
-            toplevelTyp()
-          else typedOpt()
+          if in.token == COLONEOL then in.token = COLON
+     	      // a hack to allow
+      	    //
+      	    //     def f():
+      	    //       T
+            //
+          typedOpt()
         }
         if (migrateTo3) newLineOptWhenFollowedBy(LBRACE)
         val rhs =
@@ -3581,7 +3573,7 @@ object Parsers {
         syntaxError(i"extension clause can only define methods", stat.span)
     }
 
-    /** GivenDef          ::=  [GivenSig] [‘_’ ‘<:’] Type ‘=’ Expr
+    /** GivenDef          ::=  [GivenSig] Type ‘=’ Expr
      *                      |  [GivenSig] ConstrApps [TemplateBody]
      *  GivenSig          ::=  [id] [DefTypeParamClause] {UsingParamClauses} ‘as’
      */
@@ -3601,30 +3593,19 @@ object Parsers {
         newLinesOpt()
         if isIdent(nme.as) || !name.isEmpty || !tparams.isEmpty || !vparamss.isEmpty then
           accept(nme.as)
-        def givenAlias(tpt: Tree) =
+        val parents = constrApps(commaOK = true, templateCanFollow = true)
+        if in.token == EQUALS && parents.length == 1 && parents.head.isType then
           accept(EQUALS)
           mods1 |= Final
-          DefDef(name, tparams, vparamss, tpt, subExpr())
-        if in.token == USCORE && AllowOldWhiteboxSyntax then
-          deprecationWarning("`<:` return type will no longer be supported. Use transparent modifier instead.")
-          if !mods.is(Inline) then
-            syntaxError("`_ <:` is only allowed for given with `inline` modifier")
-          in.nextToken()
-          accept(SUBTYPE)
-          mods1 = addMod(mods1, Mod.Transparent())
-          givenAlias(toplevelTyp())
+          DefDef(name, tparams, vparamss, parents.head, subExpr())
         else
-          val parents = constrApps(commaOK = true, templateCanFollow = true)
-          if in.token == EQUALS && parents.length == 1 && parents.head.isType then
-            givenAlias(parents.head)
-          else
-            possibleTemplateStart()
-            val tparams1 = tparams.map(tparam => tparam.withMods(tparam.mods | PrivateLocal))
-            val vparamss1 = vparamss.map(_.map(vparam =>
-              vparam.withMods(vparam.mods &~ Param | ParamAccessor | Protected)))
-            val templ = templateBodyOpt(makeConstructor(tparams1, vparamss1), parents, Nil)
-            if tparams.isEmpty && vparamss.isEmpty then ModuleDef(name, templ)
-            else TypeDef(name.toTypeName, templ)
+          possibleTemplateStart()
+          val tparams1 = tparams.map(tparam => tparam.withMods(tparam.mods | PrivateLocal))
+          val vparamss1 = vparamss.map(_.map(vparam =>
+            vparam.withMods(vparam.mods &~ Param | ParamAccessor | Protected)))
+          val templ = templateBodyOpt(makeConstructor(tparams1, vparamss1), parents, Nil)
+          if tparams.isEmpty && vparamss.isEmpty then ModuleDef(name, templ)
+          else TypeDef(name.toTypeName, templ)
       end gdef
       finalizeDef(gdef, mods1, start)
     }

docs/docs/internals/syntax.md

@@ -156,7 +156,7 @@ WithType          ::=  AnnotType {‘with’ AnnotType}
 AnnotType         ::=  SimpleType {Annotation}                                  Annotated(t, annot)
 
 SimpleType        ::=  SimpleLiteral                                            SingletonTypeTree(l)
-                    |  ‘?’ SubtypeBounds
+                    |  ‘?’ TypeBounds
                     |  SimpleType1 { ‘(’ Singletons ‘)’ }
 SimpleType1       ::=  id                                                       Ident(name)
                     |  Singleton ‘.’ id                                         Select(t, name)
@@ -181,8 +181,8 @@ TypeArgs          ::=  ‘[’ ArgTypes ‘]’
 NamedTypeArg      ::=  id ‘=’ Type                                              NamedArg(id, t)
 NamedTypeArgs     ::=  ‘[’ NamedTypeArg {‘,’ NamedTypeArg} ‘]’                  nts
 Refinement        ::=  ‘{’ [RefineDcl] {semi [RefineDcl]} ‘}’                   ds
-SubtypeBounds     ::=  [‘>:’ Type] [‘<:’ Type] | INT                            TypeBoundsTree(lo, hi)
-TypeParamBounds   ::=  SubtypeBounds {‘:’ Type}                                 ContextBounds(typeBounds, tps)
+TypeBounds        ::=  [‘>:’ Type] [‘<:’ Type]                                  TypeBoundsTree(lo, hi)
+TypeParamBounds   ::=  TypeBounds {‘:’ Type}                                    ContextBounds(typeBounds, tps)
 Types             ::=  Type {‘,’ Type}
 ```
 
@@ -299,11 +299,11 @@ DefTypeParamClause::=  ‘[’ DefTypeParam {‘,’ DefTypeParam} ‘]’
 DefTypeParam      ::=  {Annotation} id [HkTypeParamClause] TypeParamBounds
 
 TypTypeParamClause::=  ‘[’ TypTypeParam {‘,’ TypTypeParam} ‘]’
-TypTypeParam      ::=  {Annotation} id [HkTypeParamClause] SubtypeBounds
+TypTypeParam      ::=  {Annotation} id [HkTypeParamClause] TypeBounds
 
 HkTypeParamClause ::=  ‘[’ HkTypeParam {‘,’ HkTypeParam} ‘]’
 HkTypeParam       ::=  {Annotation} [‘+’ | ‘-’] (id [HkTypeParamClause] | ‘_’)
-                       SubtypeBounds
+                       TypeBounds
 
 ClsParamClauses   ::=  {ClsParamClause} [[nl] ‘(’ [‘implicit’] ClsParams ‘)’]
 ClsParamClause    ::=  [nl] ‘(’ ClsParams ‘)’
@@ -372,7 +372,7 @@ VarDcl            ::=  ids ‘:’ Type
 DefDcl            ::=  DefSig ‘:’ Type                                          DefDef(_, name, tparams, vparamss, tpe, EmptyTree)
 DefSig            ::=  id [DefTypeParamClause] DefParamClauses
                     |  ExtParamClause {nl} [‘.’] id DefParamClauses
-TypeDcl           ::=  id [TypeParamClause] {FunParamClause} SubtypeBounds      TypeDefTree(_, name, tparams, bound
+TypeDcl           ::=  id [TypeParamClause] {FunParamClause} TypeBounds         TypeDefTree(_, name, tparams, bound
                        [‘=’ Type]
 
 Def               ::=  ‘val’ PatDef
@@ -385,7 +385,7 @@ PatDef            ::=  ids [‘:’ Type] ‘=’ Expr
                     |  Pattern2 [‘:’ Type | Ascription] ‘=’ Expr                PatDef(_, pats, tpe?, expr)
 VarDef            ::=  PatDef
                     |  ids ‘:’ Type ‘=’ ‘_’
-DefDef            ::=  DefSig [(‘:’ | ‘<:’) Type] ‘=’ Expr                      DefDef(_, name, tparams, vparamss, tpe, expr)
+DefDef            ::=  DefSig [‘:’ Type] ‘=’ Expr                               DefDef(_, name, tparams, vparamss, tpe, expr)
                     |  ‘this’ DefParamClause DefParamClauses ‘=’ ConstrExpr     DefDef(_, <init>, Nil, vparamss, EmptyTree, expr | Block)
 
 TmplDef           ::=  ([‘case’] ‘class’ | ‘trait’) ClassDef
@@ -398,7 +398,7 @@ ClassConstr       ::=  [ClsTypeParamClause] [ConstrMods] ClsParamClauses
 ConstrMods        ::=  {Annotation} [AccessModifier]
 ObjectDef         ::=  id [Template]                                            ModuleDef(mods, name, template)  // no constructor
 EnumDef           ::=  id ClassConstr InheritClauses EnumBody                   EnumDef(mods, name, tparams, template)
-GivenDef          ::=  [GivenSig] [‘_’ ‘<:’] Type ‘=’ Expr
+GivenDef          ::=  [GivenSig] Type ‘=’ Expr
                     |  [GivenSig] ConstrApps [TemplateBody]
 GivenSig          ::=  [id] [DefTypeParamClause] {UsingParamClause} ‘as’
 ExtensionDef      ::=  [id] [‘on’ ExtParamClause {UsingParamClause}]

tests/invalid/run/typelevel-patmat.scala

@@ -78,12 +78,12 @@ object Test extends App {
   val e1 = nth(r2, 1)
   val ce1: String = e1
 
-  inline def concatTyped(xs: HList, ys: HList) <: Typed[_ <: HList] = inline xs match {
+  transparent inline def concatTyped(xs: HList, ys: HList): Typed[_ <: HList] = inline xs match {
     case HNil => Typed(ys)
     case HCons(x, xs1) => Typed(HCons(x, concatTyped(xs1, ys).value))
   }
 
-  def concatImpl(xs: HList, ys: HList) <: HList = xs match {
+  transparent def concatImpl(xs: HList, ys: HList): HList = xs match {
     case HNil => ys
     case HCons(x, xs1) => HCons(x, concatImpl(xs1, ys))
   }

tests/neg-custom-args/erased/erased-machine-state-encoding-with-inline.scala

@@ -5,11 +5,11 @@ final class On extends State
 final class Off extends State
 
 class Machine[S <: State] {
-  inline def turnOn() <: Machine[On] = inline erasedValue[S] match {
+  transparent inline def turnOn(): Machine[On] = inline erasedValue[S] match {
     case _: Off  => new Machine[On]
     case _: On   => error("Turning on an already turned on machine")
   }
-  inline def turnOff() <: Machine[Off] = inline erasedValue[S] match {
+  transparent inline def turnOff(): Machine[Off] = inline erasedValue[S] match {
     case _: On  => new Machine[Off]
     case _: Off   => error("Turning off an already turned off machine")
   }

tests/neg/i7078.scala

@@ -1,8 +1,7 @@
 trait A
 class B extends A
 
-given g1 as _ <: A = B()  // error: `_ <:' is only allowed for given with `inline' modifier
+transparent given g1 as A = B()  // error: `transparent` can only be used in conjunction with `inline`
 
 inline given g2 as _ <: A:  // error: `=' expected
   def foo = 2
-// error

tests/neg/machine-state-encoding-with-implicit-match.scala

@@ -18,10 +18,10 @@ object IsOn {
 }
 
 class Machine[S <: State] {
-  inline def turnOn()(using s: IsOff[S]) <: Machine[On] = summonFrom {
+  transparent inline def turnOn()(using s: IsOff[S]): Machine[On] = summonFrom {
     case _: IsOff[Off]  => new Machine[On]
   }
-  inline def turnOff()(using s: IsOn[S]) <: Machine[Off] = summonFrom {
+  transparent inline def turnOff()(using s: IsOn[S]): Machine[Off] = summonFrom {
     case _: IsOn[On]    => new Machine[Off]
   }
 }

tests/pos-macros/tasty-constant-type/Macro_1.scala

@@ -4,7 +4,7 @@ object Macro {
 
   trait AddInt[A <: Int, B <: Int] { type Out <: Int }
 
-  inline def ff[A <: Int, B <: Int]() <: AddInt[A, B] = ${ impl('[A], '[B]) }
+  transparent inline def ff[A <: Int, B <: Int](): AddInt[A, B] = ${ impl('[A], '[B]) }
 
   def impl[A <: Int : Type, B <: Int : Type](a: Type[A], b: Type[B])(using qctx: QuoteContext) : Expr[AddInt[A, B]] = {
     import qctx.tasty._

tests/pos/i5572.scala

@@ -1,6 +1,6 @@
 trait Foo {
   type Id[t] = t
-  inline def foo[T](t: T) <: Id[T] =
+  transparent inline def foo[T](t: T): Id[T] =
     inline t match {
       case i: Int => (i+1).asInstanceOf[Id[T]]
       case _ => t

tests/pos/implicit-match-nested.scala

@@ -8,7 +8,7 @@ object `implicit-match-nested` {
   implicit val b1: B[Int] = B[Int]()
   implicit val b2: B[String] = B[String]()
 
-  inline def locateB <: B[_] =
+  transparent inline def locateB: B[_] =
     summonFrom {
       case _: A[t] =>
         summonFrom {

tests/pos/inline-match-specialize.scala

@@ -1,6 +1,6 @@
 object `inline-match-specialize` {
   case class Box[+T](value: T)
-  inline def specialize[T](box: Box[T]) <: Box[T] = inline box match {
+  transparent inline def specialize[T](box: Box[T]): Box[T] = inline box match {
     case box: Box[t] => box
   }
 

tests/pos/inline-named-typeargs.scala

@@ -1,4 +1,4 @@
 // Working version of inline-named-typedargs, the original is currently disabled
 object t1 {
-  inline def construct[Elem, Coll[_]](xs: List[Elem]) <: Coll[Elem] = ???
+  transparent inline def construct[Elem, Coll[_]](xs: List[Elem]): Coll[Elem] = ???
 }

tests/pos/reference/compile-time.scala

@@ -14,7 +14,7 @@ class Test:
 
   final val ctwo = toIntC[2]
 
-  inline def defaultValue[T] <: Option[Any] = inline erasedValue[T] match
+  transparent inline def defaultValue[T]: Option[Any] = inline erasedValue[T] match
     case _: Byte => Some(0: Byte)
     case _: Char => Some(0: Char)
     case _: Short => Some(0: Short)

tests/pos/reference/delegate-match.scala

@@ -4,7 +4,7 @@ class Test extends App:
   import scala.collection.immutable.{TreeSet, HashSet}
   import scala.compiletime.summonFrom
 
-  inline def setFor[T] <: Set[T] = summonFrom {
+  transparent inline def setFor[T]: Set[T] = summonFrom {
     case given ord: Ordering[T] => new TreeSet[T]
     case _                      => new HashSet[T]
   }

tests/run-custom-args/typeclass-derivation2c.scala

@@ -88,7 +88,7 @@ object Lst {
       case Nil => 1
     }
     inline override def numberOfCases = 2
-    inline override def alternative(n: Int) <: Generic[_ <: Lst[T]] =
+    transparent inline override def alternative(n: Int): Generic[_ <: Lst[T]] =
       inline n match {
         case 0 => Cons.GenericCons[T]
         case 1 => Nil.GenericNil
@@ -153,7 +153,7 @@ object Either {
       case x: Right[_] => 1
     }
     inline override def numberOfCases = 2
-    inline override def alternative(n: Int) <: Generic[_ <: Either[L, R]] =
+    inline override def alternative(n: Int): _ <: Generic[_ <: Either[L, R]] =
       inline n match {
         case 0 => Left.GenericLeft[L]
         case 1 => Right.GenericRight[R]

tests/run-macros/xml-interpolation-5/Macros_1.scala

@@ -19,7 +19,7 @@ object XmlQuote {
     opaque type StringContext = scala.StringContext
     def apply(sc: scala.StringContext): StringContext = sc
   }
-  inline def (inline ctx: StringContext).xml <: SCOps.StringContext = SCOps(ctx)
+  transparent inline def (inline ctx: StringContext).xml: SCOps.StringContext = SCOps(ctx)
   inline def (inline ctx: SCOps.StringContext).apply(inline args: Any*): Xml =
     ${XmlQuote.impl('ctx, 'args)}
   // inline def (inline ctx: SCOps.StringContext).unapplySeq(...): Xml = ...

tests/run/typeclass-derivation2b.scala

@@ -49,7 +49,7 @@ object Lst {
       case x: Cons[_] => 0
       case Nil => 1
     }
-    inline def alternative(inline n: Int) <: GenericProduct[_ <: Lst[T]] =
+    transparent inline def alternative(inline n: Int): GenericProduct[_ <: Lst[T]] =
       inline n match {
         case 0 => Cons.GenericCons[T]
         case 1 => Nil.GenericNil