Merge pull request #6037 from dotty-staging/remove-view-bounds

Remove view bounds

Author: odersky

compiler/src/dotty/tools/dotc/core/TypeOps.scala

@@ -379,29 +379,31 @@ trait TypeOps { this: Context => // TODO: Make standalone object.
    *  where <prefix> is the full name of the owner followed by a "." minus
    *  the prefix "dotty.language.".
    */
-  def featureEnabled(owner: ClassSymbol, feature: TermName): Boolean = {
-    val hasImport =
+  def featureEnabled(feature: TermName, owner: Symbol = NoSymbol): Boolean = {
+    def hasImport = {
+      val owner1 = if (!owner.exists) defn.LanguageModuleClass else owner
       ctx.importInfo != null &&
-      ctx.importInfo.featureImported(owner, feature)(ctx.withPhase(ctx.typerPhase))
-    def hasOption = {
+      ctx.importInfo.featureImported(feature, owner1)(ctx.withPhase(ctx.typerPhase))
+    }
+    val hasOption = {
       def toPrefix(sym: Symbol): String =
-        if (!sym.exists || (sym eq defn.LanguageModuleClass)) ""
+        if (!sym.exists) ""
         else toPrefix(sym.owner) + sym.name + "."
       val featureName = toPrefix(owner) + feature
       ctx.base.settings.language.value exists (s => s == featureName || s == "_")
     }
-    hasImport || hasOption
+    hasOption || hasImport
   }
 
   /** Is auto-tupling enabled? */
   def canAutoTuple: Boolean =
-    !featureEnabled(defn.LanguageModuleClass, nme.noAutoTupling)
+    !featureEnabled(nme.noAutoTupling)
 
   def scala2Mode: Boolean =
-    featureEnabled(defn.LanguageModuleClass, nme.Scala2)
+    featureEnabled(nme.Scala2)
 
   def dynamicsEnabled: Boolean =
-    featureEnabled(defn.LanguageModuleClass, nme.dynamics)
+    featureEnabled(nme.dynamics)
 
   def testScala2Mode(msg: => Message, pos: SourcePosition, replace: => Unit = ()): Boolean = {
     if (scala2Mode) {
@@ -414,7 +416,8 @@ trait TypeOps { this: Context => // TODO: Make standalone object.
   /** Is option -language:Scala2 set?
    *  This test is used when we are too early in the pipeline to consider imports.
    */
-  def scala2Setting = ctx.settings.language.value.contains(nme.Scala2.toString)
+  def scala2Setting: Boolean =
+    ctx.settings.language.value.contains(nme.Scala2.toString)
 
   /** Refine child based on parent
    *

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

@@ -296,6 +296,9 @@ object Parsers {
     def deprecationWarning(msg: => Message, offset: Int = in.offset): Unit =
       ctx.deprecationWarning(msg, source.atSpan(Span(offset)))
 
+    def errorOrMigrationWarning(msg: => Message, offset: Int = in.offset): Unit =
+      ctx.errorOrMigrationWarning(msg, source.atSpan(Span(offset)))
+
     /** Issue an error at current offset that input is incomplete */
     def incompleteInputError(msg: => Message): Unit =
       ctx.incompleteInputError(msg, source.atSpan(Span(in.offset)))
@@ -1136,7 +1139,7 @@ object Parsers {
           AppliedTypeTree(toplevelTyp(), Ident(pname))
         } :: contextBounds(pname)
       case VIEWBOUND =>
-        deprecationWarning("view bounds `<%' are deprecated, use a context bound `:' instead")
+        errorOrMigrationWarning("view bounds `<%' are deprecated, use a context bound `:' instead")
         atSpan(in.skipToken()) {
           Function(Ident(pname) :: Nil, toplevelTyp())
         } :: contextBounds(pname)

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

@@ -112,7 +112,7 @@ abstract class TokensCommon {
   //final val SUPERTYPE = 81;        enter(SUPERTYPE, ">:")
   //final val HASH = 82;             enter(HASH, "#")
   final val AT = 83;               enter(AT, "@")
-  //final val VIEWBOUND = 84;        enter(VIEWBOUND, "<%") // TODO: deprecate
+  //final val VIEWBOUND = 84;        enter(VIEWBOUND, "<%")
 
   val keywords: TokenSet
 
@@ -194,7 +194,7 @@ object Tokens extends TokensCommon {
   final val SUBTYPE = 80;          enter(SUBTYPE, "<:")
   final val SUPERTYPE = 81;        enter(SUPERTYPE, ">:")
   final val HASH = 82;             enter(HASH, "#")
-  final val VIEWBOUND = 84;        enter(VIEWBOUND, "<%") // TODO: deprecate
+  final val VIEWBOUND = 84;        enter(VIEWBOUND, "<%")
   final val QUOTE = 85;            enter(QUOTE, "'")
 
   /** XML mode */

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

@@ -66,11 +66,10 @@ trait Reporting { this: Context =>
   def featureWarning(msg: => Message, pos: SourcePosition = NoSourcePosition): Unit =
     reportWarning(new FeatureWarning(msg, pos))
 
-  def featureWarning(feature: String, featureDescription: String, isScala2Feature: Boolean,
+  def featureWarning(feature: String, featureDescription: String,
       featureUseSite: Symbol, required: Boolean, pos: SourcePosition): Unit = {
     val req = if (required) "needs to" else "should"
-    val prefix = if (isScala2Feature) "scala." else "dotty."
-    val fqname = prefix + "language." + feature
+    val fqname = s"scala.language.$feature"
 
     val explain = {
       if (reporter.isReportedFeatureUseSite(featureUseSite)) ""

compiler/src/dotty/tools/dotc/typer/Checking.scala

@@ -623,7 +623,7 @@ trait Checking {
   def checkImplicitConversionDefOK(sym: Symbol)(implicit ctx: Context): Unit = {
     def check(): Unit = {
       checkFeature(
-        defn.LanguageModuleClass, nme.implicitConversions,
+        nme.implicitConversions,
         i"Definition of implicit conversion $sym",
         ctx.owner.topLevelClass,
         sym.sourcePos)
@@ -660,20 +660,17 @@ trait Checking {
         defn.isPredefClass(conv.owner) ||
         conv.name == nme.reflectiveSelectable && conv.maybeOwner.maybeOwner.maybeOwner == defn.ScalaPackageClass
       if (!conversionOK)
-        checkFeature(defn.LanguageModuleClass, nme.implicitConversions,
+        checkFeature(nme.implicitConversions,
           i"Use of implicit conversion ${conv.showLocated}", NoSymbol, posd.sourcePos)
     }
 
   /** Issue a feature warning if feature is not enabled */
-  def checkFeature(base: ClassSymbol,
-                   name: TermName,
+  def checkFeature(name: TermName,
                    description: => String,
                    featureUseSite: Symbol,
                    pos: SourcePosition)(implicit ctx: Context): Unit =
-    if (!ctx.featureEnabled(base, name))
-      ctx.featureWarning(name.toString, description,
-        isScala2Feature = base.isContainedIn(defn.LanguageModuleClass),
-        featureUseSite, required = false, pos)
+    if (!ctx.featureEnabled(name))
+      ctx.featureWarning(name.toString, description, featureUseSite, required = false, pos)
 
   /** Check that `tp` is a class type and that any top-level type arguments in this type
    *  are feasible, i.e. that their lower bound conforms to their upper bound. If a type
@@ -1056,5 +1053,5 @@ trait NoChecking extends ReChecking {
   override def checkNoForwardDependencies(vparams: List[ValDef])(implicit ctx: Context): Unit = ()
   override def checkMembersOK(tp: Type, pos: SourcePosition)(implicit ctx: Context): Type = tp
   override def checkInInlineContext(what: String, posd: Positioned)(implicit ctx: Context): Unit = ()
-  override def checkFeature(base: ClassSymbol, name: TermName, description: => String, featureUseSite: Symbol, pos: SourcePosition)(implicit ctx: Context): Unit = ()
+  override def checkFeature(name: TermName, description: => String, featureUseSite: Symbol, pos: SourcePosition)(implicit ctx: Context): Unit = ()
 }

compiler/src/dotty/tools/dotc/typer/Implicits.scala

@@ -947,7 +947,7 @@ trait Implicits { self: Typer =>
 
   private def strictEquality(implicit ctx: Context): Boolean =
     ctx.mode.is(Mode.StrictEquality) ||
-    ctx.featureEnabled(defn.LanguageModuleClass, nme.strictEquality)
+    ctx.featureEnabled(nme.strictEquality)
 
   /** An Eql[T, U] instance is assumed
    *   - if one of T, U is an error type, or

compiler/src/dotty/tools/dotc/typer/ImportInfo.scala

@@ -146,15 +146,15 @@ class ImportInfo(symf: Context => Symbol, val selectors: List[untpd.Tree],
   private[this] var myUnimported: Symbol = _
 
   /** Does this import clause or a preceding import clause import `owner.feature`? */
-  def featureImported(owner: Symbol, feature: TermName)(implicit ctx: Context): Boolean = {
+  def featureImported(feature: TermName, owner: Symbol)(implicit ctx: Context): Boolean = {
     def compute = {
-      val isImportOwner = site.widen.typeSymbol `eq` owner
+      val isImportOwner = site.widen.typeSymbol.eq(owner)
       if (isImportOwner && originals.contains(feature)) true
       else if (isImportOwner && excluded.contains(feature)) false
       else {
         var c = ctx.outer
         while (c.importInfo eq ctx.importInfo) c = c.outer
-        (c.importInfo != null) && c.importInfo.featureImported(owner, feature)(c)
+        (c.importInfo != null) && c.importInfo.featureImported(feature, owner)(c)
       }
     }
     if (lastOwner.ne(owner) || !lastResults.contains(feature)) {

compiler/src/dotty/tools/dotc/typer/Typer.scala

@@ -1695,8 +1695,7 @@ class Typer extends Namer
         !ctx.dynamicsEnabled
       if (reportDynamicInheritance) {
         val isRequired = parents1.exists(_.tpe.isRef(defn.DynamicClass))
-        ctx.featureWarning(nme.dynamics.toString, "extension of type scala.Dynamic", isScala2Feature = true,
-          cls, isRequired, cdef.sourcePos)
+        ctx.featureWarning(nme.dynamics.toString, "extension of type scala.Dynamic", cls, isRequired, cdef.sourcePos)
       }
 
       checkNonCyclicInherited(cls.thisType, cls.classParents, cls.info.decls, cdef.posd)

compiler/test/dotty/tools/dotc/CompilationTests.scala

@@ -34,7 +34,7 @@ class CompilationTests extends ParallelTesting {
   // @Test  // enable to test compileStdLib separately with detailed stats
   def compileStdLibOnly: Unit = {
     implicit val testGroup: TestGroup = TestGroup("compileStdLibOnly")
-    compileList("compileStdLib", TestSources.stdLibSources, scala2Mode.and("-migration", "-Yno-inline", "-Ydetailed-stats"))
+    compileList("compileStdLib", TestSources.stdLibSources, scala2Mode.and("-migration", "-Yno-inline"))
   }.checkCompile()
 
   @Test def pos: Unit = {

docs/docs/internals/syntax.md

@@ -171,7 +171,7 @@ NamedTypeArg      ::=  id ‘=’ Type
 NamedTypeArgs     ::=  ‘[’ NamedTypeArg {‘,’ NamedTypeArg} ‘]’                  nts
 Refinement        ::=  ‘{’ [RefineDcl] {semi [RefineDcl]} ‘}’                   ds
 SubtypeBounds     ::=  [‘>:’ Type] [‘<:’ Type] | INT                            TypeBoundsTree(lo, hi)
-TypeParamBounds   ::=  SubtypeBounds {‘<%’ Type} {‘:’ Type}                     ContextBounds(typeBounds, tps)
+TypeParamBounds   ::=  SubtypeBounds {‘:’ Type}                                 ContextBounds(typeBounds, tps)
 ```
 
 ### Expressions