Remove view bounds 🔥

Author: OlivierBlanvillain

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)))
@@ -1135,7 +1138,7 @@ 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
 
@@ -193,7 +193,7 @@ 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 */

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