Streamline feature handling in Parser

Author: odersky

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

@@ -19,11 +19,12 @@ object Feature:
   private def deprecated(str: String): TermName =
     QualifiedName(nme.deprecated, str.toTermName)
 
-  private val Xdependent = experimental("dependent")
-  private val XnamedTypeArguments = experimental("namedTypeArguments")
-  private val XgenericNumberLiterals = experimental("genericNumberLiterals")
-  private val Xmacros = experimental("macros")
-  private val symbolLiterals: TermName = deprecated("symbolLiterals")
+  private val namedTypeArguments = experimental("namedTypeArguments")
+  private val genericNumberLiterals = experimental("genericNumberLiterals")
+  private val macros = experimental("macros")
+
+  val dependent = experimental("dependent")
+  val symbolLiterals: TermName = deprecated("symbolLiterals")
 
 /** Is `feature` enabled by by a command-line setting? The enabling setting is
    *
@@ -62,15 +63,13 @@ object Feature:
 
   def dynamicsEnabled(using Context): Boolean = enabled(nme.dynamics)
 
-  def dependentEnabled(using Context) = enabled(Xdependent)
-
-  def namedTypeArgsEnabled(using Context) = enabled(XnamedTypeArguments)
+  def dependentEnabled(using Context) = enabled(dependent)
 
-  def genericNumberLiteralsEnabled(using Context) = enabled(XgenericNumberLiterals)
+  def namedTypeArgsEnabled(using Context) = enabled(namedTypeArguments)
 
-  def symbolLiteralsEnabled(using Context) = enabled(symbolLiterals)
+  def genericNumberLiteralsEnabled(using Context) = enabled(genericNumberLiterals)
 
-  def scala2ExperimentalMacroEnabled(using Context) = enabled(Xmacros)
+  def scala2ExperimentalMacroEnabled(using Context) = enabled(macros)
 
   def sourceVersionSetting(using Context): SourceVersion =
     SourceVersion.valueOf(ctx.settings.source.value)

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

@@ -28,7 +28,8 @@ import util.Chars
 import scala.annotation.{tailrec, switch}
 import rewrites.Rewrites.{patch, overlapsPatch}
 import reporting._
-import config.Feature.{sourceVersion, migrateTo3, dependentEnabled, symbolLiteralsEnabled}
+import config.Feature
+import config.Feature.{sourceVersion, migrateTo3}
 import config.SourceVersion._
 import config.SourceVersion
 
@@ -590,6 +591,8 @@ object Parsers {
         if in.currentRegion.indentWidth < nextIndentWidth then
           warning(i"Line is indented too far to the right, or a `{` or `:` is missing", in.next.offset)
 
+    def featureEnabled(name: TermName) = Feature.enabled(name)(using languageImportContext)
+
 /* -------- REWRITES ----------------------------------------------------------- */
 
     /** The last offset where a colon at the end of line would be required if a subsequent { ... }
@@ -1141,7 +1144,7 @@ object Parsers {
             Quote(t)
           }
           else
-            if !symbolLiteralsEnabled(using languageImportContext) then
+            if !featureEnabled(Feature.symbolLiterals) then
               report.errorOrMigrationWarning(
                 em"""symbol literal '${in.name} is no longer supported,
                     |use a string literal "${in.name}" or an application Symbol("${in.name}") instead,
@@ -1572,7 +1575,7 @@ object Parsers {
         typeIdent()
       else
         def singletonArgs(t: Tree): Tree =
-          if in.token == LPAREN && dependentEnabled(using languageImportContext)
+          if in.token == LPAREN && featureEnabled(Feature.dependent)
           then singletonArgs(AppliedTypeTree(t, inParens(commaSeparated(singleton))))
           else t
         singletonArgs(simpleType1())