Recognize language imports during parsing

Author: odersky

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

@@ -17,10 +17,11 @@ import NameKinds.WildcardParamName
 import NameOps._
 import ast.{Positioned, Trees}
 import ast.Trees._
+import typer.ImportInfo
 import StdNames._
 import util.Spans._
 import Constants._
-import Symbols.defn
+import Symbols.{defn, NoSymbol}
 import ScriptParsers._
 import Decorators._
 import util.Chars
@@ -492,20 +493,19 @@ object Parsers {
      *  Parameters appear in reverse order.
      */
     var placeholderParams: List[ValDef] = Nil
+    var languageImportContext: Context = ctx
 
-    def checkNoEscapingPlaceholders[T](op: => T): T = {
+    def checkNoEscapingPlaceholders[T](op: => T): T =
       val savedPlaceholderParams = placeholderParams
+      val savedLanguageImportContext = languageImportContext
       placeholderParams = Nil
-
       try op
-      finally {
-        placeholderParams match {
+      finally
+        placeholderParams match
           case vd :: _ => syntaxError(UnboundPlaceholderParameter(), vd.span)
           case _ =>
-        }
         placeholderParams = savedPlaceholderParams
-      }
-    }
+        languageImportContext = savedLanguageImportContext
 
     def isWildcard(t: Tree): Boolean = t match {
       case Ident(name1) => placeholderParams.nonEmpty && name1 == placeholderParams.head.name
@@ -1625,7 +1625,7 @@ object Parsers {
         typeIdent()
       else
         def singletonArgs(t: Tree): Tree =
-          if in.token == LPAREN && dependentEnabled
+          if in.token == LPAREN && dependentEnabled(using languageImportContext)
           then singletonArgs(AppliedTypeTree(t, inParens(commaSeparated(singleton))))
           else t
         singletonArgs(simpleType1())
@@ -3090,7 +3090,9 @@ object Parsers {
 
     /** Create an import node and handle source version imports */
     def mkImport(outermost: Boolean = false): ImportConstr = (tree, selectors) =>
+      val imp = Import(tree, selectors)
       if isLanguageImport(tree) then
+        languageImportContext = languageImportContext.importContext(imp, NoSymbol)
         for
           case ImportSelector(id @ Ident(imported), EmptyTree, _) <- selectors
           if allSourceVersionNames.contains(imported)
@@ -3101,7 +3103,7 @@ object Parsers {
             syntaxError(i"duplicate source version import", id.span)
           else
             ctx.compilationUnit.sourceVersion = Some(SourceVersion.valueOf(imported.toString))
-      Import(tree, selectors)
+      imp
 
     /** ImportExpr       ::=  SimpleRef {‘.’ id} ‘.’ ImportSpec
      *                     |  SimpleRef ‘as’ id