Refactoring: move experimental imports checking to Checking.scala

Author: odersky

compiler/src/dotty/tools/dotc/transform/PostTyper.scala

@@ -13,7 +13,6 @@ import Decorators._
 import Symbols._, SymUtils._, NameOps._
 import ContextFunctionResults.annotateContextResults
 import config.Printers.typr
-import config.Feature
 import reporting._
 
 object PostTyper {
@@ -449,30 +448,9 @@ class PostTyper extends MacroTransform with IdentityDenotTransformer { thisPhase
           throw ex
       }
 
-    /** In addition to normal processing, check that experimental language
-     *  imports are done only in experimental scopes, or in scopes where
-     *  all statements are @experimental definitions.
-     */
     override def transformStats(trees: List[Tree], exprOwner: Symbol)(using Context): List[Tree] =
-
-      def onlyExperimentalDefs = trees.forall {
-        case _: Import | EmptyTree => true
-        case stat: MemberDef => stat.symbol.isExperimental
-        case _ => false
-      }
-
-      def checkExperimentalImports =
-        for case imp @ Import(qual, selectors) <- trees do
-          languageImport(qual) match
-            case Some(nme.experimental)
-            if !ctx.owner.isInExperimentalScope && !onlyExperimentalDefs
-               && selectors.exists(sel => Feature.experimental(sel.name) != Feature.scala2macros) =>
-              Feature.checkExperimentalFeature("features", imp.srcPos)
-            case _ =>
-
       try super.transformStats(trees, exprOwner)
-      finally checkExperimentalImports
-    end transformStats
+      finally Checking.checkExperimentalImports(trees)
 
     /** Transforms the rhs tree into a its default tree if it is in an `erased` val/def.
      *  Performed to shrink the tree that is known to be erased later.

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

@@ -721,6 +721,24 @@ object Checking {
         checkValue(tree)
       case _ =>
     tree
+
+  /** Check that experimental language imports in `trees`
+   *  are done only in experimental scopes, or in scopes where
+   *  all statements are @experimental definitions.
+   */
+  def checkExperimentalImports(trees: List[Tree])(using Context): Unit =
+    def onlyExperimentalDefs = trees.forall {
+      case _: Import | EmptyTree => true
+      case stat: MemberDef => stat.symbol.isExperimental
+      case _ => false
+    }
+    for case imp @ Import(qual, selectors) <- trees do
+      languageImport(qual) match
+        case Some(nme.experimental)
+        if !ctx.owner.isInExperimentalScope && !onlyExperimentalDefs
+            && selectors.exists(sel => experimental(sel.name) != scala2macros) =>
+          checkExperimentalFeature("features", imp.srcPos)
+        case _ =>
 }
 
 trait Checking {
@@ -832,6 +850,7 @@ trait Checking {
         em"Implementation restriction: ${path.tpe.classSymbol} is not a valid prefix " +
           "for a wildcard export, as it is a package.", path.srcPos)
 
+
   /** Check that module `sym` does not clash with a class of the same name
    *  that is concurrently compiled in another source file.
    */