Change @experimental spec

Author: nicolasstucki

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

@@ -97,24 +97,20 @@ object Feature:
     else
       false
 
-  private val assumeExperimentalIn = Set("dotty.tools.vulpix.ParallelTesting")
-
   def checkExperimentalFeature(which: String, srcPos: SrcPos)(using Context) =
     if !isExperimentalEnabled then
       report.error(i"Experimental $which may only be used with a nightly or snapshot version of the compiler", srcPos)
 
   def checkExperimentalDef(sym: Symbol, srcPos: SrcPos)(using Context) =
     if !isExperimentalEnabled then
       val symMsg =
-        if sym eq defn.ExperimentalAnnot then
-          i"use of @experimental is experimental"
-        else if sym.hasAnnotation(defn.ExperimentalAnnot) then
+        if sym.hasAnnotation(defn.ExperimentalAnnot) then
           i"$sym is marked @experimental"
         else if sym.owner.hasAnnotation(defn.ExperimentalAnnot) then
           i"${sym.owner} is marked @experimental"
         else
           i"$sym inherits @experimental"
-      report.error(s"$symMsg and therefore may only be used with a nightly or snapshot version of the compiler", srcPos)
+      report.error(s"$symMsg and therefore may only be used in an experimental scope.", srcPos)
 
   /** Check that experimental compiler options are only set for snapshot or nightly compiler versions. */
   def checkExperimentalSettings(using Context): Unit =
@@ -123,9 +119,6 @@ object Feature:
     do checkExperimentalFeature(s"feature $setting", NoSourcePosition)
 
   def isExperimentalEnabled(using Context): Boolean =
-    def hasSpecialPermission =
-      Thread.currentThread.getStackTrace.exists(elem =>
-        assumeExperimentalIn.exists(elem.getClassName().startsWith(_)))
-    (Properties.experimental || hasSpecialPermission) && !ctx.settings.YnoExperimental.value
+    Properties.experimental && !ctx.settings.YnoExperimental.value
 
 end Feature

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

@@ -267,11 +267,23 @@ object SymUtils:
 
     /** Is symbol declared or inherits @experimental? */
     def isExperimental(using Context): Boolean =
-      // TODO should be add `@experimental` to `class experimental` in PostTyper?
-      self.eq(defn.ExperimentalAnnot)
-      || self.hasAnnotation(defn.ExperimentalAnnot)
+      self.hasAnnotation(defn.ExperimentalAnnot)
       || (self.maybeOwner.isClass && self.owner.hasAnnotation(defn.ExperimentalAnnot))
 
+    def isInExperimentalScope(using Context): Boolean =
+      def isDefaultArgumentOfExperimentalMethod =
+        self.name.is(DefaultGetterName)
+        && self.owner.isClass
+        && {
+          val overloads = self.owner.asClass.membersNamed(self.name.firstPart)
+          overloads.filterWithFlags(HasDefaultParams, EmptyFlags) match
+            case denot: SymDenotation => denot.symbol.isExperimental
+            case _ => false
+        }
+      self.hasAnnotation(defn.ExperimentalAnnot)
+      || isDefaultArgumentOfExperimentalMethod
+      || (!self.is(Package) && self.owner.isInExperimentalScope)
+
     /** The declared self type of this class, as seen from `site`, stripping
     *  all refinements for opaque types.
     */

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

@@ -948,12 +948,7 @@ object RefChecks {
         report.deprecationWarning(s"${sym.showLocated} is deprecated${since}${msg}", pos)
 
   private def checkExperimental(sym: Symbol, pos: SrcPos)(using Context): Unit =
-    if sym.isExperimental
-    && !sym.isConstructor // already reported on the class
-    && !ctx.owner.isExperimental // already reported on the @experimental of the owner
-    && !sym.is(ModuleClass) // already reported on the module
-    && (sym.span.exists || sym != defn.ExperimentalAnnot) // already reported on inferred annotations
-    then
+    if sym.isExperimental && !ctx.owner.isInExperimentalScope then
       Feature.checkExperimentalDef(sym, pos)
 
   private def checkExperimentalSignature(sym: Symbol, pos: SrcPos)(using Context): Unit =
@@ -963,12 +958,14 @@ object RefChecks {
           Feature.checkExperimentalDef(tp.typeSymbol, pos)
         else
           traverseChildren(tp)
-    if !sym.owner.isExperimental && !pos.span.isSynthetic then // avoid double errors
+
+    if !sym.isInExperimentalScope then
       checker.traverse(sym.info)
 
   private def checkExperimentalAnnots(sym: Symbol)(using Context): Unit =
-    for annot <- sym.annotations if annot.symbol.isExperimental && annot.tree.span.exists do
-      Feature.checkExperimentalDef(annot.symbol, annot.tree)
+    if !sym.isExperimental then
+      for annot <- sym.annotations if annot.symbol.isExperimental && annot.tree.span.exists do
+        Feature.checkExperimentalDef(annot.symbol, annot.tree)
 
   /** If @migration is present (indicating that the symbol has changed semantics between versions),
    *  emit a warning.
@@ -1338,7 +1335,6 @@ class RefChecks extends MiniPhase { thisPhase =>
   }
 
   override def transformTypeDef(tree: TypeDef)(using Context): TypeDef = {
-    checkExperimental(tree.symbol, tree.srcPos)
     checkExperimentalAnnots(tree.symbol)
     tree
   }