several fixes to CC compiler

Author: Linyxus

tests/pos-with-compiler-cc/dotc/core/GadtConstraint.scala

@@ -238,7 +238,7 @@ sealed trait GadtConstraint (
   private def tvarOrError(sym: Symbol)(using Context): TypeVar =
     mapping(sym).ensuring(_ != null, i"not a constrainable symbol: $sym").uncheckedNN
 
-  private def containsNoInternalTypes(tp: Type, theAcc: TypeAccumulator[Boolean] | Null = null)(using Context): Boolean = tp match {
+  private def containsNoInternalTypes(tp: Type, theAcc: TypeAccumulator[Boolean] @retains(caps.*) | Null = null)(using Context): Boolean = tp match {
     case tpr: TypeParamRef => !reverseMapping.contains(tpr)
     case tv: TypeVar => !reverseMapping.contains(tv.origin)
     case tp =>

tests/pos-with-compiler-cc/dotc/core/Types.scala

@@ -115,7 +115,7 @@ object Types {
     private def testProvisional(using Context): Boolean =
       class ProAcc extends TypeAccumulator[Boolean]:
         override def apply(x: Boolean, t: Type) = x || test(t, this)
-      def test(t: Type, theAcc: TypeAccumulator[Boolean] | Null): Boolean =
+      def test(t: Type, theAcc: TypeAccumulator[Boolean] @retains(caps.*) | Null): Boolean =
         if t.mightBeProvisional then
           t.mightBeProvisional = t match
             case t: TypeRef =>
@@ -3773,7 +3773,7 @@ object Types {
         val status = (x & StatusMask) max (y & StatusMask)
         val provisional = (x | y) & Provisional
         (if status == TrueDeps then status else status | provisional).toByte
-      def compute(status: DependencyStatus, tp: Type, theAcc: TypeAccumulator[DependencyStatus] | Null): DependencyStatus =
+      def compute(status: DependencyStatus, tp: Type, theAcc: TypeAccumulator[DependencyStatus] @retains(caps.*) | Null): DependencyStatus =
         def applyPrefix(tp: NamedType) =
           if tp.isInstanceOf[SingletonType] && tp.currentSymbol.isStatic
           then status // Note: a type ref with static symbol can still be dependent since the symbol might be refined in the enclosing type. See pos/15331.scala.
@@ -4351,7 +4351,7 @@ object Types {
     private var myEvalRunId: RunId = NoRunId
     private var myEvalued: Type = uninitialized
 
-    def isGround(acc: TypeAccumulator[Boolean])(using Context): Boolean =
+    def isGround(acc: TypeAccumulator[Boolean] @retains(caps.*))(using Context): Boolean =
       if myGround == 0 then myGround = if acc.foldOver(true, this) then 1 else -1
       myGround > 0
 
@@ -5750,7 +5750,7 @@ object Types {
       }
     }
 
-    private def treeTypeMap = new TreeTypeMap(typeMap = this)
+    private def treeTypeMap = new TreeTypeMap(typeMap = this.detach)
 
     def mapOver(syms: List[Symbol]): List[Symbol] = mapSymbols(syms, treeTypeMap)
 

tests/pos-with-compiler-cc/dotc/transform/TreeMapWithStages.scala

@@ -18,7 +18,7 @@ import scala.annotation.constructorOnly
  *                     and `l == -1` is code inside a top level splice (in an inline method).
  *  @param  levels     a stacked map from symbols to the levels in which they were defined
  */
-abstract class TreeMapWithStages(@constructorOnly ictx: Context) extends TreeMapWithImplicits {
+abstract class TreeMapWithStages(@constructorOnly ictx: Context) extends TreeMapWithImplicits { this: {} TreeMapWithStages =>
 
   import tpd._
   import TreeMapWithStages._

tests/pos-with-compiler-cc/dotc/transform/init/Semantic.scala

@@ -515,7 +515,7 @@ object Semantic:
   object Reporter:
     class BufferedReporter extends Reporter:
       private val buf = new mutable.ArrayBuffer[Error]
-      def errors = buf.toList
+      def errors: List[Error] = buf.toList
       def report(err: Error) = buf += err
 
     class TryBufferedReporter(backup: Cache) extends BufferedReporter with TryReporter: