Cache captureSets of CaptureRefs only at phase cc

Before they are empty.

Author: odersky

compiler/src/dotty/tools/dotc/core/Phases.scala

@@ -15,7 +15,7 @@ import dotty.tools.dotc.transform._
 import Periods._
 import parsing.Parser
 import printing.XprintMode
-import typer.{TyperPhase, RefChecks}
+import typer.{TyperPhase, RefChecks, CheckCaptures}
 import typer.ImportInfo.withRootImports
 import ast.{tpd, untpd}
 import scala.annotation.internal.sharable
@@ -217,6 +217,7 @@ object Phases {
     private var myCountOuterAccessesPhase: Phase = _
     private var myFlattenPhase: Phase = _
     private var myGenBCodePhase: Phase = _
+    private var myCheckCapturesPhase: Phase = _
 
     final def parserPhase: Phase = myParserPhase
     final def typerPhase: Phase = myTyperPhase
@@ -239,6 +240,7 @@ object Phases {
     final def countOuterAccessesPhase = myCountOuterAccessesPhase
     final def flattenPhase: Phase = myFlattenPhase
     final def genBCodePhase: Phase = myGenBCodePhase
+    final def checkCapturesPhase: Phase = myCheckCapturesPhase
 
     private def setSpecificPhases() = {
       def phaseOfClass(pclass: Class[?]) = phases.find(pclass.isInstance).getOrElse(NoPhase)
@@ -263,7 +265,8 @@ object Phases {
       myFlattenPhase = phaseOfClass(classOf[Flatten])
       myExplicitOuterPhase = phaseOfClass(classOf[ExplicitOuter])
       myGettersPhase = phaseOfClass(classOf[Getters])
-      myGenBCodePhase =  phaseOfClass(classOf[GenBCode])
+      myGenBCodePhase = phaseOfClass(classOf[GenBCode])
+      myCheckCapturesPhase = phaseOfClass(classOf[CheckCaptures])
     }
 
     final def isAfterTyper(phase: Phase): Boolean = phase.id > typerPhase.id
@@ -443,6 +446,7 @@ object Phases {
   def lambdaLiftPhase(using Context): Phase             = ctx.base.lambdaLiftPhase
   def flattenPhase(using Context): Phase                = ctx.base.flattenPhase
   def genBCodePhase(using Context): Phase               = ctx.base.genBCodePhase
+  def checkCapturesPhase(using Context): Phase          = ctx.base.checkCapturesPhase
 
   def unfusedPhases(using Context): Array[Phase] = ctx.base.phases
 

compiler/src/dotty/tools/dotc/core/Types.scala

@@ -2052,7 +2052,8 @@ object Types {
 
     def captureSetOfInfo(using Context): CaptureSet =
       if ctx.runId == myCaptureSetRunId then myCaptureSet
-      else if myCaptureSet eq CaptureSet.Pending then CaptureSet.empty
+      else if (myCaptureSet eq CaptureSet.Pending)
+        || ctx.phase != Phases.checkCapturesPhase then CaptureSet.empty
       else
         myCaptureSet = CaptureSet.Pending
         val computed =

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

@@ -67,13 +67,15 @@ abstract class Recheck extends Phase, IdentityDenotTransformer:
 
     def enterDef(stat: Tree)(using Context): Unit =
       val sym = stat.symbol
-      var newInfo = transformType(sym.info)
-      stat match
+      val transInfo = transformType(sym.info)
+      val newInfo = stat match
         case stat: ValOrDefDef if stat.tpt.isInstanceOf[InferredTypeTree] =>
-          newInfo = reinferResult(sym.info)
+          reinferResult(transInfo)
         case stat: Bind =>
-          newInfo = reinferResult(sym.info)
+          reinferResult(transInfo)
         case _ =>
+          transInfo
+      //println(i"update info $sym: ${sym.info} --> $transInfo --> $newInfo")
       sym.updateInfo(newInfo)
 
     def constFold(tree: Tree, tp: Type)(using Context): Type =