Drop old levelOwner scheme

Author: odersky

compiler/src/dotty/tools/dotc/cc/CaptureSet.scala

@@ -56,10 +56,14 @@ sealed abstract class CaptureSet extends Showable:
    */
   def isAlwaysEmpty: Boolean
 
-  /** An optional level limit, or NoSymbol if none exists. All elements of the set
-   *  must be in scopes visible from the level limit.
+  /** An optional level limit, or -1 if none exists. All elements of the set
+   *  must be at levels equal or smaller than the level of the set.
    */
-  def levelLimit: Symbol
+  def level: Int
+
+  /** An optional owner, or NoSymbol if none exists. Used for diagnstics
+   */
+  def owner: Symbol
 
   /** Is this capture set definitely non-empty? */
   final def isNotEmpty: Boolean = !elems.isEmpty
@@ -242,9 +246,7 @@ sealed abstract class CaptureSet extends Showable:
     if this.subCaptures(that, frozen = true).isOK then that
     else if that.subCaptures(this, frozen = true).isOK then this
     else if this.isConst && that.isConst then Const(this.elems ++ that.elems)
-    else Var(
-        this.levelLimit.maxNested(that.levelLimit, onConflict = (sym1, sym2) => sym1),
-        this.elems ++ that.elems)
+    else Var(initialElems = this.elems ++ that.elems)
       .addAsDependentTo(this).addAsDependentTo(that)
 
   /** The smallest superset (via <:<) of this capture set that also contains `ref`.
@@ -414,7 +416,9 @@ object CaptureSet:
 
     def withDescription(description: String): Const = Const(elems, description)
 
-    def levelLimit = NoSymbol
+    def level = -1
+
+    def owner = NoSymbol
 
     override def toString = elems.toString
   end Const
@@ -434,7 +438,7 @@ object CaptureSet:
   end Fluid
 
   /** The subclass of captureset variables with given initial elements */
-  class Var(directOwner: Symbol, initialElems: Refs = emptySet, level: Int = -1, underBox: Boolean = false)(using @constructorOnly ictx: Context) extends CaptureSet:
+  class Var(override val owner: Symbol = NoSymbol, initialElems: Refs = emptySet, val level: Int = -1, underBox: Boolean = false)(using @constructorOnly ictx: Context) extends CaptureSet:
 
     /** A unique identification number for diagnostics */
     val id =
@@ -443,9 +447,6 @@ object CaptureSet:
 
     //assert(id != 40)
 
-    override val levelLimit =
-      if directOwner.exists then directOwner.levelOwner else NoSymbol
-
     /** A variable is solved if it is aproximated to a from-then-on constant set. */
     private var isSolved: Boolean = false
 
@@ -519,9 +520,9 @@ object CaptureSet:
     private def levelOK(elem: CaptureRef)(using Context): Boolean =
       if elem.isRootCapability then !noUniversal
       else elem match
-        case elem: TermRef if levelLimit.exists =>
+        case elem: TermRef if level != -1 =>
           level == -1 || ccState.level(elem.symbol) <= level
-        case elem: ThisType if levelLimit.exists =>
+        case elem: ThisType if level != 1 =>
           level == -1 || ccState.level(elem.cls) + 1 <= level
         case ReachCapability(elem1) =>
           levelOK(elem1)
@@ -600,8 +601,8 @@ object CaptureSet:
       val debugInfo =
         if !isConst && ctx.settings.YccDebug.value then ids else ""
       val limitInfo =
-        if ctx.settings.YprintLevel.value && levelLimit.exists
-        then i"<in $levelLimit>"
+        if ctx.settings.YprintLevel.value && level != -1
+        then i"<at level $level>"
         else ""
       debugInfo ++ limitInfo
 
@@ -648,7 +649,7 @@ object CaptureSet:
    */
   class Mapped private[CaptureSet]
     (val source: Var, tm: TypeMap, variance: Int, initial: CaptureSet)(using @constructorOnly ctx: Context)
-  extends DerivedVar(source.levelLimit, initial.elems):
+  extends DerivedVar(source.owner, initial.elems):
     addAsDependentTo(initial)  // initial mappings could change by propagation
 
     private def mapIsIdempotent = tm.isInstanceOf[IdempotentCaptRefMap]
@@ -745,7 +746,7 @@ object CaptureSet:
    */
   final class BiMapped private[CaptureSet]
     (val source: Var, bimap: BiTypeMap, initialElems: Refs)(using @constructorOnly ctx: Context)
-  extends DerivedVar(source.levelLimit, initialElems):
+  extends DerivedVar(source.owner, initialElems):
 
     override def tryInclude(elem: CaptureRef, origin: CaptureSet)(using Context, VarState): CompareResult =
       if origin eq source then
@@ -779,7 +780,7 @@ object CaptureSet:
   /** A variable with elements given at any time as { x <- source.elems | p(x) } */
   class Filtered private[CaptureSet]
     (val source: Var, p: Context ?=> CaptureRef => Boolean)(using @constructorOnly ctx: Context)
-  extends DerivedVar(source.levelLimit, source.elems.filter(p)):
+  extends DerivedVar(source.owner, source.elems.filter(p)):
 
     override def tryInclude(elem: CaptureRef, origin: CaptureSet)(using Context, VarState): CompareResult =
       if accountsFor(elem) then
@@ -809,7 +810,7 @@ object CaptureSet:
   extends Filtered(source, !other.accountsFor(_))
 
   class Intersected(cs1: CaptureSet, cs2: CaptureSet)(using Context)
-  extends Var(cs1.levelLimit.minNested(cs2.levelLimit), elemIntersection(cs1, cs2)):
+  extends Var(initialElems = elemIntersection(cs1, cs2)):
     addAsDependentTo(cs1)
     addAsDependentTo(cs2)
     deps += cs1
@@ -899,7 +900,7 @@ object CaptureSet:
             if ctx.settings.YccDebug.value then printer.toText(trace, ", ")
             else blocking.show
           case LevelError(cs: CaptureSet, elem: CaptureRef) =>
-            Str(i"($elem at wrong level for $cs in ${cs.levelLimit})")
+            Str(i"($elem at wrong level for $cs at level ${cs.level})")
 
     /** The result is OK */
     def isOK: Boolean = this == OK
@@ -1142,6 +1143,6 @@ object CaptureSet:
           i"""
             |
             |Note that reference ${ref}$levelStr
-            |cannot be included in outer capture set $cs which is associated with ${cs.levelLimit}"""
+            |cannot be included in outer capture set $cs"""
 
 end CaptureSet

tests/neg-custom-args/captures/levels.check

@@ -12,6 +12,6 @@
    |           Required: box (x$0: String) ->? String
    |
    |           Note that reference (cap3 : CC^), defined in method scope
-   |           cannot be included in outer capture set ? of value r which is associated with method test2
+   |           cannot be included in outer capture set ? of value r
    |
    | longer explanation available when compiling with `-explain`

tests/neg-custom-args/captures/outer-var.check

@@ -32,7 +32,7 @@
    |        Required: () ->{p} Unit
    |
    |        Note that reference (q : Proc), defined in method inner
-   |        cannot be included in outer capture set {p} of variable y which is associated with method test
+   |        cannot be included in outer capture set {p} of variable y
    |
    | longer explanation available when compiling with `-explain`
 -- Error: tests/neg-custom-args/captures/outer-var.scala:16:53 ---------------------------------------------------------

tests/neg-custom-args/captures/reaches.check

@@ -12,7 +12,7 @@
    |       Required: box List[box () ->{xs*} Unit]^?
    |
    |       Note that reference (f : File^), defined in method $anonfun
-   |       cannot be included in outer capture set {xs*} of value cur which is associated with method runAll1
+   |       cannot be included in outer capture set {xs*} of value cur
    |
    | longer explanation available when compiling with `-explain`
 -- Error: tests/neg-custom-args/captures/reaches.scala:35:6 ------------------------------------------------------------

tests/neg-custom-args/captures/vars.check

@@ -4,15 +4,15 @@
    |             reference (cap3 : Cap) is not included in the allowed capture set {cap1} of variable a
    |
    |             Note that reference (cap3 : Cap), defined in method scope
-   |             cannot be included in outer capture set {cap1} of variable a which is associated with method test
+   |             cannot be included in outer capture set {cap1} of variable a
 -- [E007] Type Mismatch Error: tests/neg-custom-args/captures/vars.scala:23:8 ------------------------------------------
 23 |    a = g      // error
    |        ^
    |        Found:    (x: String) ->{cap3} String
    |        Required: (x$0: String) ->{cap1} String
    |
    |        Note that reference (cap3 : Cap), defined in method scope
-   |        cannot be included in outer capture set {cap1} of variable a which is associated with method test
+   |        cannot be included in outer capture set {cap1} of variable a
    |
    | longer explanation available when compiling with `-explain`
 -- [E007] Type Mismatch Error: tests/neg-custom-args/captures/vars.scala:25:12 -----------------------------------------

tests/printing/dependent-annot.check

@@ -11,12 +11,7 @@ package <empty> {
     def f(y: C, z: C): Unit =
       {
         def g(): C @ann([y,z : Any]*) = ???
-        val ac:
-          (C => Array[String])
-            {
-              def apply(x: C): Array[String @ann([x : Any]*)]
-            }
-         = ???
+        val ac: (x: C) => Array[String @ann([x : Any]*)] = ???
         val dc: Array[String] = ac.apply(g())
         ()
       }