Streamline CCState handling

Author: odersky

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

@@ -36,22 +36,26 @@ def allowUniversalInBoxed(using Context) =
 /** An exception thrown if a @retains argument is not syntactically a CaptureRef */
 class IllegalCaptureRef(tpe: Type) extends Exception
 
-/** Capture checking state, consisting of
- *   - nestingLevels: A map associating certain symbols (the nesting level owners)
- 8     with their ccNestingLevel
- *   - localRoots: A map associating nesting level owners with the local roots valid
- *     in their scopes.
- *   - levelError: Optionally, the last pair of capture reference and capture set where
- *     the reference could not be added to the set due to a level conflict.
- *  The capture checking state is stored in a context property.
- */
+/** Capture checking state, which is stored in a context property */
 class CCState:
+
+  /** Associates certain symbols (the nesting level owners) with their ccNestingLevel */
   val nestingLevels: mutable.HashMap[Symbol, Int] = new mutable.HashMap
+
+  /** Associates nesting level owners with the local roots valid in their scopes. */
   val localRoots: mutable.HashMap[Symbol, Symbol] = new mutable.HashMap
+
+  /** The last pair of capture reference and capture set where
+   *  the reference could not be added to the set due to a level conflict.
+   */
   var levelError: Option[(CaptureRef, CaptureSet)] = None
+end CCState
 
 /** Property key for capture checking state */
-val ccState: Key[CCState] = Key()
+val ccStateKey: Key[CCState] = Key()
+
+/** The currently valid CCState */
+def ccState(using Context) = ctx.property(ccStateKey).get
 
 trait FollowAliases extends TypeMap:
   def mapOverFollowingAliases(t: Type): Type = t match
@@ -348,7 +352,7 @@ extension (sym: Symbol)
     else if sym.is(Method) then
       if sym.isAnonymousFunction then
         // Setup added anonymous functions counting as level owners to nestingLevels
-        ctx.property(ccState).get.nestingLevels.contains(sym)
+        ccState.nestingLevels.contains(sym)
       else
         !sym.isConstructor && !isCaseClassSynthetic
     else false
@@ -371,21 +375,18 @@ extension (sym: Symbol)
   def ccNestingLevel(using Context): Int =
     if sym.exists then
       val lowner = sym.levelOwner
-      val cache = ctx.property(ccState).get.nestingLevels
-      cache.getOrElseUpdate(lowner,
+      ccState.nestingLevels.getOrElseUpdate(lowner,
         if lowner.isRoot then 0 else lowner.owner.ccNestingLevel + 1)
     else -1
 
   /** Optionally, the nesting level of `sym` for the purposes of `cc`, provided
    *  a capture checker is running.
    */
   def ccNestingLevelOpt(using Context): Option[Int] =
-    if ctx.property(ccState).isDefined then
-      Some(ccNestingLevel)
-    else None
+    if ctx.property(ccStateKey).isDefined then Some(ccNestingLevel) else None
 
   def setNestingLevel(level: Int)(using Context): Unit =
-    ctx.property(ccState).get.nestingLevels(sym) = level
+    ccState.nestingLevels(sym) = level
 
   /** The parameter with type caps.Root in the leading term parameter section,
    *  or NoSymbol, if none exists.
@@ -403,7 +404,7 @@ extension (sym: Symbol)
     def lclRoot =
       if owner.isTerm then owner.definedLocalRoot.orElse(newRoot)
       else newRoot
-    ctx.property(ccState).get.localRoots.getOrElseUpdate(owner, lclRoot)
+    ccState.localRoots.getOrElseUpdate(owner, lclRoot)
 
   def maxNested(other: Symbol)(using Context): Symbol =
     if sym.ccNestingLevel < other.ccNestingLevel then other else sym

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

@@ -484,7 +484,7 @@ object CaptureSet:
 
     private def recordLevelError()(using Context): Unit =
       for elem <- triedElem do
-        ctx.property(ccState).get.levelError = Some((elem, this))
+        ccState.levelError = Some((elem, this))
 
     private def levelOK(elem: CaptureRef)(using Context): Boolean = elem match
       case elem: (TermRef | ThisType) => elem.ccNestingLevel <= ownLevel
@@ -1024,7 +1024,7 @@ object CaptureSet:
   def levelErrors: Addenda = new Addenda:
     override def toAdd(using Context) =
       for
-        state <- ctx.property(ccState).toList
+        state <- ctx.property(ccStateKey).toList
         (ref, cs) <- state.levelError
       yield
         val levelStr = ref match

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

@@ -46,11 +46,11 @@ object CheckCaptures:
 
   enum EnvKind:
     case Regular        // normal case
-    case NestedInOwner  // environment is  a temporary one nested in the owner's environment,
+    case NestedInOwner  // environment is a temporary one nested in the owner's environment,
                         // and does not have a different actual owner symbol
                         // (this happens when doing box adaptation).
     case ClosureResult  // environment is for the result of a closure
-    case Boxed          // envrionment is inside a box (in which case references are not counted)
+    case Boxed          // environment is inside a box (in which case references are not counted)
 
   /** A class describing environments.
    *  @param owner     the current owner
@@ -211,7 +211,7 @@ class CheckCaptures extends Recheck, SymTransformer:
     if Synthetics.needsTransform(sym) then Synthetics.transform(sym, toCC = false)
     else super.transformSym(sym)
 
-  override def printingContext(ctx: Context) = ctx.withProperty(ccState, Some(new CCState))
+  override def printingContext(ctx: Context) = ctx.withProperty(ccStateKey, Some(new CCState))
 
   class CaptureChecker(ictx: Context) extends Rechecker(ictx):
     import ast.tpd.*
@@ -1010,7 +1010,7 @@ class CheckCaptures extends Recheck, SymTransformer:
 
     override def checkUnit(unit: CompilationUnit)(using Context): Unit =
       setup = Setup(preRecheckPhase, thisPhase, recheckDef)
-      inContext(ctx.withProperty(ccState, Some(state))):
+      inContext(ctx.withProperty(ccStateKey, Some(state))):
         setup(ctx.compilationUnit.tpdTree)
         //println(i"SETUP:\n${Recheck.addRecheckedTypes.transform(ctx.compilationUnit.tpdTree)}")
         withCaptureSetsExplained: