move synthetic case symbol detection to treeInfo

encapsulate creating synthetic case labels while we're at it

Author: Adriaan Moors

src/compiler/scala/tools/nsc/ast/TreeGen.scala

@@ -72,8 +72,6 @@ abstract class TreeGen extends reflect.internal.TreeGen with TreeDSL {
     Annotated(Ident(nme.synthSwitch), expr)
   }
 
-  def hasSynthCaseSymbol(t: Tree) = (t.symbol ne null) && (t.symbol hasFlag (CASE | SYNTHETIC))
-
   // TODO: would be so much nicer if we would know during match-translation (i.e., type checking)
   // whether we should emit missingCase-style apply (and isDefinedAt), instead of transforming trees post-factum
   class MatchMatcher {
@@ -94,13 +92,13 @@ abstract class TreeGen extends reflect.internal.TreeGen with TreeDSL {
       case Apply(Apply(TypeApply(Select(tgt, nme.runOrElse), targs), List(scrut)), List(matcher)) if opt.virtPatmat => // println("virt match: "+ (tgt, targs, scrut, matcher) + "for:\n"+ matchExpr )
         caseVirtualizedMatch(matchExpr, tgt, targs, scrut, matcher)
       // optimized version of virtpatmat
-      case Block(stats, matchEndDef) if opt.virtPatmat && (stats forall hasSynthCaseSymbol) =>
+      case Block(stats, matchEndDef) if opt.virtPatmat && (stats forall treeInfo.hasSynthCaseSymbol) =>
         // the assumption is once we encounter a case, the remainder of the block will consist of cases
         // the prologue may be empty, usually it is the valdef that stores the scrut
         val (prologue, cases) = stats span (s => !s.isInstanceOf[LabelDef])
         caseVirtualizedMatchOpt(matchExpr, prologue, cases, matchEndDef, identity)
       // optimized version of virtpatmat
-      case Block(outerStats, orig@Block(stats, matchEndDef)) if opt.virtPatmat && (stats forall hasSynthCaseSymbol) =>
+      case Block(outerStats, orig@Block(stats, matchEndDef)) if opt.virtPatmat && (stats forall treeInfo.hasSynthCaseSymbol) =>
         val (prologue, cases) = stats span (s => !s.isInstanceOf[LabelDef])
         caseVirtualizedMatchOpt(matchExpr, prologue, cases, matchEndDef, m => copyBlock(matchExpr, outerStats, m))
       case other =>

src/compiler/scala/tools/nsc/transform/TailCalls.scala

@@ -36,7 +36,7 @@ abstract class TailCalls extends Transform {
     }
   }
 
-  import gen.hasSynthCaseSymbol
+  import treeInfo.hasSynthCaseSymbol
 
   /**
    * A Tail Call Transformer

src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala

@@ -113,7 +113,6 @@ trait PatternMatching extends Transform with TypingTransformers with ast.TreeDSL
   import definitions._
   import analyzer._ //Typer
 
-  val SYNTH_CASE = Flags.CASE | SYNTHETIC
 
   case class DefaultOverrideMatchAttachment(default: Tree)
 
@@ -241,7 +240,8 @@ trait PatternMatching extends Transform with TypingTransformers with ast.TreeDSL
       // append the default to the list of cases and suppress the unreachable case error that may arise (once we detect that...)
       val matchFailGenOverride = match_.attachments.get[DefaultOverrideMatchAttachment].map{case DefaultOverrideMatchAttachment(default) => ((scrut: Tree) => default)}
 
-      val selectorSym  = freshSym(selector.pos, pureType(selectorTp)) setFlag SYNTH_CASE
+      val selectorSym  = freshSym(selector.pos, pureType(selectorTp)) setFlag treeInfo.SYNTH_CASE_FLAGS
+
       // pt = Any* occurs when compiling test/files/pos/annotDepMethType.scala  with -Xexperimental
       val combined = combineCases(selector, selectorSym, cases map translateCase(selectorSym, pt), pt, matchOwner, matchFailGenOverride)
 
@@ -1316,6 +1316,9 @@ trait PatternMatching extends Transform with TypingTransformers with ast.TreeDSL
     def freshSym(pos: Position, tp: Type = NoType, prefix: String = "x") =
       NoSymbol.newTermSymbol(freshName(prefix), pos) setInfo tp
 
+    def newSynthCaseLabel(name: String) =
+      NoSymbol.newLabel(freshName(name), NoPosition) setFlag treeInfo.SYNTH_CASE_FLAGS
+
     // codegen relevant to the structure of the translation (how extractors are combined)
     trait AbsCodegen {
       def matcher(scrut: Tree, scrutSym: Symbol, restpe: Type)(cases: List[Casegen => Tree], matchFailGen: Option[Tree => Tree]): Tree
@@ -1486,7 +1489,7 @@ trait PatternMatching extends Transform with TypingTransformers with ast.TreeDSL
     case object FalseCond extends Cond {override def toString = "F"}
 
     case class AndCond(a: Cond, b: Cond) extends Cond {override def toString = a +"/\\"+ b}
-    case class OrCond(a: Cond, b: Cond) extends Cond  {override def toString = "("+a+") \\/ ("+ b +")"}
+    case class OrCond(a: Cond, b: Cond)  extends Cond {override def toString = "("+a+") \\/ ("+ b +")"}
 
     object EqualityCond {
       private val uniques = new collection.mutable.HashMap[(Tree, Tree), EqualityCond]
@@ -3108,7 +3111,7 @@ trait PatternMatching extends Transform with TypingTransformers with ast.TreeDSL
           }
       }
 
-      private val defaultLabel: Symbol =  NoSymbol.newLabel(freshName("default"), NoPosition) setFlag SYNTH_CASE
+      private val defaultLabel: Symbol =  newSynthCaseLabel("default")
 
       /** Collapse guarded cases that switch on the same constant (the last case may be unguarded).
        *
@@ -3476,11 +3479,11 @@ trait PatternMatching extends Transform with TypingTransformers with ast.TreeDSL
        * if keepGoing is false, the result Some(x) of the naive translation is encoded as matchRes == x
        */
       def matcher(scrut: Tree, scrutSym: Symbol, restpe: Type)(cases: List[Casegen => Tree], matchFailGen: Option[Tree => Tree]): Tree = {
-        val matchEnd = NoSymbol.newLabel(freshName("matchEnd"), NoPosition) setFlag SYNTH_CASE
+        val matchEnd = newSynthCaseLabel("matchEnd")
         val matchRes = NoSymbol.newValueParameter(newTermName("x"), NoPosition, SYNTHETIC) setInfo restpe.withoutAnnotations //
         matchEnd setInfo MethodType(List(matchRes), restpe)
 
-        def newCaseSym = NoSymbol.newLabel(freshName("case"), NoPosition) setInfo MethodType(Nil, restpe) setFlag SYNTH_CASE
+        def newCaseSym = newSynthCaseLabel("case") setInfo MethodType(Nil, restpe)
         var _currCase = newCaseSym
 
         val caseDefs = cases map { (mkCase: Casegen => Tree) =>

src/compiler/scala/tools/nsc/typechecker/RefChecks.scala

@@ -1718,7 +1718,7 @@ abstract class RefChecks extends InfoTransform with reflect.internal.transform.R
             val pat1 = transform(pat)
             inPattern = false
             treeCopy.CaseDef(tree, pat1, transform(guard), transform(body))
-          case LabelDef(_, _, _) if gen.hasSynthCaseSymbol(result) =>
+          case LabelDef(_, _, _) if treeInfo.hasSynthCaseSymbol(result) =>
             val old = inPattern
             inPattern = true
             val res = deriveLabelDef(result)(transform)

src/continuations/plugin/scala/tools/selectivecps/SelectiveANFTransform.scala

@@ -99,11 +99,11 @@ abstract class SelectiveANFTransform extends PluginComponent with Transform with
                 treeCopy.Block(body, List(transform(selDef)), transformPureMatch(mat, selector, cases))
 
               // virtpatmat
-              case b@Block(matchStats@((selDef: ValDef) :: cases), matchEnd) if ext.isDefined && pureBody && (matchStats forall gen.hasSynthCaseSymbol) =>
+              case b@Block(matchStats@((selDef: ValDef) :: cases), matchEnd) if ext.isDefined && pureBody && (matchStats forall treeInfo.hasSynthCaseSymbol) =>
                 transformPureVirtMatch(b, selDef, cases, matchEnd)
 
               // virtpatmat that stores the scrut separately -- TODO: can we eliminate this case??
-              case Block(List(selDef0: ValDef), mat@Block(matchStats@((selDef: ValDef) :: cases), matchEnd)) if ext.isDefined && pureBody  && (matchStats forall gen.hasSynthCaseSymbol)=>
+              case Block(List(selDef0: ValDef), mat@Block(matchStats@((selDef: ValDef) :: cases), matchEnd)) if ext.isDefined && pureBody  && (matchStats forall treeInfo.hasSynthCaseSymbol)=>
                 treeCopy.Block(body, List(transform(selDef0)), transformPureVirtMatch(mat, selDef, cases, matchEnd))
 
               case _ =>
@@ -253,7 +253,7 @@ abstract class SelectiveANFTransform extends PluginComponent with Transform with
             // calling each labeldef is wrong, since some labels may be jumped over
             // we can get away with this for now since the only other labels we emit are for tailcalls/while loops,
             // which do not have consecutive labeldefs (and thus fall-through is irrelevant)
-            if (gen.hasSynthCaseSymbol(ldef)) (List(stm1), localTyper.typed{Literal(Constant(()))}, cpsA)
+            if (treeInfo.hasSynthCaseSymbol(ldef)) (List(stm1), localTyper.typed{Literal(Constant(()))}, cpsA)
             else {
               assert(params.isEmpty, "problem in ANF transforming label with non-empty params "+ ldef)
               (List(stm1), localTyper.typed{Apply(Ident(sym), List())}, cpsA)
@@ -469,9 +469,9 @@ abstract class SelectiveANFTransform extends PluginComponent with Transform with
 
       val (anfStats, anfExpr) = rec(stms, cpsA, List())
       // println("\nanf-block:\n"+ ((stms :+ expr) mkString ("{", "\n", "}")) +"\nBECAME\n"+ ((anfStats :+ anfExpr) mkString ("{", "\n", "}")))
-      // println("synth case? "+ (anfStats map (t => (t, t.isDef, gen.hasSynthCaseSymbol(t)))))
+      // println("synth case? "+ (anfStats map (t => (t, t.isDef, treeInfo.hasSynthCaseSymbol(t)))))
       // SUPER UGLY HACK: handle virtpatmat-style matches, whose labels have already been turned into DefDefs
-      if (anfStats.nonEmpty && (anfStats forall (t => !t.isDef || gen.hasSynthCaseSymbol(t)))) {
+      if (anfStats.nonEmpty && (anfStats forall (t => !t.isDef || treeInfo.hasSynthCaseSymbol(t)))) {
         val (prologue, rest) = (anfStats :+ anfExpr) span (s => !s.isInstanceOf[DefDef]) // find first case
         // println("rest: "+ rest)
         // val (defs, calls) = rest partition (_.isInstanceOf[DefDef])

src/reflect/scala/reflect/internal/TreeInfo.scala

@@ -464,6 +464,16 @@ abstract class TreeInfo {
     case _        => false
   }
 
+
+  // used in the symbols for labeldefs and valdefs emitted by the pattern matcher
+  // tailcalls, cps,... use this flag combination to detect translated matches
+  // TODO: move to Flags
+  final val SYNTH_CASE_FLAGS  = CASE | SYNTHETIC
+
+  def isSynthCaseSymbol(sym: Symbol) = sym hasAllFlags SYNTH_CASE_FLAGS
+  def hasSynthCaseSymbol(t: Tree)    = t.symbol != null && isSynthCaseSymbol(t.symbol)
+
+
   /** The method part of an application node
    */
   def methPart(tree: Tree): Tree = tree match {