Implement creator applications

compiler/src/dotty/tools/dotc/ast/TreeInfo.scala

@@ -106,6 +106,13 @@ trait TreeInfo[T >: Untyped <: Type] { self: Trees.Instance[T] =>
     case _ => Nil
   }
 
+  /** Is tree a path? */
+  def isPath(tree: Tree): Boolean = unsplice(tree) match {
+    case Ident(_) | This(_) | Super(_, _) => true
+    case Select(qual, _) => isPath(qual)
+    case _ => false
+  }
+
   /** Is tree a self constructor call this(...)? I.e. a call to a constructor of the
    *  same object?
    */

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

@@ -17,8 +17,8 @@ abstract class Constraint extends Showable {
 
   type This <: Constraint
 
-  /** Does the constraint's domain contain the type parameters of `pt`? */
-  def contains(pt: TypeLambda): Boolean
+  /** Does the constraint's domain contain the type parameters of `tl`? */
+  def contains(tl: TypeLambda): Boolean
 
   /** Does the constraint's domain contain the type parameter `param`? */
   def contains(param: TypeParamRef): Boolean
@@ -106,14 +106,22 @@ abstract class Constraint extends Showable {
    */
   def replace(param: TypeParamRef, tp: Type)(implicit ctx: Context): This
 
-  /** Is entry associated with `pt` removable? This is the case if
+  /** Is entry associated with `tl` removable? This is the case if
    *  all type parameters of the entry are associated with type variables
    *  which have their `inst` fields set.
    */
-  def isRemovable(pt: TypeLambda): Boolean
+  def isRemovable(tl: TypeLambda): Boolean
 
-  /** A new constraint with all entries coming from `pt` removed. */
-  def remove(pt: TypeLambda)(implicit ctx: Context): This
+  /** A new constraint with all entries coming from `tl` removed. */
+  def remove(tl: TypeLambda)(implicit ctx: Context): This
+
+  /** A new constraint with entry `tl` renamed to a fresh type lambda */
+  def rename(tl: TypeLambda)(implicit ctx: Context): This
+
+  /** The given `tl` in case it is not contained in this constraint,
+   *  a fresh copy of `tl` otherwise.
+   */
+  def ensureFresh(tl: TypeLambda)(implicit ctx: Context): TypeLambda
 
   /** The type lambdas constrained by this constraint */
   def domainLambdas: List[TypeLambda]

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

@@ -69,6 +69,8 @@ object NameOps {
     def isSetterName: Boolean = name endsWith str.SETTER_SUFFIX
     def isScala2LocalSuffix: Boolean = testSimple(_.endsWith(" "))
     def isSelectorName: Boolean = testSimple(n => n.startsWith("_") && n.drop(1).forall(_.isDigit))
+    def isAnonymousClassName: Boolean = name.startsWith(str.ANON_CLASS)
+    def isAnonymousFunctionName: Boolean = name.startsWith(str.ANON_FUN)
 
     /** Is name a variable name? */
     def isVariableName: Boolean = testSimple { n =>

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

@@ -8,6 +8,7 @@ import collection.mutable
 import printing.Printer
 import printing.Texts._
 import config.Config
+import config.Printers.constr
 import reflect.ClassTag
 import annotation.tailrec
 import annotation.internal.sharable
@@ -503,6 +504,7 @@ class OrderingConstraint(private val boundsMap: ParamBounds,
     }
 
   def & (other: Constraint, otherHasErrors: Boolean)(implicit ctx: Context): OrderingConstraint = {
+
     def merge[T](m1: ArrayValuedMap[T], m2: ArrayValuedMap[T], join: (T, T) => T): ArrayValuedMap[T] = {
       var merged = m1
       def mergeArrays(xs1: Array[T], xs2: Array[T]) = {
@@ -527,21 +529,71 @@ class OrderingConstraint(private val boundsMap: ParamBounds,
         case (e1: TypeBounds, e2: TypeBounds) => e1 & e2
         case (e1: TypeBounds, _) if e1 contains e2 => e2
         case (_, e2: TypeBounds) if e2 contains e1 => e1
-        case (tv1: TypeVar, tv2: TypeVar) if tv1.instanceOpt eq tv2.instanceOpt => e1
+        case (tv1: TypeVar, tv2: TypeVar) if tv1 eq tv2 => e1
         case _ =>
           if (otherHasErrors)
             e1
           else
             throw new AssertionError(i"cannot merge $this with $other, mergeEntries($e1, $e2) failed")
       }
 
-    val that = other.asInstanceOf[OrderingConstraint]
+    /** Ensure that constraint `c` does not associate different TypeVars for the
+     *  same type lambda than this constraint. Do this by renaming type lambdas
+     *  in `c` where necessary.
+     */
+    def ensureNotConflicting(c: OrderingConstraint): OrderingConstraint = {
+      def hasConflictingTypeVarsFor(tl: TypeLambda) =
+        this.typeVarOfParam(tl.paramRefs(0)) ne c.typeVarOfParam(tl.paramRefs(0))
+          // Note: Since TypeVars are allocated in bulk for each type lambda, we only
+          // have to check the first one to find out if some of them are different.
+      val conflicting = c.domainLambdas.find(tl =>
+        this.contains(tl) && hasConflictingTypeVarsFor(tl))
+      conflicting match {
+        case Some(tl) => ensureNotConflicting(c.rename(tl))
+        case None => c
+      }
+    }
+
+    val that = ensureNotConflicting(other.asInstanceOf[OrderingConstraint])
+
     new OrderingConstraint(
         merge(this.boundsMap, that.boundsMap, mergeEntries),
         merge(this.lowerMap, that.lowerMap, mergeParams),
         merge(this.upperMap, that.upperMap, mergeParams))
+  }.reporting(res => i"constraint merge $this with $other = $res", constr)
+
+  def rename(tl: TypeLambda)(implicit ctx: Context): OrderingConstraint = {
+    assert(contains(tl))
+    val tl1 = ensureFresh(tl)
+    def swapKey[T](m: ArrayValuedMap[T]) = m.remove(tl).updated(tl1, m(tl))
+    var current = newConstraint(swapKey(boundsMap), swapKey(lowerMap), swapKey(upperMap))
+    def subst[T <: Type](x: T): T = x.subst(tl, tl1).asInstanceOf[T]
+    current.foreachParam {(p, i) =>
+      current = boundsLens.map(this, current, p, i, subst)
+      current = lowerLens.map(this, current, p, i, _.map(subst))
+      current = upperLens.map(this, current, p, i, _.map(subst))
+    }
+    current.foreachTypeVar { tvar =>
+      val TypeParamRef(binder, n) = tvar.origin
+      if (binder eq tl) tvar.setOrigin(tl1.paramRefs(n))
+    }
+    constr.println(i"renamd $this to $current")
+    current
   }
 
+  def ensureFresh(tl: TypeLambda)(implicit ctx: Context): TypeLambda =
+    if (contains(tl)) {
+      var paramInfos = tl.paramInfos
+      if (tl.isInstanceOf[HKLambda]) {
+        // HKLambdas are hash-consed, need to create an artificial difference by adding
+        // a LazyRef to a bound.
+        val TypeBounds(lo, hi) :: pinfos1 = tl.paramInfos
+        paramInfos = TypeBounds(lo, LazyRef(_ => hi)) :: pinfos1
+      }
+      ensureFresh(tl.newLikeThis(tl.paramNames, paramInfos, tl.resultType))
+    }
+    else tl
+
   override def checkClosed()(implicit ctx: Context): Unit = {
     def isFreeTypeParamRef(tp: Type) = tp match {
       case TypeParamRef(binder: TypeLambda, _) => !contains(binder)

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

@@ -484,13 +484,13 @@ object SymDenotations {
 
     /** Is this symbol an anonymous class? */
     final def isAnonymousClass(implicit ctx: Context): Boolean =
-      isClass && (initial.name startsWith str.ANON_CLASS)
+      isClass && initial.name.isAnonymousClassName
 
     final def isAnonymousFunction(implicit ctx: Context): Boolean =
-      this.symbol.is(Method) && (initial.name startsWith str.ANON_FUN)
+      this.symbol.is(Method) && initial.name.isAnonymousFunctionName
 
     final def isAnonymousModuleVal(implicit ctx: Context): Boolean =
-      this.symbol.is(ModuleVal) && (initial.name startsWith str.ANON_CLASS)
+      this.symbol.is(ModuleVal) && initial.name.isAnonymousClassName
 
     /** Is this a synthetic method that represents conversions between representations of a value class
       *  These methods are generated in ExtensionMethods

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

@@ -7,17 +7,19 @@ import Contexts._
 import util.{SimpleIdentityMap, SimpleIdentitySet}
 import reporting._
 import config.Config
+import config.Printers.constr
 import collection.mutable
 import java.lang.ref.WeakReference
 import util.Stats
+import Decorators._
 
 import scala.annotation.internal.sharable
 
 object TyperState {
   @sharable private var nextId: Int = 0
 }
 
-class TyperState(previous: TyperState /* | Null */) {
+class TyperState(private val previous: TyperState /* | Null */) {
 
   Stats.record("typerState")
 
@@ -143,10 +145,11 @@ class TyperState(previous: TyperState /* | Null */) {
   def commit()(implicit ctx: Context): Unit = {
     Stats.record("typerState.commit")
     val targetState = ctx.typerState
+    if (constraint ne targetState.constraint)
+      constr.println(i"committing $this to $targetState, fromConstr = $constraint, toConstr = ${targetState.constraint}")
     assert(isCommittable)
-    targetState.constraint =
-      if (targetState.constraint eq previousConstraint) constraint
-      else targetState.constraint & (constraint, otherHasErrors = reporter.errorsReported)
+    if (targetState.constraint eq previousConstraint) targetState.constraint = constraint
+    else targetState.mergeConstraintWith(this)
     constraint foreachTypeVar { tvar =>
       if (tvar.owningState.get eq this) tvar.owningState = new WeakReference(targetState)
     }
@@ -156,6 +159,9 @@ class TyperState(previous: TyperState /* | Null */) {
     isCommitted = true
   }
 
+  def mergeConstraintWith(that: TyperState)(implicit ctx: Context): Unit =
+    constraint = constraint & (that.constraint, otherHasErrors = that.reporter.errorsReported)
+
   /** Make type variable instances permanent by assigning to `inst` field if
    *  type variable instantiation cannot be retracted anymore. Then, remove
    *  no-longer needed constraint entries.
@@ -176,7 +182,12 @@ class TyperState(previous: TyperState /* | Null */) {
       constraint = constraint.remove(poly)
   }
 
-  override def toString: String = s"TS[$id]"
+  override def toString: String = {
+    def ids(state: TyperState): List[String] =
+      s"${state.id}${if (state.isCommittable) "" else "X"}" ::
+        (if (state.previous == null) Nil else ids(state.previous))
+    s"TS[${ids(this).mkString(", ")}]"
+  }
 
   def stateChainStr: String = s"$this${if (previous == null) "" else previous.stateChainStr}"
 }

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

@@ -3667,7 +3667,14 @@ object Types {
    *  `owningTree` and `owner` are used to determine whether a type-variable can be instantiated
    *  at some given point. See `Inferencing#interpolateUndetVars`.
    */
-  final class TypeVar(val origin: TypeParamRef, creatorState: TyperState) extends CachedProxyType with ValueType {
+  final class TypeVar(private var _origin: TypeParamRef, creatorState: TyperState) extends CachedProxyType with ValueType {
+
+    def origin: TypeParamRef = _origin
+
+    /** Set origin to new parameter. Called if we merge two conflicting constraints.
+     *  See OrderingConstraint#merge, OrderingConstraint#rename
+     */
+    def setOrigin(p: TypeParamRef) = _origin = p
 
     /** The permanent instance type of the variable, or NoType is none is given yet */
     private[this] var myInst: Type = NoType

compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala

@@ -15,7 +15,7 @@ import Denotations._
 import SymDenotations._
 import StdNames.{nme, tpnme}
 import ast.{Trees, untpd}
-import typer.{Implicits, Namer}
+import typer.{Implicits, Namer, Applications}
 import typer.ProtoTypes._
 import Trees._
 import TypeApplications._
@@ -578,6 +578,8 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
         else keywordStr("'{") ~ toTextGlobal(dropBlock(tree)) ~ keywordStr("}")
       case Splice(tree) =>
         keywordStr("${") ~ toTextGlobal(dropBlock(tree)) ~ keywordStr("}")
+      case tree: Applications.IntegratedTypeArgs =>
+        toText(tree.app) ~ Str("(with integrated type args)").provided(ctx.settings.YprintDebug.value)
       case Thicket(trees) =>
         "Thicket {" ~~ toTextGlobal(trees, "\n") ~~ "}"
       case _ =>

compiler/src/dotty/tools/dotc/reporting/Reporter.scala

@@ -95,18 +95,19 @@ trait Reporting { this: Context =>
   def strictWarning(msg: => Message, pos: SourcePosition = NoSourcePosition): Unit = {
     val fullPos = addInlineds(pos)
     if (this.settings.strict.value) error(msg, fullPos)
-    else reportWarning(new ExtendMessage(() => msg)(_ + "\n(This would be an error under strict mode)").warning(fullPos))
+    else reportWarning(
+      new ExtendMessage(() => msg)(_ + "\n(This would be an error under strict mode)")
+        .warning(fullPos))
   }
 
-  def error(msg: => Message, pos: SourcePosition = NoSourcePosition): Unit = {
-    reporter.report(new Error(msg, addInlineds(pos)))
-  }
-
-  def errorOrMigrationWarning(msg: => Message, pos: SourcePosition = NoSourcePosition): Unit = {
+  def error(msg: => Message, pos: SourcePosition = NoSourcePosition, sticky: Boolean = false): Unit = {
     val fullPos = addInlineds(pos)
-    if (ctx.scala2Mode) migrationWarning(msg, fullPos) else error(msg, fullPos)
+    reporter.report(if (sticky) new StickyError(msg, fullPos) else new Error(msg, fullPos))
   }
 
+  def errorOrMigrationWarning(msg: => Message, pos: SourcePosition = NoSourcePosition): Unit =
+    if (ctx.scala2Mode) migrationWarning(msg, pos) else error(msg, pos)
+
   def restrictionError(msg: => Message, pos: SourcePosition = NoSourcePosition): Unit =
     reporter.report {
       new ExtendMessage(() => msg)(m => s"Implementation restriction: $m").error(addInlineds(pos))
@@ -203,6 +204,9 @@ abstract class Reporter extends interfaces.ReporterResult {
   /** All errors reported by this reporter (ignoring outer reporters) */
   def allErrors: List[Error] = errors
 
+  /** Were sticky errors reported? Overridden in StoreReporter. */
+  def hasStickyErrors: Boolean = false
+
   /** Have errors been reported by this reporter, or in the
    *  case where this is a StoreReporter, by an outer reporter?
    */

compiler/src/dotty/tools/dotc/reporting/StoreReporter.scala

@@ -31,6 +31,9 @@ class StoreReporter(outer: Reporter) extends Reporter {
   override def hasUnreportedErrors: Boolean =
     outer != null && infos != null && infos.exists(_.isInstanceOf[Error])
 
+  override def hasStickyErrors: Boolean =
+    infos != null && infos.exists(_.isInstanceOf[StickyError])
+
   override def removeBufferedMessages(implicit ctx: Context): List[MessageContainer] =
     if (infos != null) try infos.toList finally infos = null
     else Nil

compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala

@@ -35,6 +35,15 @@ object messages {
     pos: SourcePosition
   ) extends MessageContainer(msgFn, pos, ERROR)
 
+  /** A sticky error is an error that should not be hidden by backtracking and
+   *  trying some alternative path. Typcially, errors issued after catching
+   *  a TypeError exception are sticky.
+   */
+  class StickyError(
+    msgFn: => Message,
+    pos: SourcePosition
+  ) extends Error(msgFn, pos)
+
   class Warning(
     msgFn: => Message,
     pos: SourcePosition

compiler/src/dotty/tools/dotc/sbt/ExtractAPI.scala

@@ -249,7 +249,7 @@ private class ExtractAPICollector(implicit val ctx: Context) extends ThunkHolder
           case ex: TypeError =>
             // See neg/i1750a for an example where a cyclic error can arise.
             // The root cause in this example is an illegal "override" of an inner trait
-            ctx.error(ex.toMessage, csym.sourcePos)
+            ctx.error(ex.toMessage, csym.sourcePos, sticky = true)
             defn.ObjectType :: Nil
         }
       if (ValueClasses.isDerivedValueClass(csym)) {

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

@@ -64,7 +64,7 @@ abstract class MacroTransform extends Phase {
         }
       catch {
         case ex: TypeError =>
-          ctx.error(ex.toMessage, tree.sourcePos)
+          ctx.error(ex.toMessage, tree.sourcePos, sticky = true)
           tree
       }
 

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

@@ -205,7 +205,7 @@ class MegaPhase(val miniPhases: Array[MiniPhase]) extends Phase {
         }
       catch {
         case ex: TypeError =>
-          ctx.error(ex.toMessage, tree.sourcePos)
+          ctx.error(ex.toMessage, tree.sourcePos, sticky = true)
           tree
       }
     if (tree.isInstanceOf[NameTree]) goNamed(tree, start) else goUnnamed(tree, start)

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

@@ -134,7 +134,7 @@ object OverridingPairs {
             case ex: TypeError =>
               // See neg/i1750a for an example where a cyclic error can arise.
               // The root cause in this example is an illegal "override" of an inner trait
-              ctx.error(ex.toMessage, base.sourcePos)
+              ctx.error(ex.toMessage, base.sourcePos, sticky = true)
           }
         } else {
           curEntry = curEntry.prev