Fix nullary overrides

odersky · odersky · commit 1f37b0c5b3b7 · 2017-06-23T11:07:06.000+02:00
Fix situations where a ()T method overrides a =&gt; T one, and vice versa.
diff --git a/compiler/src/dotty/tools/dotc/core/Denotations.scala b/compiler/src/dotty/tools/dotc/core/Denotations.scala
@@ -408,7 +408,8 @@ object Denotations {
 
         /** Sym preference provided types also override */
         def prefer(sym1: Symbol, sym2: Symbol, info1: Type, info2: Type) =
-          preferSym(sym1, sym2) && info1.overrides(info2)
+          preferSym(sym1, sym2) &&
+          info1.overrides(info2, sym1.matchNullaryLoosely || sym2.matchNullaryLoosely)
 
         def handleDoubleDef =
           if (preferSym(sym1, sym2)) denot1
diff --git a/compiler/src/dotty/tools/dotc/core/SymDenotations.scala b/compiler/src/dotty/tools/dotc/core/SymDenotations.scala
@@ -763,6 +763,20 @@ object SymDenotations {
 
     def isInlineMethod(implicit ctx: Context): Boolean = is(InlineMethod, butNot = Accessor)
 
+    /** ()T and => T types should be treated as equivalent for this symbol.
+     *  Note: For the moment, we treat Scala-2 compiled symbols as loose matching,
+     *  because the Scala library does not always follow the right conventions.
+     *  Examples are: isWhole(), toInt(), toDouble() in BigDecimal, Numeric, RichInt, ScalaNumberProxy.
+     */
+    def matchNullaryLoosely(implicit ctx: Context): Boolean = {
+      def test(sym: Symbol) =
+        sym.is(JavaDefined) ||
+        sym.owner == defn.AnyClass ||
+        sym == defn.Object_clone ||
+        sym.owner.is(Scala2x)
+      test(symbol) || allOverriddenSymbols.exists(test)
+    }
+
     // ------ access to related symbols ---------------------------------
 
     /* Modules and module classes are represented as follows:
@@ -938,7 +952,6 @@ object SymDenotations {
       else if (this.isClass) companionNamed(effectiveName.moduleClassName).sourceModule.moduleClass
       else NoSymbol
 
-
     /** Find companion class symbol with given name, or NoSymbol if none exists.
      *  Three alternative strategies:
      *  1. If owner is a class, look in its members, otherwise
diff --git a/compiler/src/dotty/tools/dotc/core/Types.scala b/compiler/src/dotty/tools/dotc/core/Types.scala
@@ -769,21 +769,23 @@ object Types {
     def relaxed_<:<(that: Type)(implicit ctx: Context) =
       (this <:< that) || (this isValueSubType that)
 
-    /** Is this type a legal type for a member that overrides another
-     *  member of type `that`? This is the same as `<:<`, except that
-     *  the types `()T`, `=> T` and `T` are seen as overriding
-     *  each other.
+    /** Is this type a legal type for member `sym1` that overrides another
+     *  member `sym2` of type `that`? This is the same as `<:<`, except that
+     *  if `matchLoosely` evaluates to true the types `=> T` and `()T` are seen
+     *  as overriding each other.
      */
-    final def overrides(that: Type)(implicit ctx: Context) = {
-      def result(tp: Type): Type = tp match {
-        case ExprType(_) | MethodType(Nil) => tp.resultType
+    final def overrides(that: Type, matchLoosely: => Boolean)(implicit ctx: Context): Boolean = {
+      def widenNullary(tp: Type) = tp match {
+        case tp @ MethodType(Nil) => tp.resultType
         case _ => tp
       }
-      (this frozen_<:< that) || {
-        val rthat = result(that)
-        val rthis = result(this)
-        (rthat.ne(that) || rthis.ne(this)) && (rthis frozen_<:< rthat)
-      }
+      ((this.widenExpr frozen_<:< that.widenExpr) ||
+        matchLoosely && {
+          val this1 = widenNullary(this)
+          val that1 = widenNullary(that)
+          ((this1 `ne` this) || (that1 `ne` that)) && this1.overrides(this1, matchLoosely = false)
+        }
+      )
     }
 
     /** Is this type close enough to that type so that members
diff --git a/compiler/src/dotty/tools/dotc/sbt/ThunkHolder.scala b/compiler/src/dotty/tools/dotc/sbt/ThunkHolder.scala
@@ -114,7 +114,7 @@ private object SafeLazy {
       eval = null // clear the reference, ensuring the only memory we hold onto is the result
       t
     }
-    def get: T = _t
+    def get(): T = _t
   }
 
   private[this] final class Strict[T <: AnyRef](val get: T) extends xsbti.api.Lazy[T] with java.io.Serializable
diff --git a/compiler/src/dotty/tools/dotc/typer/RefChecks.scala b/compiler/src/dotty/tools/dotc/typer/RefChecks.scala
@@ -257,7 +257,10 @@ object RefChecks {
           }
           else
             member.name.is(DefaultGetterName) || // default getters are not checked for compatibility
-            memberTp.overrides(otherTp)
+            memberTp.overrides(otherTp,
+                member.matchNullaryLoosely || other.matchNullaryLoosely ||
+                ctx.testScala2Mode(overrideErrorMsg("no longer has compatible type"),
+                   (if (member.owner == clazz) member else clazz).pos))
         catch {
           case ex: MissingType =>
             // can happen when called with upwardsSelf as qualifier of memberTp and otherTp,
diff --git a/compiler/src/dotty/tools/dotc/typer/Typer.scala b/compiler/src/dotty/tools/dotc/typer/Typer.scala
@@ -2045,16 +2045,8 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
 
         /** Is reference to this symbol `f` automatically expanded to `f()`? */
         def isAutoApplied(sym: Symbol): Boolean = {
-          def test(sym1: Symbol) =
-            sym1.is(JavaDefined) ||
-            sym1.owner == defn.AnyClass ||
-            sym1 == defn.Object_clone
           sym.isConstructor ||
-          test(sym) ||
-          sym.allOverriddenSymbols.exists(test) ||
-          sym.owner.is(Scala2x) || // need to exclude Scala-2 compiled symbols for now, since the
-                                   // Scala library does not always follow the right conventions.
-                                   // Examples are: isWhole(), toInt(), toDouble() in BigDecimal, Numeric, RichInt, ScalaNumberProxy.
+          sym.matchNullaryLoosely ||
           ctx.testScala2Mode(em"${sym.showLocated} requires () argument", tree.pos,
               patch(tree.pos.endPos, "()"))
         }
diff --git a/compiler/src/dotty/tools/dotc/util/Set.scala b/compiler/src/dotty/tools/dotc/util/Set.scala
@@ -23,5 +23,5 @@ abstract class Set[T >: Null] {
 
   def toList = iterator.toList
 
-  def clear: Unit
+  def clear(): Unit
 }
diff --git a/compiler/src/dotty/tools/io/AbstractFile.scala b/compiler/src/dotty/tools/io/AbstractFile.scala
@@ -186,7 +186,7 @@ abstract class AbstractFile extends Iterable[AbstractFile] {
   }
 
   /** Returns all abstract subfiles of this abstract directory. */
-  def iterator: Iterator[AbstractFile]
+  def iterator(): Iterator[AbstractFile]
 
   /** Returns the abstract file in this abstract directory with the specified
    *  name. If there is no such file, returns `null`. The argument
diff --git a/compiler/src/dotty/tools/io/PlainFile.scala b/compiler/src/dotty/tools/io/PlainFile.scala
@@ -9,7 +9,7 @@ package io
 /** ''Note:  This library is considered experimental and should not be used unless you know what you are doing.'' */
 class PlainDirectory(givenPath: Directory) extends PlainFile(givenPath) {
   override def isDirectory = true
-  override def iterator = givenPath.list filter (_.exists) map (x => new PlainFile(x))
+  override def iterator() = givenPath.list filter (_.exists) map (x => new PlainFile(x))
   override def delete(): Unit = givenPath.deleteRecursively()
 }
 
diff --git a/compiler/src/dotty/tools/io/VirtualDirectory.scala b/compiler/src/dotty/tools/io/VirtualDirectory.scala
@@ -47,7 +47,7 @@ extends AbstractFile {
 
   // the toList is so that the directory may continue to be
   // modified while its elements are iterated
-  def iterator = files.values.toList.iterator
+  def iterator() = files.values.toList.iterator
 
   override def lookupName(name: String, directory: Boolean): AbstractFile =
     (files get name filter (_.isDirectory == directory)).orNull
diff --git a/compiler/src/dotty/tools/io/ZipArchive.scala b/compiler/src/dotty/tools/io/ZipArchive.scala
@@ -197,7 +197,7 @@ final class FileZipArchive(file: JFile) extends ZipArchive(file) {
 }
 
 final class ManifestResources(val url: URL) extends ZipArchive(null) {
-  def iterator = {
+  def iterator() = {
     val root     = new DirEntry("/")
     val dirs     = mutable.HashMap[String, DirEntry]("/" -> root)
     val manifest = new Manifest(input)
diff --git a/tests/pos-special/strawman-collections/CollectionStrawMan4.scala b/tests/pos-special/strawman-collections/CollectionStrawMan4.scala
@@ -135,7 +135,7 @@ object CollectionStrawMan4 {
     def iterator = new Iterator[A] {
       private[this] var current = self
       def hasNext = !current.isEmpty
-      def next = { val r = current.head; current = current.tail; r }
+      def next() = { val r = current.head; current = current.tail; r }
     }
     def fromIterable[B](c: Iterable[B]): List[B] = List.fromIterable(c)
     def apply(i: Int): A = {
@@ -349,7 +349,7 @@ object CollectionStrawMan4 {
     def iterator: Iterator[A] = new Iterator[A] {
       private var current = start
       def hasNext = current < end
-      def next: A = {
+      def next(): A = {
         val r = apply(current)
         current += 1
         r
@@ -529,7 +529,7 @@ object CollectionStrawMan4 {
   object Iterator {
     val empty: Iterator[Nothing] = new Iterator[Nothing] {
       def hasNext = false
-      def next = throw new NoSuchElementException("next on empty iterator")
+      def next() = throw new NoSuchElementException("next on empty iterator")
     }
     def apply[A](xs: A*): Iterator[A] = new RandomAccessView[A] {
       val start = 0
diff --git a/tests/pos-special/strawman-collections/CollectionStrawMan5.scala b/tests/pos-special/strawman-collections/CollectionStrawMan5.scala
@@ -157,7 +157,7 @@ object CollectionStrawMan5 {
     def iterator = new Iterator[A] {
       private[this] var current = self
       def hasNext = !current.isEmpty
-      def next = { val r = current.head; current = current.tail; r }
+      def next() = { val r = current.head; current = current.tail; r }
     }
     def fromIterable[B](c: Iterable[B]): List[B] = List.fromIterable(c)
     def apply(i: Int): A = {
@@ -360,7 +360,7 @@ object CollectionStrawMan5 {
     def iterator: Iterator[A] = new Iterator[A] {
       private var current = start
       def hasNext = current < end
-      def next: A = {
+      def next(): A = {
         val r = apply(current)
         current += 1
         r
@@ -511,7 +511,7 @@ object CollectionStrawMan5 {
   object Iterator {
     val empty: Iterator[Nothing] = new Iterator[Nothing] {
       def hasNext = false
-      def next = throw new NoSuchElementException("next on empty iterator")
+      def next() = throw new NoSuchElementException("next on empty iterator")
     }
     def apply[A](xs: A*): Iterator[A] = new RandomAccessView[A] {
       val start = 0
diff --git a/tests/pos-special/strawman-collections/CollectionStrawMan6.scala b/tests/pos-special/strawman-collections/CollectionStrawMan6.scala
@@ -142,7 +142,7 @@ object CollectionStrawMan6 extends LowPriority {
     def iterator = new Iterator[A] {
       private[this] var current: Seq[A] = self
       def hasNext = !current.isEmpty
-      def next = { val r = current.head; current = current.tail; r }
+      def next() = { val r = current.head; current = current.tail; r }
     }
 
     /** `length is defined in terms of `iterator` */
@@ -891,7 +891,7 @@ object CollectionStrawMan6 extends LowPriority {
     def iterator: Iterator[A] = new Iterator[A] {
       private var current = 0
       def hasNext = current < self.length
-      def next: A = {
+      def next(): A = {
         val r = apply(current)
         current += 1
         r
@@ -1010,7 +1010,7 @@ object CollectionStrawMan6 extends LowPriority {
     def take(n: Int): Iterator[A] = new Iterator[A] {
       private var i = 0
       def hasNext = self.hasNext && i < n
-      def next =
+      def next() =
         if (hasNext) {
           i += 1
           self.next()
@@ -1035,7 +1035,7 @@ object CollectionStrawMan6 extends LowPriority {
   object Iterator {
     val empty: Iterator[Nothing] = new Iterator[Nothing] {
       def hasNext = false
-      def next = throw new NoSuchElementException("next on empty iterator")
+      def next() = throw new NoSuchElementException("next on empty iterator")
     }
     def apply[A](xs: A*): Iterator[A] = new IndexedView[A] {
       val length = xs.length
diff --git a/tests/pos/rbtree.scala b/tests/pos/rbtree.scala
@@ -470,7 +470,7 @@ object RedBlackTree {
 
     override def hasNext: Boolean = lookahead ne null
 
-    override def next: R = lookahead match {
+    override def next(): R = lookahead match {
       case null =>
         throw new NoSuchElementException("next on empty iterator")
       case tree =>
diff --git a/tests/pos/tcpoly_seq.scala b/tests/pos/tcpoly_seq.scala
@@ -111,7 +111,7 @@ trait HOSeq {
     def iterator: Iterator[t] = new Iterator[t] {
     var these = List.this
     def hasNext: Boolean = !these.isEmpty
-    def next: t =
+    def next(): t =
       if (!hasNext)
         throw new NoSuchElementException("next on empty Iterator")
       else {
diff --git a/tests/pos/tcpoly_seq_typealias.scala b/tests/pos/tcpoly_seq_typealias.scala
@@ -115,7 +115,7 @@ trait HOSeq {
     def iterator: Iterator[t] = new Iterator[t] {
       var these = List.this
       def hasNext: Boolean = !these.isEmpty
-      def next: t =
+      def next(): t =
         if (!hasNext)
           throw new NoSuchElementException("next on empty Iterator")
         else {
diff --git a/tests/run/CollectionTests.scala b/tests/run/CollectionTests.scala
@@ -156,7 +156,7 @@ object CollectionStrawMan5 {
     def iterator = new Iterator[A] {
       private[this] var current = self
       def hasNext = !current.isEmpty
-      def next = { val r = current.head; current = current.tail; r }
+      def next() = { val r = current.head; current = current.tail; r }
     }
     def fromIterable[B](c: Iterable[B]): List[B] = List.fromIterable(c)
     def apply(i: Int): A = {
@@ -359,7 +359,7 @@ object CollectionStrawMan5 {
     def iterator: Iterator[A] = new Iterator[A] {
       private var current = start
       def hasNext = current < end
-      def next: A = {
+      def next(): A = {
         val r = apply(current)
         current += 1
         r
@@ -510,7 +510,7 @@ object CollectionStrawMan5 {
   object Iterator {
     val empty: Iterator[Nothing] = new Iterator[Nothing] {
       def hasNext = false
-      def next = throw new NoSuchElementException("next on empty iterator")
+      def next() = throw new NoSuchElementException("next on empty iterator")
     }
     def apply[A](xs: A*): Iterator[A] = new RandomAccessView[A] {
       val start = 0
diff --git a/tests/run/colltest4/CollectionStrawMan4_1.scala b/tests/run/colltest4/CollectionStrawMan4_1.scala
@@ -134,7 +134,7 @@ object CollectionStrawMan4 {
     def iterator = new Iterator[A] {
       private[this] var current = self
       def hasNext = !current.isEmpty
-      def next = { val r = current.head; current = current.tail; r }
+      def next() = { val r = current.head; current = current.tail; r }
     }
     def fromIterable[B](c: Iterable[B]): List[B] = List.fromIterable(c)
     def apply(i: Int): A = {
@@ -348,7 +348,7 @@ object CollectionStrawMan4 {
     def iterator: Iterator[A] = new Iterator[A] {
       private var current = start
       def hasNext = current < end
-      def next: A = {
+      def next(): A = {
         val r = apply(current)
         current += 1
         r
@@ -528,7 +528,7 @@ object CollectionStrawMan4 {
   object Iterator {
     val empty: Iterator[Nothing] = new Iterator[Nothing] {
       def hasNext = false
-      def next = throw new NoSuchElementException("next on empty iterator")
+      def next() = throw new NoSuchElementException("next on empty iterator")
     }
     def apply[A](xs: A*): Iterator[A] = new RandomAccessView[A] {
       val start = 0
diff --git a/tests/run/colltest5/CollectionStrawMan5_1.scala b/tests/run/colltest5/CollectionStrawMan5_1.scala
@@ -149,7 +149,7 @@ object CollectionStrawMan5 {
     def iterator = new Iterator[A] {
       private[this] var current = self
       def hasNext = !current.isEmpty
-      def next = { val r = current.head; current = current.tail; r }
+      def next() = { val r = current.head; current = current.tail; r }
     }
     def fromIterable[B](c: Iterable[B]): List[B] = List.fromIterable(c)
     def apply(i: Int): A = {
@@ -352,7 +352,7 @@ object CollectionStrawMan5 {
     def iterator: Iterator[A] = new Iterator[A] {
       private var current = start
       def hasNext = current < end
-      def next: A = {
+      def next(): A = {
         val r = apply(current)
         current += 1
         r
@@ -503,7 +503,7 @@ object CollectionStrawMan5 {
   object Iterator {
     val empty: Iterator[Nothing] = new Iterator[Nothing] {
       def hasNext = false
-      def next = throw new NoSuchElementException("next on empty iterator")
+      def next() = throw new NoSuchElementException("next on empty iterator")
     }
     def apply[A](xs: A*): Iterator[A] = new RandomAccessView[A] {
       val start = 0
diff --git a/tests/run/colltest6/CollectionStrawMan6_1.scala b/tests/run/colltest6/CollectionStrawMan6_1.scala
@@ -143,7 +143,7 @@ object CollectionStrawMan6 extends LowPriority {
     def iterator = new Iterator[A] {
       private[this] var current: Seq[A] = self
       def hasNext = !current.isEmpty
-      def next = { val r = current.head; current = current.tail; r }
+      def next() = { val r = current.head; current = current.tail; r }
     }
 
     /** `length is defined in terms of `iterator` */
@@ -892,7 +892,7 @@ object CollectionStrawMan6 extends LowPriority {
     def iterator: Iterator[A] = new Iterator[A] {
       private var current = 0
       def hasNext = current < self.length
-      def next: A = {
+      def next(): A = {
         val r = apply(current)
         current += 1
         r
@@ -1011,7 +1011,7 @@ object CollectionStrawMan6 extends LowPriority {
     def take(n: Int): Iterator[A] = new Iterator[A] {
       private var i = 0
       def hasNext = self.hasNext && i < n
-      def next =
+      def next() =
         if (hasNext) {
           i += 1
           self.next()
@@ -1036,7 +1036,7 @@ object CollectionStrawMan6 extends LowPriority {
   object Iterator {
     val empty: Iterator[Nothing] = new Iterator[Nothing] {
       def hasNext = false
-      def next = throw new NoSuchElementException("next on empty iterator")
+      def next() = throw new NoSuchElementException("next on empty iterator")
     }
     def apply[A](xs: A*): Iterator[A] = new IndexedView[A] {
       val length = xs.length

Original file line number	Diff line number	Diff line change
`@@ -114,7 +114,7 @@ private object SafeLazy {`
`114`	`114`	`eval = null // clear the reference, ensuring the only memory we hold onto is the result`
`115`	`115`	`t`
`116`	`116`	`}`
`117`		`- def get: T = _t`
	`117`	`+ def get(): T = _t`
`118`	`118`	`}`
`119`	`119`
`120`	`120`	`private[this] final class Strict[T <: AnyRef](val get: T) extends xsbti.api.Lazy[T] with java.io.Serializable`
Original file line number	Diff line number	Diff line change
`@@ -23,5 +23,5 @@ abstract class Set[T >: Null] {`
`23`	`23`
`24`	`24`	`def toList = iterator.toList`
`25`	`25`
`26`		`- def clear: Unit`
	`26`	`+ def clear(): Unit`
`27`	`27`	`}`
Original file line number	Diff line number	Diff line change
`@@ -186,7 +186,7 @@ abstract class AbstractFile extends Iterable[AbstractFile] {`
`186`	`186`	`}`
`187`	`187`
`188`	`188`	`/** Returns all abstract subfiles of this abstract directory. */`
`189`		`- def iterator: Iterator[AbstractFile]`
	`189`	`+ def iterator(): Iterator[AbstractFile]`
`190`	`190`
`191`	`191`	`/** Returns the abstract file in this abstract directory with the specified`
`192`	`192`	* name. If there is no such file, returns `null`. The argument
Original file line number	Diff line number	Diff line change
`@@ -9,7 +9,7 @@ package io`
`9`	`9`	`/** ''Note: This library is considered experimental and should not be used unless you know what you are doing.'' */`
`10`	`10`	`class PlainDirectory(givenPath: Directory) extends PlainFile(givenPath) {`
`11`	`11`	`override def isDirectory = true`
`12`		`- override def iterator = givenPath.list filter (_.exists) map (x => new PlainFile(x))`
	`12`	`+ override def iterator() = givenPath.list filter (_.exists) map (x => new PlainFile(x))`
`13`	`13`	`override def delete(): Unit = givenPath.deleteRecursively()`
`14`	`14`	`}`
`15`	`15`