Migration message and version cleanup

The @migration annotation can now be used like @Deprecation. Old syntax is still supported, but deprecated. Improve wording and consistency of migration messages, migration warnings also print the version in which the change occurred now. Partially fixes SI-4990.
scala · paulp · Dec 8, 2011 · Dec 7, 2011 · Dec 7, 2011 · 60b90b18d6407b886ed9f12061406fd3ece05e29
commit 60b90b18d6407b886ed9f12061406fd3ece05e29
diff --git a/src/compiler/scala/reflect/internal/Symbols.scala b/src/compiler/scala/reflect/internal/Symbols.scala
@@ -494,8 +494,8 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
     // string.  So this needs attention.  For now the fact that migration is
     // private[scala] ought to provide enough protection.
     def hasMigrationAnnotation = hasAnnotation(MigrationAnnotationClass)
-    def migrationMessage    = getAnnotation(MigrationAnnotationClass) flatMap { _.stringArg(2) }
-    def migrationVersion    = getAnnotation(MigrationAnnotationClass) map { version => version.intArg(0).get + "." + version.intArg(1).get }
+    def migrationMessage    = getAnnotation(MigrationAnnotationClass) flatMap { _.stringArg(0) }
+    def migrationVersion    = getAnnotation(MigrationAnnotationClass) flatMap { _.stringArg(1) }
     def elisionLevel        = getAnnotation(ElidableMethodClass) flatMap { _.intArg(0) }
     def implicitNotFoundMsg = getAnnotation(ImplicitNotFoundClass) flatMap { _.stringArg(0) }
 

diff --git a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
@@ -1273,8 +1273,10 @@ abstract class RefChecks extends InfoTransform with reflect.internal.transform.R
      *  indicating it has changed semantics between versions.
      */
     private def checkMigration(sym: Symbol, pos: Position) = {
-      for (msg <- sym.migrationMessage)
-        unit.warning(pos, sym.fullLocationString + " has changed semantics:\n" + msg)
+      if (sym.hasMigrationAnnotation)
+        unit.warning(pos, "%s has changed semantics in version %s:\n%s".format(
+          sym.fullLocationString, sym.migrationVersion.get, sym.migrationMessage.get)
+        )
     }
 
     private def lessAccessible(otherSym: Symbol, memberSym: Symbol): Boolean = (

diff --git a/src/library/scala/annotation/migration.scala b/src/library/scala/annotation/migration.scala
@@ -14,15 +14,17 @@ package scala.annotation
  * reason or another retain the same name and type signature,
  * but some aspect of their behavior is different.  An illustrative
  * examples is Stack.iterator, which reversed from LIFO to FIFO
- * order between scala 2.7 and 2.8.
+ * order between Scala 2.7 and 2.8.
  *
- * The version numbers are to mark the scala major/minor release
- * version where the change took place.
+ * @param message A message describing the change, which is emitted
+ * by the compiler if the flag `-Xmigration` is set.
+ *
+ * @param changedIn The version, in which the behaviour change was
+ * introduced.
  *
  * @since 2.8
  */
-private[scala] final class migration(
-  majorVersion: Int,
-  minorVersion: Int,
-  message: String)
-extends annotation.StaticAnnotation {}
+ private[scala] final class migration(message: String, changedIn: String) extends annotation.StaticAnnotation {
+   @deprecated("Use the constructor taking two Strings instead.", "2.10")
+   def this(majorVersion: Int, minorVersion: Int, message: String) = this(message, majorVersion + "." + minorVersion)
+ }
diff --git a/src/library/scala/collection/GenTraversableLike.scala b/src/library/scala/collection/GenTraversableLike.scala
@@ -123,10 +123,7 @@ trait GenTraversableLike[+A, +Repr] extends GenTraversableOnce[A] with Paralleli
    *  @param bf      $bfinfo
    *  @return        collection with intermediate results
    */
-  @migration(2, 9,
-    "This scanRight definition has changed in 2.9.\n" +
-    "The previous behavior can be reproduced with scanRight.reverse."
-  )
+  @migration("The behavior of `scanRight` has changed. The previous behavior can be reproduced with scanRight.reverse.", "2.9.0")
   def scanRight[B, That](z: B)(op: (A, B) => B)(implicit bf: CanBuildFrom[Repr, B, That]): That
 
   /** Applies a function `f` to all elements of this $coll.

diff --git a/src/library/scala/collection/GenTraversableViewLike.scala b/src/library/scala/collection/GenTraversableViewLike.scala
@@ -12,8 +12,6 @@ package scala.collection
 import generic._
 import mutable.{ Builder, ArrayBuffer }
 import TraversableView.NoBuilder
-import annotation.migration
-
 
 
 trait GenTraversableViewLike[+A,

diff --git a/src/library/scala/collection/Iterator.scala b/src/library/scala/collection/Iterator.scala
@@ -9,7 +9,7 @@
 package scala.collection
 
 import mutable.ArrayBuffer
-import annotation.{ tailrec, migration }
+import annotation.migration
 import immutable.Stream
 
 /** The `Iterator` object provides various functions for creating specialized iterators.
@@ -52,7 +52,7 @@ object Iterator {
 
   /** Creates iterator that produces the results of some element computation a number of times.
    *
-   *  @param   n  the number of elements returned by the iterator.
+   *  @param   len  the number of elements returned by the iterator.
    *  @param   elem the element computation
    *  @return  An iterator that produces the results of `n` evaluations of `elem`.
    */
@@ -66,7 +66,7 @@ object Iterator {
 
   /** Creates an iterator producing the values of a given function over a range of integer values starting from 0.
    *
-   *  @param  n   The number of elements returned by the iterator
+   *  @param  end The number of elements returned by the iterator
    *  @param  f   The function computing element values
    *  @return An iterator that produces the values `f(0), ..., f(n -1)`.
    */
@@ -410,10 +410,7 @@ trait Iterator[+A] extends TraversableOnce[A] {
   *  which `pf` is defined the image `pf(x)`.
   *  @note     Reuse: $consumesAndProducesIterator
   */
-  @migration(2, 8,
-    "This collect implementation bears no relationship to the one before 2.8.\n"+
-    "The previous behavior can be reproduced with toSeq."
-  )
+  @migration("`collect` has changed. The previous behavior can be reproduced with `toSeq`.", "2.8.0")
   def collect[B](pf: PartialFunction[A, B]): Iterator[B] = {
     val self = buffered
     new AbstractIterator[B] {
@@ -1033,9 +1030,9 @@ trait Iterator[+A] extends TraversableOnce[A] {
 
   /** Returns this iterator with patched values.
    *
-   *  @param from     The start index from which to patch
-   *  @param ps       The iterator of patch values
-   *  @param replaced The number of values in the original iterator that are replaced by the patch.
+   *  @param from       The start index from which to patch
+   *  @param patchElems The iterator of patch values
+   *  @param replaced   The number of values in the original iterator that are replaced by the patch.
    *  @note           Reuse: $consumesTwoAndProducesOneIterator
    */
   def patch[B >: A](from: Int, patchElems: Iterator[B], replaced: Int): Iterator[B] = new AbstractIterator[B] {

diff --git a/src/library/scala/collection/MapLike.scala b/src/library/scala/collection/MapLike.scala
@@ -182,14 +182,14 @@ self =>
    *
    *  @return the keys of this map as an iterable.
    */
-  @migration(2, 8, "As of 2.8, keys returns Iterable[A] rather than Iterator[A].")
+  @migration("`keys` returns `Iterable[A]` rather than `Iterator[A]`.", "2.8.0")
   def keys: Iterable[A] = keySet
 
   /** Collects all values of this map in an iterable collection.
    *
    *  @return the values of this map as an iterable.
    */
-  @migration(2, 8, "As of 2.8, values returns Iterable[B] rather than Iterator[B].")
+  @migration("`values` returns `Iterable[B]` rather than `Iterator[B]`.", "2.8.0")
   def values: Iterable[B] = new DefaultValuesIterable
 
   /** The implementation class of the iterable returned by `values`.

diff --git a/src/library/scala/collection/SetLike.scala b/src/library/scala/collection/SetLike.scala
@@ -89,7 +89,7 @@ self =>
   // note: this is only overridden here to add the migration annotation,
   // which I hope to turn into an Xlint style warning as the migration aspect
   // is not central to its importance.
-  @migration(2, 8, "Set.map now returns a Set, so it will discard duplicate values.")
+  @migration("Set.map now returns a Set, so it will discard duplicate values.", "2.8.0")
   override def map[B, That](f: A => B)(implicit bf: CanBuildFrom[This, B, That]): That = super.map(f)(bf)
 
   /** Tests if some element is contained in this set.

diff --git a/src/library/scala/collection/TraversableLike.scala b/src/library/scala/collection/TraversableLike.scala
@@ -390,10 +390,7 @@ trait TraversableLike[+A, +Repr] extends HasNewBuilder[A, Repr]
     b.result
   }
 
-  @migration(2, 9,
-    "This scanRight definition has changed in 2.9.\n" +
-    "The previous behavior can be reproduced with scanRight.reverse."
-  )
+  @migration("The behavior of `scanRight` has changed. The previous behavior can be reproduced with scanRight.reverse.", "2.9.0")
   def scanRight[B, That](z: B)(op: (A, B) => B)(implicit bf: CanBuildFrom[Repr, B, That]): That = {
     var scanned = List(z)
     var acc = z

diff --git a/src/library/scala/collection/TraversableViewLike.scala b/src/library/scala/collection/TraversableViewLike.scala
@@ -185,10 +185,7 @@ trait TraversableViewLike[+A,
   override def scanLeft[B, That](z: B)(op: (B, A) => B)(implicit bf: CanBuildFrom[This, B, That]): That =
     newForced(thisSeq.scanLeft(z)(op)).asInstanceOf[That]
 
-  @migration(2, 9,
-    "This scanRight definition has changed in 2.9.\n" +
-    "The previous behavior can be reproduced with scanRight.reverse."
-  )
+  @migration("The behavior of `scanRight` has changed. The previous behavior can be reproduced with scanRight.reverse.", "2.9.0")
   override def scanRight[B, That](z: B)(op: (A, B) => B)(implicit bf: CanBuildFrom[This, B, That]): That =
     newForced(thisSeq.scanRight(z)(op)).asInstanceOf[That]
 

diff --git a/src/library/scala/collection/generic/GenericTraversableTemplate.scala b/src/library/scala/collection/generic/GenericTraversableTemplate.scala
@@ -13,7 +13,6 @@ package generic
 
 import mutable.Builder
 import annotation.migration
-import annotation.bridge
 import annotation.unchecked.uncheckedVariance
 
 /** A template class for companion objects of ``regular`` collection classes
@@ -148,7 +147,7 @@ trait GenericTraversableTemplate[+A, +CC[X] <: GenTraversable[X]] extends HasNew
    *  @throws `IllegalArgumentException` if all collections in this $coll
    *          are not of the same size.
    */
-  @migration(2, 9, "As of 2.9, transpose throws an exception if collections are not uniformly sized.")
+  @migration("`transpose` throws an `IllegalArgumentException` if collections are not uniformly sized.", "2.9.0")
   def transpose[B](implicit asTraversable: A => /*<:<!!!*/ GenTraversableOnce[B]): CC[CC[B] @uncheckedVariance] = {
     if (isEmpty)
       return genericBuilder[CC[B]].result

diff --git a/src/library/scala/collection/mutable/BufferLike.scala b/src/library/scala/collection/mutable/BufferLike.scala
@@ -152,7 +152,7 @@ trait BufferLike[A, +This <: BufferLike[A, This] with Buffer[A]]
   def prepend(elems: A*) { prependAll(elems) }
 
   /** Prepends the elements contained in a traversable object to this buffer.
-   *  @param elems  the collection containing the elements to prepend.
+   *  @param xs  the collection containing the elements to prepend.
    */
   def prependAll(xs: TraversableOnce[A]) { xs ++=: this }
 
@@ -220,10 +220,7 @@ trait BufferLike[A, +This <: BufferLike[A, This] with Buffer[A]]
    *  @param xs     the traversable object.
    *  @return       a new collection consisting of all the elements of this collection and `xs`.
    */
-  @migration(2, 8,
-    "As of 2.8, ++ always creates a new collection, even on Buffers.\n"+
-    "Use ++= instead if you intend to add by side effect to an existing collection.\n"
-  )
+  @migration("`++` creates a new buffer. Use `++=` to add an element from this buffer and return that buffer itself.", "2.8.0")
   def ++(xs: GenTraversableOnce[A]): This = clone() ++= xs.seq
 
   @bridge
@@ -234,10 +231,7 @@ trait BufferLike[A, +This <: BufferLike[A, This] with Buffer[A]]
    *  @param elem  the element to remove.
    *  @return      a new collection consisting of all the elements of this collection except `elem`.
    */
-  @migration(2, 8,
-    "As of 2.8, - always creates a new collection, even on Buffers.\n"+
-    "Use -= instead if you intend to remove by side effect from an existing collection.\n"
-  )
+  @migration("`-` creates a new buffer. Use `-=` to remove an element from this buffer and return that buffer itself.", "2.8.0")
   override def -(elem: A): This = clone() -= elem
 
   /** Creates a new collection with all the elements of this collection except the two
@@ -249,10 +243,7 @@ trait BufferLike[A, +This <: BufferLike[A, This] with Buffer[A]]
    *  @return      a new collection consisting of all the elements of this collection except
    *               `elem1`, `elem2` and those in `elems`.
    */
-  @migration(2, 8,
-    "As of 2.8, - always creates a new collection, even on Buffers.\n"+
-    "Use -= instead if you intend to remove by side effect from an existing collection.\n"
-  )
+  @migration("`-` creates a new buffer. Use `-=` to remove an element from this buffer and return that buffer itself.", "2.8.0")
   override def -(elem1: A, elem2: A, elems: A*): This = clone() -= elem1 -= elem2 --= elems
 
   /** Creates a new collection with all the elements of this collection except those
@@ -262,10 +253,7 @@ trait BufferLike[A, +This <: BufferLike[A, This] with Buffer[A]]
    *  @return         a new collection with all the elements of this collection except
    *                  those in `xs`
    */
-  @migration(2, 8,
-    "As of 2.8, -- always creates a new collection, even on Buffers.\n"+
-    "Use --= instead if you intend to remove by side effect from an existing collection.\n"
-  )
+  @migration("`--` creates a new buffer. Use `--=` to remove an element from this buffer and return that buffer itself.", "2.8.0")
   override def --(xs: GenTraversableOnce[A]): This = clone() --= xs.seq
 
   @bridge def --(xs: TraversableOnce[A]): This = --(xs: GenTraversableOnce[A])

diff --git a/src/library/scala/collection/mutable/DoubleLinkedListLike.scala b/src/library/scala/collection/mutable/DoubleLinkedListLike.scala
@@ -91,7 +91,7 @@ trait DoubleLinkedListLike[A, This <: Seq[A] with DoubleLinkedListLike[A, This]]
    *  current node, i.e. `this` node itself will still point "into" the list it
    *  was in.
    */
-  @migration(2, 9, "Double linked list now removes the current node from the list.")
+  @migration("Double linked list now removes the current node from the list.", "2.9.0")
   def remove(): Unit = if (nonEmpty) {
     next.prev = prev
     if (prev ne null) prev.next = next // because this could be the first node

diff --git a/src/library/scala/collection/mutable/ImmutableMapAdaptor.scala b/src/library/scala/collection/mutable/ImmutableMapAdaptor.scala
@@ -46,12 +46,12 @@ extends AbstractMap[A, B]
 
   override def keysIterator: Iterator[A] = imap.keysIterator
 
-  @migration(2, 8, "As of 2.8, keys returns Iterable[A] rather than Iterator[A].")
+  @migration("`keys` returns Iterable[A] rather than Iterator[A].", "2.8.0")
   override def keys: collection.Iterable[A] = imap.keys
 
   override def valuesIterator: Iterator[B] = imap.valuesIterator
 
-  @migration(2, 8, "As of 2.8, values returns Iterable[B] rather than Iterator[B].")
+  @migration("`values` returns Iterable[B] rather than Iterator[B].", "2.8.0")
   override def values: collection.Iterable[B] = imap.values
 
   def iterator: Iterator[(A, B)] = imap.iterator

diff --git a/src/library/scala/collection/mutable/MapLike.scala b/src/library/scala/collection/mutable/MapLike.scala
@@ -90,10 +90,7 @@ trait MapLike[A, B, +This <: MapLike[A, B, This] with Map[A, B]]
    *  @param kv    the key/value mapping to be added
    *  @return      a new map containing mappings of this map and the mapping `kv`.
    */
-  @migration(2, 8,
-    "As of 2.8, this operation creates a new map.  To add an element as a\n"+
-    "side effect to an existing map and return that map itself, use +=."
-  )
+  @migration("`+` creates a new map. Use `+=` to add an element to this map and return that map itself.", "2.8.0")
   def + [B1 >: B] (kv: (A, B1)): Map[A, B1] = clone().asInstanceOf[Map[A, B1]] += kv
 
  /** Creates a new map containing two or more key/value mappings and all the key/value
@@ -106,10 +103,7 @@ trait MapLike[A, B, +This <: MapLike[A, B, This] with Map[A, B]]
    *  @param elems the remaining elements to add.
    *  @return      a new map containing mappings of this map and two or more specified mappings.
    */
-  @migration(2, 8,
-    "As of 2.8, this operation creates a new map.  To add an element as a\n"+
-    "side effect to an existing map and return that map itself, use +=."
-  )
+  @migration("`+` creates a new map. Use `+=` to add an element to this map and return that map itself.", "2.8.0")
   override def + [B1 >: B] (elem1: (A, B1), elem2: (A, B1), elems: (A, B1) *): Map[A, B1] =
     clone().asInstanceOf[Map[A, B1]] += elem1 += elem2 ++= elems
 
@@ -121,10 +115,7 @@ trait MapLike[A, B, +This <: MapLike[A, B, This] with Map[A, B]]
    *  @param xs     the traversable object.
    *  @return       a new map containing mappings of this map and those provided by `xs`.
    */
-  @migration(2, 8,
-    "As of 2.8, this operation creates a new map.  To add the elements as a\n"+
-    "side effect to an existing map and return that map itself, use ++=."
-  )
+  @migration("`++` creates a new map. Use `++=` to add an element to this map and return that map itself.", "2.8.0")
   override def ++[B1 >: B](xs: GenTraversableOnce[(A, B1)]): Map[A, B1] =
     clone().asInstanceOf[Map[A, B1]] ++= xs.seq
 
@@ -154,10 +145,7 @@ trait MapLike[A, B, +This <: MapLike[A, B, This] with Map[A, B]]
    *  @param    key the key to be removed
    *  @return   a new map with all the mappings of this map except that with a key `key`.
    */
-  @migration(2, 8,
-    "As of 2.8, this operation creates a new map.  To remove an element as a\n"+
-    "side effect to an existing map and return that map itself, use -=."
-  )
+  @migration("`-` creates a new map. Use `-=` to remove an element from this map and return that map itself.", "2.8.0")
   override def -(key: A): This = clone() -= key
 
   /** Removes all bindings from the map. After this operation has completed,
@@ -223,10 +211,7 @@ trait MapLike[A, B, +This <: MapLike[A, B, This] with Map[A, B]]
    *  @return      a new map containing all the mappings of this map except mappings
    *               with a key equal to `elem1`, `elem2` or any of `elems`.
    */
-  @migration(2, 8,
-    "As of 2.8, this operation creates a new map.  To remove an element as a\n"+
-    "side effect to an existing map and return that map itself, use -=."
-  )
+  @migration("`-` creates a new map. Use `-=` to remove an element from this map and return that map itself.", "2.8.0")
   override def -(elem1: A, elem2: A, elems: A*): This =
     clone() -= elem1 -= elem2 --= elems
 
@@ -237,10 +222,7 @@ trait MapLike[A, B, +This <: MapLike[A, B, This] with Map[A, B]]
    *  @return         a new map with all the key/value mappings of this map except mappings
    *                  with a key equal to a key from `xs`.
    */
-  @migration(2, 8,
-    "As of 2.8, this operation creates a new map.  To remove the elements as a\n"+
-    "side effect to an existing map and return that map itself, use --=."
-  )
+  @migration("`--` creates a new map. Use `--=` to remove an element from this map and return that map itself.", "2.8.0")
   override def --(xs: GenTraversableOnce[A]): This = clone() --= xs.seq
 
   @bridge def --(xs: TraversableOnce[A]): This =  --(xs: GenTraversableOnce[A])

diff --git a/src/library/scala/collection/mutable/PriorityQueue.scala b/src/library/scala/collection/mutable/PriorityQueue.scala
@@ -12,7 +12,7 @@ package scala.collection
 package mutable
 
 import generic._
-import annotation.{migration, bridge}
+import annotation.bridge
 
 /** This class implements priority queues using a heap.
  *  To prioritize elements of type A there must be an implicit