Merge pull request scala#958 from adriaanm/ticket-1832

SI-1832 consistent symbols in casedef's pattern&body

Author: jsuereth

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

@@ -225,38 +225,15 @@ abstract class UnCurry extends InfoTransform
     }
 
 
-    /*  Transform a function node (x_1,...,x_n) => body of type FunctionN[T_1, .., T_N, R] to
+    /**  Transform a function node (x_1,...,x_n) => body of type FunctionN[T_1, .., T_N, R] to
      *
      *    class $anon() extends AbstractFunctionN[T_1, .., T_N, R] with Serializable {
      *      def apply(x_1: T_1, ..., x_N: T_n): R = body
      *    }
      *    new $anon()
      *
-     *  transform a function node (x => body) of type PartialFunction[T, R] where
-     *    body = expr match { case P_i if G_i => E_i }_i=1..n
-     *  to:
+     * If `settings.XoldPatmat.value`, also synthesized AbstractPartialFunction subclasses (see synthPartialFunction).
      *
-     //TODO: correct code template below
-     *    class $anon() extends AbstractPartialFunction[T, R] with Serializable {
-     *      def applyOrElse[A1 <: A, B1 >: B](x: A1, default: A1 => B1): B1 = (expr: @unchecked) match {
-     *        case P_1 if G_1 => E_1
-     *        ...
-     *        case P_n if G_n => E_n
-     *        case _ => default(expr)
-     *      }
-     *      def isDefinedAt(x: T): boolean = (x: @unchecked) match {
-     *        case P_1 if G_1 => true
-     *        ...
-     *        case P_n if G_n => true
-     *        case _ => false
-     *      }
-     *    }
-     *    new $anon()
-     *
-     *  However, if one of the patterns P_i if G_i is a default pattern,
-     *  drop the last default clause in the definition of `apply` and generate for `_isDefinedAt` instead
-     *
-     *      def isDefinedAtCurrent(x: T): boolean = true
      */
     def transformFunction(fun: Function): Tree =
       deEta(fun) match {
@@ -300,6 +277,28 @@ abstract class UnCurry extends InfoTransform
 
       }
 
+    /** Transform a function node (x => body) of type PartialFunction[T, R] where
+     *    body = expr match { case P_i if G_i => E_i }_i=1..n
+     *  to (assuming none of the cases is a default case):
+     *
+     *    class $anon() extends AbstractPartialFunction[T, R] with Serializable {
+     *      def applyOrElse[A1 <: A, B1 >: B](x: A1, default: A1 => B1): B1 = (expr: @unchecked) match {
+     *        case P_1 if G_1 => E_1
+     *        ...
+     *        case P_n if G_n => E_n
+     *        case _ => default(expr)
+     *      }
+     *      def isDefinedAt(x: T): boolean = (x: @unchecked) match {
+     *        case P_1 if G_1 => true
+     *        ...
+     *        case P_n if G_n => true
+     *        case _ => false
+     *      }
+     *    }
+     *    new $anon()
+     *
+     *  If there's a default case, the original match is used for applyOrElse, and isDefinedAt returns `true`
+     */
     def synthPartialFunction(fun: Function) = {
       if (!settings.XoldPatmat.value) debugwarn("Under the new pattern matching scheme, PartialFunction should have been synthesized during typers.")
 

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

@@ -3884,40 +3884,51 @@ trait Typers extends Modes with Adaptations with Tags {
         }
       }
 
-      def typedBind(name: Name, body: Tree) = {
-        var vble = tree.symbol
-        def typedBindType(name: TypeName) = {
-          assert(body == EmptyTree, context.unit + " typedBind: " + name.debugString + " " + body + " " + body.getClass)
-          if (vble == NoSymbol)
-            vble =
-              if (isFullyDefined(pt))
-                context.owner.newAliasType(name, tree.pos) setInfo pt
-              else
-                context.owner.newAbstractType(name, tree.pos) setInfo TypeBounds.empty
-          val rawInfo = vble.rawInfo
-          vble = if (vble.name == tpnme.WILDCARD) context.scope.enter(vble)
-                 else namer.enterInScope(vble)
-          tree setSymbol vble setType vble.tpe
-        }
-        def typedBindTerm(name: TermName) = {
-          if (vble == NoSymbol)
-            vble = context.owner.newValue(name, tree.pos)
-          if (vble.name.toTermName != nme.WILDCARD) {
-            if ((mode & ALTmode) != 0)
-              VariableInPatternAlternativeError(tree)
-            vble = namer.enterInScope(vble)
-          }
-          val body1 = typed(body, mode, pt)
-          vble.setInfo(
-            if (treeInfo.isSequenceValued(body)) seqType(body1.tpe)
-            else body1.tpe)
-          treeCopy.Bind(tree, name, body1) setSymbol vble setType body1.tpe   // burak, was: pt
-        }
+      def typedBind(name: Name, body: Tree) =
         name match {
-          case x: TypeName  => typedBindType(x)
-          case x: TermName  => typedBindTerm(x)
+          case name: TypeName  => assert(body == EmptyTree, context.unit + " typedBind: " + name.debugString + " " + body + " " + body.getClass)
+            val sym =
+              if (tree.symbol != NoSymbol) tree.symbol
+              else {
+                if (isFullyDefined(pt))
+                  context.owner.newAliasType(name, tree.pos) setInfo pt
+                else
+                  context.owner.newAbstractType(name, tree.pos) setInfo TypeBounds.empty
+              }
+
+            if (name != tpnme.WILDCARD) namer.enterInScope(sym)
+            else context.scope.enter(sym)
+
+            tree setSymbol sym setType sym.tpe
+
+          case name: TermName  =>
+            val sym =
+              if (tree.symbol != NoSymbol) tree.symbol
+              else context.owner.newValue(name, tree.pos)
+
+            if (name != nme.WILDCARD) {
+              if ((mode & ALTmode) != 0) VariableInPatternAlternativeError(tree)
+              namer.enterInScope(sym)
+            }
+
+            val body1 = typed(body, mode, pt)
+            val symTp =
+              if (treeInfo.isSequenceValued(body)) seqType(body1.tpe)
+              else body1.tpe
+            sym setInfo symTp
+
+            // have to imperatively set the symbol for this bind to keep it in sync with the symbols used in the body of a case
+            // when type checking a case we imperatively update the symbols in the body of the case
+            // those symbols are bound by the symbols in the Binds in the pattern of the case,
+            // so, if we set the symbols in the case body, but not in the patterns,
+            // then re-type check the casedef (for a second try in typedApply for example -- SI-1832),
+            // we are no longer in sync: the body has symbols set that do not appear in the patterns
+            // since body1 is not necessarily equal to body, we must return a copied tree,
+            // but we must still mutate the original bind
+            tree setSymbol sym
+            treeCopy.Bind(tree, name, body1) setSymbol sym setType body1.tpe
         }
-      }
+
 
       def typedArrayValue(elemtpt: Tree, elems: List[Tree]) = {
         val elemtpt1 = typedType(elemtpt, mode)

test/files/pos/t1832.scala

@@ -0,0 +1,8 @@
+trait Cloning {
+  trait Foo
+  def fn(g: Any => Unit): Foo
+  
+  implicit def mkStar(i: Int) = new { def *(a: Foo): Foo = null }
+
+  val pool = 4 * fn { case ghostSYMBOL: Int => ghostSYMBOL * 2 }
+}