Merge pull request #1530 from retronym/ticket/6575-2

SI-6575 Plug inference leak of AbstractPartialFunction

7 files changed, 71 insertions, 20 deletions

diff --git a/src/compiler/scala/tools/nsc/transform/Mixin.scala b/src/compiler/scala/tools/nsc/transform/Mixin.scala
index 2b0520592b..80900a1a0a 100644
--- a/src/compiler/scala/tools/nsc/transform/Mixin.scala
+++ b/src/compiler/scala/tools/nsc/transform/Mixin.scala
@@ -481,7 +481,7 @@ abstract class Mixin extends InfoTransform with ast.TreeDSL {
 
     /** The typer */
     private var localTyper: erasure.Typer = _
-    private def typedPos(pos: Position)(tree: Tree) = localTyper typed { atPos(pos)(tree) }
+    private def typedPos(pos: Position)(tree: Tree): Tree = localTyper.typedPos(pos)(tree)
     private def localTyped(pos: Position, tree: Tree, pt: Type) = localTyper.typed(atPos(pos)(tree), pt)
 
     /** Map lazy values to the fields they should null after initialization. */
diff --git a/src/compiler/scala/tools/nsc/typechecker/Duplicators.scala b/src/compiler/scala/tools/nsc/typechecker/Duplicators.scala
index 97e86d183e..aa507efe5a 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Duplicators.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Duplicators.scala
@@ -321,7 +321,9 @@ abstract class Duplicators extends Analyzer {
           // we use the symbol name instead of the tree name because the symbol may have been
           // name mangled, rendering the tree name obsolete
           // log(tree)
-          val t = super.typed(atPos(tree.pos)(Select(This(newClassOwner), tree.symbol.name)), mode, pt)
+          val t = super.typedPos(tree.pos, mode, pt) {
+            Select(This(newClassOwner), tree.symbol.name)
+          }
           // log("typed to: " + t + "; tpe = " + t.tpe + "; " + inspectTpe(t.tpe))
           t
 
@@ -331,7 +333,7 @@ abstract class Duplicators extends Analyzer {
           val tree1 = This(newClassOwner)
           // log("tree1: " + tree1)
           debuglog("mapped " + tree + " to " + tree1)
-          super.typed(atPos(tree.pos)(tree1), mode, pt)
+          super.typedPos(tree.pos, mode, pt)(tree1)
 
         case This(_) =>
           debuglog("selection on this, plain: " + tree)
@@ -368,7 +370,7 @@ abstract class Duplicators extends Analyzer {
               cases
           }
 
-          super.typed(atPos(tree.pos)(Match(scrut, cases1)), mode, pt)
+          super.typedPos(tree.pos, mode, pt)(Match(scrut, cases1))
 
         case EmptyTree =>
           // no need to do anything, in particular, don't set the type to null, EmptyTree.tpe_= asserts
diff --git a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
index 7852ff49e1..99301cebcf 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
@@ -1172,7 +1172,7 @@ trait Implicits {
         }
 
         try {
-          val tree1 = typed(atPos(pos.focus)(arg))
+          val tree1 = typedPos(pos.focus)(arg)
           if (context.hasErrors) processMacroExpansionError(context.errBuffer.head.errPos, context.errBuffer.head.errMsg)
           else new SearchResult(tree1, EmptyTreeTypeSubstituter)
         } catch {
diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index f82786da35..c5bd92a943 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -1049,7 +1049,9 @@ trait Typers extends Modes with Adaptations with Tags {
           case other =>
             other
         }
-        typed(atPos(tree.pos)(Select(qual setPos tree.pos.makeTransparent, nme.apply)), mode, pt)
+        typedPos(tree.pos, mode, pt) {
+          Select(qual setPos tree.pos.makeTransparent, nme.apply)
+        }
       }
 
       // begin adapt
@@ -1147,11 +1149,15 @@ trait Typers extends Modes with Adaptations with Tags {
                       if (sym == UnitClass && tree.tpe <:< AnyClass.tpe) { // (12)
                         if (settings.warnValueDiscard.value)
                           context.unit.warning(tree.pos, "discarded non-Unit value")
-                        return typed(atPos(tree.pos)(Block(List(tree), Literal(Constant()))), mode, pt)
+                        return typedPos(tree.pos, mode, pt) {
+                          Block(List(tree), Literal(Constant()))
+                        }
                       } else if (isNumericValueClass(sym) && isNumericSubType(tree.tpe, pt)) {
                         if (settings.warnNumericWiden.value)
                           context.unit.warning(tree.pos, "implicit numeric widening")
-                        return typed(atPos(tree.pos)(Select(tree, "to" + sym.name)), mode, pt)
+                        return typedPos(tree.pos, mode, pt) {
+                          Select(tree, "to" + sym.name)
+                        }
                       }
                     case AnnotatedType(_, _, _) if canAdaptAnnotations(tree, mode, pt) => // (13)
                       return typed(adaptAnnotations(tree, mode, pt), mode, pt)
@@ -2590,7 +2596,17 @@ trait Typers extends Modes with Adaptations with Tags {
 
       def translated =
         if (members.head eq EmptyTree) setError(tree)
-        else typed(atPos(tree.pos)(Block(List(ClassDef(anonClass, NoMods, ListOfNil, ListOfNil, members, tree.pos.focus)), atPos(tree.pos.focus)(New(anonClass.tpe)))), mode, pt)
+        else {
+          val typedBlock = typedPos(tree.pos, mode, pt) {
+            Block(ClassDef(anonClass, NoMods, ListOfNil, ListOfNil, members, tree.pos.focus), atPos(tree.pos.focus)(New(anonClass.tpe)))
+          }
+          // Don't leak implementation details into the type, see SI-6575
+          if (isPartial && !typedBlock.isErrorTyped)
+            typedPos(tree.pos, mode, pt) {
+              Typed(typedBlock, TypeTree(typedBlock.tpe baseType PartialFunctionClass))
+            }
+          else typedBlock
+        }
     }
 
     // Function(params, Match(sel, cases)) ==> new <Partial>Function { def apply<OrElse>(params) = `translateMatch('sel match { cases }')` }
@@ -5494,6 +5510,7 @@ trait Typers extends Modes with Adaptations with Tags {
       ret
     }
 
+    def typedPos(pos: Position, mode: Int, pt: Type)(tree: Tree) = typed(atPos(pos)(tree), mode, pt)
     def typedPos(pos: Position)(tree: Tree) = typed(atPos(pos)(tree))
     // TODO: see if this formulation would impose any penalty, since
     // it makes for a lot less casting.
diff --git a/src/continuations/plugin/scala/tools/selectivecps/SelectiveCPSTransform.scala b/src/continuations/plugin/scala/tools/selectivecps/SelectiveCPSTransform.scala
index 54a0079f40..4482bf2b7c 100644
--- a/src/continuations/plugin/scala/tools/selectivecps/SelectiveCPSTransform.scala
+++ b/src/continuations/plugin/scala/tools/selectivecps/SelectiveCPSTransform.scala
@@ -193,12 +193,12 @@ abstract class SelectiveCPSTransform extends PluginComponent with
 
           val pos = catches.head.pos
           val funSym = currentOwner.newValueParameter(cpsNames.catches, pos).setInfo(appliedType(PartialFunctionClass.tpe, List(ThrowableClass.tpe, targettp)))
-          val funDef = localTyper.typed(atPos(pos) {
+          val funDef = localTyper.typedPos(pos) {
             ValDef(funSym, Match(EmptyTree, catches1))
-          })
-          val expr2 = localTyper.typed(atPos(pos) {
+          }
+          val expr2 = localTyper.typedPos(pos) {
             Apply(Select(expr1, expr1.tpe.member(cpsNames.flatMapCatch)), List(Ident(funSym)))
-          })
+          }
 
           val exSym = currentOwner.newValueParameter(cpsNames.ex, pos).setInfo(ThrowableClass.tpe)
 
@@ -223,7 +223,7 @@ abstract class SelectiveCPSTransform extends PluginComponent with
             val pos = finalizer.pos
             val finalizer2 = duplicateTree(finalizer1)
             val fun = Function(List(), finalizer2)
-            val expr3 = localTyper.typed(atPos(pos) { Apply(Select(expr2, expr2.tpe.member("mapFinally")), List(fun)) })
+            val expr3 = localTyper.typedPos(pos) { Apply(Select(expr2, expr2.tpe.member("mapFinally")), List(fun)) }
 
             val chown = new ChangeOwnerTraverser(currentOwner, fun.symbol)
             chown.traverse(finalizer2)
@@ -290,7 +290,7 @@ abstract class SelectiveCPSTransform extends PluginComponent with
 
                 val body1 = (new TreeSymSubstituter(List(vd.symbol), List(ctxValSym)))(body)
 
-                val body2 = localTyper.typed(atPos(vd.symbol.pos) { body1 })
+                val body2 = localTyper.typedPos(vd.symbol.pos) { body1 }
 
                 // in theory it would be nicer to look for an @cps annotation instead
                 // of testing for Context
@@ -304,7 +304,7 @@ abstract class SelectiveCPSTransform extends PluginComponent with
               def applyCombinatorFun(ctxR: Tree, body: Tree) = {
                 val arg = currentOwner.newValueParameter(name, ctxR.pos).setInfo(tpe)
                 val body1 = (new TreeSymSubstituter(List(vd.symbol), List(arg)))(body)
-                val fun = localTyper.typed(atPos(vd.symbol.pos) { Function(List(ValDef(arg)), body1) }) // types body as well
+                val fun = localTyper.typedPos(vd.symbol.pos) { Function(List(ValDef(arg)), body1) } // types body as well
                 arg.owner = fun.symbol
                 body1.changeOwner(currentOwner -> fun.symbol)
 
@@ -328,9 +328,9 @@ abstract class SelectiveCPSTransform extends PluginComponent with
 
                 debuglog("will use method:"+methodName)
 
-                localTyper.typed(atPos(vd.symbol.pos) {
+                localTyper.typedPos(vd.symbol.pos) {
                   Apply(Select(ctxR, ctxR.tpe.member(methodName)), List(fun))
-                })
+                }
               }
 
               def mkBlock(stms: List[Tree], expr: Tree) = if (stms.nonEmpty) Block(stms, expr) else expr
@@ -352,12 +352,12 @@ abstract class SelectiveCPSTransform extends PluginComponent with
                   def ctxRef = localTyper.typed(Ident(ctxSym))
                   val argSym = currentOwner.newValue(vd.symbol.name).setInfo(tpe)
                   val argDef = localTyper.typed(ValDef(argSym, Select(ctxRef, ctxRef.tpe.member(cpsNames.getTrivialValue))))
-                  val switchExpr = localTyper.typed(atPos(vd.symbol.pos) {
+                  val switchExpr = localTyper.typedPos(vd.symbol.pos) {
                     val body2 = mkBlock(bodyStms, bodyExpr).duplicate // dup before typing!
                     If(Select(ctxRef, ctxSym.tpe.member(cpsNames.isTrivial)),
                       applyTrivial(argSym, mkBlock(argDef::bodyStms, bodyExpr)),
                       applyCombinatorFun(ctxRef, body2))
-                  })
+                  }
                   (List(ctxDef), switchExpr)
                 } else {
                   // ctx.flatMap { <lhs> => ... }
diff --git a/test/files/pos/t6575a.scala b/test/files/pos/t6575a.scala
new file mode 100644
index 0000000000..f128714dab
--- /dev/null
+++ b/test/files/pos/t6575a.scala
@@ -0,0 +1,15 @@
+trait X { def foo: PartialFunction[Int, Int] }
+
+trait Y extends X {
+  // Inferred type was AbstractPartialFunction[Int, Int] with Serializable
+  abstract override def foo = { case i => super.foo(i) * 2 }
+}
+trait Z extends X {
+  // ditto
+  abstract override def foo = { case i => super.foo(i) + 3 }
+}
+
+trait Comb extends Y with Z {
+  // ... which led to a type error here.
+  abstract override def foo: PartialFunction[Int, Int] = { case i => super.foo(i) - 2 }
+}
diff --git a/test/files/pos/t6575b.scala b/test/files/pos/t6575b.scala
new file mode 100644
index 0000000000..d3e58b2a16
--- /dev/null
+++ b/test/files/pos/t6575b.scala
@@ -0,0 +1,17 @@
+// inferred types were okay here as Function nodes aren't
+// translated into anoymous subclasses of AbstractFunctionN
+// until after the typer.
+//
+// So this test is just confirmation.
+trait X { def foo: Function1[Int, Int] }
+
+trait Y extends X {
+  abstract override def foo = { case i => super.foo(i) * 2 }
+}
+trait Z extends X {
+  abstract override def foo = { case i => super.foo(i) + 3 }
+}
+
+trait Comb extends Y with Z {
+  abstract override def foo: Function1[Int, Int] = { case i => super.foo(i) - 2 }
+}