Merge pull request #720 from phaller/cps-ticket-1681

CPS: enable return expressions in CPS code if they are in tail position

2 files changed, 6 insertions, 1 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/Modes.scala b/src/compiler/scala/tools/nsc/typechecker/Modes.scala
index 3eff5ef024..bde3ad98c9 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Modes.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Modes.scala
@@ -86,6 +86,10 @@ trait Modes {
    */
   final val TYPEPATmode   = 0x10000
 
+  /** RETmode is set when we are typing a return expression.
+   */
+  final val RETmode       = 0x20000
+  
   final private val StickyModes   = EXPRmode | PATTERNmode | TYPEmode | ALTmode
 
   final def onlyStickyModes(mode: Int) =
diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index 2bdae4164a..1193d3013a 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -3987,7 +3987,8 @@ trait Typers extends Modes with Adaptations with Tags {
             ReturnWithoutTypeError(tree, enclMethod.owner)
           } else {
             context.enclMethod.returnsSeen = true
-            val expr1: Tree = typed(expr, EXPRmode | BYVALmode, restpt.tpe)
+            val expr1: Tree = typed(expr, EXPRmode | BYVALmode | RETmode, restpt.tpe)
+            
             // Warn about returning a value if no value can be returned.
             if (restpt.tpe.typeSymbol == UnitClass) {
               // The typing in expr1 says expr is Unit (it has already been coerced if