Warn about catching non-local returns.

Almost every time someone is shooting themself in the foot
by catching a non-local return, it is apparent from the
structure of the AST that they are doing so.  Warn them.

1 files changed, 6 insertions, 0 deletions

diff --git a/src/compiler/scala/tools/nsc/transform/UnCurry.scala b/src/compiler/scala/tools/nsc/transform/UnCurry.scala
index 72dd8acad7..fc61997cd5 100644
--- a/src/compiler/scala/tools/nsc/transform/UnCurry.scala
+++ b/src/compiler/scala/tools/nsc/transform/UnCurry.scala
@@ -204,6 +204,12 @@ abstract class UnCurry extends InfoTransform
         val keyDef   = ValDef(key, New(ObjectClass.tpe))
         val tryCatch = Try(body, pat -> rhs)
 
+        body foreach {
+          case Try(t, catches, _) if catches exists treeInfo.catchesThrowable =>
+            unit.warning(body.pos, "catch block may intercept non-local return from " + meth)
+          case _ =>
+        }
+
         Block(List(keyDef), tryCatch)
       }
     }