From 530f4a544b95d77eff378d31122615eea195618a Mon Sep 17 00:00:00 2001 From: Jason Zaugg Date: Sun, 10 Feb 2013 15:40:01 +0100 Subject: SI-7110 Warn about naked try without catch/finally Before, this was allowed: scala> try ( 1 / 0 ) java.lang.ArithmeticException: / by zero But since the advent of util.Try, the subtle difference to the following seems dangerous: scala> import util.Try import util.Try scala> Try ( 1 / 0 ) res4: scala.util.Try[Int] = Failure(java.lang.ArithmeticException: / by zero) Discussion: https://groups.google.com/d/topic/scala-language/fy2vXD_3fF8/discussion There was some concern that this curtails a handy, temporary way to remove the exception handlers from some code. But after thinking about this, I contend that: a) those people can easily stomach the warning temporarily (modulo, of course, those with -Xfatal-warnings.) b) putting this warning behind Xlint will disable it for those who need it most: beginners. I also chose not to refer to 'scala.util.Try' in the error message as I think that has as much potential to confuse as it does to clarify. --- src/compiler/scala/tools/nsc/typechecker/Typers.scala | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'src') diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala index 910c5256c2..fa5603dcb8 100644 --- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala +++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala @@ -4993,6 +4993,13 @@ trait Typers extends Adaptations with Tags { } def typedTry(tree: Try) = { + tree match { + case Try(_, Nil, EmptyTree) => + if (!isPastTyper) context.warning(tree.pos, + "A try without a catch or finally is equivalent to putting its body in a block; no exceptions are handled.") + case _ => + } + var block1 = typed(tree.block, pt) var catches1 = typedCases(tree.catches, ThrowableClass.tpe, pt) -- cgit v1.2.3