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author | Jason Zaugg <jzaugg@gmail.com> | 2013-02-10 15:40:01 +0100 |
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committer | Jason Zaugg <jzaugg@gmail.com> | 2013-03-29 19:22:02 +0100 |
commit | 530f4a544b95d77eff378d31122615eea195618a (patch) | |
tree | b3da412c8778983b1f2c1db40cebf4761aba02dd | |
parent | 1debc74374e9c3de52d1333b695db61e7a69a57b (diff) | |
download | scala-530f4a544b95d77eff378d31122615eea195618a.tar.gz scala-530f4a544b95d77eff378d31122615eea195618a.tar.bz2 scala-530f4a544b95d77eff378d31122615eea195618a.zip |
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.
-rw-r--r-- | src/compiler/scala/tools/nsc/typechecker/Typers.scala | 7 | ||||
-rw-r--r-- | test/files/neg/t7110.check | 6 | ||||
-rw-r--r-- | test/files/neg/t7110.flags | 1 | ||||
-rw-r--r-- | test/files/neg/t7110.scala | 6 |
4 files changed, 20 insertions, 0 deletions
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) diff --git a/test/files/neg/t7110.check b/test/files/neg/t7110.check new file mode 100644 index 0000000000..e484dc4325 --- /dev/null +++ b/test/files/neg/t7110.check @@ -0,0 +1,6 @@ +t7110.scala:2: warning: A try without a catch or finally is equivalent to putting its body in a block; no exceptions are handled. + try { ??? } // warn + ^ +error: No warnings can be incurred under -Xfatal-warnings. +one warning found +one error found diff --git a/test/files/neg/t7110.flags b/test/files/neg/t7110.flags new file mode 100644 index 0000000000..e8fb65d50c --- /dev/null +++ b/test/files/neg/t7110.flags @@ -0,0 +1 @@ +-Xfatal-warnings
\ No newline at end of file diff --git a/test/files/neg/t7110.scala b/test/files/neg/t7110.scala new file mode 100644 index 0000000000..79ac325216 --- /dev/null +++ b/test/files/neg/t7110.scala @@ -0,0 +1,6 @@ +object Test { + try { ??? } // warn + + try { ??? } finally ??? // no warn + try { ??? } catch { case _: Throwable => } // no warn +} |