From 802771b403f6dd0f09e01e4e3e1189c70d4b7bec Mon Sep 17 00:00:00 2001 From: Paul Phillips Date: Wed, 8 Aug 2012 05:29:43 -0700 Subject: Better pattern matcher error message. For the common case when someone hasn't quite grokked the significance of lower case in a pattern match. I'd like to make all the unreachables errors, not warnings, but there may be a bug or two to clear out first. class A { def badEquals(x: Any, y: Any) = x match { case y => true case _ => false } } a.scala:3: warning: patterns after a variable pattern cannot match (SLS 8.1.1) If you intended to match against parameter y of method badEquals, you must use backticks, like: case `y` => case y => true ^ a.scala:4: warning: unreachable code due to variable pattern 'y' on line 3 case _ => false ^ two warnings found --- test/files/neg/newpat_unreachable.scala | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) create mode 100644 test/files/neg/newpat_unreachable.scala (limited to 'test/files/neg/newpat_unreachable.scala') diff --git a/test/files/neg/newpat_unreachable.scala b/test/files/neg/newpat_unreachable.scala new file mode 100644 index 0000000000..c9cc85cec6 --- /dev/null +++ b/test/files/neg/newpat_unreachable.scala @@ -0,0 +1,29 @@ +object Test { + class A { + val d = 55 + + def contrivedExample[A, B, C](a: A, b: B, c: C): Unit = a match { + case b => println("matched b") + case c => println("matched c") + case d => println("matched d") + case _ => println("matched neither") + } + + def correctExample[A, B, C](a: A, b: B, c: C): Unit = a match { + case `b` => println("matched b") + case `c` => println("matched c") + case `d` => println("matched d") + case _ => println("matched neither") + } + + def f[A](a: A) = { + def g[B](b: B) = { + def h[C](c: C) = a match { + case b => 1 + case c => 2 + case _ => 3 + } + } + } + } +} -- cgit v1.2.3