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

1 files changed, 4 insertions, 4 deletions

diff --git a/test/files/neg/macro-invalidsig-implicit-params.check b/test/files/neg/macro-invalidsig-implicit-params.check
index 029b8a4634..98b3167b7a 100644
--- a/test/files/neg/macro-invalidsig-implicit-params.check
+++ b/test/files/neg/macro-invalidsig-implicit-params.check
@@ -1,4 +1,4 @@
-Impls_Macros_1.scala:5: error: macro implementations cannot have implicit parameters other than AbsTypeTag evidences

-  def foo_targs[T, U: c.AbsTypeTag](c: Ctx)(implicit x: c.Expr[Int]) = {

-                                                     ^

-one error found

+Impls_Macros_1.scala:5: error: macro implementations cannot have implicit parameters other than AbsTypeTag evidences
+  def foo_targs[T, U: c.AbsTypeTag](c: Ctx)(implicit x: c.Expr[Int]) = {
+                                                     ^
+one error found