Warning! Warning! Yes, that's what's in this co...

Warning! Warning! Yes, that's what's in this commit. Why are you
panicking?

Mostly new command line options:

  -Xlint // basically, the ones which aren't noisy Ywarn-all
  -Ywarn-dead-code Ywarn-inaccessible // try this one on the library:
  -it makes some good points Ywarn-nullary-override Ywarn-nullary-unit
  -Ywarn-numeric-widen Ywarn-value-discard

Some accumulated motivations:

The wontfix resolution of ticket #4506 indicates that "def foo" and "def
foo()" are always going to be treated differently in some situations
and the same in others without users having any way to fix it. Summary
expressed in latest comment with which I agree (and quite sadly, given
that I've done a lot of work to try to make them usable) is "avoid using
structural types like the plague." But the least we can do is warn if
you're using parentheses "wrong".

I think it would be better if the warning about "def foo()" overriding
"def foo" were an error instead. If we have to live with this...

  trait Me { def f(): Int }
  class A { def f: Int = 5 }
  class C extends A with Me { }

  // error: Int does not take parameters
  def f(x: C) = x.f()

  // compiles
  def f(x: Me) = x.f()

  // error: Int does not take parameters. Mmph, how can a method be
  // legal with parameter "Foo" and illegal with parameter "Foo with
  // Bar" ?

  def f(x: Me with C) = x.f()

The warning about a method contains a reference to a type which is less
accessible than the method itself is obviously to those who recall it
a response to GenTraversable being private and appearing in flatMap's
signature during the 2.9.0 RCs. It avoids warning in the case where the
unnormalized type is inaccessible but the normalized version would be,
but it could use further refinement.

1 files changed, 3 insertions, 9 deletions

diff --git a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
index 70f6ea0b89..03e6e508f6 100644
--- a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
+++ b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
@@ -12,7 +12,9 @@ import annotation.elidable
 import scala.tools.util.PathResolver.Defaults
 import scala.collection.mutable.HashSet
 
-trait ScalaSettings extends AbsScalaSettings with StandardScalaSettings {
+trait ScalaSettings extends AbsScalaSettings
+                       with StandardScalaSettings
+                       with Warnings {
   self: MutableSettings =>
 
   import Defaults.scalaUserClassPath
@@ -79,9 +81,6 @@ trait ScalaSettings extends AbsScalaSettings with StandardScalaSettings {
   val showPhases    = BooleanSetting    ("-Xshow-phases", "Print a synopsis of compiler phases.")
   val sourceReader  = StringSetting     ("-Xsource-reader", "classname", "Specify a custom method for reading source files.", "")
 
-  val Xwarnfatal    = BooleanSetting    ("-Xfatal-warnings", "Fail the compilation if there are any warnings.")
-  val Xchecknull    = BooleanSetting    ("-Xcheck-null", "Emit warning on selection of nullable reference.")
-
   // Experimental Extensions
   val Xexperimental = BooleanSetting    ("-Xexperimental", "Enable experimental extensions.") .
                           withPostSetHook(set => List(YdepMethTpes, YmethodInfer) foreach (_.value = set.value)) //YvirtClasses,
@@ -163,11 +162,6 @@ trait ScalaSettings extends AbsScalaSettings with StandardScalaSettings {
   def stop = stopAfter
 
   /**
-   * Warnings
-   */
-  val Ywarndeadcode = BooleanSetting    ("-Ywarn-dead-code", "Emit warnings for dead code")
-
-  /**
    * IDE-specific settings
    */
   val YpresentationVerbose = BooleanSetting("-Ypresentation-verbose", "Print information about presentation compiler tasks.")