Rename -YnoDoubleBindings to -Yno-double-bindings

This aligns with the "-" instead of CamelCase convention for
the other command line options.

Also, enable -Yno-double-bindings for dotc_core.

Author: odersky

src/dotty/tools/dotc/ast/TreeTypeMap.scala

@@ -30,7 +30,7 @@ import dotty.tools.dotc.transform.SymUtils._
  *  have two substitutons S1 = [outer#1 := outer#3], S2 = [inner#2 := inner#4] where
  *  hashtags precede symbol ids. If we do S1 first, we get outer#2.inner#3. If we then
  *  do S2 we get outer#2.inner#4. But that means that the named type outer#2.inner
- *  gets two different denotations in the same period. Hence, if -YnoDoubleBindings is
+ *  gets two different denotations in the same period. Hence, if -Yno-double-bindings is
  *  set, we would get a data race assertion error.
  */
 final class TreeTypeMap(

src/dotty/tools/dotc/config/ScalaSettings.scala

@@ -170,7 +170,7 @@ class ScalaSettings extends Settings.SettingGroup {
   val Ytyperdebug = BooleanSetting("-Ytyper-debug", "Trace all type assignments.")
   val Ypatmatdebug = BooleanSetting("-Ypatmat-debug", "Trace pattern matching translation.")
   val Yexplainlowlevel = BooleanSetting("-Yexplain-lowlevel", "When explaining type errors, show types at a lower level.")
-  val YnoDoubleBindings = BooleanSetting("-YnoDoubleBindings", "Assert no namedtype is bound twice (should be enabled only if program is error-free).")
+  val YnoDoubleBindings = BooleanSetting("-Yno-double-bindings", "Assert no namedtype is bound twice (should be enabled only if program is error-free).")
 
   val optimise = BooleanSetting("-optimise", "Generates faster bytecode by applying optimisations to the program") withAbbreviation "-optimize"
 

test/dotc/tests.scala

@@ -25,7 +25,7 @@ class tests extends CompilerTest {
   val testPickling = List("-Xprint-types", "-Ytest-pickler", "-Ystop-after:pickler")
 
   val failedOther = List("-Ystop-before:collectEntryPoints") // some non-obvious reason. need to look deeper
-  val twice = List("#runs", "2", "-YnoDoubleBindings")
+  val twice = List("#runs", "2", "-Yno-double-bindings")
   val staleSymbolError: List[String] = List()
 
   val allowDeepSubtypes = defaultOptions diff List("-Yno-deep-subtypes")
@@ -130,8 +130,8 @@ class tests extends CompilerTest {
   @Test def dotc = compileDir(dotcDir + "tools/dotc", failedOther)(allowDeepSubtypes ++ twice) // see dotc_core
   @Test def dotc_ast = compileDir(dotcDir + "tools/dotc/ast", failedOther ++ twice)
     //similar to dotc_core_pickling but for another anon class. Still during firstTransform
-  @Test def dotc_config = compileDir(dotcDir + "tools/dotc/config", twice)
-  @Test def dotc_core = compileDir(dotcDir + "tools/dotc/core", failedOther)(allowDeepSubtypes) // !!!twice gives "data race?" error in InterceptedMethods
+  @Test def dotc_config = compileDir(dotcDir + "tools/dotc/config")
+  @Test def dotc_core = compileDir(dotcDir + "tools/dotc/core", failedOther)("-Yno-double-bindings" :: allowDeepSubtypes)// twice omitted to make tests run faster
     // error: error while loading ConstraintHandling$$anon$1$,
     // class file 'target/scala-2.11/dotty_2.11-0.1-SNAPSHOT.jar(dotty/tools/dotc/core/ConstraintHandling$$anon$1.class)'
     // has location not matching its contents: contains class $anon