Option for testing for double bindings

A double binding is if a named type gets assigned two denotations in the same period. This is
a side-effect and also a race condition, so it's very bad. I am trying to eliminate all causes of this. But one cause which will likely remain are double defitions in a prgram, if a user writes

    class C {
      val x: Int
      val x: Int
    }

Then it's really hard to avoid setting two meanings of C.this.x! That's why the testing
against double bindings is enabled by a -YnoDoubleBindings option. The understanding is that
-YnoDoubleBindings should be set only if there are no double def errors anticipated. Otherwise
the program might fail with an assertion error before the double def error is reported.

1 files changed, 2 insertions, 2 deletions

diff --git a/test/dotc/tests.scala b/test/dotc/tests.scala
index 9665ec206..3228c3474 100644
--- a/test/dotc/tests.scala
+++ b/test/dotc/tests.scala
@@ -14,7 +14,7 @@ class tests extends CompilerTest {
 //        "-Yshow-suppressed-errors",
         "-pagewidth", "160"
     )
-  val twice = List("#runs", "2")
+  val twice = List("#runs", "2", "-YnoDoubleBindings")
   val doErase = List("-Ystop-before:terminal")
 
   val posDir = "./tests/pos/"
@@ -55,7 +55,7 @@ class tests extends CompilerTest {
   @Test def neg_typedapply() = compileFile(negDir, "typedapply", xerrors = 4)
   @Test def neg_typedidents() = compileFile(negDir, "typedIdents", xerrors = 2)
   @Test def neg_assignments() = compileFile(negDir, "assignments", xerrors = 3)
-  @Test def neg_typers() = compileFile(negDir, "typers", xerrors = 10)
+  @Test def neg_typers() = compileFile(negDir, "typers", xerrors = 13)
   @Test def neg_privates() = compileFile(negDir, "privates", xerrors = 2)
   @Test def neg_rootImports = compileFile(negDir, "rootImplicits", xerrors = 2)
   @Test def neg_templateParents() = compileFile(negDir, "templateParents", xerrors = 3)