Merge pull request #3218 from som-snytt/issue/8027-repl-dbltab

SI-8027 REPL double tab regression

1 files changed, 10 insertions, 6 deletions

diff --git a/src/reflect/scala/reflect/internal/util/StringOps.scala b/src/reflect/scala/reflect/internal/util/StringOps.scala
index 14f349f502..efb8126ff0 100644
--- a/src/reflect/scala/reflect/internal/util/StringOps.scala
+++ b/src/reflect/scala/reflect/internal/util/StringOps.scala
@@ -23,12 +23,16 @@ trait StringOps {
   def oempty(xs: String*)        = xs filterNot (x => x == null || x == "")
   def ojoin(xs: String*): String = oempty(xs: _*) mkString " "
   def longestCommonPrefix(xs: List[String]): String = xs match {
-    case Nil                  => ""
-    case xs if xs contains "" => ""
-    case x :: xs             =>
-      val ch = x charAt 0
-      if (xs exists (_.head != ch)) ""
-      else "" + ch + longestCommonPrefix(xs map (_ substring 1))
+    case Nil      => ""
+    case w :: Nil => w
+    case _        =>
+      def lcp(ss: List[String]): String = {
+        val w :: ws = ss
+        if (w == "") ""
+        else if (ws exists (s => s == "" || (s charAt 0) != (w charAt 0))) ""
+        else w.substring(0, 1) + lcp(ss map (_ substring 1))
+      }
+      lcp(xs)
   }
   /** Like String#trim, but trailing whitespace only.
    */