Compile scala.collection.Seq without double-binding error

This commit fixes two issues which caused us to complete Seq too early and
read it from the classpath instead of from the sources:
- Evaluting RepeatedParamClass forced Seq, this is not necessary
  because the type of RepeatedParamClass is a LazyType
- TypeErasure#sigName on a Scala type always forced Seq, even if
  the type is not a repeated param type.

This fixes #980.

1 files changed, 4 insertions, 2 deletions

diff --git a/src/dotty/tools/dotc/core/TypeErasure.scala b/src/dotty/tools/dotc/core/TypeErasure.scala
index 7cca37911..108d862a9 100644
--- a/src/dotty/tools/dotc/core/TypeErasure.scala
+++ b/src/dotty/tools/dotc/core/TypeErasure.scala
@@ -126,9 +126,11 @@ object TypeErasure {
     erasureFn(isJava = false, semiEraseVCs = true, isConstructor = false, wildcardOK = false)(tp)(erasureCtx)
 
   def sigName(tp: Type, isJava: Boolean)(implicit ctx: Context): TypeName = {
-    val seqClass = if (isJava) defn.ArrayClass else defn.SeqClass
     val normTp =
-      if (tp.isRepeatedParam) tp.translateParameterized(defn.RepeatedParamClass, seqClass)
+      if (tp.isRepeatedParam) {
+        val seqClass = if (isJava) defn.ArrayClass else defn.SeqClass
+        tp.translateParameterized(defn.RepeatedParamClass, seqClass)
+      }
       else tp
     val erase = erasureFn(isJava, semiEraseVCs = false, isConstructor = false, wildcardOK = true)
     erase.sigName(normTp)(erasureCtx)