Pickle signatures using qualified names.

Would like to do use more semantic names in pickled file, but it's hard without
having semantic names to start with.

Author: odersky

src/dotty/tools/dotc/core/pickling/NameBuffer.scala

@@ -32,6 +32,14 @@ class NameBuffer extends TastyBuffer(100000) {
 
   def nameIndex(str: String): NameRef = nameIndex(str.toTermName)
 
+  def fullNameIndex(name: Name): NameRef = {
+    val pos = name.lastIndexOf('.')
+    if (pos > 0)
+      nameIndex(Qualified(fullNameIndex(name.take(pos)), nameIndex(name.drop(pos + 1))))
+    else
+      nameIndex(name)
+  }
+  
   private def withLength(op: => Unit): Unit = {
     val lengthAddr = currentAddr
     writeByte(0)

src/dotty/tools/dotc/core/pickling/TreePickler.scala

@@ -14,7 +14,7 @@ class TreePickler(pickler: TastyPickler) {
   val buf = new TreeBuffer
   pickler.newSection("ASTs", buf)
   import buf._
-  import pickler.nameBuffer.nameIndex
+  import pickler.nameBuffer.{nameIndex, fullNameIndex}
   import ast.tpd._
 
   private val symRefs = new mutable.HashMap[Symbol, Addr]
@@ -61,7 +61,7 @@ class TreePickler(pickler: TastyPickler) {
   private def pickleName(name: TastyName) = writeNat(nameIndex(name).index)
   private def pickleNameAndSig(name: Name, sig: Signature) = {
     val Signature(params, result) = sig
-    pickleName(TastyName.Signed(nameIndex(name), params.map(nameIndex), nameIndex(result)))
+    pickleName(TastyName.Signed(nameIndex(name), params.map(fullNameIndex), fullNameIndex(result)))
   }
 
   private def pickleSymRef(sym: Symbol)(implicit ctx: Context) = symRefs.get(sym) match {