Add -Yprintpos-syms to print the position of symbols

And add it to the set of options passed to the pickling tests so that we
can start checking that symbol positions are properly pickled and unpickled.

Author: smarter

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

@@ -96,6 +96,7 @@ class ScalaSettings extends Settings.SettingGroup {
   val YdetailedStats = BooleanSetting("-Ydetailed-stats", "show detailed internal compiler stats (needs Stats.enabled to be set to true).")
   val Yheartbeat = BooleanSetting("-Ydetailed-stats", "show heartbeat stack trace of compiler operations (needs Stats.enabled to be set to true).")
   val YprintPos = BooleanSetting("-Yprint-pos", "show tree positions.")
+  val YprintPosSyms = BooleanSetting("-Yprint-pos-syms", "show symbol definitions positions.")
   val YnoDeepSubtypes = BooleanSetting("-Yno-deep-subtypes", "throw an exception on deep subtyping call stacks.")
   val YnoPatmatOpt = BooleanSetting("-Yno-patmat-opt", "disable all pattern matching optimizations.")
   val YplainPrinter = BooleanSetting("-Yplain-printer", "Pretty-print using a plain printer.")

compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala

@@ -13,6 +13,7 @@ import Trees._
 import TypeApplications._
 import Decorators._
 import config.Config
+import util.Positions._
 import transform.SymUtils._
 import scala.annotation.switch
 import language.implicitConversions
@@ -630,14 +631,18 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
       else if (tree.isType && !homogenizedView)
         txt = toText(tp)
     }
-    if (printPos && !suppressPositions) {
-      // add positions
-      val pos =
-        if (homogenizedView && !tree.isInstanceOf[MemberDef]) tree.pos.toSynthetic
-        else tree.pos
-      val clsStr = ""//if (tree.isType) tree.getClass.toString else ""
-      txt = (txt ~ "@" ~ pos.toString ~ clsStr).close
-    }
+    if (!suppressPositions) {
+      if (printPos) {
+        val pos =
+          if (homogenizedView && !tree.isInstanceOf[MemberDef]) tree.pos.toSynthetic
+          else tree.pos
+        val clsStr = ""//if (tree.isType) tree.getClass.toString else ""
+        txt = (txt ~ "@" ~ pos.toString ~ clsStr).close
+      }
+      if (ctx.settings.YprintPosSyms.value && tree.isDef)
+        txt = (txt ~
+          s"@@(${tree.symbol.name}=" ~ tree.symbol.pos.toString ~ ")").close
+   }
     if (ctx.settings.YshowTreeIds.value)
       txt = (txt ~ "#" ~ tree.uniqueId.toString).close
     tree match {

compiler/test/dotc/tests.scala

@@ -73,7 +73,7 @@ class tests extends CompilerTest {
     else List("-Ycheck:tailrec,resolveSuper,mixin,elimStaticThis,labelDef,simplify")
   } ++ checkOptions ++ classPath
 
-  val testPickling = List("-Xprint-types", "-Ytest-pickler", "-Ystop-after:pickler", "-Yprint-pos")
+  val testPickling = List("-Xprint-types", "-Ytest-pickler", "-Ystop-after:pickler", "-Yprint-pos", "-Yprint-pos-syms")
 
   val twice = List("#runs", "2")
   val staleSymbolError: List[String] = List()

compiler/test/dotty/tools/vulpix/TestConfiguration.scala

@@ -54,7 +54,8 @@ object TestConfiguration {
   val picklingOptions = defaultUnoptimised and (
     "-Xprint-types",
     "-Ytest-pickler",
-    "-Yprint-pos"
+    "-Yprint-pos",
+    "-Yprint-pos-syms"
   )
   val scala2Mode = defaultOptions and "-language:Scala2"
   val explicitUTF8 = defaultOptions and ("-encoding", "UTF8")