Extract only under -Ysemanticdb

Author: odersky

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

@@ -150,7 +150,7 @@ class ScalaSettings extends Settings.SettingGroup {
   val YdumpSbtInc: Setting[Boolean] = BooleanSetting("-Ydump-sbt-inc", "For every compiled foo.scala, output the API representation and dependencies used for sbt incremental compilation in foo.inc, implies -Yforce-sbt-phases.")
   val YcheckAllPatmat: Setting[Boolean] = BooleanSetting("-Ycheck-all-patmat", "Check exhaustivity and redundancy of all pattern matching (used for testing the algorithm)")
   val YretainTrees: Setting[Boolean] = BooleanSetting("-Yretain-trees", "Retain trees for top-level classes, accessible from ClassSymbol#tree")
-  val YsemanticDB: Setting[Boolean] = BooleanSetting("-Ysemanticdb", "Store information in SemanticDB")
+  val Ysemanticdb: Setting[Boolean] = BooleanSetting("-Ysemanticdb", "Store information in SemanticDB")
   val YshowTreeIds: Setting[Boolean] = BooleanSetting("-Yshow-tree-ids", "Uniquely tag all tree nodes in debugging output.")
 
   val YprofileEnabled: Setting[Boolean] = BooleanSetting("-Yprofile-enabled", "Enable profiling.")

compiler/src/dotty/tools/dotc/semanticdb/ExtractSemanticDB.scala

@@ -23,7 +23,7 @@ class ExtractSemanticDB extends Phase {
   override val phaseName: String = ExtractSemanticDB.name
 
   override def isRunnable(implicit ctx: Context) =
-    true || super.isRunnable && ctx.settings.YretainTrees.value
+    super.isRunnable && ctx.settings.Ysemanticdb.value
 
   // Check not needed since it does not transform trees
   override def isCheckable: Boolean = false