Use asymptotically better Map

src/main/scala/decider/Z3ProverAPI.scala

@@ -22,7 +22,6 @@ import scala.collection.mutable
 import com.microsoft.z3._
 import viper.silicon.reporting.ExternalToolError
 
-import scala.collection.immutable.ListMap
 import scala.jdk.CollectionConverters.MapHasAsJava
 import scala.util.Random
 
@@ -339,7 +338,7 @@ class Z3ProverAPI(uniqueId: String,
     for (e <- statistics.getEntries()) {
       result.update(e.Key, e.getValueString)
     }
-    ListMap.from(result)
+    Map.from(result)
   }
 
   def comment(str: String): Unit = {

src/main/scala/logger/SymbExLogger.scala

@@ -221,7 +221,7 @@ object SymbExLogger {
   /**
     * stores the last SMT solver statistics to calculate the diff
     */
-  private var prevSmtStatistics: Map[String, String] = new Map()
+  private var prevSmtStatistics: Map[String, String] = Map.empty
 
   /** Add a new log for a method, function or predicate (member).
     *
@@ -304,13 +304,13 @@ object SymbExLogger {
     uidCounter = 0
     filePath = null
     logConfig = LogConfig.default()
-    prevSmtStatistics = new Map()
+    prevSmtStatistics = Map.empty
   }
 
   def resetMemberList(): Unit = {
     memberList = Seq[SymbLog]()
     // or reset by calling it from Decider.reset
-    prevSmtStatistics = new Map()
+    prevSmtStatistics = Map.empty
   }
 
   /**

src/main/scala/logger/writer/SymbExLogReportWriter.scala

@@ -158,7 +158,7 @@ object SymbExLogReportWriter {
       case _ =>
     }
 
-    var fields: Map[String, JsValue] = new Map()
+    var fields: Map[String, JsValue] = Map.empty
 
     fields = fields + ("id" -> JsNumber(record.id))
     fields = fields + ("kind" -> JsString(record.toTypeString))
@@ -188,7 +188,7 @@ object SymbExLogReportWriter {
   }
 
   def toJSON(data: RecordData): Option[JsObject] = {
-    var fields: Map[String, JsValue] = new Map()
+    var fields: Map[String, JsValue] = Map.empty
 
     data.refId.foreach(refId => fields = fields + ("refId" -> JsNumber(refId)))
 

src/main/scala/package.scala

@@ -14,8 +14,8 @@ package object silicon {
 
   /* Immutable collections with a deterministic iteration order */
 
-  type Map[K, +V] = scala.collection.immutable.ListMap[K, V]
-  val Map = scala.collection.immutable.ListMap
+  type Map[K, +V] = scala.collection.immutable.TreeSeqMap[K, V]
+  val Map = scala.collection.immutable.TreeSeqMap
 
   @inline
   def toMap[K, V](it: Iterable[(K, V)]): Map[K, V] = Map.empty ++ it