Extend whitelist in global initialization checker (#20290)

This PR extends the whitelist in global object initialization checker in
order to suppress initialization irrelevance errors in
Scala2LibraryTasty.

Author: olhotak

compiler/src/dotty/tools/dotc/transform/init/Objects.scala

@@ -29,6 +29,7 @@ import scala.collection.mutable
 import scala.annotation.tailrec
 import scala.annotation.constructorOnly
 import dotty.tools.dotc.core.Flags.AbstractOrTrait
+import Decorators.*
 
 /** Check initialization safety of static objects
  *
@@ -68,11 +69,21 @@ import dotty.tools.dotc.core.Flags.AbstractOrTrait
  *
  */
 class Objects(using Context @constructorOnly):
-  val immutableHashSetBuider: Symbol = requiredClass("scala.collection.immutable.HashSetBuilder")
+  val immutableHashSetNode: Symbol = requiredClass("scala.collection.immutable.SetNode")
   // TODO: this should really be an annotation on the rhs of the field initializer rather than the field itself.
-  val HashSetBuilder_rootNode: Symbol = immutableHashSetBuider.requiredValue("rootNode")
-
-  val whiteList = Set(HashSetBuilder_rootNode)
+  val SetNode_EmptySetNode: Symbol = Denotations.staticRef("scala.collection.immutable.SetNode.EmptySetNode".toTermName).symbol
+  val immutableHashSet: Symbol = requiredModule("scala.collection.immutable.HashSet")
+  val HashSet_EmptySet: Symbol = Denotations.staticRef("scala.collection.immutable.HashSet.EmptySet".toTermName).symbol
+  val immutableVector: Symbol = requiredModule("scala.collection.immutable.Vector")
+  val Vector_EmptyIterator: Symbol = immutableVector.requiredValue("emptyIterator")
+  val immutableMapNode: Symbol = requiredModule("scala.collection.immutable.MapNode")
+  val MapNode_EmptyMapNode: Symbol = immutableMapNode.requiredValue("EmptyMapNode")
+  val immutableHashMap: Symbol = requiredModule("scala.collection.immutable.HashMap")
+  val HashMap_EmptyMap: Symbol = immutableHashMap.requiredValue("EmptyMap")
+  val immutableLazyList: Symbol = requiredModule("scala.collection.immutable.LazyList")
+  val LazyList_empty: Symbol = immutableLazyList.requiredValue("_empty")
+
+  val whiteList: Set[Symbol] = Set(SetNode_EmptySetNode, HashSet_EmptySet, Vector_EmptyIterator, MapNode_EmptyMapNode, HashMap_EmptyMap, LazyList_empty)
 
   // ----------------------------- abstract domain -----------------------------
 

tests/init-global/pos/EmptyMap.scala

@@ -0,0 +1,6 @@
+import scala.collection.immutable.HashMap
+
+object O {
+  val emptyMap: HashMap[Int, Int] = HashMap.empty
+  val key = emptyMap.get(0)
+}

tests/init-global/pos/EmptyMap2.scala

@@ -0,0 +1,4 @@
+import scala.collection.immutable.HashMap
+
+object A:
+  val a = HashMap.empty[Int, Int].updated(1, 2)

tests/init-global/pos/EmptySet.scala

@@ -0,0 +1,6 @@
+import scala.collection.immutable.HashSet
+
+object O {
+  val emptySet = HashSet.empty
+  val emptySetSize = emptySet.size
+}

tests/init-global/pos/EmptySet2.scala

@@ -0,0 +1,4 @@
+import scala.collection.immutable.HashSet
+
+object A:
+  val a = HashSet.empty[Int] + 1

tests/init-global/pos/EmptyVectorIterator.scala

@@ -0,0 +1,7 @@
+import scala.collection.immutable.Vector
+
+object O {
+  val emptyVector = Vector.empty
+  val emptyVectorIterator = emptyVector.iterator
+  val hasNext = emptyVectorIterator.hasNext
+}

tests/init-global/pos/LazyList.scala

@@ -0,0 +1,4 @@
+import scala.collection.immutable.LazyList
+
+object A:
+  val a = LazyList.empty[Int] :+ 1