Avoid withFilter in some warm spots

Author: odersky

compiler/src/dotty/tools/dotc/ast/TreeInfo.scala

@@ -10,6 +10,7 @@ import reporting.trace
 import dotty.tools.dotc.transform.SymUtils._
 import Decorators._
 import Constants.Constant
+import scala.collection.mutable
 
 import scala.annotation.tailrec
 
@@ -698,7 +699,10 @@ trait TypedTreeInfo extends TreeInfo[Type] { self: Trees.Instance[Type] =>
 
   /** The symbols defined locally in a statement list */
   def localSyms(stats: List[Tree])(using Context): List[Symbol] =
-    for (stat <- stats if stat.isDef && stat.symbol.exists) yield stat.symbol
+    val locals = new mutable.ListBuffer[Symbol]
+    for stat <- stats do
+      if stat.isDef && stat.symbol.exists then locals += stat.symbol
+    locals.toList
 
   /** If `tree` is a DefTree, the symbol defined by it, otherwise NoSymbol */
   def definedSym(tree: Tree)(using Context): Symbol =