Retype collection fetches

And do some minor cleanup

Author: fredericDelaporte

src/NHibernate/Hql/Ast/ANTLR/QueryTranslatorImpl.cs

@@ -37,7 +37,7 @@ public partial class QueryTranslatorImpl : IFilterTranslator
 		private IStatement _sqlAst;
 		private IDictionary<string, string> _tokenReplacements;
 		private HqlSqlGenerator _generator;
-		private IList<IASTNode> collectionFetches;
+		private List<FromElement> collectionFetches;
 
 		/// <summary>
 		/// Creates a new AST-based query translator.
@@ -292,7 +292,7 @@ public bool CanAddFetchedCollectionToCache
 		{
 			get
 			{
-				foreach (FromElement fromElement in CollectionFetches)
+				foreach (var fromElement in CollectionFetches)
 				{
 					var hasCache = fromElement.QueryableCollection.HasCache;
 
@@ -457,14 +457,14 @@ private bool ContainsRestrictionOnTable(FromElement fromElement)
 				.Any(rn => rn.FromElement == fromElement);
 		}
 
-		private IList<IASTNode> CollectionFetches
+		private IList<FromElement> CollectionFetches
 		{
 			get
 			{
 				if (collectionFetches == null)
 				{
 					ErrorIfDML();
-					collectionFetches = ((QueryNode) _sqlAst).FromClause.GetCollectionFetches() ?? new List<IASTNode>();
+					collectionFetches = ((QueryNode) _sqlAst).FromClause.GetCollectionFetches().Cast<FromElement>().ToList();
 				}
 
 				return collectionFetches;

src/NHibernate/Hql/Ast/ANTLR/Tree/FromClause.cs

@@ -9,6 +9,9 @@
 
 namespace NHibernate.Hql.Ast.ANTLR.Tree
 {
+	// 6.0 TODO: consider retyping methods yielding IList<IASTNode> as IList<FromElement>
+	// They all do actually yield FromElement, and most of their callers end up recasting
+	// them.
 	/// <summary>
 	/// Represents the 'FROM' part of a query or subquery, containing all mapped class references.
 	/// Author: josh

src/NHibernate/Hql/Ast/ANTLR/Util/ASTUtil.cs

@@ -109,15 +109,15 @@ public static IList<IASTNode> CollectChildren(IASTNode root, FilterPredicate pre
 		/// </summary>
 		internal static IEnumerable<TRequiredType> IterateChildrenOfType<TRequiredType>(IASTNode root, Func<TRequiredType, bool> skipSearchInChildrenWhen)
 		{
-			foreach(var child in root)
+			foreach (var child in root)
 			{
-				bool searchInChildren = true;
+				var searchInChildren = true;
 				if (child is TRequiredType typedChild)
 				{
 					searchInChildren = !skipSearchInChildrenWhen(typedChild);
 					yield return typedChild;
 				}
-				if(searchInChildren)
+				if (searchInChildren)
 				{
 					foreach (var subChild in IterateChildrenOfType(child, skipSearchInChildrenWhen))
 					{