QL: Fix up parent-child relation in tree

Author: asgerf

ql/ql/src/codeql_ql/ast/Ast.qll

@@ -79,6 +79,7 @@ class AstNode extends TAstNode {
 
   /** Gets an annotation of this AST node. */
   Annotation getAnAnnotation() {
+    not this instanceof Annotation and // avoid cyclic parent-child relationship
     toQL(this).getParent() = pragma[only_bind_out](toQL(result)).getParent()
   }
 
@@ -125,6 +126,9 @@ class TopLevel extends TTopLevel, AstNode {
   /** Gets a `newtype` defined at the top-level of this module. */
   NewType getANewType() { result = this.getAMember() }
 
+  /** Gets a `select` clause in the top-level of this module. */
+  Select getASelect() { result = this.getAMember() }
+
   override ModuleMember getAChild(string pred) {
     pred = directMember("getAnImport") and result = this.getAnImport()
     or
@@ -137,6 +141,8 @@ class TopLevel extends TTopLevel, AstNode {
     pred = directMember("getANewType") and result = this.getANewType()
     or
     pred = directMember("getQLDoc") and result = this.getQLDoc()
+    or
+    pred = directMember("getASelect") and result = this.getASelect()
   }
 
   QLDoc getQLDocFor(ModuleMember m) {