addressed review comments

Author: mdfazlay

clang/include/clang/AST/OpenMPClause.h

@@ -2332,10 +2332,16 @@ class OMPNowaitClause final : public OMPClause {
   /// Returns condition.
   Expr *getCondition() const { return cast_or_null<Expr>(Condition); }
 
-  child_range children() { return child_range(&Condition, &Condition + 1); }
+  child_range children() {
+    if (Condition)
+      return child_range(&Condition, &Condition + 1);
+    return child_range(child_iterator(), child_iterator());
+  }
 
   const_child_range children() const {
-    return const_child_range(&Condition, &Condition + 1);
+    if (Condition)
+      return const_child_range(&Condition, &Condition + 1);
+    return const_child_range(const_child_iterator(), const_child_iterator());
   }
 
   child_range used_children();

clang/lib/AST/OpenMPClause.cpp

@@ -312,8 +312,7 @@ OMPClause::child_range OMPIfClause::used_children() {
 OMPClause::child_range OMPNowaitClause::used_children() {
   if (Condition)
     return child_range(&Condition, &Condition + 1);
-  Stmt *Null = nullptr;
-  return child_range(&Null, &Null);
+  return children();
 }
 
 OMPClause::child_range OMPGrainsizeClause::used_children() {

clang/test/OpenMP/nowait_ast_print.cpp

@@ -19,7 +19,6 @@ void nowait() {
 
   // DUMP: OMPTargetDirective
   // DUMP-NEXT: OMPNowaitClause
-  // DUMP-NEXT: <<<NULL>>>
   // PRINT: #pragma omp target nowait
   #pragma omp target nowait
   {