ScheduleTree::fromList: statically check for Sequence/Set node type

Statically assert that the type of node being constructed is Sequence or
Set.  This function is not called for other types and would have failed
to compile anyway since it constructs a tree element from an isl::ctx
only, which is impossible for other types.  Remove the useless dynamic
check before calling flattenSequenceOrSet.

Author: ftynse

tc/core/polyhedral/schedule_tree.h

@@ -377,14 +377,12 @@ struct ScheduleTree {
 
   template <typename... Args>
   static ScheduleTreeUPtr makeSet(Args&&... args) {
-    return fromList<ScheduleTreeElemSet>(
-        detail::ScheduleTreeType::Set, std::forward<Args>(args)...);
+    return fromList<ScheduleTreeElemSet>(std::forward<Args>(args)...);
   }
 
   template <typename... Args>
   static ScheduleTreeUPtr makeSequence(Args&&... args) {
-    return fromList<ScheduleTreeElemSequence>(
-        detail::ScheduleTreeType::Sequence, std::forward<Args>(args)...);
+    return fromList<ScheduleTreeElemSequence>(std::forward<Args>(args)...);
   }
 
   // Flatten nested nodes of the same type.
@@ -409,11 +407,11 @@ struct ScheduleTree {
 
   // disallow empty lists in syntax
   template <typename T, typename Arg, typename... Args>
-  static ScheduleTreeUPtr
-  fromList(detail::ScheduleTreeType type, Arg&& arg, Args&&... args) {
+  static ScheduleTreeUPtr fromList(Arg&& arg, Args&&... args) {
     static_assert(
-        std::is_base_of<ScheduleTree, T>::value,
-        "Can only construct elements derived from ScheduleTree");
+        std::is_same<ScheduleTreeElemSet, T>::value ||
+            std::is_same<ScheduleTreeElemSequence, T>::value,
+        "Can only construct Set or Sequence elements");
     static_assert(
         std::is_same<
             typename std::remove_reference<Arg>::type,
@@ -424,11 +422,7 @@ struct ScheduleTree {
     auto res = ScheduleTreeUPtr(new T(ctx));
     res->appendChildren(
         vectorFromArgs(std::forward<Arg>(arg), std::forward<Args>(args)...));
-
-    if (type == detail::ScheduleTreeType::Sequence ||
-        type == detail::ScheduleTreeType::Set) {
-      res->flattenSequenceOrSet();
-    }
+    res->flattenSequenceOrSet();
     return res;
   }