1 files changed, 3 insertions, 0 deletions
diff --git a/gcc/tree.c b/gcc/tree.c
index f401145..e67a00c 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -2108,6 +2108,9 @@ nreverse (tree t)
   tree prev = 0, decl, next;
   for (decl = t; decl; decl = next)
     {
+      /* We shouldn't be using this function to reverse BLOCK chains; we
+	 have blocks_nreverse for that.  */
+      gcc_checking_assert (TREE_CODE (decl) != BLOCK);
       next = TREE_CHAIN (decl);
       TREE_CHAIN (decl) = prev;
       prev = decl;