[Bug c++/70488] [6 Regression] ICE in tree.c:7345 triggered by warning of placement new too small on VLA

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70488

--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
I believe we should add these two checks:
--- a/gcc/cp/init.c
+++ b/gcc/cp/init.c
@@ -2430,7 +2430,8 @@ warn_placement_new_too_small (tree type, tree nelts, tree
size, tree oper)
     though the size of a member of a union may be viewed as extending
     to the end of the union itself (it is by __builtin_object_size).  */
       if ((TREE_CODE (oper) == VAR_DECL || use_obj_size)
-     && DECL_SIZE_UNIT (oper))
+     && DECL_SIZE_UNIT (oper)
+     && valid_constant_size_p (DECL_SIZE_UNIT (oper)))
    {
      /* Use the size of the entire array object when the expression
         refers to a variable or its size depends on an expression
@@ -2438,7 +2439,8 @@ warn_placement_new_too_small (tree type, tree nelts, tree
size, tree oper)
      bytes_avail = tree_to_uhwi (DECL_SIZE_UNIT (oper));
      exact_size = !use_obj_size;
    }
-      else if (TYPE_SIZE_UNIT (TREE_TYPE (oper)))
+      else if (TYPE_SIZE_UNIT (TREE_TYPE (oper))
+          && valid_constant_size_p (TYPE_SIZE_UNIT (TREE_TYPE (oper))))
    {
      /* Use the size of the type of the destination buffer object
         as the optimistic estimate of the available space in it.  */

before calling tree_to_uhwi on those *_SIZE_UNITs.