diff -u gcc/cp/constexpr.c gcc/cp/constexpr.c
--- gcc/cp/constexpr.c	2019-10-03 14:53:59.268559514 +0200
+++ gcc/cp/constexpr.c	2019-10-03 14:53:59.268559514 +0200
@@ -3398,21 +3398,13 @@
     {
       tree type_domain = TYPE_DOMAIN (optype);
       tree min_val = size_zero_node;
-      tree max_val = NULL_TREE;
       if (type_domain && TYPE_MIN_VALUE (type_domain))
 	min_val = TYPE_MIN_VALUE (type_domain);
-      if (type_domain && TYPE_MAX_VALUE (type_domain))
-	max_val = TYPE_MAX_VALUE (type_domain);
       unsigned HOST_WIDE_INT el_sz
 	= tree_to_uhwi (TYPE_SIZE_UNIT (TREE_TYPE (optype)));
       unsigned HOST_WIDE_INT idx = off / el_sz;
       unsigned HOST_WIDE_INT rem = off % el_sz;
-      if (tree_fits_uhwi_p (min_val)
-	  && (max_val == NULL_TREE
-	      /* Punt on checking VLA bounds here.  */
-	      || TREE_CODE (max_val) != INTEGER_CST
-	      || (tree_fits_uhwi_p (max_val)
-		  && idx <= tree_to_uhwi (max_val))))
+      if (tree_fits_uhwi_p (min_val))
 	{
 	  tree index = size_int (idx + tree_to_uhwi (min_val));
 	  op = build4_loc (loc, ARRAY_REF, TREE_TYPE (optype), op, index,
@@ -3422,7 +3414,7 @@
 	}
     }
   /* ((foo *)&struct_with_foo_field)[x] => COMPONENT_REF */
-  else if (RECORD_OR_UNION_TYPE_P (optype))
+  else if (TREE_CODE (optype) == RECORD_TYPE)
     {
       for (tree field = TYPE_FIELDS (optype);
 	   field; field = DECL_CHAIN (field))
reverted:
--- gcc/testsuite/g++.dg/cpp0x/constexpr-array13.C	2019-10-03 16:13:58.636977962 +0200
+++ gcc/testsuite/g++.dg/cpp0x/constexpr-array13.C.jj	2015-11-26 10:40:59.546389024 +0100
@@ -3,4 +3,4 @@
 
 constexpr char c[] = "hello";
 constexpr const char *p = c;
+constexpr char ch = *(p-1);  // { dg-error "array subscript" }
-constexpr char ch = *(p-1);  // { dg-error "is not a constant expression" }
reverted:
--- gcc/testsuite/g++.dg/ubsan/pr63956.C	2019-10-03 18:57:25.541783658 +0200
+++ gcc/testsuite/g++.dg/ubsan/pr63956.C.jj	2019-06-19 10:20:12.390666122 +0200
@@ -80,7 +80,7 @@
 fn5 (const int *a, int b)
 {
   if (b != 2)
+    b = a[b]; // { dg-error "array subscript" }
-    b = a[b]; // { dg-error "is not a constant expression" }
   return b;
 }