[Bug sanitizer/66977] -fsanitize=shift may introduce uninitialized variables

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66977

--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
This works (can't use unshare_expr here), but I'll try to come up with
something nicer...

diff --git a/gcc/cp/decl2.c b/gcc/cp/decl2.c
index a45755e..f1b6475 100644
--- a/gcc/cp/decl2.c
+++ b/gcc/cp/decl2.c
@@ -4926,6 +4926,8 @@ build_offset_ref_call_from_tree (tree fn, vec<tree,
va_gc> **args,
       fn = TREE_OPERAND (fn, 1);
       fn = get_member_function_from_ptrfunc (&object_addr, fn,
                         complain);
+      if (flag_sanitize & SANITIZE_SHIFT)
+   walk_tree (&object_addr, copy_tree_r, NULL, NULL);
       vec_safe_insert (*args, 0, object_addr);
     }