format strings

Author: paleolimbot

inst/include/cpp11/protect.hpp

@@ -279,7 +279,9 @@ static struct {
   void print() {
     static SEXP list = get_preserve_list();
     for (SEXP cell = list; cell != R_NilValue; cell = CDR(cell)) {
-      REprintf("%x CAR: %x CDR: %x TAG: %x\n", cell, CAR(cell), CDR(cell), TAG(cell));
+      REprintf("%p CAR: %p CDR: %p TAG: %p\n", reinterpret_cast<void*>(cell),
+               reinterpret_cast<void*>(CAR(cell)), reinterpret_cast<void*>(CDR(cell)),
+               reinterpret_cast<void*>(TAG(cell)));
     }
     REprintf("---\n");
   }