+ #define FOLLY_FBVECTOR_INSERT_PRE(cpos, n) \
+ if (n == 0) return (iterator)cpos; \
+ bool at_end = cpos == cend(); \
+ bool fresh = insert_use_fresh(at_end, n); \
+ if (!at_end) { \
+ if (!fresh) {
+
+ // check for internal data (technically not required by the standard)
+