diff options
| -rw-r--r-- | libstdc++-v3/include/bits/cow_string.h | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/libstdc++-v3/include/bits/cow_string.h b/libstdc++-v3/include/bits/cow_string.h index 389b395..b21a742 100644 --- a/libstdc++-v3/include/bits/cow_string.h +++ b/libstdc++-v3/include/bits/cow_string.h @@ -3366,10 +3366,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION basic_string<_CharT, _Traits, _Alloc>:: _M_leak_hard() { -#if _GLIBCXX_FULLY_DYNAMIC_STRING == 0 - if (_M_rep() == &_S_empty_rep()) + // No need to create a new copy of an empty string when a non-const + // reference/pointer/iterator into it is obtained. Modifying the + // trailing null character is undefined, so the ref/pointer/iterator + // is effectively const anyway. + if (this->empty()) return; -#endif + if (_M_rep()->_M_is_shared()) _M_mutate(0, 0, 0); _M_rep()->_M_set_leaked(); |