add correct asan support libc++'s string

Author: trcrsired

include/fast_io_unit/string_impl/libc++.h

@@ -124,6 +124,14 @@ inline void set_size(::std::basic_string<elem, traits, alloc> &str,
 	decltype(auto) __r_{hack_rep(str)};
 	if (bool(__r_.__s.__is_long_))
 	{
+#if !defined(_LIBCPP_HAS_NO_ASAN) && defined(_LIBCPP_INSTRUMENTED_WITH_ASAN)
+		if (!::std::__libcpp_is_constant_evaluated())
+		{
+			auto dataptr{str.data()};
+			auto edptr{dataptr + __r_.__l.__size_};
+			::std::__annotate_contiguous_container<alloc>(dataptr, dataptr + str.capacity(), dataptr + s + 1, edptr + 1);
+		}
+#endif
 		__r_.__l.__size_ = s;
 	}
 	else

include/fast_io_unit/string_impl/ostring_ref.h

@@ -111,8 +111,8 @@ strlike_set_curr(io_strlike_type_t<char_type, ::std::basic_string<char_type, tra
 	else
 #endif
 	{
-		traits_type::assign(*p, char_type());
 		::fast_io::details::string_hack::set_end_ptr(str, p);
+		traits_type::assign(*p, char_type());
 	}
 }