Marko Mäkelä added a comment - 2024-08-14 05:34 Here is an example of a warning from GCC 14.2.0: 10.6 2e580dc2a8da4aaf3a7f1b3cfb4f897dbb5f7089 In file included from /mariadb/10.6/sql/sql_plugin.h:33, from /mariadb/10.6/sql/mysqld.h:22, from /mariadb/10.6/sql/semisync.h:21, from /mariadb/10.6/sql/semisync_master.h:22, from /mariadb/10.6/sql/semisync_master.cc:20: /mariadb/10.6/include/m_string.h: In member function ‘int Repl_semi_sync_master::report_binlog_update(THD*, THD*, const char*, my_off_t)’: /mariadb/10.6/include/m_string.h:260:10: warning: ‘char* __builtin_strncpy(char*, const char*, long unsigned int)’ specified bound 512 equals destination size [-Wstringop-truncation] 260 | strncpy(dst, src, dst_size); | ^ I tried to fix it with the following patch: diff --git a/include/m_string.h b/include/m_string.h index 0cd6ff4513e..f9b8656623d 100644 --- a/include/m_string.h +++ b/include/m_string.h @@ -249,6 +249,7 @@ static inline void lex_string_set3(LEX_CSTRING *lex_str, const char *c_str, static inline void safe_strcpy(char *dst, size_t dst_size, const char *src) { DBUG_ASSERT(dst_size > 0); + dst_size--; /* 1) IF there is a 0 byte in the first dst_size bytes of src, strncpy will * 0-terminate dst, and pad dst with additional 0 bytes out to dst_size. @@ -258,7 +259,7 @@ static inline void safe_strcpy(char *dst, size_t dst_size, const char *src) */ strncpy(dst, src, dst_size); - dst[dst_size - 1]= 0; + dst[dst_size]= 0; } /** This would result in another type of warning elsewhere, which I guess would also be output by some older versions of GCC: 10.6 2e580dc2a8da4aaf3a7f1b3cfb4f897dbb5f7089 with patch In file included from /mariadb/10.6/include/my_bitmap.h:22, from /mariadb/10.6/sql/log_event.h:36, from /mariadb/10.6/sql/rpl_parallel.h:4, from /mariadb/10.6/sql/rpl_parallel.cc:2: /mariadb/10.6/include/m_string.h: In function ‘int rpt_handle_event(rpl_parallel_thread::queued_event*, rpl_parallel_thread*)’: /mariadb/10.6/include/m_string.h:261:10: warning: ‘char* __builtin_strncpy(char*, const char*, long unsigned int)’ output may be truncated copying 511 bytes from a string of length 511 [-Wstringop-truncation] 261 | strncpy(dst, src, dst_size); | ^ /mariadb/10.6/include/m_string.h:261:10: warning: ‘char* __builtin_strncpy(char*, const char*, long unsigned int)’ output may be truncated copying 511 bytes from a string of length 511 [-Wstringop-truncation] /mariadb/10.6/include/m_string.h: In member function ‘rpl_parallel_thread::queued_event* rpl_parallel_thread::get_qev(Log_event*, ulonglong, Relay_log_info*)’: /mariadb/10.6/include/m_string.h:261:10: warning: ‘char* __builtin_strncpy(char*, const char*, long unsigned int)’ output may be truncated copying 511 bytes from a string of length 511 [-Wstringop-truncation] /mariadb/10.6/include/m_string.h:261:10: warning: ‘char* __builtin_strncpy(char*, const char*, long unsigned int)’ output may be truncated copying 511 bytes from a string of length 511 [-Wstringop-truncation] /mariadb/10.6/include/m_string.h: In member function ‘rpl_parallel_thread::queued_event* rpl_parallel_thread::retry_get_qev(Log_event*, queued_event*, const char*, ulonglong, ulonglong)’: /mariadb/10.6/include/m_string.h:261:10: warning: ‘char* __builtin_strncpy(char*, const char*, long unsigned int)’ output may be truncated copying 511 bytes from a string of length 511 [-Wstringop-truncation] /mariadb/10.6/include/m_string.h: In function ‘void* handle_rpl_parallel_thread(void*)’: /mariadb/10.6/include/m_string.h:261:10: warning: ‘char* __builtin_strncpy(char*, const char*, long unsigned int)’ output may be truncated copying 511 bytes from a string of length 511 [-Wstringop-truncation] The 511 would likely be FN_REFLEN-1 . It looks like the #pragma must be reinstated to keep GCC 14 happy.