for every deprecated sysvar note a version when it happened

sql/sys_vars.cc

@@ -934,7 +934,7 @@ static Sys_var_dbug Sys_dbug(
        "debug", "Built-in DBUG debugger", sys_var::SESSION,
        CMD_LINE(OPT_ARG, '#'), DEFAULT(""), NO_MUTEX_GUARD, NOT_IN_BINLOG,
        ON_CHECK(check_has_super), ON_UPDATE(0),
-       DEPRECATED("'@@debug_dbug'"));
+       DEPRECATED("'@@debug_dbug'")); // since 5.5.37
 
 static Sys_var_dbug Sys_debug_dbug(
        "debug_dbug", "Built-in DBUG debugger", sys_var::SESSION,
@@ -2379,7 +2379,7 @@ static Sys_var_ulong Sys_max_tmp_tables(
        SESSION_VAR(max_tmp_tables), CMD_LINE(REQUIRED_ARG),
        VALID_RANGE(1, UINT_MAX), DEFAULT(32), BLOCK_SIZE(1),
        NO_MUTEX_GUARD, NOT_IN_BINLOG, ON_CHECK(0), ON_UPDATE(0),
-       DEPRECATED(""));
+       DEPRECATED("")); // since 10.1.2
 
 static Sys_var_ulong Sys_max_write_lock_count(
        "max_write_lock_count",
@@ -2601,7 +2601,7 @@ static bool fix_optimizer_switch(sys_var *self, THD *thd,
     push_warning_printf(current_thd, Sql_condition::WARN_LEVEL_WARN,
                         ER_WARN_DEPRECATED_SYNTAX_NO_REPLACEMENT,
                         ER_THD(thd, ER_WARN_DEPRECATED_SYNTAX_NO_REPLACEMENT),
-                        "engine_condition_pushdown=on");
+                        "engine_condition_pushdown=on"); // since 10.1.1
   return false;
 }
 static Sys_var_flagset Sys_optimizer_switch(
@@ -2876,7 +2876,7 @@ static Sys_var_ulong Sys_thread_concurrency(
        CMD_LINE(REQUIRED_ARG, OPT_THREAD_CONCURRENCY),
        VALID_RANGE(1, 512), DEFAULT(DEFAULT_CONCURRENCY), BLOCK_SIZE(1),
        NO_MUTEX_GUARD, NOT_IN_BINLOG, ON_CHECK(0), ON_UPDATE(0),
-       DEPRECATED(""));
+       DEPRECATED("")); // since 5.5.37
 
 static Sys_var_ulonglong Sys_thread_stack(
        "thread_stack", "The stack size for each thread",
@@ -3897,7 +3897,7 @@ static Sys_var_mybool Sys_timed_mutexes(
        "Specify whether to time mutexes. Deprecated, has no effect.",
        GLOBAL_VAR(timed_mutexes), CMD_LINE(OPT_ARG), DEFAULT(0),
        NO_MUTEX_GUARD, NOT_IN_BINLOG, ON_CHECK(0), ON_UPDATE(0),
-       DEPRECATED(""));
+       DEPRECATED("")); // since 5.5.39
 
 static Sys_var_charptr Sys_version(
        "version", "Server version number. It may also include a suffix "
@@ -4078,21 +4078,24 @@ static Sys_var_charptr Sys_date_format(
        READ_ONLY GLOBAL_VAR(global_date_format.format.str),
        CMD_LINE(REQUIRED_ARG), IN_SYSTEM_CHARSET,
        DEFAULT(known_date_time_formats[ISO_FORMAT].date_format),
-       NO_MUTEX_GUARD, NOT_IN_BINLOG, ON_CHECK(0), ON_UPDATE(0), DEPRECATED(""));
+       NO_MUTEX_GUARD, NOT_IN_BINLOG, ON_CHECK(0), ON_UPDATE(0),
+       DEPRECATED("")); // since 10.1.2
 
 static Sys_var_charptr Sys_datetime_format(
        "datetime_format", "The DATETIME format (ignored)",
        READ_ONLY GLOBAL_VAR(global_datetime_format.format.str),
        CMD_LINE(REQUIRED_ARG), IN_SYSTEM_CHARSET,
        DEFAULT(known_date_time_formats[ISO_FORMAT].datetime_format),
-       NO_MUTEX_GUARD, NOT_IN_BINLOG, ON_CHECK(0), ON_UPDATE(0), DEPRECATED(""));
+       NO_MUTEX_GUARD, NOT_IN_BINLOG, ON_CHECK(0), ON_UPDATE(0),
+       DEPRECATED("")); // since 10.1.2
 
 static Sys_var_charptr Sys_time_format(
        "time_format", "The TIME format (ignored)",
        READ_ONLY GLOBAL_VAR(global_time_format.format.str),
        CMD_LINE(REQUIRED_ARG), IN_SYSTEM_CHARSET,
        DEFAULT(known_date_time_formats[ISO_FORMAT].time_format),
-       NO_MUTEX_GUARD, NOT_IN_BINLOG, ON_CHECK(0), ON_UPDATE(0), DEPRECATED(""));
+       NO_MUTEX_GUARD, NOT_IN_BINLOG, ON_CHECK(0), ON_UPDATE(0),
+       DEPRECATED("")); //  since 10.1.2
 
 static bool fix_autocommit(sys_var *self, THD *thd, enum_var_type type)
 {
@@ -4166,7 +4169,7 @@ static Sys_var_mybool Sys_big_tables(
        "longer needed, as the server now handles this automatically.",
        SESSION_VAR(big_tables), CMD_LINE(OPT_ARG), DEFAULT(FALSE),
        NO_MUTEX_GUARD, NOT_IN_BINLOG, ON_CHECK(0), ON_UPDATE(0),
-       DEPRECATED(""));
+       DEPRECATED("")); // since 10.5.0
 
 static Sys_var_bit Sys_big_selects(
        "sql_big_selects", "If set to 0, MariaDB will not perform large SELECTs."
@@ -5663,7 +5666,7 @@ static Sys_var_mybool Sys_wsrep_causal_reads(
        CMD_LINE(OPT_ARG, OPT_WSREP_CAUSAL_READS), DEFAULT(FALSE),
        NO_MUTEX_GUARD, NOT_IN_BINLOG, ON_CHECK(0),
        ON_UPDATE(wsrep_causal_reads_update),
-       DEPRECATED("'@@wsrep_sync_wait=1'"));
+       DEPRECATED("'@@wsrep_sync_wait=1'")); // since 10.1.3
 
 static Sys_var_uint Sys_wsrep_sync_wait(
        "wsrep_sync_wait", "Ensure \"synchronous\" read view before executing "
@@ -5737,7 +5740,7 @@ static Sys_var_mybool Sys_wsrep_load_data_splitting(
        "transaction after every 10K rows inserted (deprecated)",
        GLOBAL_VAR(wsrep_load_data_splitting), 
        CMD_LINE(OPT_ARG), DEFAULT(0), NO_MUTEX_GUARD, NOT_IN_BINLOG,
-       ON_CHECK(0), ON_UPDATE(0), DEPRECATED(""));
+       ON_CHECK(0), ON_UPDATE(0), DEPRECATED("")); // since 10.4.3
 
 static Sys_var_mybool Sys_wsrep_slave_FK_checks(
        "wsrep_slave_FK_checks", "Should slave thread do "