Fixed warnings when using deprecated variables

Also fixed that all unused variables are using the same variable comment.
The warning will be tested with the next commit that deprecates the
variable alter_algorithm.

mysql-test/main/secondary_key_costs.result

@@ -29,8 +29,8 @@ explain select * from t1  where nm like '500%' AND fl2 = 0;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	range	idx1,idx2	idx1	35	NULL	1	Using index condition; Using where
 Warnings:
-Warning	1287	'@@optimizer_adjust_secondary_key_costs' is deprecated and will be removed in a future release
-Warning	1287	'@@optimizer_adjust_secondary_key_costs' is deprecated and will be removed in a future release
+Warning	4200	The variable '@@optimizer_adjust_secondary_key_costs' is deleted and ignored. It it only exists for compatiblity with old installations
+Warning	4200	The variable '@@optimizer_adjust_secondary_key_costs' is deleted and ignored. It it only exists for compatiblity with old installations
 set @trace=(select trace from information_schema.optimizer_trace);
 select json_detailed(json_extract(@trace, '$**.considered_access_paths'));
 json_detailed(json_extract(@trace, '$**.considered_access_paths'))
@@ -97,8 +97,8 @@ explain select * from t1  where nm like '500%' AND fl2 = 0;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	range	idx1,idx2	idx1	35	NULL	1	Using index condition; Using where
 Warnings:
-Warning	1287	'@@optimizer_adjust_secondary_key_costs' is deprecated and will be removed in a future release
-Warning	1287	'@@optimizer_adjust_secondary_key_costs' is deprecated and will be removed in a future release
+Warning	4200	The variable '@@optimizer_adjust_secondary_key_costs' is deleted and ignored. It it only exists for compatiblity with old installations
+Warning	4200	The variable '@@optimizer_adjust_secondary_key_costs' is deleted and ignored. It it only exists for compatiblity with old installations
 set @trace=(select trace from information_schema.optimizer_trace);
 select json_detailed(json_extract(@trace, '$**.considered_access_paths'));
 json_detailed(json_extract(@trace, '$**.considered_access_paths'))

mysql-test/suite/sys_vars/r/sysvars_server_embedded.result

@@ -1545,7 +1545,7 @@ COMMAND_LINE_ARGUMENT	OPTIONAL
 VARIABLE_NAME	LARGE_PAGE_SIZE
 VARIABLE_SCOPE	GLOBAL
 VARIABLE_TYPE	INT UNSIGNED
-VARIABLE_COMMENT	Previously showed the size of large memory pages, unused since multiple page size support was added
+VARIABLE_COMMENT	Unused
 NUMERIC_MIN_VALUE	0
 NUMERIC_MAX_VALUE	4294967295
 NUMERIC_BLOCK_SIZE	1

mysql-test/suite/sys_vars/r/sysvars_server_notembedded.result

@@ -1695,7 +1695,7 @@ COMMAND_LINE_ARGUMENT	OPTIONAL
 VARIABLE_NAME	LARGE_PAGE_SIZE
 VARIABLE_SCOPE	GLOBAL
 VARIABLE_TYPE	INT UNSIGNED
-VARIABLE_COMMENT	Previously showed the size of large memory pages, unused since multiple page size support was added
+VARIABLE_COMMENT	Unused
 NUMERIC_MIN_VALUE	0
 NUMERIC_MAX_VALUE	4294967295
 NUMERIC_BLOCK_SIZE	1

sql/set_var.cc

@@ -420,20 +420,28 @@ double sys_var::val_real(bool *is_null,
   return ret;
 }
 
+/* Marker if the variable is deleted instead of depricated */
+const char *UNUSED_HELP="Unused";
 
 void sys_var::do_deprecated_warning(THD *thd)
 {
   if (option.deprecation_substitute != NULL)
   {
     char buf1[NAME_CHAR_LEN + 3];
-    char buf2[NAME_CHAR_LEN + 3];
     strxnmov(buf1, sizeof(buf1)-1, "@@", name.str, 0);
+
+    if (option.comment == UNUSED_HELP)
+      my_error(ER_VARIABLE_DELETED, MYF(ME_WARNING), buf1);
+    else
+    {
+      char buf2[NAME_CHAR_LEN + 3];
       if (!IS_DEPRECATED_NO_REPLACEMENT(option.deprecation_substitute))
         strxnmov(buf2, sizeof(buf2)-1, "@@", option.deprecation_substitute, 0);
       else
         buf2[0]= 0;
       warn_deprecated<999999>(thd, buf1, buf2);
     }
+  }
 }
 
 /**

sql/share/errmsg-utf8.txt

@@ -12278,3 +12278,5 @@ ER_SEQUENCE_TABLE_CANNOT_HAVE_ANY_CONSTRAINTS
         eng "Sequence tables cannot have any constraints"
 ER_SEQUENCE_TABLE_ORDER_BY
         eng "ORDER BY"
+ER_VARIABLE_DELETED
+        eng "The variable '%s' is deleted and ignored. It it only exists for compatiblity with old installations"

sql/sys_vars.cc

@@ -1511,8 +1511,7 @@ static Sys_var_mybool Sys_large_files_support(
 
 static Sys_var_uint Sys_large_page_size(
        "large_page_size",
-       "Previously showed the size of large memory pages, unused since "
-       "multiple page size support was added",
+       UNUSED_HELP,
        READ_ONLY GLOBAL_VAR(opt_large_page_size), NO_CMD_LINE,
        VALID_RANGE(0, UINT_MAX), DEFAULT(0), BLOCK_SIZE(1),
        NO_MUTEX_GUARD, NOT_IN_BINLOG, ON_CHECK(0), ON_UPDATE(0),
@@ -1901,7 +1900,7 @@ static Sys_var_ulonglong Sys_max_heap_table_size(
 
 static ulong mdl_locks_cache_size;
 static Sys_var_ulong Sys_metadata_locks_cache_size(
-       "metadata_locks_cache_size", "Unused",
+       "metadata_locks_cache_size", UNUSED_HELP,
        READ_ONLY GLOBAL_VAR(mdl_locks_cache_size), CMD_LINE(REQUIRED_ARG),
        VALID_RANGE(1, 1024*1024), DEFAULT(1024),
        BLOCK_SIZE(1), NO_MUTEX_GUARD, NOT_IN_BINLOG, ON_CHECK(0), ON_UPDATE(0),
@@ -1909,7 +1908,7 @@ static Sys_var_ulong Sys_metadata_locks_cache_size(
 
 static ulong mdl_locks_hash_partitions;
 static Sys_var_ulong Sys_metadata_locks_hash_instances(
-       "metadata_locks_hash_instances", "Unused",
+      "metadata_locks_hash_instances", UNUSED_HELP,
        READ_ONLY GLOBAL_VAR(mdl_locks_hash_partitions), CMD_LINE(REQUIRED_ARG),
        VALID_RANGE(1, 1024), DEFAULT(8),
        BLOCK_SIZE(1), NO_MUTEX_GUARD, NOT_IN_BINLOG, ON_CHECK(0), ON_UPDATE(0),
@@ -2989,7 +2988,7 @@ static Sys_var_ulong Sys_optimizer_trace_max_mem_size(
 
 static Sys_var_ulong Sys_optimizer_adjust_secondary_key_costs(
     "optimizer_adjust_secondary_key_costs",
-    "Unused",
+    UNUSED_HELP,
     SESSION_VAR(optimizer_adjust_secondary_key_costs), CMD_LINE(REQUIRED_ARG),
     VALID_RANGE(0, 2), DEFAULT(0), BLOCK_SIZE(1),
     NO_MUTEX_GUARD, NOT_IN_BINLOG, ON_CHECK(0), ON_UPDATE(0),

sql/sys_vars.inl

@@ -64,6 +64,8 @@
 #define PARSED_EARLY sys_var::PARSE_EARLY+
 #define NO_SET_STMT sys_var::NO_SET_STATEMENT+
 
+extern const char *UNUSED_HELP;
+
 /*
   Sys_var_bit meaning is reversed, like in
   @@foreign_key_checks <-> OPTION_NO_FOREIGN_KEY_CHECKS