Make THDVAR_INT variables to be signed in SELECT in SHOW

mysql-test/r/plugin.result

@@ -40,15 +40,20 @@ SELECT * FROM t1;
 a
 set global example_ulong_var=500;
 set global example_enum_var= e1;
+set session example_int_var= -1;
 show status like 'example%';
 Variable_name	Value
-example_func_example	enum_var is 0, ulong_var is 500, double_var is 8.500000, really
+example_func_example	enum_var is 0, ulong_var is 500, int_var is -1, double_var is 8.500000, really
 show variables like 'example%';
 Variable_name	Value
 example_double_thdvar	8.500000
 example_double_var	8.500000
 example_enum_var	e1
+example_int_var	-1
 example_ulong_var	500
+select @@session.example_int_var;
+@@session.example_int_var
+-1
 UNINSTALL SONAME 'ha_example';
 Warnings:
 Warning	1620	Plugin is busy and will be uninstalled on shutdown

mysql-test/t/plugin.test

@@ -25,9 +25,12 @@ SELECT * FROM t1;
 # a couple of tests for variables
 set global example_ulong_var=500;
 set global example_enum_var= e1;
+set session example_int_var= -1;
 show status like 'example%';
 show variables like 'example%';
 
+select @@session.example_int_var;
+
 UNINSTALL SONAME 'ha_example';
 --replace_column 5 #
 --replace_regex /\.dll/.so/

sql/sql_plugin.cc

@@ -3165,15 +3165,21 @@ static void plugin_vars_free_values(sys_var *vars)
 
 static SHOW_TYPE pluginvar_show_type(st_mysql_sys_var *plugin_var)
 {
-  switch (plugin_var->flags & PLUGIN_VAR_TYPEMASK) {
+  switch (plugin_var->flags & (PLUGIN_VAR_TYPEMASK | PLUGIN_VAR_UNSIGNED)) {
   case PLUGIN_VAR_BOOL:
     return SHOW_MY_BOOL;
   case PLUGIN_VAR_INT:
-    return SHOW_INT;
+    return SHOW_SINT;
+  case PLUGIN_VAR_INT | PLUGIN_VAR_UNSIGNED:
+    return SHOW_UINT;
   case PLUGIN_VAR_LONG:
-    return SHOW_LONG;
+    return SHOW_SLONG;
+  case PLUGIN_VAR_LONG | PLUGIN_VAR_UNSIGNED:
+    return SHOW_ULONG;
   case PLUGIN_VAR_LONGLONG:
-    return SHOW_LONGLONG;
+    return SHOW_SLONGLONG;
+  case PLUGIN_VAR_LONGLONG | PLUGIN_VAR_UNSIGNED:
+    return SHOW_ULONGLONG;
   case PLUGIN_VAR_STR:
     return SHOW_CHAR_PTR;
   case PLUGIN_VAR_ENUM:

sql/sql_show.cc

@@ -2703,7 +2703,7 @@ static bool show_status_array(THD *thd, const char *wild,
           end= int10_to_str((long) *(uint*) value, buff, 10);
           break;
         case SHOW_SINT:
-          end= int10_to_str((long) *(uint*) value, buff, -10);
+          end= int10_to_str((long) *(int*) value, buff, -10);
           break;
         case SHOW_SLONG:
           end= int10_to_str(*(long*) value, buff, -10);

storage/example/ha_example.cc

@@ -1081,6 +1081,9 @@ static MYSQL_SYSVAR_ENUM(
   0,                              // def
   &enum_var_typelib);             // typelib
 
+static MYSQL_THDVAR_INT(int_var, PLUGIN_VAR_RQCMDARG, "-1..1",
+  NULL, NULL, 0, -1, 1, 0);
+
 static MYSQL_SYSVAR_ULONG(
   ulong_var,
   srv_ulong_var,
@@ -1119,6 +1122,7 @@ static MYSQL_THDVAR_DOUBLE(
 static struct st_mysql_sys_var* example_system_variables[]= {
   MYSQL_SYSVAR(enum_var),
   MYSQL_SYSVAR(ulong_var),
+  MYSQL_SYSVAR(int_var),
   MYSQL_SYSVAR(double_var),
   MYSQL_SYSVAR(double_thdvar),
   NULL
@@ -1131,9 +1135,10 @@ static int show_func_example(MYSQL_THD thd, struct st_mysql_show_var *var,
   var->type= SHOW_CHAR;
   var->value= buf; // it's of SHOW_VAR_FUNC_BUFF_SIZE bytes
   my_snprintf(buf, SHOW_VAR_FUNC_BUFF_SIZE,
-              "enum_var is %lu, ulong_var is %lu, "
+              "enum_var is %lu, ulong_var is %lu, int_var is %d, "
               "double_var is %f, %.6b", // %b is a MySQL extension
-              srv_enum_var, srv_ulong_var, srv_double_var, "really");
+              srv_enum_var, srv_ulong_var, THDVAR(thd, int_var),
+              srv_double_var, "really");
   return 0;
 }