MDEV-19639 + MDEV-19640 fix + preparatory changes for WL#4179

This patch includes:
- MDEV-19639 sql_mode=ORACLE: Wrong SHOW PROCEDURE output for sysvar:=expr
- MDEV-19640 Wrong SHOW PROCEDURE output for SET GLOBAL sysvar1=expr, sysvar2=expr
- Preparatory refactoring for MySQL WL#4179

Detailed change list:

1. Changing sp_create_assignment_lex() to accept the position
   in the exact query buffer instead of a "bool no_lookahead".
   This actually fixes MDEV-19639.
   In the previous reduction sp_create_assignment_lex() was
   called too late, when the parser went far the from beginning
   of the statement, so only a part of the statement got into
   sp_instr_stmt.

2. Generating "SET" or "SET GLOBAL" inside sp_create_assignment_instr()
   depending on the option type.
   This fixes MDEV-19640.
   In the previous reduction the code passed (through no_lookahead)
   the position of the
   word GLOBAL inside sp_create_assignment_lex(), which
   worked only for the left-most assignment.

3. Fixing the affected rules to use:
   - ident_cli instead of ident
   - ident_cli_set_usual_case instead of ident_set_usual_case

4. Changing the input parameter in:
   - LEX::set_system_variable()
   - LEX::call_statement_start()
   - LEX::set_variable()
   from just LEX_CSTRING to Lex_ident_sys_st for stricter data type constrol:
   to make sure that noone passes an ident_cli
   (a fragment of the original query in the client character set)
   instead of server-side identifier
   (utf8 identifier allocated on THD when needed).

5. Adding Lex_ident_sys() in places where the affected functions are called.

6. Moving all calls of sp_create_assignment_lex() to the places
   just before parsing set_expr_or_default.
   This makes the grammar clearer, because
   sp_create_assignment_lex() and sp_create_assignment_instr()
   now stay near each other, so the balance of LEX's push/pop
   can be read easier.
   This will also help to WL#4179.

7. Adding class sp_lex_set_var
   Moving the initialization code from
   sp_create_assignment_lex() to the constructor of sp_lex_set_var.
   This will also help to WL#4179.

8. Moving a part of the "set" grammar rule into a separate
   rule "set_param".
   This makes the grammar easier to read and removes
   one shift/reduce conflict.

mysql-test/main/sp-code.result

@@ -847,8 +847,8 @@ drop procedure if exists p_20906_b;
 create procedure p_20906_a() SET @a=@a+1, @b=@b+1;
 show procedure code p_20906_a;
 Pos	Instruction
-0	stmt 31 "SET  @a=@a+1"
-1	stmt 31 "SET  @b=@b+1"
+0	stmt 31 "SET @a=@a+1"
+1	stmt 31 "SET @b=@b+1"
 set @a=1;
 set @b=1;
 call p_20906_a();
@@ -858,9 +858,9 @@ select @a, @b;
 create procedure p_20906_b() SET @a=@a+1, @b=@b+1, @c=@c+1;
 show procedure code p_20906_b;
 Pos	Instruction
-0	stmt 31 "SET  @a=@a+1"
-1	stmt 31 "SET  @b=@b+1"
-2	stmt 31 "SET  @c=@c+1"
+0	stmt 31 "SET @a=@a+1"
+1	stmt 31 "SET @b=@b+1"
+2	stmt 31 "SET @c=@c+1"
 set @a=1;
 set @b=1;
 set @c=1;
@@ -1328,3 +1328,18 @@ Pos	Instruction
 4	jump 2
 5	hpop 1
 drop function f1;
+#
+# MDEV-19640 Wrong SHOW PROCEDURE output for SET GLOBAL sysvar1=expr, sysvar2=expr
+#
+CREATE OR REPLACE PROCEDURE p1()
+BEGIN
+SET GLOBAL max_allowed_packet=16000000, max_error_count=60;
+SELECT @@GLOBAL.max_allowed_packet, @@GLOBAL.max_error_count;
+END;
+$$
+SHOW PROCEDURE CODE p1;
+Pos	Instruction
+0	stmt 31 "SET GLOBAL max_allowed_packet=16000000"
+1	stmt 31 "SET GLOBAL max_error_count=60"
+2	stmt 0 "SELECT @@GLOBAL.max_allowed_packet, @..."
+DROP PROCEDURE p1;

mysql-test/main/sp-code.test

@@ -946,3 +946,19 @@ end|
 delimiter ;|
 show function code f1;
 drop function f1;
+
+
+--echo #
+--echo # MDEV-19640 Wrong SHOW PROCEDURE output for SET GLOBAL sysvar1=expr, sysvar2=expr
+--echo #
+
+DELIMITER $$;
+CREATE OR REPLACE PROCEDURE p1()
+BEGIN
+  SET GLOBAL max_allowed_packet=16000000, max_error_count=60;
+  SELECT @@GLOBAL.max_allowed_packet, @@GLOBAL.max_error_count;
+END;
+$$
+DELIMITER ;$$
+SHOW PROCEDURE CODE p1;
+DROP PROCEDURE p1;

mysql-test/suite/compat/oracle/r/sp-code.result

@@ -1487,3 +1487,30 @@ CALL p1();
 x0	x1.a	x1.b
 100	101	102
 DROP PROCEDURE p1;
+#
+# MDEV-19640 Wrong SHOW PROCEDURE output for SET GLOBAL sysvar1=expr, sysvar2=expr
+#
+CREATE OR REPLACE PROCEDURE p1() AS
+BEGIN
+SET GLOBAL max_allowed_packet=16000000, max_error_count=60;
+SELECT @@GLOBAL.max_allowed_packet, @@GLOBAL.max_error_count;
+END;
+$$
+SHOW PROCEDURE CODE p1;
+Pos	Instruction
+0	stmt 31 "SET GLOBAL max_allowed_packet=16000000"
+1	stmt 31 "SET GLOBAL max_error_count=60"
+2	stmt 0 "SELECT @@GLOBAL.max_allowed_packet, @..."
+DROP PROCEDURE p1;
+#
+# MDEV-19639 sql_mode=ORACLE: Wrong SHOW PROCEDURE output for sysvar:=expr
+#
+CREATE OR REPLACE PROCEDURE p1() AS
+BEGIN
+max_error_count:=10;
+END;
+$$
+SHOW PROCEDURE CODE p1;
+Pos	Instruction
+0	stmt 31 "max_error_count:=10"
+DROP PROCEDURE p1;

mysql-test/suite/compat/oracle/t/sp-code.test

@@ -1055,3 +1055,34 @@ DELIMITER ;$$
 SHOW PROCEDURE CODE p1;
 CALL p1();
 DROP PROCEDURE p1;
+
+--echo #
+--echo # MDEV-19640 Wrong SHOW PROCEDURE output for SET GLOBAL sysvar1=expr, sysvar2=expr
+--echo #
+
+DELIMITER $$;
+CREATE OR REPLACE PROCEDURE p1() AS
+BEGIN
+  SET GLOBAL max_allowed_packet=16000000, max_error_count=60;
+  SELECT @@GLOBAL.max_allowed_packet, @@GLOBAL.max_error_count;
+END;
+$$
+DELIMITER ;$$
+SHOW PROCEDURE CODE p1;
+DROP PROCEDURE p1;
+
+--echo #
+--echo # MDEV-19639 sql_mode=ORACLE: Wrong SHOW PROCEDURE output for sysvar:=expr
+--echo #
+
+DELIMITER $$;
+CREATE OR REPLACE PROCEDURE p1() AS
+BEGIN
+  max_error_count:=10;
+END;
+$$
+DELIMITER ;$$
+SHOW PROCEDURE CODE p1;
+DROP PROCEDURE p1;
+
+

sql/sql_lex.cc

@@ -2023,7 +2023,7 @@ int Lex_input_stream::lex_one_token(YYSTYPE *yylval, THD *thd)
         next_state= MY_LEX_HOSTNAME;
         break;
       }
-      yylval->lex_str.str= (char*) get_ptr();
+      yylval->lex_str.str= (char*) get_ptr() - 1;
       yylval->lex_str.length= 1;
       return((int) '@');
     case MY_LEX_HOSTNAME:               // end '@' of user@hostname
@@ -5579,6 +5579,7 @@ void LEX::set_stmt_init()
   mysql_init_select(this);
   option_type= OPT_SESSION;
   autocommit= 0;
+  var_list.empty();
 };
 
 
@@ -7574,7 +7575,7 @@ Item *LEX::create_item_ident_sp(THD *thd, Lex_ident_sys_st *name,
 
 
 
-bool LEX::set_variable(const LEX_CSTRING *name, Item *item)
+bool LEX::set_variable(const Lex_ident_sys_st *name, Item *item)
 {
   sp_pcontext *ctx;
   const Sp_rcontext_handler *rh;
@@ -7588,8 +7589,8 @@ bool LEX::set_variable(const LEX_CSTRING *name, Item *item)
   Generate instructions for:
     SET x.y= expr;
 */
-bool LEX::set_variable(const LEX_CSTRING *name1,
-                       const LEX_CSTRING *name2,
+bool LEX::set_variable(const Lex_ident_sys_st *name1,
+                       const Lex_ident_sys_st *name2,
                        Item *item)
 {
   const Sp_rcontext_handler *rh;
@@ -7619,10 +7620,10 @@ bool LEX::set_variable(const LEX_CSTRING *name1,
 
 
 bool LEX::set_default_system_variable(enum_var_type var_type,
-                                      const LEX_CSTRING *name,
+                                      const Lex_ident_sys_st *name,
                                       Item *val)
 {
-  static LEX_CSTRING default_base_name= {STRING_WITH_LEN("default")};
+  static Lex_ident_sys default_base_name= {STRING_WITH_LEN("default")};
   sys_var *var= find_sys_var(thd, name->str, name->length);
   if (!var)
     return true;
@@ -7636,18 +7637,19 @@ bool LEX::set_default_system_variable(enum_var_type var_type,
 
 
 bool LEX::set_system_variable(enum_var_type var_type,
-                              const LEX_CSTRING *name,
+                              const Lex_ident_sys_st *name,
                               Item *val)
 {
   sys_var *var= find_sys_var(thd, name->str, name->length);
   DBUG_ASSERT(thd->is_error() || var != NULL);
-  return likely(var) ? set_system_variable(var_type, var, &null_clex_str, val) : true;
+  static Lex_ident_sys null_str;
+  return likely(var) ? set_system_variable(var_type, var, &null_str, val) : true;
 }
 
 
 bool LEX::set_system_variable(THD *thd, enum_var_type var_type,
-                              const LEX_CSTRING *name1,
-                              const LEX_CSTRING *name2,
+                              const Lex_ident_sys_st *name1,
+                              const Lex_ident_sys_st *name2,
                               Item *val)
 {
   sys_var *tmp;
@@ -8328,15 +8330,15 @@ bool LEX::call_statement_start(THD *thd, sp_name *name)
 }
 
 
-bool LEX::call_statement_start(THD *thd, const LEX_CSTRING *name)
+bool LEX::call_statement_start(THD *thd, const Lex_ident_sys_st *name)
 {
   sp_name *spname= make_sp_name(thd, name);
   return unlikely(!spname) || call_statement_start(thd, spname);
 }
 
 
-bool LEX::call_statement_start(THD *thd, const LEX_CSTRING *name1,
-                                         const LEX_CSTRING *name2)
+bool LEX::call_statement_start(THD *thd, const Lex_ident_sys_st *name1,
+                                         const Lex_ident_sys_st *name2)
 {
   sp_name *spname= make_sp_name(thd, name1, name2);
   return unlikely(!spname) || call_statement_start(thd, spname);

sql/sql_lex.h

@@ -3741,15 +3741,15 @@ struct LEX: public Query_tables_list
   bool set_trigger_field(const LEX_CSTRING *name1, const LEX_CSTRING *name2,
                          Item *val);
   bool set_system_variable(enum_var_type var_type, sys_var *var,
-                           const LEX_CSTRING *base_name, Item *val);
-  bool set_system_variable(enum_var_type var_type, const LEX_CSTRING *name,
-                           Item *val);
+                           const Lex_ident_sys_st *base_name, Item *val);
+  bool set_system_variable(enum_var_type var_type,
+                           const Lex_ident_sys_st *name, Item *val);
   bool set_system_variable(THD *thd, enum_var_type var_type,
-                           const LEX_CSTRING *name1,
-                           const LEX_CSTRING *name2,
+                           const Lex_ident_sys_st *name1,
+                           const Lex_ident_sys_st *name2,
                            Item *val);
   bool set_default_system_variable(enum_var_type var_type,
-                                   const LEX_CSTRING *name,
+                                   const Lex_ident_sys_st *name,
                                    Item *val);
   bool set_user_variable(THD *thd, const LEX_CSTRING *name, Item *val);
   void set_stmt_init();
@@ -3779,9 +3779,9 @@ struct LEX: public Query_tables_list
                                const char *body_start,
                                const char *body_end);
   bool call_statement_start(THD *thd, sp_name *name);
-  bool call_statement_start(THD *thd, const LEX_CSTRING *name);
-  bool call_statement_start(THD *thd, const LEX_CSTRING *name1,
-                                      const LEX_CSTRING *name2);
+  bool call_statement_start(THD *thd, const Lex_ident_sys_st *name);
+  bool call_statement_start(THD *thd, const Lex_ident_sys_st *name1,
+                                      const Lex_ident_sys_st *name2);
   sp_variable *find_variable(const LEX_CSTRING *name,
                              sp_pcontext **ctx,
                              const Sp_rcontext_handler **rh) const;
@@ -3791,9 +3791,9 @@ struct LEX: public Query_tables_list
     sp_pcontext *not_used_ctx;
     return find_variable(name, &not_used_ctx, rh);
   }
-  bool set_variable(const LEX_CSTRING *name, Item *item);
-  bool set_variable(const LEX_CSTRING *name1, const LEX_CSTRING *name2,
-                    Item *item);
+  bool set_variable(const Lex_ident_sys_st *name, Item *item);
+  bool set_variable(const Lex_ident_sys_st *name1,
+                    const Lex_ident_sys_st *name2, Item *item);
   void sp_variable_declarations_init(THD *thd, int nvars);
   bool sp_variable_declarations_finalize(THD *thd, int nvars,
                                          const Column_definition *cdef,
@@ -4439,6 +4439,12 @@ struct LEX: public Query_tables_list
   SELECT_LEX_UNIT *create_unit(SELECT_LEX*);
   SELECT_LEX *wrap_unit_into_derived(SELECT_LEX_UNIT *unit);
   SELECT_LEX *wrap_select_chain_into_derived(SELECT_LEX *sel);
+  void init_select()
+  {
+    current_select->init_select();
+    wild= 0;
+    exchange= 0;
+  }
   bool main_select_push();
   bool insert_select_hack(SELECT_LEX *sel);
   SELECT_LEX *create_priority_nest(SELECT_LEX *first_in_nest);
@@ -4747,6 +4753,22 @@ class sp_lex_local: public st_lex_local
 };
 
 
+class sp_lex_set_var: public sp_lex_local
+{
+public:
+  sp_lex_set_var(THD *thd, const LEX *oldlex)
+   :sp_lex_local(thd, oldlex)
+  {
+    // Set new LEX as if we at start of set rule
+    init_select();
+    sql_command= SQLCOM_SET_OPTION;
+    var_list.empty();
+    autocommit= 0;
+    option_type= oldlex->option_type; // Inherit from the outer lex
+  }
+};
+
+
 /**
   An assignment specific LEX, which additionally has an Item (an expression)
   and an associated with the Item free_list, which is usually freed
@@ -4826,8 +4848,9 @@ Virtual_column_info *add_virtual_expression(THD *thd, Item *expr);
 Item* handle_sql2003_note184_exception(THD *thd, Item* left, bool equal,
                                        Item *expr);
 
-void sp_create_assignment_lex(THD *thd, bool no_lookahead);
-bool sp_create_assignment_instr(THD *thd, bool no_lookahead);
+bool sp_create_assignment_lex(THD *thd, const char *pos);
+bool sp_create_assignment_instr(THD *thd, bool no_lookahead,
+                                bool need_set_keyword= true);
 
 void mark_or_conds_to_avoid_pushdown(Item *cond);
 

sql/sql_parse.cc

@@ -7760,10 +7760,7 @@ void THD::reset_for_next_command(bool do_clear_error)
 void
 mysql_init_select(LEX *lex)
 {
-  SELECT_LEX *select_lex= lex->current_select;
-  select_lex->init_select();
-  lex->wild= 0;
-  lex->exchange= 0;
+  lex->init_select();
 }