MDEV-12775 Reuse data type aggregation code for hybrid functions and UNION

Introducing a new class Type_holder (used internally in sql_union.cc),
to reuse exactly the same data type attribute aggregation Type_handler API
for hybrid functions and UNION.

This fixes a number of bugs in UNION:

- MDEV-9495 Wrong field type for a UNION of a signed and an unsigned INT expression
- MDEV-9497 UNION and COALESCE produce different field types for DECIMAL+INT
- MDEV-12594 UNION between fixed length double columns does not always preserve scale
- MDEV-12595 UNION converts INT to BIGINT
- MDEV-12599 UNION is not symmetric when mixing INT and CHAR

Details:

- sql_union.cc: Reusing attribute aggregation for UNION.
  Adding new methods:
  * st_select_lex_unit::join_union_type_handlers()
  * st_select_lex_unit::join_union_type_attributes()
  * st_select_lex_unit::join_union_item_types()
  Removing the old join_types()-based code.

- Changing Type_handler::Item_hybrid_func_fix_attributes()
  to accept "name", Type_handler_hybrid_field_type, Type_all_attributes
  as three separate parameters instead of a single Item_hybrid_func parameter,
  to make it possible to pass both Item_hybrid_func and Type_holder.

- Moving the former special GEOMETRY and ENUM/SET attribute aggregation code
  from Item_type_holder::join_types() to
  * Type_handler_typelib::Item_hybrid_func_fix_attributes().
  * Type_handler_geometry::Item_hybrid_func_fix_attrubutes().
  This makes GEOMETRY/ENUM/SET symmetric with all other data types
  (from the UNION point of view).
  Removing Item_type_holder::join_types() and Item_type_holder::get_full_info().

- Adding new methods into Type_all_attributes:
  * Type_all_attributes::set_geometry_type() and
    Item_hybrid_func::set_geometry_type().
  * Adding Type_all_attributes::get_typelib().
  * Adding Type_all_attributes::set_typelib().

- Adding Type_handler_typelib as a common parent for
  Type_handler_enum and Type_handler_set, to avoid code duplication: they have
  already had two common methods, and we're adding one more shared method.

- Adding Type_all_attributes::set_maybe_null(), as some type handlers
  may want to set maybe_null (e.g. Type_handler_geometry) during data type
  attribute aggregation.

- Changing Type_geometry_attributes() to accept Type_handler
  and Type_all_attributes as two separate parameters, instead
  of a single Item parameter, to make it possible to pass Type_holder.

- Adding Item_args::add_argument().

- Moving Item_args::alloc_arguments() from "protected" to "public".

- Moving Item_type_holder::Item_type_holder() from item.cc to item.h, as
  now it's very simple.
  Btw, this constructor should probably be eventually removed.
  It's now used only in sql_show.cc, which could be modified to use
  Item_return_decimal (for symmetry with Item_return_xxx created for all
  other data types). Or, another option: remove all Item_return_xxx and
  use Item_type_holder for all data types instead.

- storage/tokudb/mysql-test/tokudb/r/type_float.result
  Recording new results (MDEV-12594).

- mysql-test/r/cte_recursive.result
  Recording new results (MDEV-9497)

- mysql-test/r/subselect*.result
  Recording new results (MDEV-12595)

- mysql-test/r/metadata.result
  Recording new results (MDEV-9495)

- mysql-test/r/temp_table.result
  Recording new results (MDEV-12594)

- mysql-test/r/type_float.result
  Recording new results (MDEV-12594)

1 files changed, 127 insertions, 0 deletions

diff --git a/mysql-test/t/union.test b/mysql-test/t/union.test
index 04ab71588be..ce8b2bc9c2a 100644
--- a/mysql-test/t/union.test
+++ b/mysql-test/t/union.test
@@ -1545,5 +1545,132 @@ SHOW CREATE TABLE t1;
 DROP TABLE t1;
 
 --echo #
+--echo # MDEV-9495 Wrong field type for a UNION of a signed and an unsigned INT expression
+--echo #
+CREATE TABLE t1 (a INT, b INT UNSIGNED);
+INSERT INTO t1 VALUES (0x7FFFFFFF,0xFFFFFFFF);
+CREATE TABLE t2 AS SELECT a FROM t1 UNION SELECT b FROM t1;
+SHOW CREATE TABLE t2;
+SELECT * FROM t2 ORDER BY a;
+DROP TABLE t2;
+CREATE TABLE t2 AS SELECT COALESCE(a,b), COALESCE(b,a) FROM t1;
+SHOW CREATE TABLE t2;
+SELECT * FROM t2;
+DROP TABLE t2;
+DROP TABLE t1;
+
+--echo #
+--echo # MDEV-9497 UNION and COALESCE produce different field types for DECIMAL+INT
+--echo #
+CREATE TABLE t1 AS SELECT COALESCE(10.1,CAST(10 AS UNSIGNED)) AS a;
+SHOW CREATE TABLE t1;
+DROP TABLE t1;
+CREATE OR REPLACE TABLE t1 AS SELECT 10.1 AS a UNION SELECT CAST(10 AS UNSIGNED);
+SHOW CREATE TABLE t1;
+DROP TABLE t1;
+
+--echo #
+--echo # MDEV-12594 UNION between fixed length double columns does not always preserve scale
+--echo #
+CREATE TABLE t1 (a FLOAT(20,4), b FLOAT(20,3), c FLOAT(20,4));
+INSERT INTO t1 VALUES (1111,2222,3333);
+
+CREATE TABLE t2 AS SELECT a FROM t1 UNION SELECT a FROM t1;
+SHOW CREATE TABLE t2;
+DROP TABLE t2;
+
+CREATE OR REPLACE TABLE t2 SELECT a FROM t1 UNION SELECT c FROM t1;
+SHOW CREATE TABLE t2;
+DROP TABLE t2;
+
+CREATE OR REPLACE TABLE t2 SELECT b FROM t1 UNION SELECT b FROM t1;
+SHOW CREATE TABLE t2;
+DROP TABLE t2;
+
+CREATE OR REPLACE TABLE t2 SELECT c FROM t1 UNION SELECT c FROM t1;
+SHOW CREATE TABLE t2;
+DROP TABLE t2;
+
+CREATE OR REPLACE TABLE t2 SELECT c FROM t1 UNION SELECT a FROM t1;
+SHOW CREATE TABLE t2;
+DROP TABLE t2;
+
+CREATE OR REPLACE TABLE t2 AS SELECT a FROM t1 UNION SELECT b FROM t1;
+SHOW CREATE TABLE t2;
+DROP TABLE t2;
+
+CREATE OR REPLACE TABLE t2 AS SELECT b FROM t1 UNION SELECT a FROM t1;
+SHOW CREATE TABLE t2;
+DROP TABLE t2;
+
+DROP TABLE t1;
+
+--echo # Corner case
+CREATE TABLE t1 (a FLOAT(255,4), b FLOAT(255,3));
+INSERT INTO t1 VALUES (1111,2222);
+CREATE OR REPLACE TABLE t2 AS SELECT b FROM t1 UNION SELECT a FROM t1;
+SHOW CREATE TABLE t2;
+DROP TABLE t2;
+DROP TABLE t1;
+
+
+--echo #
+--echo # MDEV-12595 UNION converts INT to BIGINT
+--echo #
+CREATE TABLE t1 AS SELECT
+  1,
+  -1,
+  COALESCE(1,1),
+  COALESCE(-1,-1),
+  COALESCE(1,-1),
+  COALESCE(-1,1);
+SHOW CREATE TABLE t1;
+DROP TABLE t1;
+CREATE TABLE t1 AS SELECT 1 AS c1,1 AS c2,-1 AS c3,-1 AS c4 UNION SELECT 1,-1,1,-1;
+SHOW CREATE TABLE t1;
+DROP TABLE t1;
+
+
+--echo #
+--echo # MDEV-12599 UNION is not symmetric when mixing INT and CHAR
+--echo #
+
+CREATE OR REPLACE TABLE t1 AS SELECT 1 AS c1, 'a' AS c2 UNION SELECT 'a', 1;
+SHOW CREATE TABLE t1;
+DROP TABLE t1;
+
+CREATE OR REPLACE TABLE t1 AS SELECT 11112222 AS c1, 'a' AS c2 UNION SELECT 'a', 11112222;
+SHOW CREATE TABLE t1;
+DROP TABLE t1;
+
+
+CREATE OR REPLACE TABLE t1 AS SELECT 111122223333 AS c1, 'a' AS c2 UNION SELECT 'a', 111122223333;
+SHOW CREATE TABLE t1;
+DROP TABLE t1;
+
+CREATE OR REPLACE TABLE t1 AS SELECT 1111222233334444 AS c1, 'a' AS c2 UNION SELECT 'a', 1111222233334444;
+SHOW CREATE TABLE t1;
+DROP TABLE t1;
+
+CREATE TABLE t1 (a INT(3), b VARCHAR(1));
+CREATE TABLE t2 AS SELECT a,b FROM t1 UNION SELECT b,a FROM t1;
+SHOW CREATE TABLE t2;
+DROP TABLE t2;
+DROP TABLE t1;
+
+CREATE TABLE t1 (a BIGINT(3), b VARCHAR(1));
+CREATE TABLE t2 AS SELECT a,b FROM t1 UNION SELECT b,a FROM t1;
+SHOW CREATE TABLE t2;
+DROP TABLE t2;
+DROP TABLE t1;
+
+CREATE TABLE t1 (a BIGINT(12), b VARCHAR(1));
+CREATE TABLE t2 AS SELECT a,b FROM t1 UNION SELECT b,a FROM t1;
+SHOW CREATE TABLE t2;
+DROP TABLE t2;
+DROP TABLE t1;
+
+
+--echo #
 --echo # End of 10.3 tests
 --echo #