MDEV-29458: Role grant commands do not propagate all grants

There was an issue in updating in-memory role datastructures when
propagating role grants.

The issue is that changing a particular role's privilege (on any
privilege level, global, database, etc.)
was done such that it overwrote the entire set of bits for that
particular level of privileges.

For example:
grant select on *.* to r1 -> sets the access bits to r1 to select,
regardless of what bits were present for role r1 (inherited from any
other roles).

Before this fix, the rights of role r1 were propagated to any roles r1
was granted to, however the propagated rights did *not* include the
complete rights r1 inherited from its own grants.

For example:
  grant r2 to r1;
  grant select on *.* to r2;
  grant insert on *.* to r1; # This command completely disregards the
                             # select privilege from r2.

In order to correct this, ensure that before rights are propagated
onwards, that the current's role rights have been updated from its
grants.

Additionally, the patch exposed a flaw in the DROP ROLE code.
When deleting a role we removed all its previous grants, but what
remained was the actual links of roles granted to the dropped role.
Having these links present when propagating grants meant that we would
have leftover ACL_xxx entries.

Ensure that the links are removed before propagating grants.

mysql-test/suite/roles/recursive_dbug.result

@@ -56,7 +56,7 @@ connection default;
 grant select on *.* to role1;
 show status like 'debug%';
 Variable_name	Value
-Debug_role_merges_global	19
+Debug_role_merges_global	20
 Debug_role_merges_db	0
 Debug_role_merges_table	0
 Debug_role_merges_column	0
@@ -106,7 +106,7 @@ connection default;
 revoke select on *.* from role1;
 show status like 'debug%';
 Variable_name	Value
-Debug_role_merges_global	27
+Debug_role_merges_global	29
 Debug_role_merges_db	0
 Debug_role_merges_table	0
 Debug_role_merges_column	0
@@ -124,8 +124,8 @@ connection default;
 grant select on mysql.* to role1;
 show status like 'debug%';
 Variable_name	Value
-Debug_role_merges_global	27
-Debug_role_merges_db	8
+Debug_role_merges_global	29
+Debug_role_merges_db	9
 Debug_role_merges_table	0
 Debug_role_merges_column	0
 Debug_role_merges_routine	0
@@ -164,8 +164,8 @@ connection default;
 revoke select on mysql.* from role1;
 show status like 'debug%';
 Variable_name	Value
-Debug_role_merges_global	27
-Debug_role_merges_db	16
+Debug_role_merges_global	29
+Debug_role_merges_db	17
 Debug_role_merges_table	0
 Debug_role_merges_column	0
 Debug_role_merges_routine	0
@@ -177,9 +177,9 @@ connection default;
 grant select on mysql.roles_mapping to role1;
 show status like 'debug%';
 Variable_name	Value
-Debug_role_merges_global	27
-Debug_role_merges_db	16
-Debug_role_merges_table	8
+Debug_role_merges_global	29
+Debug_role_merges_db	17
+Debug_role_merges_table	9
 Debug_role_merges_column	0
 Debug_role_merges_routine	0
 connection foo;
@@ -217,9 +217,9 @@ connection default;
 revoke select on mysql.roles_mapping from role1;
 show status like 'debug%';
 Variable_name	Value
-Debug_role_merges_global	27
-Debug_role_merges_db	16
-Debug_role_merges_table	16
+Debug_role_merges_global	29
+Debug_role_merges_db	17
+Debug_role_merges_table	17
 Debug_role_merges_column	0
 Debug_role_merges_routine	0
 connection foo;
@@ -230,10 +230,10 @@ connection default;
 grant select(User) on mysql.roles_mapping to role1;
 show status like 'debug%';
 Variable_name	Value
-Debug_role_merges_global	27
-Debug_role_merges_db	16
-Debug_role_merges_table	24
-Debug_role_merges_column	8
+Debug_role_merges_global	29
+Debug_role_merges_db	17
+Debug_role_merges_table	26
+Debug_role_merges_column	9
 Debug_role_merges_routine	0
 connection foo;
 select count(*) from mysql.roles_mapping;
@@ -272,10 +272,10 @@ connection default;
 grant select(Host) on mysql.roles_mapping to role3;
 show status like 'debug%';
 Variable_name	Value
-Debug_role_merges_global	27
-Debug_role_merges_db	16
-Debug_role_merges_table	30
-Debug_role_merges_column	14
+Debug_role_merges_global	29
+Debug_role_merges_db	17
+Debug_role_merges_table	33
+Debug_role_merges_column	16
 Debug_role_merges_routine	0
 connection foo;
 select count(concat(User,Host,Role)) from mysql.roles_mapping;
@@ -312,10 +312,10 @@ connection default;
 revoke select(User) on mysql.roles_mapping from role1;
 show status like 'debug%';
 Variable_name	Value
-Debug_role_merges_global	27
-Debug_role_merges_db	16
-Debug_role_merges_table	38
-Debug_role_merges_column	22
+Debug_role_merges_global	29
+Debug_role_merges_db	17
+Debug_role_merges_table	41
+Debug_role_merges_column	24
 Debug_role_merges_routine	0
 connection foo;
 select count(concat(User,Host)) from mysql.roles_mapping;
@@ -327,10 +327,10 @@ connection default;
 revoke select(Host) on mysql.roles_mapping from role3;
 show status like 'debug%';
 Variable_name	Value
-Debug_role_merges_global	27
-Debug_role_merges_db	16
-Debug_role_merges_table	44
-Debug_role_merges_column	28
+Debug_role_merges_global	29
+Debug_role_merges_db	17
+Debug_role_merges_table	47
+Debug_role_merges_column	30
 Debug_role_merges_routine	0
 connection foo;
 select count(concat(Host)) from mysql.roles_mapping;
@@ -342,11 +342,11 @@ create function fn1() returns char(10) return "fn1";
 grant execute on procedure test.pr1 to role1;
 show status like 'debug%';
 Variable_name	Value
-Debug_role_merges_global	27
-Debug_role_merges_db	16
-Debug_role_merges_table	44
-Debug_role_merges_column	28
-Debug_role_merges_routine	8
+Debug_role_merges_global	29
+Debug_role_merges_db	17
+Debug_role_merges_table	47
+Debug_role_merges_column	30
+Debug_role_merges_routine	9
 connection foo;
 call pr1();
 ERROR 42000: execute command denied to user 'foo'@'localhost' for routine 'test.pr1'
@@ -360,11 +360,11 @@ connection default;
 grant execute on function test.fn1 to role5;
 show status like 'debug%';
 Variable_name	Value
-Debug_role_merges_global	27
-Debug_role_merges_db	16
-Debug_role_merges_table	44
-Debug_role_merges_column	28
-Debug_role_merges_routine	13
+Debug_role_merges_global	29
+Debug_role_merges_db	17
+Debug_role_merges_table	47
+Debug_role_merges_column	30
+Debug_role_merges_routine	15
 connection foo;
 select fn1();
 fn1()
@@ -373,11 +373,11 @@ connection default;
 revoke execute on procedure test.pr1 from role1;
 show status like 'debug%';
 Variable_name	Value
-Debug_role_merges_global	27
-Debug_role_merges_db	16
-Debug_role_merges_table	44
-Debug_role_merges_column	28
-Debug_role_merges_routine	21
+Debug_role_merges_global	29
+Debug_role_merges_db	17
+Debug_role_merges_table	47
+Debug_role_merges_column	30
+Debug_role_merges_routine	23
 connection foo;
 call pr1();
 ERROR 42000: execute command denied to user 'foo'@'localhost' for routine 'test.pr1'
@@ -388,11 +388,11 @@ connection default;
 revoke execute on function test.fn1 from role5;
 show status like 'debug%';
 Variable_name	Value
-Debug_role_merges_global	27
-Debug_role_merges_db	16
-Debug_role_merges_table	44
-Debug_role_merges_column	28
-Debug_role_merges_routine	26
+Debug_role_merges_global	29
+Debug_role_merges_db	17
+Debug_role_merges_table	47
+Debug_role_merges_column	30
+Debug_role_merges_routine	28
 connection foo;
 select fn1();
 ERROR 42000: execute command denied to user 'foo'@'localhost' for routine 'test.fn1'
@@ -403,67 +403,67 @@ drop function fn1;
 grant select on mysql.roles_mapping to role3;
 show status like 'debug%';
 Variable_name	Value
-Debug_role_merges_global	27
-Debug_role_merges_db	16
-Debug_role_merges_table	50
-Debug_role_merges_column	28
-Debug_role_merges_routine	26
+Debug_role_merges_global	29
+Debug_role_merges_db	17
+Debug_role_merges_table	54
+Debug_role_merges_column	30
+Debug_role_merges_routine	28
 grant select on mysql.roles_mapping to role1;
 show status like 'debug%';
 Variable_name	Value
-Debug_role_merges_global	27
-Debug_role_merges_db	16
-Debug_role_merges_table	53
-Debug_role_merges_column	28
-Debug_role_merges_routine	26
+Debug_role_merges_global	29
+Debug_role_merges_db	17
+Debug_role_merges_table	58
+Debug_role_merges_column	30
+Debug_role_merges_routine	28
 revoke select on mysql.roles_mapping from role3;
 show status like 'debug%';
 Variable_name	Value
-Debug_role_merges_global	27
-Debug_role_merges_db	16
-Debug_role_merges_table	54
-Debug_role_merges_column	28
-Debug_role_merges_routine	26
+Debug_role_merges_global	29
+Debug_role_merges_db	17
+Debug_role_merges_table	59
+Debug_role_merges_column	30
+Debug_role_merges_routine	28
 revoke select on mysql.roles_mapping from role1;
 show status like 'debug%';
 Variable_name	Value
-Debug_role_merges_global	27
-Debug_role_merges_db	16
-Debug_role_merges_table	62
-Debug_role_merges_column	28
-Debug_role_merges_routine	26
+Debug_role_merges_global	29
+Debug_role_merges_db	17
+Debug_role_merges_table	67
+Debug_role_merges_column	30
+Debug_role_merges_routine	28
 grant select on mysql.* to role1;
 show status like 'debug%';
 Variable_name	Value
-Debug_role_merges_global	27
-Debug_role_merges_db	24
-Debug_role_merges_table	62
-Debug_role_merges_column	28
-Debug_role_merges_routine	26
+Debug_role_merges_global	29
+Debug_role_merges_db	26
+Debug_role_merges_table	67
+Debug_role_merges_column	30
+Debug_role_merges_routine	28
 grant select on test.* to role1;
 show status like 'debug%';
 Variable_name	Value
-Debug_role_merges_global	27
-Debug_role_merges_db	32
-Debug_role_merges_table	62
-Debug_role_merges_column	28
-Debug_role_merges_routine	26
+Debug_role_merges_global	29
+Debug_role_merges_db	35
+Debug_role_merges_table	67
+Debug_role_merges_column	30
+Debug_role_merges_routine	28
 revoke select on mysql.* from role1;
 show status like 'debug%';
 Variable_name	Value
-Debug_role_merges_global	27
-Debug_role_merges_db	40
-Debug_role_merges_table	62
-Debug_role_merges_column	28
-Debug_role_merges_routine	26
+Debug_role_merges_global	29
+Debug_role_merges_db	43
+Debug_role_merges_table	67
+Debug_role_merges_column	30
+Debug_role_merges_routine	28
 revoke select on test.* from role1;
 show status like 'debug%';
 Variable_name	Value
-Debug_role_merges_global	27
-Debug_role_merges_db	48
-Debug_role_merges_table	62
-Debug_role_merges_column	28
-Debug_role_merges_routine	26
+Debug_role_merges_global	29
+Debug_role_merges_db	51
+Debug_role_merges_table	67
+Debug_role_merges_column	30
+Debug_role_merges_routine	28
 connection default;
 drop user foo@localhost;
 drop role role1;