Let us create and drop a separate database for getting rid of the
default database in the MDEV-22781 test.

The warning message says the file contains a character which can not be
represented in current codepage (not exactly accurate)

Disable lock elision, due to buggy intrin.h (_xbegin is misspelled)
Fix warnings.

restore the old behavior where without a debugger mtr does not
wait for mysqld to start. It was broken in feacc0aa

MDEV-27036: repeated "table" key resolve for print_explain_json

MDEV-27036: duplicated keys in best_access_path

MDEV-27036: Explain_aggr_filesort::print_json_members: resolve duplicated "filesort" member in Json object

MDEV-27036: Explain_basic_join::
            print_explain_json_interns fixed start_dups_weedout case for main.explain_json test

close_connections() in mysqld.cc sends a signal to all threads.
But InnoDB is too busy purging, doesn't react immediately.
close_connections() waits 20 seconds, which isn't enough in this
particular case, and then unlinks all threads from
the list and forcibly closes their vio connection.

InnoDB background  threads have no vio connection to close, but
they're unlinked all the same. So when later they finally notice
the shutdown request and try to unlink themselves, they fail to
assert that they're still linked.

Fix: don't assert_linked, as another thread can unlink this THD anytime

MDEV-20330 Combination of "," (comma), cross join and left join fails to parse

From 10.4.13, the `mariadb.sys` user was created to replace `root` definers.
 - In commit 0253ea7f, definer of
   Add/DropGeometryColumn procedures was changed to `mariadb.sys`, in
   `scripts/maria_add_gis_sp.sql.in`.
   However, maria_add_gis_sp.sql only applies to new databases created by
   installation script. Databases upgraded from old versions will miss this
   change.
 - In addition, according to commit
   0d6d801e(MDEV-23102), in some scenarios
   when root user is replaced it will skip creating `mariadb.sys` user.

This commit is to update the definer from `root` to `mariadb.sys` during
upgrade. It only makes the change if the original definers are root.

Doesn't choose to execute `maria_add_gis_sp.sql` in upgrade script to
recreate the procedures is because of considering the scenarios of
MDEV-23102 that `root` user is replaced and `mariadb.sys` is not created.

All new code of the whole pull request, including one or several files
that are either new files or modified ones, are contributed under the
BSD-new license. I am contributing on behalf of my employer Amazon Web
Services, Inc.

This fixes up 4489a89c
and the test binlog.binlog_truncate_multi_engine
that indirectly invokes the DBUG_SUICIDE.

Occasionally, the test would fail with a result difference for
ddl_log_file_alter_table (0 instead of 1) due to some
nondeterminism in the test. Let us remove that nondeterminism.

In commit 1193a793 we
set innodb_use_native_aio=OFF when using io_uring
on a kernel where write requests could potentially be lost.

The last reproducible issue was fixed in Linux 5.16-rc1
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v5.16-rc1&id=d3e3c102d107bb84251455a298cf475f24bab995
and the fix was backported to 5.15.3.

Hence, using a 5.16 or later kernel should be fine.
The Debian kernel 5.15.0-1-amd64 (5.15.3-1) was tested.
On Debian, utsname::release or uname -r does not reflect the
exact minor version while utsname::version and uname -v does.

On Fedora however the utsname::version is rather different:

  $ uname -r
  5.14.20-200.fc34.x86_64
  $ uname -v
  #1 SMP Thu Nov 18 22:03:20 UTC 2021

As such we use the version, but fall back to the release if
there isn't the beginnings of a kernel version in the version.

Thanks to Daniel Black for reporting the Linux kernel bug and
Jens Axboe for actually fixing it.
Co-Authored-By: Daniel Black <daniel@mariadb.org>

Closes: #1953

The DYNAMIC_ARRAY copies values in and copies values out. Without a
comparitor function, get_index_dynamic() does not make sense.

This function is not used. If we have a need for a function like it
in the future, I propose we write a new one with unit tests showing
how it is used and demostrating that it behaves as expected.

Fix a potential deadlock bug between locks ctrl_mutex and entry->mutex

Sys_lc_messages, Sys_lc_time_names: Use offsetof(MY_LOCALE, ...)
because the type has standard layout.

The macro my_offsetof() performs pointer arithmetics that may be
undefined behavior. As reported in MDEV-26272, it may cause
clang -fsanitize=undefined to generate invalid memory references.

struct PFS_events_statements: Convert to std::is_standard_layout
by encapsulating the standard-layout struct PFS_events instead of
deriving from it, so that the standard macro offsetof() can be used.

PFS_events_statements::copy(): Renamed from copy_events_statements().
A cast to void* is now needed in memcpy() to avoid GCC -Wclass-memaccess
"writing to an object ... leaves 64 bytes unchanged".

The weight scanner routine scanner_next() did not properly handle the cases
when a contraction produces no weights (is ignorable).

Adding a helper routine my_uca_scanner_set_weight() and using
it in all cases:

- A single ASCII character
- A contraction starting with an ASCII character
- A multi-byte character
- A contraction starting with a multi-byte character

Also adding two other helper routines:

- my_uca_scanner_next_expansion_weight()
- my_uca_scanner_set_weight_outside_maxchar()

to avoid using scanner->wbeg directly inside scanner_next().
This reduces the probability of similar future bugs.

This patch prepares the code for upcoming changes:

MDEV-27009 Add UCA-14.0.0 collations
MDEV-27042 UCA: Resetting contractions to ignorable does not work well

1. Adding "const" qualifiers to return type and parameters in functions:
- my_uca_contraction2_weight()
- my_wmemcmp()
- my_uca_contraction_weight()
- my_uca_scanner_contraction_find()
- my_uca_previous_context_find()
- my_uca_context_weight_find()

2. Adding a helper function my_uca_true_contraction_eq()

3. Changing the way how scanner->wbeg is set during context weight handling.
   It was previously set inside functions:
   - my_uca_scanner_contraction_find()
   - my_uca_previous_context_find()
   Now it's set inside scanner_next(), which makes the code more symmetric
   for context-free and context-dependent sequences.
   This makes then upcoming fix for MDEV-27042 simpler.