The code did not take into account that:
- U+005C (backslash) can occupy more than mbminlen characters (e.g. in sjis)
- Some character sets do not have a code for U+005C (e.g. swe7)

Adding a new function my_wc_to_printable into MY_CHARSET_HANDLER to
cover all special cases easier.

The titlebar scrambled var/log/Stdout.log and can becasue of this not be
on by default.

MDEV-22488 test failures: parts.partition_debug_innodb /
           parts.partition_debug_myisam

The reason for the failure was a wrong printf() that accessed not existing
things on the stack.
The reason the falure was hard to find was that the partition_debug_...
tests disables core dumps, so there was no trace that the server had
crashed in the logs.

Fixed by fixing the faulty push_warning_printf() and splitting the tests
into two parts, one that test failures (with core dumps enabled) and one
part that test crash recovery.

The review and test splitting was done by Monty

In commit ea37b144
we removed the MDEV-16222 test case but forgot to remove
the debug instrumentation.

ibuf_read_merge_pages(): Request a possibly freed page.
The change buffer is discarded lazily for freed pages either
by this function or when buf_page_create() reuses a page.

buf_page_get_low(): Relax a debug assertion.
Do not attempt change buffer merge on freed pages.

ibuf_merge_or_delete_for_page(): Assert that the page state is NORMAL.
INIT_ON_FLUSH is not possible, because in that case buf_page_create()
should have removed any buffered changes for the page.

buf_page_get_gen(): Apply buffered changes also in the case when
we can avoid reading the page based on buffered redo log records.
This addresses a hard-to-reproduce scenario that was broken in
commit 6697135c.

Let us use the common accessor function fil_page_get_type()
instead of accessing the page header field FIL_PAGE_TYPE directly.

fsp0pagecompress.h: Remove.
Invoke fil_page_get_type() and FSP_FLAGS_GET_PAGE_COMPRESSION_LEVEL
directly.

log_block_get_flush_bit(), log_block_set_flush_bit():
Access the byte directly.

dict_sys_read_row_id(): Remove (unused function).

Part of
MDEV-18353 - Shutdown may miss to wait for connection thread

MDEV-22130 SHOW WARNINGS will SIGSEGV 10.5 optimized build after setting CHARACTER_SET_RESULTS to NULL and running any invalid SQL | Binary_string::copy_printable_hhhh

The old code did not take into account that
thd->variables.character_set_results can be NULL.

MDEV-22424 Server crashes in handler::check_duplicate_long_entry_key or Assertion `inited == NONE || lookup_handler != this' failed upon DELETE FOR PORTION on table with long unique key

even if we're *allowed to* convert DELETE .. FOR PERIOD OF
into an update internally, doesn't think we'll *be able to*.

We always have to prepare for insert.

MDEV-22185 Failing assertion: node->pcur->rel_pos == BTR_PCUR_ON or ER_KEY_NOT_FOUND or Assertion `inited==NONE' failed in handler::ha_index_init

long unique checks should be done for a partitioned table as a whole,
not for individual partitions.

Followup for f3f31eaa that extends it to UPDATE

as mentioned in f9f33b85 and generally to make it
easier to talk about

ha_innobase::check_if_supported_inplace_alter(): Do not allow
ALGORITHM=INSTANT for operations that avoid a table rebuild
but involve dropping (or creating) secondary indexes.

Now all access goes through _current_thd() and set_current_thd()
functions.

Some functions like THD::store_globals() can not fail now.

MDEV-20502 Queries against spider tables return wrong values for columns following constant declarations.

Add test cases.

MDEV-20502 Queries against spider tables return wrong values for columns following constant declarations.

Add test cases.

Do not show exact value as it depends order of test execution.
Instead use # for correct values and ERROR for incorrect.

fil_flush_file_spaces(): Remove the constant parameter.

buf_flush_start(), buf_flush_end(): Use static linkage.

fil_page_get_prev(), fil_page_get_next(), fil_addr_is_null(): Remove.

commit 5e7e7153 accidentally
broke the build without WSREP, by misplacing an #endif.

commit d467bb7e accidentally
broke the build without WSREP, by misplacing an #endif.

This is a partial backport of
commit 5e7e7153 from 10.4.

assert_trx_is_free(): Assert !is_wsrep().

trx_init(): Do not initialize trx->wsrep, because it must have been
initialized already.

trx_commit_in_memory(): Invoke wsrep_commit_ordered(). This call
was being skipped, because the transaction object had already been
freed to the pool.

trx_rollback_for_mysql(), innobase_commit_low(),
innobase_rollback_trx(): Always reset trx->wsrep.

This is a follow-up fix to the changes that were made in MDEV-7962.

assert_trx_is_free(): Assert !is_wsrep().

trx_init(): Do not initialize trx->wsrep, because it must have been
initialized already.

trx_t::commit_in_memory(): Invoke wsrep_commit_ordered(). This call
was being skipped, because the transaction object had already been
freed to the pool.

trx_rollback_for_mysql(), innobase_commit_low(),
innobase_close_connection(): Always reset trx->wsrep.

- InnoDB gives "table is marked as crashed and should be repaired" when
table schema mismatch.

Disable IPO (interprocedural optimization, aka /GL) on Windows
on libraries, from which server.dll exports symbols -  exporting symbols
does not work for objects compiled with /GL.

- Instant alter should change the metadata alone when table is
discarded. It shouldn't try to add metadata record in clustered index.
Also make the clustered index to non-instant format.

		FOREIGN_KEY_CHECKS is disabled

- Referenced index can be null While renaming the referenced column name.
In that case, rename the referenced column name in dict_foreign_t and
find the equivalent referenced index.