This fixes warnings that were emitted when running InnoDB test
suites on a debug server that was compiled with GCC 7.1.0 using
the flags -O3 -fsanitize=undefined.

thd_requested_durability(): XtraDB can call this with trx->mysql_thd=NULL.
Remove the function in InnoDB, because it is not used there.

calc_row_difference(): Do not call memcmp(o_ptr, NULL, 0).

innobase_index_name_is_reserved(): This can be called with
key_info=NULL, num_of_keys=0.

innobase_dropping_foreign(), innobase_check_foreigns_low(),
innobase_check_foreigns(): This can be called with
drop_fk=NULL, n_drop_fk=0.

rec_convert_dtuple_to_rec_comp(): Do not invoke memcpy(end, NULL, 0).

On 64-bit systems, the constant 1 would be 32-bit (int or unsigned)
by default. Cast the constant to ulint before shifting to avoid a
-fsanitize=undefined warning or any potential overflow.

Fix a -fsanitizer=undefined warning that trx_undo_report_row_operation()
was being passed thr=NULL when the BTR_NO_UNDO_LOG_FLAG flag was set.

trx_undo_report_row_operation(): Remove the first two parameters.
The parameter clust_entry!=NULL distinguishes inserts from updates.

This should be a non-functional change (no observable change in
behaviour; slightly smaller code).

Allocate srv_sys statically so that the desired alignment can be
guaranteed. This silences -fsanitize=undefined warnings.
There probably is no performance impact of this, because the
reason for the alignment to ensure the absence of false sharing
between counters. Even with the misalignment, each counter would
have been been aligned at 64 bits, and the counters would reside
in separate cache lines.

The parameter thr of the function btr_cur_optimistic_insert()
is not declared as nonnull, but GCC 7.1.0 with -O3 is wrongly
optimizing away the first part of the condition
UNIV_UNLIKELY(thr && thr_get_trx(thr)->fake_changes)
when the function is being called by row_merge_insert_index_tuples()
with thr==NULL.

The fake_changes is an XtraDB addition. This GCC bug only appears
to have an impact on XtraDB, not InnoDB.

We work around the problem by not attempting to dereference thr
when both BTR_NO_LOCKING_FLAG and BTR_NO_UNDO_LOG_FLAG are set
in the flags. Probably BTR_NO_LOCKING_FLAG alone should suffice.

btr_cur_optimistic_insert(), btr_cur_pessimistic_insert(),
btr_cur_pessimistic_update(): Correct comments that disagree with
usage and with nonnull attributes. No other parameter than thr can
actually be NULL.

row_ins_duplicate_error_in_clust(): Remove an unused parameter.

innobase_is_fake_change(): Unused function; remove.

ibuf_insert_low(), row_log_table_apply(), row_log_apply(),
row_undo_mod_clust_low():
Because we will be passing BTR_NO_LOCKING_FLAG | BTR_NO_UNDO_LOG_FLAG
in the flags, the trx->fake_changes flag will be treated as false,
which is the right thing to do at these low-level operations
(change buffer merge, ALTER TABLE…LOCK=NONE, or ROLLBACK).
This might be fixing actual XtraDB bugs.

Other callers that pass these two flags are also passing thr=NULL,
implying fake_changes=false. (Some callers in ROLLBACK are passing
BTR_NO_LOCKING_FLAG and a nonnull thr. In these callers, fake_changes
better be false, to avoid corruption.)

Post xtradb 5.6.36 merge the output has changed.

This merge reverts commit 6ca4f693c1ce472e2b1bf7392607c2d1124b4293
from current 5.6.36 innodb.

Bug #23481444	OPTIMISER CALL ROW_SEARCH_MVCC() AND READ THE
                       INDEX APPLIED BY UNCOMMITTED ROW
Problem:
========
row_search_for_mysql() does whole table traversal for range query
even though the end range is passed. Whole table traversal happens
when the record is not with in transaction read view.

Solution:
=========

Convert the innodb last record of page to mysql format and compare
with end range if the traversal of row_search_mvcc() exceeds 100,
no ICP involved. If it is out of range then InnoDB can avoid the
whole table traversal. Need to refactor the code little bit to
make it compile.
Reviewed-by: Jimmy Yang <jimmy.yang@oracle.com>
Reviewed-by: Knut Hatlen <knut.hatlen@oracle.com>
Reviewed-by: Dmitry Shulga <dmitry.shulga@oracle.com>
RB: 14660

The parameter path can be passed as NULL.
This error was reported by GCC 7.1.0 when compiling
CMAKE_BUILD_TYPE=Debug with -O3.

This reverts commit 4799af09.

Upstream provided adequate fix. This commit is no longer necessary.

The macro UT_LIST_INIT() zero-initializes the UT_LIST_NODE.
There is no need to call this macro on a buffer that has
already been zero-initialized by mem_zalloc() or mem_heap_zalloc()
or similar.

For some reason, the statement UT_LIST_INIT(srv_sys->tasks) in
srv_init() caused a SIGSEGV on server startup when compiling with
GCC 7.1.0 for AMD64 using -O3. The zero-initialization was attempted
by the instruction movaps %xmm0,0x50(%rax), while the proper offset
of srv_sys->tasks would seem to have been 0x48.

Do not silence uncertain cases, or fix any bugs.

The only functional change should be that ha_federated::extra()
is not calling DBUG_PRINT to report an unhandled case for
HA_EXTRA_PREPARE_FOR_DROP.

When an IN subquery predicate was converted to a semi-join that were
materialized and the result of the materialization happened to be
the last in the execution plan then any conjunctive condition with RAND()
turned out to be lost.

Fixed by attaching this condition to the last top base table.

The feature is too dangerous for a stable version.

Translate "multi:" to SPH_GROUPBY_MULTIPLE.
SPH_GROUPBY_ATTRPAIR is still not supported.

Don't use instal_jar() from Use_Java.cmake -
at least in CentOS 7 (cmake 2.8.12.2) it doesn't yet support
the COMPONENT option.

remove dead code: this "return rc" could've never happened,
because reset_stmt_handle can only possibly fail if RESET_SERVER
flag is used.

But this "return rc" was confusing, it was under DBUG_ENTER (while
not being DBUG_RETURN) and it was skipping required stmt cleanup
at the end of the function.

CSV engine didn't expect CSM files to be read-only

remove useless checks
and a couple of others

bunch of bugs when external_lock() fails on unlock:
* mi_lock_database() used mi_mark_crashed() under share->intern_lock,
  but mi_mark_crashed() itself locks this mutex.
* handler::close() required table to be unlocked, but failed
  external_lock didn't count as unlock
* mysql_unlock_tables() ignored all unlock errors, but they still set
  the error status in stmt_da.

post-review fixes
* move pcre-specific variable out of mysys
* don't use current_thd
* move a commonly used macro to my_sys.h
* remove new sysvar