Clean compilation warning for InnoDB in 5.5.8

[Vadim Tkachenko]

I am having next warnings

/mnt/data/vadim/percona-patches/5.5.8/Percona-Server/storage/innobase/srv/srv0srv.c: In function ‘srv_conc_enter_innodb_timer_based’:
/mnt/data/vadim/percona-patches/5.5.8/Percona-Server/storage/innobase/srv/srv0srv.c:1195: warning: value computed is not used
/mnt/data/vadim/percona-patches/5.5.8/Percona-Server/storage/innobase/srv/srv0srv.c: In function ‘srv_conc_exit_innodb_timer_based’:
/mnt/data/vadim/percona-patches/5.5.8/Percona-Server/storage/innobase/srv/srv0srv.c:1225: warning: value computed is not used
/mnt/data/vadim/percona-patches/5.5.8/Percona-Server/storage/innobase/srv/srv0srv.c: In function ‘srv_conc_force_enter_innodb’:
/mnt/data/vadim/percona-patches/5.5.8/Percona-Server/storage/innobase/srv/srv0srv.c:1434: warning: value computed is not used
/mnt/data/vadim/percona-patches/5.5.8/Percona-Server/storage/innobase/srv/srv0srv.c: In function ‘srv_master_thread’:
/mnt/data/vadim/percona-patches/5.5.8/Percona-Server/storage/innobase/srv/srv0srv.c:2902: warning: ‘n_pages_flushed’ may be used uninitialized in this function

a lot like:
/mnt/data/vadim/percona-patches/5.5.8/Percona-Server/storage/innobase/handler/ha_innodb.cc:11932: warning: type-punning to incomplete type might break strict-aliasing rules
/mnt/data/vadim/percona-patches/5.5.8/Percona-Server/storage/innobase/handler/ha_innodb.cc:11933: warning: type-punning to incomplete type might break strict-aliasing rules

and
[ 35%] Building C object storage/innobase/CMakeFiles/innobase.dir/btr/btr0sea.c.o
/mnt/data/vadim/percona-patches/5.5.8/Percona-Server/storage/innobase/btr/btr0sea.c: In function ‘btr_search_drop_page_hash_index’:
/mnt/data/vadim/percona-patches/5.5.8/Percona-Server/storage/innobase/btr/btr0sea.c:1095: warning: assignment discards qualifiers from pointer target type
[ 35%] Building C object storage/innobase/CMakeFiles/innobase.dir/buf/buf0buddy.c.o
[ 35%] Building C object storage/innobase/CMakeFiles/innobase.dir/buf/buf0buf.c.o
/mnt/data/vadim/percona-patches/5.5.8/Percona-Server/storage/innobase/buf/buf0buf.c: In function ‘_increment_page_get_statistics’:
/mnt/data/vadim/percona-patches/5.5.8/Percona-Server/storage/innobase/buf/buf0buf.c:86: warning: comparison is always false due to limited range of data type
/mnt/data/vadim/percona-patches/5.5.8/Percona-Server/storage/innobase/buf/buf0buf.c: In function ‘buf_pool_init_instance’:
/mnt/data/vadim/percona-patches/5.5.8/Percona-Server/storage/innobase/buf/buf0buf.c:1639: warning: ‘chunk’ may be used uninitialized in this function
[ 36%] Building C object storage/innobase/CMakeFiles/innobase.dir/buf/buf0flu.c.o
[ 36%] Building C object storage/innobase/CMakeFiles/innobase.dir/buf/buf0lru.c.o
/mnt/data/vadim/percona-patches/5.5.8/Percona-Server/storage/innobase/buf/buf0lru.c: In function ‘buf_LRU_file_restore’:
/mnt/data/vadim/percona-patches/5.5.8/Percona-Server/storage/innobase/buf/buf0lru.c:2403: warning: ‘records’ may be used uninitialized in this function

[Yasufumi Kinoshita (yasufumi-kinoshita)]

Only confirmed warnings will be fixed in following.

------------
"warning: value computed is not used"
#################################
Your build should be wrong as intended!
#################################
if HAVE_IB_GCC_ATOMIC_BUILTINS and HAVE_ATOMIC_BUILTINS defined,
os_atomic_increment_lint() should be as __sync_add_and_fetch() GCC internal function.
Basically, there are no value 'computed' in the source code.

Please build correctly.
~~~~~~~~~~~~~~~~~

you should check the startup message at .err file like
"InnoDB: Mutexes and rw_locks use GCC atomic builtins"

------------
"warning: 'n_pages_flushed' may be used uninitialized in this function"
* Confirmed to be introduced by innodb_io_patches.patch

------------
"warning: type-punning to incomplete type might break strict-aliasing rules"
I never meet such warnings.
It may be GCC version specific general warning can be ignored for now.
http://bugs.mysql.com/bug.php?id=42733

------------
"warning: assignment discards qualifiers from pointer target type"
* Confirmed to be introduced by innodb_adaptive_hash_index_partitions.patch

------------
"warning: comparison is always false due to limited range of data type"
buf0buf.c:86: No problem.
unsigned type compared with "< 0".
But avoiding future change to introduce the bug by changing the signement of the data type,
it should be ignored for now.

------------
"warning: ‘chunk’ may be used uninitialized in this function"
* Confirmed to be introduced by innodb_buffer_pool_shm.patch

------------
"warning: ‘records’ may be used uninitialized in this function"
* Confirmed to be introduced by innodb_lru_dump_restore.patch

[Yasufumi Kinoshita (yasufumi-kinoshita)]

Fixed only about "Confirmed" warnings.

[Vadim Tkachenko (vadim-tk)]

Yasufumi,

I still have these

/mnt/data/vadim/percona-patches/5.5.8/Percona-Server/storage/innobase/srv/srv0srv.c: In function ‘srv_conc_enter_innodb_timer_based’:
/mnt/data/vadim/percona-patches/5.5.8/Percona-Server/storage/innobase/srv/srv0srv.c:1195: warning: value computed is not used
/mnt/data/vadim/percona-patches/5.5.8/Percona-Server/storage/innobase/srv/srv0srv.c: In function ‘srv_conc_exit_innodb_timer_based’:
/mnt/data/vadim/percona-patches/5.5.8/Percona-Server/storage/innobase/srv/srv0srv.c:1225: warning: value computed is not used
/mnt/data/vadim/percona-patches/5.5.8/Percona-Server/storage/innobase/srv/srv0srv.c: In function ‘srv_conc_force_enter_innodb’:
/mnt/data/vadim/percona-patches/5.5.8/Percona-Server/storage/innobase/srv/srv0srv.c:1434: warning: value computed is not used

Can we fix them also ?

[Vadim Tkachenko (vadim-tk)]

line 1195 is
os_atomic_increment_lint(&srv_conc_n_threads, -1);
1225 is
os_atomic_increment_lint(&srv_conc_n_threads, -1);

I use gcc (GCC) 4.1.2 20080704 (Red Hat 4.1.2-48) on CentOS 5.5

[Yasufumi Kinoshita (yasufumi-kinoshita)]

Vadim,

I said,
"
you should check the startup message at .err file like
"InnoDB: Mutexes and rw_locks use GCC atomic builtins"
"

How is it?

And,

I meant, it is not MySQL/InnoDB matter.
It is GCC matter of the distribution.

The code is not wrong.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26632
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27825
might be related

[Vadim Tkachenko (vadim-tk)]

I do not have this problem in gcc4.4

I close this bug

[Shahriyar Rzayev (rzayev-sehriyar)]

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PS-454