Bug#45288: pb2 returns a lot of compilation warnings on linux

Fix warnings flagged by the new warning option -Wunused-but-set-variable
that was added to GCC 4.6 and that is enabled by -Wunused and -Wall. The
option causes a warning whenever a local variable is assigned to but is
later unused. It also warns about meaningless pointer dereferences.

client/mysql.cc:
  Meaningless pointer dereferences.
client/mysql_upgrade.c:
  Check whether reading from the file succeeded.
extra/comp_err.c:
  Unused.
extra/yassl/src/yassl_imp.cpp:
  Skip instead of reading data that is discarded.
include/my_pthread.h:
  Variable is only used in debug builds.
include/mysys_err.h:
  Add new error messages.
mysys/errors.c:
  Add new error message for permission related functions.
mysys/mf_iocache.c:
  Variable is only checked under THREAD.
mysys/my_copy.c:
  Raise a error if chmod or chown fails.
mysys/my_redel.c:
  Raise a error if chmod or chown fails.
regex/engine.c:
  Use a equivalent variable for the assert.
server-tools/instance-manager/instance_options.cc:
  Unused.
sql/field.cc:
  Unused.
sql/item.cc:
  Unused.
sql/log.cc:
  Do not ignore the return value of freopen: only set buffer if
  reopening succeeds.
  
  Adjust doxygen comment to the right function.
  
  Pass message lenght to log function.
sql/mysqld.cc:
  Do not ignore the return value of freopen: only set buffer if
  reopening succeeds.
sql/partition_info.cc:
  Unused.
sql/slave.cc:
  No need to set pointer to the address of '\0'.
sql/spatial.cc:
  Unused. Left for historical purposes.
sql/sql_acl.cc:
  Unused.
sql/sql_base.cc:
  Pointers are always set to the same variables.
sql/sql_parse.cc:
  End statement if reading fails.
  
  Store the buffer after it has actually been updated.
sql/sql_repl.cc:
  No need to set pointer to the address of '\0'.
sql/sql_show.cc:
  Put variable under the same ifdef block.
sql/udf_example.c:
  Set null pointer flag appropriately.
storage/csv/ha_tina.cc:
  Meaningless dereferences.
storage/example/ha_example.cc:
  Return the error since it's available.
storage/myisam/mi_locking.c:
  Remove unused and dead code.

1 files changed, 7 insertions, 4 deletions

diff --git a/mysys/mf_iocache.c b/mysys/mf_iocache.c
index 1a47982b221..e9b947b04a6 100644
--- a/mysys/mf_iocache.c
+++ b/mysys/mf_iocache.c
@@ -1701,16 +1701,19 @@ int my_block_write(register IO_CACHE *info, const uchar *Buffer, size_t Count,
 #endif
 
 
-int my_b_flush_io_cache(IO_CACHE *info, int need_append_buffer_lock)
+int my_b_flush_io_cache(IO_CACHE *info,
+                        int need_append_buffer_lock __attribute__((unused)))
 {
   size_t length;
-  my_bool append_cache;
   my_off_t pos_in_file;
+  my_bool append_cache= (info->type == SEQ_READ_APPEND);
   DBUG_ENTER("my_b_flush_io_cache");
   DBUG_PRINT("enter", ("cache: 0x%lx", (long) info));
 
-  if (!(append_cache = (info->type == SEQ_READ_APPEND)))
-    need_append_buffer_lock=0;
+#ifdef THREAD
+  if (!append_cache)
+    need_append_buffer_lock= 0;
+#endif
 
   if (info->type == WRITE_CACHE || append_cache)
   {