Bug#42733: Type-punning warnings when compiling MySQL --

           strict aliasing violations.

Essentially, the problem is that large parts of the server were
developed in simpler times (last decades, pre C99 standard) when
strict aliasing and compilers supporting such optimizations were
rare to non-existent. Thus, when compiling the server with a modern
compiler that uses strict aliasing rules to perform optimizations,
there are several places in the code that might trigger undefined
behavior.

As evinced by some recent bugs, GCC does a somewhat good of job
misoptimizing such code, but on the other hand also gives warnings
about suspicious code. One problem is that the warnings aren't
always accurate, yet we can't afford to just shut them off as we
might miss real cases. False-positive cases are aggravated mostly
by casts that are likely to trigger undefined behavior.

The solution is to start a cleanup process focused on fixing and
reducing the amount of strict-aliasing related warnings produced
by GCC and others compilers. A good deal of noise reduction can
be achieved by just removing useless casts that are product of
historical cruft and are likely to trigger undefined behavior if
dereferenced.

client/mysql.cc:
  Remove now-unnecessary casts.
  Break up large strings.
client/mysql_upgrade.c:
  Remove now-unnecessary casts.
client/mysqladmin.cc:
  Remove now-unnecessary casts.
  Break up large strings.
client/mysqlbinlog.cc:
  Remove now-unnecessary casts.
client/mysqlcheck.c:
  Remove now-unnecessary casts.
client/mysqldump.c:
  Remove now-unnecessary casts.
client/mysqlimport.c:
  Remove now-unnecessary casts.
client/mysqlshow.c:
  Remove now-unnecessary casts.
client/mysqlslap.c:
  Remove now-unnecessary casts.
client/mysqltest.cc:
  Remove now-unnecessary casts.
extra/comp_err.c:
  Remove now-unnecessary casts.
extra/my_print_defaults.c:
  Remove now-unnecessary casts.
  Break up large strings.
extra/mysql_waitpid.c:
  Remove now-unnecessary casts.
extra/perror.c:
  Remove now-unnecessary casts.
extra/resolve_stack_dump.c:
  Remove now-unnecessary casts.
extra/resolveip.c:
  Remove now-unnecessary casts.
include/my_getopt.h:
  Use a void pointer type as the opaque type to avoid problems with type
  incompatibility -- GCC issues warnings when the type name is not type
  compatible with a operand. As a side bonus, a explicit cast won't be
  necessary anymore.
include/sslopt-longopts.h:
  Remove now-unnecessary casts.
  Break up large strings.
mysys/my_getopt.c:
  Update opaque type and introduce a type definition for the
  argument to my_getopt_register_get_addr.
server-tools/instance-manager/options.cc:
  Remove now-unnecessary casts.
sql/mysqld.cc:
  Remove now-unnecessary casts.
  Break up large strings.
  Update mysql_getopt_value prototype (the old prototype
  was different from the definition anyway).
sql/sql_plugin.cc:
  The type of a pointer to a function must be compatible with the
  pointed-to function type, otherwise the behavior is undefined.
sql/table.cc:
  The variable buf pointer to pointer to pointer to constant char
  could improperly alias a incompatible type in call to fix_type_
  pointers. Since this was actually dead code, it is simply removed.
sql/unireg.cc:
  Remove call to get_form_pos. The code creates a new FRM file which
  is always truncated and writes the form position as 0. Hence, no
  need to retrieve it, we now for sure it is 0.
storage/archive/archive_reader.c:
  Remove now-unnecessary casts.
storage/myisam/ft_nlq_search.c:
  Read weight directly from the buffer.
storage/myisam/fulltext.h:
  Add explanation about the type duality of a key buffer.
  Add accessor macro to retrieve a FT float value.
storage/myisam/mi_test1.c:
  Remove now-unnecessary casts.
storage/myisam/myisam_ftdump.c:
  Read weight directly from the buffer.
storage/myisam/myisamchk.c:
  Remove now-unnecessary casts.
storage/myisam/myisamlog.c:
  A pointer to char was used to alias a pointer to pointer to
  unsigned char, thus violating strict aliasing rules.
storage/myisam/myisampack.c:
  Remove now-unnecessary casts.
strings/decimal.c:
  Remove aliasing violation, printing the value is enough for
  debugging purposes.
tests/mysql_client_test.c:
  Remove now-unnecessary casts.

1 files changed, 29 insertions, 29 deletions

diff --git a/client/mysqlcheck.c b/client/mysqlcheck.c
index d88fa6e46c2..4183ab1dd5e 100644
--- a/client/mysqlcheck.c
+++ b/client/mysqlcheck.c
@@ -54,13 +54,13 @@ static struct my_option my_long_options[] =
 {
   {"all-databases", 'A',
    "Check all the databases. This is the same as --databases with all databases selected.",
-   (uchar**) &opt_alldbs, (uchar**) &opt_alldbs, 0, GET_BOOL, NO_ARG, 0, 0, 0, 0,
+   &opt_alldbs, &opt_alldbs, 0, GET_BOOL, NO_ARG, 0, 0, 0, 0,
    0, 0},
   {"analyze", 'a', "Analyze given tables.", 0, 0, 0, GET_NO_ARG, NO_ARG, 0, 0,
    0, 0, 0, 0},
   {"all-in-1", '1',
    "Instead of issuing one query for each table, use one query per database, naming all tables in the database in a comma-separated list.",
-   (uchar**) &opt_all_in_1, (uchar**) &opt_all_in_1, 0, GET_BOOL, NO_ARG, 0, 0, 0,
+   &opt_all_in_1, &opt_all_in_1, 0, GET_BOOL, NO_ARG, 0, 0, 0,
    0, 0, 0},
 #ifdef __NETWARE__
   {"autoclose", OPT_AUTO_CLOSE, "Automatically close the screen on exit for Netware.",
@@ -68,11 +68,11 @@ static struct my_option my_long_options[] =
 #endif
   {"auto-repair", OPT_AUTO_REPAIR,
    "If a checked table is corrupted, automatically fix it. Repairing will be done after all tables have been checked, if corrupted ones were found.",
-   (uchar**) &opt_auto_repair, (uchar**) &opt_auto_repair, 0, GET_BOOL, NO_ARG, 0,
+   &opt_auto_repair, &opt_auto_repair, 0, GET_BOOL, NO_ARG, 0,
    0, 0, 0, 0, 0},
   {"character-sets-dir", OPT_CHARSETS_DIR,
-   "Directory for character set files.", (uchar**) &charsets_dir,
-   (uchar**) &charsets_dir, 0, GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
+   "Directory for character set files.", &charsets_dir,
+   &charsets_dir, 0, GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
   {"check", 'c', "Check table for errors.", 0, 0, 0, GET_NO_ARG, NO_ARG, 0, 0,
    0, 0, 0, 0},
   {"check-only-changed", 'C',
@@ -82,11 +82,11 @@ static struct my_option my_long_options[] =
    "Check tables for version-dependent changes. May be used with --auto-repair to correct tables requiring version-dependent updates.",
    0, 0, 0, GET_NO_ARG, NO_ARG, 0, 0, 0, 0, 0, 0},
   {"compress", OPT_COMPRESS, "Use compression in server/client protocol.",
-   (uchar**) &opt_compress, (uchar**) &opt_compress, 0, GET_BOOL, NO_ARG, 0, 0, 0,
+   &opt_compress, &opt_compress, 0, GET_BOOL, NO_ARG, 0, 0, 0,
    0, 0, 0},
   {"databases", 'B',
    "Check several databases. Note the difference in usage; in this case no tables are given. All name arguments are regarded as database names.",
-   (uchar**) &opt_databases, (uchar**) &opt_databases, 0, GET_BOOL, NO_ARG,
+   &opt_databases, &opt_databases, 0, GET_BOOL, NO_ARG,
    0, 0, 0, 0, 0, 0},
 #ifdef DBUG_OFF
   {"debug", '#', "This is a non-debug version. Catch this and exit.",
@@ -96,40 +96,40 @@ static struct my_option my_long_options[] =
    0, 0, 0, GET_STR, OPT_ARG, 0, 0, 0, 0, 0, 0},
 #endif
   {"debug-check", OPT_DEBUG_CHECK, "Check memory and open file usage at exit.",
-   (uchar**) &debug_check_flag, (uchar**) &debug_check_flag, 0,
+   &debug_check_flag, &debug_check_flag, 0,
    GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
   {"debug-info", OPT_DEBUG_INFO, "Print some debug info at exit.",
-   (uchar**) &debug_info_flag, (uchar**) &debug_info_flag,
+   &debug_info_flag, &debug_info_flag,
    0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
   {"default-character-set", OPT_DEFAULT_CHARSET,
-   "Set the default character set.", (uchar**) &default_charset,
-   (uchar**) &default_charset, 0, GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
+   "Set the default character set.", &default_charset,
+   &default_charset, 0, GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
   {"fast",'F', "Check only tables that haven't been closed properly.",
-   (uchar**) &opt_fast, (uchar**) &opt_fast, 0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0,
+   &opt_fast, &opt_fast, 0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0,
    0},
   {"fix-db-names", OPT_FIX_DB_NAMES, "Fix database names.",
-    (uchar**) &opt_fix_db_names, (uchar**) &opt_fix_db_names,
+    &opt_fix_db_names, &opt_fix_db_names,
     0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
   {"fix-table-names", OPT_FIX_TABLE_NAMES, "Fix table names.",
-    (uchar**) &opt_fix_table_names, (uchar**) &opt_fix_table_names,
+    &opt_fix_table_names, &opt_fix_table_names,
     0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
   {"force", 'f', "Continue even if we get an SQL error.",
-   (uchar**) &ignore_errors, (uchar**) &ignore_errors, 0, GET_BOOL, NO_ARG, 0, 0,
+   &ignore_errors, &ignore_errors, 0, GET_BOOL, NO_ARG, 0, 0,
    0, 0, 0, 0},
   {"extended", 'e',
    "If you are using this option with CHECK TABLE, it will ensure that the table is 100 percent consistent, but will take a long time. If you are using this option with REPAIR TABLE, it will force using old slow repair with keycache method, instead of much faster repair by sorting.",
-   (uchar**) &opt_extended, (uchar**) &opt_extended, 0, GET_BOOL, NO_ARG, 0, 0, 0,
+   &opt_extended, &opt_extended, 0, GET_BOOL, NO_ARG, 0, 0, 0,
    0, 0, 0},
   {"help", '?', "Display this help message and exit.", 0, 0, 0, GET_NO_ARG,
    NO_ARG, 0, 0, 0, 0, 0, 0},
-  {"host",'h', "Connect to host.", (uchar**) &current_host,
-   (uchar**) &current_host, 0, GET_STR_ALLOC, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
+  {"host",'h', "Connect to host.", &current_host,
+   &current_host, 0, GET_STR_ALLOC, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
   {"medium-check", 'm',
    "Faster than extended-check, but only finds 99.99 percent of all errors. Should be good enough for most cases.",
    0, 0, 0, GET_NO_ARG, NO_ARG, 0, 0, 0, 0, 0, 0},
   {"write-binlog", OPT_WRITE_BINLOG,
    "Log ANALYZE, OPTIMIZE and REPAIR TABLE commands. Enabled by default; use --skip-write-binlog when commands should not be sent to replication slaves.",
-   (uchar**) &opt_write_binlog, (uchar**) &opt_write_binlog, 0, GET_BOOL, NO_ARG,
+   &opt_write_binlog, &opt_write_binlog, 0, GET_BOOL, NO_ARG,
    1, 0, 0, 0, 0, 0},
   {"optimize", 'o', "Optimize table.", 0, 0, 0, GET_NO_ARG, NO_ARG, 0, 0, 0, 0,
    0, 0},
@@ -146,38 +146,38 @@ static struct my_option my_long_options[] =
    "/etc/services, "
 #endif
    "built-in default (" STRINGIFY_ARG(MYSQL_PORT) ").",
-   (uchar**) &opt_mysql_port,
-   (uchar**) &opt_mysql_port, 0, GET_UINT, REQUIRED_ARG, 0, 0, 0, 0, 0,
+   &opt_mysql_port,
+   &opt_mysql_port, 0, GET_UINT, REQUIRED_ARG, 0, 0, 0, 0, 0,
    0},
   {"protocol", OPT_MYSQL_PROTOCOL, "The protocol to use for connection (tcp, socket, pipe, memory).",
    0, 0, 0, GET_STR,  REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
   {"quick", 'q',
    "If you are using this option with CHECK TABLE, it prevents the check from scanning the rows to check for wrong links. This is the fastest check. If you are using this option with REPAIR TABLE, it will try to repair only the index tree. This is the fastest repair method for a table.",
-   (uchar**) &opt_quick, (uchar**) &opt_quick, 0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0,
+   &opt_quick, &opt_quick, 0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0,
    0},
   {"repair", 'r',
    "Can fix almost anything except unique keys that aren't unique.",
    0, 0, 0, GET_NO_ARG, NO_ARG, 0, 0, 0, 0, 0, 0},
 #ifdef HAVE_SMEM
   {"shared-memory-base-name", OPT_SHARED_MEMORY_BASE_NAME,
-   "Base name of shared memory.", (uchar**) &shared_memory_base_name, (uchar**) &shared_memory_base_name,
+   "Base name of shared memory.", &shared_memory_base_name, &shared_memory_base_name,
    0, GET_STR_ALLOC, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
 #endif
-  {"silent", 's', "Print only error messages.", (uchar**) &opt_silent,
-   (uchar**) &opt_silent, 0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
+  {"silent", 's', "Print only error messages.", &opt_silent,
+   &opt_silent, 0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
   {"socket", 'S', "The socket file to use for connection.",
-   (uchar**) &opt_mysql_unix_port, (uchar**) &opt_mysql_unix_port, 0, GET_STR,
+   &opt_mysql_unix_port, &opt_mysql_unix_port, 0, GET_STR,
    REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
 #include <sslopt-longopts.h>
   {"tables", OPT_TABLES, "Overrides option --databases (-B).", 0, 0, 0,
    GET_NO_ARG, NO_ARG, 0, 0, 0, 0, 0, 0},
   {"use-frm", OPT_FRM,
    "When used with REPAIR, get table structure from .frm file, so the table can be repaired even if .MYI header is corrupted.",
-   (uchar**) &opt_frm, (uchar**) &opt_frm, 0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0,
+   &opt_frm, &opt_frm, 0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0,
    0},
 #ifndef DONT_ALLOW_USER_CHANGE
-  {"user", 'u', "User for login if not current user.", (uchar**) &current_user,
-   (uchar**) &current_user, 0, GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
+  {"user", 'u', "User for login if not current user.", &current_user,
+   &current_user, 0, GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
 #endif
   {"verbose", 'v', "Print info about the various stages.", 0, 0, 0, GET_NO_ARG,
    NO_ARG, 0, 0, 0, 0, 0, 0},