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.

1 files changed, 36 insertions, 36 deletions

diff --git a/client/mysqlimport.c b/client/mysqlimport.c
index d346cd567e7..404106560c1 100644
--- a/client/mysqlimport.c
+++ b/client/mysqlimport.c
@@ -73,68 +73,68 @@ static struct my_option my_long_options[] =
    0, 0, 0, GET_NO_ARG, NO_ARG, 0, 0, 0, 0, 0, 0},
 #endif
   {"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},
   {"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},
   {"columns", 'c',
    "Use only these columns to import the data to. Give the column names in a comma separated list. This is same as giving columns to LOAD DATA INFILE.",
-   (uchar**) &opt_columns, (uchar**) &opt_columns, 0, GET_STR, REQUIRED_ARG, 0, 0, 0,
+   &opt_columns, &opt_columns, 0, GET_STR, REQUIRED_ARG, 0, 0, 0,
    0, 0, 0},
   {"compress", 'C', "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},
   {"debug",'#', "Output debug log. Often this is 'd:t:o,filename'.", 0, 0, 0,
    GET_STR, OPT_ARG, 0, 0, 0, 0, 0, 0},
   {"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},
-  {"delete", 'd', "First delete all rows from table.", (uchar**) &opt_delete,
-   (uchar**) &opt_delete, 0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
+  {"delete", 'd', "First delete all rows from table.", &opt_delete,
+   &opt_delete, 0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
   {"fields-terminated-by", OPT_FTB,
    "Fields in the input file are terminated by the given string.", 
-   (uchar**) &fields_terminated, (uchar**) &fields_terminated, 0, 
+   &fields_terminated, &fields_terminated, 0, 
    GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
   {"fields-enclosed-by", OPT_ENC,
    "Fields in the import file are enclosed by the given character.", 
-   (uchar**) &enclosed, (uchar**) &enclosed, 0, 
+   &enclosed, &enclosed, 0, 
    GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
   {"fields-optionally-enclosed-by", OPT_O_ENC,
    "Fields in the input file are optionally enclosed by the given character.", 
-   (uchar**) &opt_enclosed, (uchar**) &opt_enclosed, 0, 
+   &opt_enclosed, &opt_enclosed, 0, 
    GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
   {"fields-escaped-by", OPT_ESC, 
    "Fields in the input file are escaped by the given character.",
-   (uchar**) &escaped, (uchar**) &escaped, 0, GET_STR, REQUIRED_ARG, 0, 0, 0, 0,
+   &escaped, &escaped, 0, GET_STR, REQUIRED_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},
   {"help", '?', "Displays this help and exits.", 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, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
+  {"host", 'h', "Connect to host.", &current_host,
+   &current_host, 0, GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
   {"ignore", 'i', "If duplicate unique key was found, keep old row.",
-   (uchar**) &ignore, (uchar**) &ignore, 0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
+   &ignore, &ignore, 0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
   {"ignore-lines", OPT_IGN_LINES, "Ignore first n lines of data infile.",
-   (uchar**) &opt_ignore_lines, (uchar**) &opt_ignore_lines, 0, GET_LL,
+   &opt_ignore_lines, &opt_ignore_lines, 0, GET_LL,
    REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
   {"lines-terminated-by", OPT_LTB, 
    "Lines in the input file are terminated by the given string.",
-   (uchar**) &lines_terminated, (uchar**) &lines_terminated, 0, GET_STR,
+   &lines_terminated, &lines_terminated, 0, GET_STR,
    REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
-  {"local", 'L', "Read all files through the client.", (uchar**) &opt_local_file,
-   (uchar**) &opt_local_file, 0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
+  {"local", 'L', "Read all files through the client.", &opt_local_file,
+   &opt_local_file, 0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
   {"lock-tables", 'l', "Lock all tables for write (this disables threads).",
-    (uchar**) &lock_tables, (uchar**) &lock_tables, 0, GET_BOOL, NO_ARG, 
+    &lock_tables, &lock_tables, 0, GET_BOOL, NO_ARG, 
     0, 0, 0, 0, 0, 0},
   {"low-priority", OPT_LOW_PRIORITY,
-   "Use LOW_PRIORITY when updating the table.", (uchar**) &opt_low_priority,
-   (uchar**) &opt_low_priority, 0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
+   "Use LOW_PRIORITY when updating the table.", &opt_low_priority,
+   &opt_low_priority, 0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
   {"password", 'p',
    "Password to use when connecting to server. If password is not given it's asked from the tty.",
    0, 0, 0, GET_STR, OPT_ARG, 0, 0, 0, 0, 0, 0},
@@ -148,35 +148,35 @@ 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},
   {"replace", 'r', "If duplicate unique key was found, replace old row.",
-   (uchar**) &replace, (uchar**) &replace, 0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
+   &replace, &replace, 0, GET_BOOL, 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', "Be more silent.", (uchar**) &silent, (uchar**) &silent, 0,
+  {"silent", 's', "Be more silent.", &silent, &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>
   {"use-threads", OPT_USE_THREADS,
    "Load files in parallel. The argument is the number "
    "of threads to use for loading data.",
-   (uchar**) &opt_use_threads, (uchar**) &opt_use_threads, 0, 
+   &opt_use_threads, &opt_use_threads, 0, 
    GET_UINT, REQUIRED_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.", (uchar**) &verbose,
-   (uchar**) &verbose, 0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
+  {"verbose", 'v', "Print info about the various stages.", &verbose,
+   &verbose, 0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
   {"version", 'V', "Output version information and exit.", 0, 0, 0, GET_NO_ARG,
    NO_ARG, 0, 0, 0, 0, 0, 0},
   { 0, 0, 0, 0, 0, 0, GET_NO_ARG, NO_ARG, 0, 0, 0, 0, 0, 0}