Bug #43414 Parenthesis (and other) warnings compiling MySQL

with gcc 4.3.2
      
This patch fixes a number of GCC warnings about variables used
before initialized. A new macro UNINIT_VAR() is introduced for
use in the variable declaration, and LINT_INIT() usage will be
gradually deprecated. (A workaround is used for g++, pending a
patch for a g++ bug.)
      
GCC warnings for unused results (attribute warn_unused_result)
for a number of system calls (present at least in later
Ubuntus, where the usual void cast trick doesn't work) are
also fixed.


client/mysqlmanager-pwgen.c:
  A fix for warn_unused_result, adding fallback to use of
  srand()/rand() if /dev/random cannot be used. Also actually
  adds calls to rand() in the second branch so that it actually
  creates a random password.

17 files changed, 44 insertions, 83 deletions

diff --git a/sql/field.cc b/sql/field.cc
index 2322c5d7b9d..b61e5fd2d79 100644
--- a/sql/field.cc
+++ b/sql/field.cc
@@ -1736,16 +1736,16 @@ int Field_decimal::store(const char *from, uint len, CHARSET_INFO *cs)
     Pointers used when digits move from the left of the '.' to the
     right of the '.' (explained below)
   */
-  const char *int_digits_tail_from;
+  const char *UNINIT_VAR(int_digits_tail_from);
   /* Number of 0 that need to be added at the left of the '.' (1E3: 3 zeros) */
-  uint int_digits_added_zeros;
+  uint UNINIT_VAR(int_digits_added_zeros);
   /*
     Pointer used when digits move from the right of the '.' to the left
     of the '.'
   */
-  const char *frac_digits_head_end;
+  const char *UNINIT_VAR(frac_digits_head_end);
   /* Number of 0 that need to be added at the right of the '.' (for 1E-3) */
-  uint frac_digits_added_zeros;
+  uint UNINIT_VAR(frac_digits_added_zeros);
   char *pos,*tmp_left_pos,*tmp_right_pos;
   /* Pointers that are used as limits (begin and end of the field buffer) */
   char *left_wall,*right_wall;
@@ -1756,11 +1756,6 @@ int Field_decimal::store(const char *from, uint len, CHARSET_INFO *cs)
   */
   bool is_cuted_fields_incr=0;
 
-  LINT_INIT(int_digits_tail_from);
-  LINT_INIT(int_digits_added_zeros);
-  LINT_INIT(frac_digits_head_end);
-  LINT_INIT(frac_digits_added_zeros);
-
   /*
     There are three steps in this function :
     - parse the input string
@@ -8854,10 +8849,8 @@ Field *make_field(char *ptr, uint32 field_length,
 		  const char *field_name,
 		  struct st_table *table)
 {
-  uchar *bit_ptr;
-  uchar bit_offset;
-  LINT_INIT(bit_ptr);
-  LINT_INIT(bit_offset);
+  uchar *UNINIT_VAR(bit_ptr);
+  uchar UNINIT_VAR(bit_offset);
   if (field_type == FIELD_TYPE_BIT && !f_bit_as_char(pack_flag))
   {
     bit_ptr= null_pos;
diff --git a/sql/ha_myisammrg.cc b/sql/ha_myisammrg.cc
index fef2e21d271..7983ffbc6c8 100644
--- a/sql/ha_myisammrg.cc
+++ b/sql/ha_myisammrg.cc
@@ -78,7 +78,7 @@ static void split_file_name(const char *file_name,
 
 extern "C" void myrg_print_wrong_table(const char *table_name)
 {
-  LEX_STRING db, name;
+  LEX_STRING db= {NULL, 0}, name;
   char buf[FN_REFLEN];
   split_file_name(table_name, &db, &name);
   memcpy(buf, db.str, db.length);
diff --git a/sql/item.cc b/sql/item.cc
index eecb48aa16f..03d752a85d9 100644
--- a/sql/item.cc
+++ b/sql/item.cc
@@ -1635,7 +1635,7 @@ bool agg_item_collations_for_comparison(DTCollation &c, const char *fname,
 bool agg_item_set_converter(DTCollation &coll, const char *fname,
                             Item **args, uint nargs, uint flags, int item_sep)
 {
-  Item **arg, *safe_args[2];
+  Item **arg, *safe_args[2]= {NULL, NULL};
 
   /*
     For better error reporting: save the first and the second argument.
@@ -1644,8 +1644,6 @@ bool agg_item_set_converter(DTCollation &coll, const char *fname,
       doesn't display each argument's characteristics.
     - if nargs is 1, then this error cannot happen.
   */
-  LINT_INIT(safe_args[0]);
-  LINT_INIT(safe_args[1]);
   if (nargs >=2 && nargs <= 3)
   {
     safe_args[0]= args[0];
@@ -5122,9 +5120,8 @@ bool Item_null::send(Protocol *protocol, String *packet)
 
 bool Item::send(Protocol *protocol, String *buffer)
 {
-  bool result;
+  bool UNINIT_VAR(result);                       // Will be set if null_value == 0
   enum_field_types f_type;
-  LINT_INIT(result);                     // Will be set if null_value == 0
 
   switch ((f_type=field_type())) {
   default:
diff --git a/sql/item_cmpfunc.cc b/sql/item_cmpfunc.cc
index c940c4ab3c0..8c655cdc369 100644
--- a/sql/item_cmpfunc.cc
+++ b/sql/item_cmpfunc.cc
@@ -352,8 +352,7 @@ static bool convert_constant_item(THD *thd, Item_field *field_item,
     /* For comparison purposes allow invalid dates like 2000-01-32 */
     ulong orig_sql_mode= thd->variables.sql_mode;
     enum_check_fields orig_count_cuted_fields= thd->count_cuted_fields;
-    ulonglong orig_field_val; /* original field value if valid */
-    LINT_INIT(orig_field_val);
+    ulonglong UNINIT_VAR(orig_field_val); /* original field value if valid */
     thd->variables.sql_mode= (orig_sql_mode & ~MODE_NO_ZERO_DATE) | 
                              MODE_INVALID_DATES;
     thd->count_cuted_fields= CHECK_FIELD_IGNORE;
@@ -2453,19 +2452,13 @@ Item_func_nullif::is_null()
 
 Item *Item_func_case::find_item(String *str)
 {
-  String *first_expr_str, *tmp;
-  my_decimal *first_expr_dec, first_expr_dec_val;
-  longlong first_expr_int;
-  double   first_expr_real;
+  String *UNINIT_VAR(first_expr_str), *tmp;
+  my_decimal *UNINIT_VAR(first_expr_dec), first_expr_dec_val;
+  longlong UNINIT_VAR(first_expr_int);
+  double   UNINIT_VAR(first_expr_real);
   char buff[MAX_FIELD_WIDTH];
   String buff_str(buff,sizeof(buff),default_charset());
 
-  /* These will be initialized later */
-  LINT_INIT(first_expr_str);
-  LINT_INIT(first_expr_int);
-  LINT_INIT(first_expr_real);
-  LINT_INIT(first_expr_dec);
-
   if (first_expr_num != -1)
   {
     switch (cmp_type)
diff --git a/sql/item_create.cc b/sql/item_create.cc
index c897b7aef79..cbd015f300b 100644
--- a/sql/item_create.cc
+++ b/sql/item_create.cc
@@ -451,10 +451,9 @@ Item *create_func_cast(Item *a, Cast_target cast_type,
                        const char *c_len, const char *c_dec,
 		       CHARSET_INFO *cs)
 {
-  Item *res;
+  Item *UNINIT_VAR(res);
   ulong len;
   uint dec;
-  LINT_INIT(res);
 
   switch (cast_type) {
   case ITEM_CAST_BINARY: 	res= new Item_func_binary(a); break;
@@ -542,6 +541,9 @@ Item *create_func_cast(Item *a, Cast_target cast_type,
     res= new Item_char_typecast(a, len, cs ? cs : 
 				current_thd->variables.collation_connection);
     break;
+    
+  default:
+    DBUG_ASSERT(0);
   }
   return res;
 }
diff --git a/sql/item_func.cc b/sql/item_func.cc
index 6193ab285f2..3c1e2126008 100644
--- a/sql/item_func.cc
+++ b/sql/item_func.cc
@@ -2275,9 +2275,8 @@ void Item_func_min_max::fix_length_and_dec()
 
 uint Item_func_min_max::cmp_datetimes(ulonglong *value)
 {
-  longlong min_max;
+  longlong UNINIT_VAR(min_max);
   uint min_max_idx= 0;
-  LINT_INIT(min_max);
 
   for (uint i=0; i < arg_count ; i++)
   {
@@ -2345,8 +2344,7 @@ String *Item_func_min_max::val_str(String *str)
   }
   case STRING_RESULT:
   {
-    String *res;
-    LINT_INIT(res);
+    String *UNINIT_VAR(res);
     for (uint i=0; i < arg_count ; i++)
     {
       if (i == 0)
@@ -2435,8 +2433,7 @@ longlong Item_func_min_max::val_int()
 my_decimal *Item_func_min_max::val_decimal(my_decimal *dec)
 {
   DBUG_ASSERT(fixed == 1);
-  my_decimal tmp_buf, *tmp, *res;
-  LINT_INIT(res);
+  my_decimal tmp_buf, *tmp, *UNINIT_VAR(res);
 
   if (compare_as_dates)
   {
@@ -4974,8 +4971,7 @@ void Item_func_match::init_search(bool no_order)
 bool Item_func_match::fix_fields(THD *thd, Item **ref)
 {
   DBUG_ASSERT(fixed == 0);
-  Item *item;
-  LINT_INIT(item);				// Safe as arg_count is > 1
+  Item *UNINIT_VAR(item);                        // Safe as arg_count is > 1
 
   maybe_null=1;
   join_key=0;
diff --git a/sql/lock.cc b/sql/lock.cc
index 3102497576f..97abd76b7c2 100644
--- a/sql/lock.cc
+++ b/sql/lock.cc
@@ -1216,11 +1216,10 @@ void unlock_global_read_lock(THD *thd)
 bool wait_if_global_read_lock(THD *thd, bool abort_on_refresh,
                               bool is_not_commit)
 {
-  const char *old_message;
+  const char *UNINIT_VAR(old_message);
   bool result= 0, need_exit_cond;
   DBUG_ENTER("wait_if_global_read_lock");
 
-  LINT_INIT(old_message);
   /*
     Assert that we do not own LOCK_open. If we would own it, other
     threads could not close their tables. This would make a pretty
diff --git a/sql/log.cc b/sql/log.cc
index ec8f5fe820b..c042651216c 100644
--- a/sql/log.cc
+++ b/sql/log.cc
@@ -2635,9 +2635,10 @@ bool flush_error_log()
     else
      result= 1;
 #else
+   FILE *reopen;
    my_rename(log_error_file,err_renamed,MYF(0));
    if (freopen(log_error_file,"a+",stdout))
-     freopen(log_error_file,"a+",stderr);
+       reopen= freopen(log_error_file,"a+",stderr);
    else
      result= 1;
 #endif
diff --git a/sql/opt_range.cc b/sql/opt_range.cc
index 778fc418392..fdf6cc03a44 100644
--- a/sql/opt_range.cc
+++ b/sql/opt_range.cc
@@ -3514,11 +3514,10 @@ static TRP_RANGE *get_key_scans_params(PARAM *param, SEL_TREE *tree,
 {
   int idx;
   SEL_ARG **key,**end, **key_to_read= NULL;
-  ha_rows best_records;
+  ha_rows UNINIT_VAR(best_records);              /* protected by key_to_read */
   TRP_RANGE* read_plan= NULL;
   bool pk_is_clustered= param->table->file->primary_key_is_clustered();
   DBUG_ENTER("get_key_scans_params");
-  LINT_INIT(best_records); /* protected by key_to_read */
   /*
     Note that there may be trees that have type SEL_TREE::KEY but contain no
     key reads at all, e.g. tree for expression "key1 is not null" where key1
@@ -5370,8 +5369,7 @@ static bool eq_tree(SEL_ARG* a,SEL_ARG *b)
 SEL_ARG *
 SEL_ARG::insert(SEL_ARG *key)
 {
-  SEL_ARG *element,**par,*last_element;
-  LINT_INIT(par); LINT_INIT(last_element);
+  SEL_ARG *element,**UNINIT_VAR(par),*UNINIT_VAR(last_element);
 
   for (element= this; element != &null_element ; )
   {
@@ -7918,7 +7916,9 @@ get_best_group_min_max(PARAM *param, SEL_TREE *tree)
         goto next_index;
     }
     else
+    {
       DBUG_ASSERT(FALSE);
+    }
 
     /* Check (SA2). */
     if (min_max_arg_item)
diff --git a/sql/spatial.cc b/sql/spatial.cc
index 80506f16d0f..6e1da589527 100644
--- a/sql/spatial.cc
+++ b/sql/spatial.cc
@@ -935,13 +935,10 @@ int Gis_polygon::interior_ring_n(uint32 num, String *result) const
 int Gis_polygon::centroid_xy(double *x, double *y) const
 {
   uint32 n_linear_rings;
-  double res_area;
-  double res_cx, res_cy;
+  double UNINIT_VAR(res_area);
+  double UNINIT_VAR(res_cx), UNINIT_VAR(res_cy);
   const char *data= m_data;
   bool first_loop= 1;
-  LINT_INIT(res_area);
-  LINT_INIT(res_cx);
-  LINT_INIT(res_cy);
 
   if (no_data(data, 4))
     return 1;
@@ -1634,14 +1631,10 @@ int Gis_multi_polygon::centroid(String *result) const
   uint32 n_polygons;
   bool first_loop= 1;
   Gis_polygon p;
-  double res_area, res_cx, res_cy;
+  double UNINIT_VAR(res_area), UNINIT_VAR(res_cx), UNINIT_VAR(res_cy);
   double cur_area, cur_cx, cur_cy;
   const char *data= m_data;
 
-  LINT_INIT(res_area);
-  LINT_INIT(res_cx);
-  LINT_INIT(res_cy);
-
   if (no_data(data, 4))
     return 1;
   n_polygons= uint4korr(data);
diff --git a/sql/sql_acl.cc b/sql/sql_acl.cc
index ab4e518d5dd..ea17a4227ef 100644
--- a/sql/sql_acl.cc
+++ b/sql/sql_acl.cc
@@ -5067,17 +5067,13 @@ static int handle_grant_struct(uint struct_no, bool drop,
   uint elements;
   const char *user;
   const char *host;
-  ACL_USER *acl_user;
-  ACL_DB *acl_db;
-  GRANT_NAME *grant_name;
+  ACL_USER *UNINIT_VAR(acl_user);
+  ACL_DB *UNINIT_VAR(acl_db);
+  GRANT_NAME *UNINIT_VAR(grant_name);
   DBUG_ENTER("handle_grant_struct");
   DBUG_PRINT("info",("scan struct: %u  search: '%s'@'%s'",
                      struct_no, user_from->user.str, user_from->host.str));
 
-  LINT_INIT(acl_user);
-  LINT_INIT(acl_db);
-  LINT_INIT(grant_name);
-
   safe_mutex_assert_owner(&acl_cache->lock);
 
   /* Get the number of elements in the in-memory structure. */
diff --git a/sql/sql_base.cc b/sql/sql_base.cc
index 6a99d5d1541..db4ab29d6de 100644
--- a/sql/sql_base.cc
+++ b/sql/sql_base.cc
@@ -706,7 +706,7 @@ void close_temporary_tables(THD *thd)
     return;
   }
 
-  TABLE *next,
+  TABLE *UNINIT_VAR(next),
     *prev_table /* prev link is not maintained in TABLE's double-linked list */;
   bool was_quote_show= true; /* to assume thd->options has OPTION_QUOTE_SHOW_CREATE */
   // Better add "if exists", in case a RESET MASTER has been done
@@ -716,7 +716,6 @@ void close_temporary_tables(THD *thd)
   memcpy(buf, stub, stub_len);
   String s_query= String(buf, sizeof(buf), system_charset_info);
   bool found_user_tables= false;
-  LINT_INIT(next);
 
   /*
      insertion sort of temp tables by pseudo_thread_id to build ordered list
@@ -4142,8 +4141,7 @@ find_item_in_list(Item *find, List<Item> &items, uint *counter,
     (and not an item that happens to have a name).
   */
   bool is_ref_by_name= 0;
-  uint unaliased_counter;
-  LINT_INIT(unaliased_counter);                 // Dependent on found_unaliased
+  uint UNINIT_VAR(unaliased_counter);           // Dependent on found_unaliased
 
   *resolution= NOT_RESOLVED;
 
diff --git a/sql/sql_parse.cc b/sql/sql_parse.cc
index 45f70964f50..65b2a9d60b0 100644
--- a/sql/sql_parse.cc
+++ b/sql/sql_parse.cc
@@ -1325,7 +1325,7 @@ pthread_handler_t handle_bootstrap(void *arg)
   thd->init_for_queries();
   while (fgets(buff, thd->net.max_packet, file))
   {
-    char *query;
+    char *query, *res;
    ulong length= (ulong) strlen(buff);
    while (buff[length-1] != '\n' && !feof(file))
    {
@@ -1340,7 +1340,7 @@ pthread_handler_t handle_bootstrap(void *arg)
        break;
      }
      buff= (char*) thd->net.buff;
-     fgets(buff + length, thd->net.max_packet - length, file);
+     res= fgets(buff + length, thd->net.max_packet - length, file);
      length+= (ulong) strlen(buff + length);
    }
    if (thd->is_fatal_error)
diff --git a/sql/sql_prepare.cc b/sql/sql_prepare.cc
index d14f14b526e..06f77f9689c 100644
--- a/sql/sql_prepare.cc
+++ b/sql/sql_prepare.cc
@@ -2072,10 +2072,9 @@ void mysql_sql_stmt_prepare(THD *thd)
   LEX_STRING *name= &lex->prepared_stmt_name;
   Prepared_statement *stmt;
   const char *query;
-  uint query_len;
+  uint UNINIT_VAR(query_len);
   DBUG_ENTER("mysql_sql_stmt_prepare");
   DBUG_ASSERT(thd->protocol == &thd->protocol_simple);
-  LINT_INIT(query_len);
 
   if ((stmt= (Prepared_statement*) thd->stmt_map.find_by_name(name)))
   {
diff --git a/sql/sql_show.cc b/sql/sql_show.cc
index 9eac750c22e..13045280c5f 100644
--- a/sql/sql_show.cc
+++ b/sql/sql_show.cc
@@ -2172,8 +2172,8 @@ int get_all_tables(THD *thd, TABLE_LIST *tables, COND *cond)
   ST_SCHEMA_TABLE *schema_table= tables->schema_table;
   SELECT_LEX sel;
   INDEX_FIELD_VALUES idx_field_vals;
-  char path[FN_REFLEN], *end, *base_name, *orig_base_name, *file_name;
-  uint len;
+  char path[FN_REFLEN], *UNINIT_VAR(end), *base_name, *orig_base_name, *file_name;
+  uint UNINIT_VAR(len);
   bool with_i_schema;
   enum enum_schema_tables schema_table_idx;
   List<char> bases;
@@ -2190,9 +2190,6 @@ int get_all_tables(THD *thd, TABLE_LIST *tables, COND *cond)
 #endif
   DBUG_ENTER("get_all_tables");
 
-  LINT_INIT(end);
-  LINT_INIT(len);
-
   lex->view_prepare_mode= TRUE;
   lex->reset_n_backup_query_tables_list(&query_tables_list_backup);
 
diff --git a/sql/sql_update.cc b/sql/sql_update.cc
index c18c34fc1d1..06d1bcaa8fb 100644
--- a/sql/sql_update.cc
+++ b/sql/sql_update.cc
@@ -125,7 +125,7 @@ int mysql_update(THD *thd,
   uint		want_privilege;
 #endif
   uint          table_count= 0;
-  query_id_t	query_id=thd->query_id, timestamp_query_id;
+  query_id_t	query_id=thd->query_id, UNINIT_VAR(timestamp_query_id);
   ha_rows	updated, found;
   key_map	old_used_keys;
   TABLE		*table;
@@ -137,8 +137,6 @@ int mysql_update(THD *thd,
   THD::killed_state killed_status= THD::NOT_KILLED;
   DBUG_ENTER("mysql_update");
 
-  LINT_INIT(timestamp_query_id);
-
   for ( ; ; )
   {
     if (open_tables(thd, &table_list, &table_count, 0))
diff --git a/sql/sql_view.cc b/sql/sql_view.cc
index 96077aeeb12..8cf25e9d88c 100644
--- a/sql/sql_view.cc
+++ b/sql/sql_view.cc
@@ -955,7 +955,7 @@ bool mysql_make_view(THD *thd, File_parser *parser, TABLE_LIST *table,
   TABLE_LIST *top_view= table->top_table();
   int res;
   bool result, view_is_mergeable;
-  TABLE_LIST *view_main_select_tables;
+  TABLE_LIST *UNINIT_VAR(view_main_select_tables);
   DBUG_ENTER("mysql_make_view");
   DBUG_PRINT("info", ("table: 0x%lx (%s)", (ulong) table, table->table_name));
 
@@ -1218,7 +1218,6 @@ bool mysql_make_view(THD *thd, File_parser *parser, TABLE_LIST *table,
 
     view_is_mergeable= (table->algorithm != VIEW_ALGORITHM_TMPTABLE &&
                         lex->can_be_merged());
-    LINT_INIT(view_main_select_tables);
 
     if (view_is_mergeable)
     {