Bug#12727287: Maintainer mode compilation fails with gcc 4.6 (#trunk)

GCC 4.6 has a new -Wunused-but-set-variable flag, which is enabled
by -Wall, that causes GCC to emit a warning whenever a local variable
is assigned to, but otherwise unused (aside from its declaration).

Since the maintainer mode uses -Wall and -Werror, source code which
triggers these warnings will be rejected. That is, these warnings
become hard errors.

The solution is to fix the code which triggers these specific warnings.
In most of the cases, this is a welcome cleanup as code which triggers
this warning is probably dead anyway.

Author: Davi Arnaut

sql/handler.cc

@@ -5278,7 +5278,7 @@ bool DsMrr_impl::get_disk_sweep_mrr_cost(uint keynr, ha_rows rows, uint flags,
                                          uint *buffer_size, COST_VECT *cost)
 {
   ulong max_buff_entries, elem_size;
-  ha_rows rows_in_full_step, rows_in_last_step;
+  ha_rows rows_in_last_step;
   uint n_full_steps;
   double index_read_cost;
 
@@ -5290,15 +5290,13 @@ bool DsMrr_impl::get_disk_sweep_mrr_cost(uint keynr, ha_rows rows, uint flags,
 
   /* Number of iterations we'll make with full buffer */
   n_full_steps= (uint)floor(rows2double(rows) / max_buff_entries);
-  
-  /* 
-    Get numbers of rows we'll be processing in 
-     - non-last sweep, with full buffer 
-     - last iteration, with non-full buffer
+
+  /*
+    Get numbers of rows we'll be processing in last iteration, with
+    non-full buffer
   */
-  rows_in_full_step= max_buff_entries;
   rows_in_last_step= rows % max_buff_entries;
-  
+
   /* Adjust buffer size if we expect to use only part of the buffer */
   if (n_full_steps)
   {
@@ -5312,11 +5310,11 @@ bool DsMrr_impl::get_disk_sweep_mrr_cost(uint keynr, ha_rows rows, uint flags,
                       (size_t)(1.2*rows_in_last_step) * elem_size + 
                       h->ref_length + table->key_info[keynr].key_length);
   }
-  
+
   COST_VECT last_step_cost;
   get_sort_and_sweep_cost(table, rows_in_last_step, &last_step_cost);
   cost->add(&last_step_cost);
- 
+
   if (n_full_steps != 0)
     cost->mem_cost= *buffer_size;
   else

sql/item_geofunc.cc

@@ -661,7 +661,7 @@ static double distance_points(const Gcalc_heap::Info *a,
 static int calc_distance(double *result, Gcalc_heap *collector, uint obj2_si,
                          Gcalc_function *func, Gcalc_scan_iterator *scan_it)
 {
-  bool above_cur_point, cur_point_edge;
+  bool cur_point_edge;
   const Gcalc_scan_iterator::point *evpos;
   const Gcalc_heap::Info *cur_point, *dist_point;
   Gcalc_scan_events ev;
@@ -670,7 +670,6 @@ static int calc_distance(double *result, Gcalc_heap *collector, uint obj2_si,
 
   DBUG_ENTER("calc_distance");
 
-  above_cur_point= false;
   distance= DBL_MAX;
 
   while (scan_it->more_points())
@@ -781,7 +780,6 @@ static int calc_distance(double *result, Gcalc_heap *collector, uint obj2_si,
 
 int Item_func_spatial_rel::func_touches()
 {
-  bool above_cur_point;
   double x1, x2, y1, y2, ex, ey;
   double distance, area;
   int result= 0;
@@ -836,7 +834,6 @@ int Item_func_spatial_rel::func_touches()
   scan_it.reset();
   scan_it.init(&collector);
 
-  above_cur_point= false;
   distance= DBL_MAX;
 
   while (scan_it.more_trapezoids())
@@ -1677,7 +1674,7 @@ longlong Item_func_srid::val_int()
 
 double Item_func_distance::val_real()
 {
-  bool above_cur_point, cur_point_edge;
+  bool cur_point_edge;
   const Gcalc_scan_iterator::point *evpos;
   const Gcalc_heap::Info *cur_point, *dist_point;
   Gcalc_scan_events ev;
@@ -1724,7 +1721,6 @@ double Item_func_distance::val_real()
   collector.prepare_operation();
   scan_it.init(&collector);
 
-  above_cur_point= false;
   distance= DBL_MAX;
   while (scan_it.more_points())
   {

sql/partition_info.cc

@@ -636,12 +636,11 @@ char *partition_info::find_duplicate_name()
   HASH partition_names;
   uint max_names;
   const uchar *curr_name= NULL;
-  size_t length;
   List_iterator<partition_element> parts_it(partitions);
-  partition_element *p_elem;  
+  partition_element *p_elem;
 
   DBUG_ENTER("partition_info::find_duplicate_name");
-  
+
   /*
     TODO: If table->s->ha_part_data->partition_name_hash.elements is > 0,
     then we could just return NULL, but that has not been verified.
@@ -661,7 +660,6 @@ char *partition_info::find_duplicate_name()
   while ((p_elem= (parts_it++)))
   {
     curr_name= (const uchar*) p_elem->partition_name;
-    length= strlen(p_elem->partition_name);
     if (my_hash_insert(&partition_names, curr_name))
       goto error;
 
@@ -676,7 +674,7 @@ char *partition_info::find_duplicate_name()
           goto error;
       }
     }
-  } 
+  }
   my_hash_free(&partition_names);
   DBUG_RETURN(NULL);
 error:

sql/rpl_info_file.cc

@@ -482,8 +482,9 @@ bool init_dynarray_intvar_from_file(char *buffer, size_t size,
           (decimal size + space) - 1 + `\n' + '\0'
     */
     size_t max_size= (1 + num_items) * (sizeof(long) * 3 + 1) + 1;
-    buf_act= (char*) my_malloc(max_size, MYF(MY_WME));
-    buffer_act= &buf_act;
+    if (! (buf_act= (char*) my_malloc(max_size, MYF(MY_WME))))
+      DBUG_RETURN(TRUE);
+    *buffer_act= buf_act;
     memcpy(buf_act, buf, read_size);
     snd_size= my_b_gets(f, buf_act + read_size, max_size - read_size);
     if (snd_size == 0 ||

sql/sql_load.cc

@@ -1122,12 +1122,9 @@ read_xml_field(THD *thd, COPY_INFO &info, TABLE_LIST *table_list,
   List_iterator_fast<Item> it(fields_vars);
   Item *item;
   TABLE *table= table_list->table;
-  bool no_trans_update_stmt;
   const CHARSET_INFO *cs= read_info.read_charset;
   DBUG_ENTER("read_xml_field");
-  
-  no_trans_update_stmt= !table->file->has_transactions();
-  
+
   for ( ; ; it.rewind())
   {
     if (thd->killed)

sql/sql_select.cc

@@ -3955,7 +3955,7 @@ bool convert_subquery_to_semijoin(JOIN *parent_join,
   st_select_lex *subq_lex= subq_pred->unit->first_select();
   nested_join->join_list.empty();
   List_iterator_fast<TABLE_LIST> li(subq_lex->top_join_list);
-  TABLE_LIST *tl, *last_leaf;
+  TABLE_LIST *tl;
   while ((tl= li++))
   {
     tl->embedding= sj_nest;
@@ -3973,7 +3973,6 @@ bool convert_subquery_to_semijoin(JOIN *parent_join,
   for (tl= parent_lex->leaf_tables; tl->next_leaf; tl= tl->next_leaf)
   {}
   tl->next_leaf= subq_lex->leaf_tables;
-  last_leaf= tl;
 
   /*
     Same as above for next_local chain
@@ -4258,7 +4257,6 @@ bool JOIN::flatten_subqueries()
       DBUG_RETURN(TRUE);
   }
 skip_conversion:
-  bool converted= FALSE;
   /* 
     3. Finalize the subqueries that we did not convert,
        ie. perform IN->EXISTS rewrite.
@@ -4272,7 +4270,6 @@ bool JOIN::flatten_subqueries()
 
     SELECT_LEX *save_select_lex= thd->lex->current_select;
     thd->lex->current_select= (*subq)->unit->first_select();
-    converted= TRUE;
 
     res= (*subq)->select_transformer(child_join);
 
@@ -11822,8 +11819,6 @@ static bool
 make_join_readinfo(JOIN *join, ulonglong options, uint no_jbuf_after)
 {
   const bool statistics= test(!(join->select_options & SELECT_DESCRIBE));
-  uint first_sjm_table= MAX_TABLES;
-  uint last_sjm_table= MAX_TABLES;
 
   /* First table sorted if ORDER or GROUP BY was specified */
   bool sorted= (join->order || join->group_list);
@@ -11857,8 +11852,6 @@ make_join_readinfo(JOIN *join, ulonglong options, uint no_jbuf_after)
     if (sj_is_materialize_strategy(join->best_positions[i].sj_strategy))
     {
       /* This is a start of semi-join nest */
-      first_sjm_table= i;
-      last_sjm_table= i + join->best_positions[i].n_sj_tables;
       if (i == join->const_tables)
         join->first_select= sub_select_sjm;
       else
@@ -16841,7 +16834,7 @@ TABLE *create_duplicate_weedout_tmp_table(THD *thd,
   bool using_unique_constraint=FALSE;
   bool use_packed_rows= FALSE;
   Field *field, *key_field;
-  uint blob_count, null_pack_length, null_count;
+  uint null_pack_length, null_count;
   uchar *null_flags;
   uchar *pos;
   DBUG_ENTER("create_duplicate_weedout_tmp_table");
@@ -16922,8 +16915,6 @@ TABLE *create_duplicate_weedout_tmp_table(THD *thd,
   share->keys_for_keyread.init();
   share->keys_in_use.init();
 
-  blob_count= 0;
-
   /* Create the field */
   {
     /*

storage/innobase/trx/trx0purge.c

@@ -216,7 +216,6 @@ trx_purge_add_update_undo_to_history(
 	trx_rseg_t*	rseg;
 	trx_rsegf_t*	rseg_header;
 	trx_ulogf_t*	undo_header;
-	trx_upagef_t*	page_header;
 
 	undo = trx->update_undo;
 	rseg = undo->rseg;
@@ -226,7 +225,6 @@ trx_purge_add_update_undo_to_history(
 		mtr);
 
 	undo_header = undo_page + undo->hdr_offset;
-	page_header = undo_page + TRX_UNDO_PAGE_HDR;
 
 	if (undo->state != TRX_UNDO_CACHED) {
 		ulint		hist_size;
@@ -559,7 +557,6 @@ trx_purge_rseg_get_next_history_log(
 	const void*	ptr;
 	page_t*		undo_page;
 	trx_ulogf_t*	log_hdr;
-	trx_usegf_t*	seg_hdr;
 	fil_addr_t	prev_log_addr;
 	trx_id_t	trx_no;
 	ibool		del_marks;
@@ -580,7 +577,6 @@ trx_purge_rseg_get_next_history_log(
 		rseg->space, rseg->zip_size, rseg->last_page_no, &mtr);
 
 	log_hdr = undo_page + rseg->last_offset;
-	seg_hdr = undo_page + TRX_UNDO_SEG_HDR;
 
 	/* Increase the purge page count by one for every handled log */
 

storage/innobase/trx/trx0rec.c

@@ -1468,7 +1468,6 @@ trx_undo_prev_version_build(
 	table_id_t	table_id;
 	trx_id_t	trx_id;
 	roll_ptr_t	roll_ptr;
-	roll_ptr_t	old_roll_ptr;
 	upd_t*		update;
 	byte*		ptr;
 	ulint		info_bits;
@@ -1486,7 +1485,6 @@ trx_undo_prev_version_build(
 	ut_a(dict_index_is_clust(index));
 
 	roll_ptr = row_get_rec_roll_ptr(rec, index, offsets);
-	old_roll_ptr = roll_ptr;
 
 	*old_vers = NULL;
 

storage/perfschema/pfs_instr.cc

@@ -1411,12 +1411,10 @@ void aggregate_all_event_names(PFS_single_stat *from_array,
   PFS_single_stat *from;
   PFS_single_stat *from_last;
   PFS_single_stat *to;
-  PFS_single_stat *to_last;
 
   from= from_array;
   from_last= from_array + wait_class_max;
   to= to_array;
-  to_last= to_array + wait_class_max;
 
   for ( ; from < from_last ; from++, to++)
   {
@@ -1435,16 +1433,12 @@ void aggregate_all_event_names(PFS_single_stat *from_array,
   PFS_single_stat *from;
   PFS_single_stat *from_last;
   PFS_single_stat *to_1;
-  PFS_single_stat *to_1_last;
   PFS_single_stat *to_2;
-  PFS_single_stat *to_2_last;
 
   from= from_array;
   from_last= from_array + wait_class_max;
   to_1= to_array_1;
-  to_1_last= to_array_1 + wait_class_max;
   to_2= to_array_2;
-  to_2_last= to_array_2 + wait_class_max;
 
   for ( ; from < from_last ; from++, to_1++, to_2++)
   {
@@ -1463,12 +1457,10 @@ void aggregate_all_stages(PFS_stage_stat *from_array,
   PFS_stage_stat *from;
   PFS_stage_stat *from_last;
   PFS_stage_stat *to;
-  PFS_stage_stat *to_last;
 
   from= from_array;
   from_last= from_array + stage_class_max;
   to= to_array;
-  to_last= to_array + stage_class_max;
 
   for ( ; from < from_last ; from++, to++)
   {
@@ -1486,12 +1478,10 @@ void aggregate_all_statements(PFS_statement_stat *from_array,
   PFS_statement_stat *from;
   PFS_statement_stat *from_last;
   PFS_statement_stat *to;
-  PFS_statement_stat *to_last;
 
   from= from_array;
   from_last= from_array + statement_class_max;
   to= to_array;
-  to_last= to_array + statement_class_max;
 
   for ( ; from < from_last ; from++, to++)
   {

storage/perfschema/unittest/pfs_instr_class-t.cc

@@ -80,10 +80,10 @@ void test_no_registration()
   file_key= register_file_class("FOO", 3, 0);
   ok(file_key == 0, "no file registered");
 
+#ifdef LATER
   PFS_thread fake_thread;
   fake_thread.m_table_share_hash_pins= NULL;
 
-#ifdef LATER
   table= find_or_create_table_share(& fake_thread, false, "foo_db", 6, "foo_table", 9);
   ok(table == NULL, "not created");
   table= find_or_create_table_share(& fake_thread, false, "bar_db", 6, "bar_table", 9);