From 0f9ddfa9d8bb8d071266bcc63e92813cf18ccd2b Mon Sep 17 00:00:00 2001 From: Davi Arnaut Date: Thu, 10 Jun 2010 17:45:22 -0300 Subject: Bug#42733: Type-punning warnings when compiling MySQL -- strict aliasing violations. One somewhat major source of strict-aliasing violations and related warnings is the SQL_LIST structure. For example, consider its member function `link_in_list` which takes a pointer to pointer of type T (any type) as a pointer to pointer to unsigned char. Dereferencing this pointer, which is done to reset the next field, violates strict-aliasing rules and might cause problems for surrounding code that uses the next field of the object being added to the list. The solution is to use templates to parametrize the SQL_LIST structure in order to deference the pointers with compatible types. As a side bonus, it becomes possible to remove quite a few casts related to acessing data members of SQL_LIST. sql/handler.h: Use the appropriate template type argument. sql/item.cc: Remove now-unnecessary cast. sql/item_subselect.cc: Remove now-unnecessary casts. sql/item_sum.cc: Use the appropriate template type argument. Remove now-unnecessary cast. sql/mysql_priv.h: Move SQL_LIST structure to sql_list.h Use the appropriate template type argument. sql/sp.cc: Remove now-unnecessary casts. sql/sql_delete.cc: Use the appropriate template type argument. Remove now-unnecessary casts. sql/sql_derived.cc: Remove now-unnecessary casts. sql/sql_lex.cc: Remove now-unnecessary casts. sql/sql_lex.h: SQL_LIST now takes a template type argument which must match the type of the elements of the list. Use forward declaration when the type is not available, it is used in pointers anyway. sql/sql_list.h: Rename SQL_LIST to SQL_I_List. The template parameter is the type of object that is stored in the list. sql/sql_olap.cc: Remove now-unnecessary casts. sql/sql_parse.cc: Remove now-unnecessary casts. sql/sql_prepare.cc: Remove now-unnecessary casts. sql/sql_select.cc: Remove now-unnecessary casts. sql/sql_show.cc: Remove now-unnecessary casts. sql/sql_table.cc: Remove now-unnecessary casts. sql/sql_trigger.cc: Remove now-unnecessary casts. sql/sql_union.cc: Remove now-unnecessary casts. sql/sql_update.cc: Remove now-unnecessary casts. sql/sql_view.cc: Remove now-unnecessary casts. sql/sql_yacc.yy: Remove now-unnecessary casts. storage/myisammrg/ha_myisammrg.cc: Remove now-unnecessary casts. --- sql/sql_lex.cc | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-) (limited to 'sql/sql_lex.cc') diff --git a/sql/sql_lex.cc b/sql/sql_lex.cc index a3776f59241..7eb2607147c 100644 --- a/sql/sql_lex.cc +++ b/sql/sql_lex.cc @@ -1641,7 +1641,7 @@ void st_select_lex::init_select() linkage= UNSPECIFIED_TYPE; order_list.elements= 0; order_list.first= 0; - order_list.next= (uchar**) &order_list.first; + order_list.next= &order_list.first; /* Set limit and offset to default values */ select_limit= 0; /* denotes the default limit = HA_POS_ERROR */ offset_limit= 0; /* denotes the default offset = 0 */ @@ -1963,7 +1963,7 @@ uint st_select_lex::get_in_sum_expr() TABLE_LIST* st_select_lex::get_table_list() { - return (TABLE_LIST*) table_list.first; + return table_list.first; } List* st_select_lex::get_item_list() @@ -2020,9 +2020,8 @@ void st_select_lex_unit::print(String *str, enum_query_type query_type) if (fake_select_lex->order_list.elements) { str->append(STRING_WITH_LEN(" order by ")); - fake_select_lex->print_order( - str, - (ORDER *) fake_select_lex->order_list.first, + fake_select_lex->print_order(str, + fake_select_lex->order_list.first, query_type); } fake_select_lex->print_limit(thd, str, query_type); @@ -2667,7 +2666,7 @@ TABLE_LIST *st_lex::unlink_first_table(bool *link_to_local) { select_lex.context.table_list= select_lex.context.first_name_resolution_table= first->next_local; - select_lex.table_list.first= (uchar*) (first->next_local); + select_lex.table_list.first= first->next_local; select_lex.table_list.elements--; //safety first->next_local= 0; /* @@ -2699,7 +2698,7 @@ TABLE_LIST *st_lex::unlink_first_table(bool *link_to_local) void st_lex::first_lists_tables_same() { - TABLE_LIST *first_table= (TABLE_LIST*) select_lex.table_list.first; + TABLE_LIST *first_table= select_lex.table_list.first; if (query_tables != first_table && first_table != 0) { TABLE_LIST *next; @@ -2746,9 +2745,9 @@ void st_lex::link_first_table_back(TABLE_LIST *first, if (link_to_local) { - first->next_local= (TABLE_LIST*) select_lex.table_list.first; + first->next_local= select_lex.table_list.first; select_lex.context.table_list= first; - select_lex.table_list.first= (uchar*) first; + select_lex.table_list.first= first; select_lex.table_list.elements++; //safety } } @@ -2914,7 +2913,7 @@ void st_select_lex::fix_prepare_information(THD *thd, Item **conds, prep_having= *having_conds; *having_conds= having= prep_having->copy_andor_structure(thd); } - fix_prepare_info_in_table_list(thd, (TABLE_LIST *)table_list.first); + fix_prepare_info_in_table_list(thd, table_list.first); } } -- cgit v1.2.1