MDEV-25362 Incorrect name resolution for subqueries in ON expressions

This patch sets the proper name resolution context for outer references
used in a subquery from an ON clause. Usually this context is more narrow
than the name resolution context of the parent select that were used before
this fix.
This fix revealed another problem that concerned ON expressions used in
from clauses of specifications of derived tables / views / CTEs. The name
resolution outer context for such ON expression must be set to NULL to
prevent name resolution beyond the derived table where it is used.
The solution to resolve this problem applied in sql_derived.cc was provided
by Sergei Petrunia <sergey@mariadb.com>.

The change in sql_parse.cc is not good for 10.4+. A corresponding diff for
10.4+ will be provided in JIRA entry for this bug.

Approved by Oleksandr Byelkin <sanja@mariadb.com>

mysql-test/r/join_outer.result

@@ -2682,4 +2682,44 @@ id	timestamp	modifiedBy	id	REV	REVTYPE	profile_id	id	REV	person_id	id	REV
 12	1294650860266	u62C^Kzx3wH8	8	12	2	2	2	117548	300006	300006	97697
 DROP TABLE t1,t2,t3,t4;
 # end of 10.1 tests
+#
+# MDEV-25362: name resolution for subqueries in ON expressions
+#
+create table t1 (a int, b int);
+create table t2 (c int, d int);
+create table t3 (e int, f int);
+create table t4 (g int, h int);
+explain
+select *
+from
+t1 left join
+(t2
+join
+t3 on
+(t3.f=t1.a)
+) on (t2.c=t1.a );
+ERROR 42S22: Unknown column 't1.a' in 'on clause'
+explain
+select *
+from
+t1 left join
+(t2
+join
+t3 on
+(t3.f=(select max(g) from t4 where t4.h=t1.a))
+) on (t2.c=t1.a );
+ERROR 42S22: Unknown column 't1.a' in 'where clause'
+drop table t1,t2,t3,t4;
+create table t1 (a int);
+insert into t1 values (1),(2);
+create table t2 (b int);
+insert into t2 values (1),(2);
+create table t3 (c int);
+insert into t3 values (1),(2);
+select * from ( select * from t1 left join t2
+on b in (select x from t3 as sq1)
+) as sq2;
+ERROR 42S22: Unknown column 'x' in 'field list'
+drop table t1,t2,t3;
+# end of 10.2 tests
 SET optimizer_switch=@org_optimizer_switch;

mysql-test/r/join_outer_jcl6.result

@@ -2690,6 +2690,46 @@ id	timestamp	modifiedBy	id	REV	REVTYPE	profile_id	id	REV	person_id	id	REV
 12	1294650860266	u62C^Kzx3wH8	8	12	2	2	2	117548	300006	300006	97697
 DROP TABLE t1,t2,t3,t4;
 # end of 10.1 tests
+#
+# MDEV-25362: name resolution for subqueries in ON expressions
+#
+create table t1 (a int, b int);
+create table t2 (c int, d int);
+create table t3 (e int, f int);
+create table t4 (g int, h int);
+explain
+select *
+from
+t1 left join
+(t2
+join
+t3 on
+(t3.f=t1.a)
+) on (t2.c=t1.a );
+ERROR 42S22: Unknown column 't1.a' in 'on clause'
+explain
+select *
+from
+t1 left join
+(t2
+join
+t3 on
+(t3.f=(select max(g) from t4 where t4.h=t1.a))
+) on (t2.c=t1.a );
+ERROR 42S22: Unknown column 't1.a' in 'where clause'
+drop table t1,t2,t3,t4;
+create table t1 (a int);
+insert into t1 values (1),(2);
+create table t2 (b int);
+insert into t2 values (1),(2);
+create table t3 (c int);
+insert into t3 values (1),(2);
+select * from ( select * from t1 left join t2
+on b in (select x from t3 as sq1)
+) as sq2;
+ERROR 42S22: Unknown column 'x' in 'field list'
+drop table t1,t2,t3;
+# end of 10.2 tests
 SET optimizer_switch=@org_optimizer_switch;
 set join_cache_level=default;
 set @@optimizer_switch=@save_optimizer_switch_jcl6;

mysql-test/t/join_outer.test

@@ -2190,4 +2190,54 @@ DROP TABLE t1,t2,t3,t4;
 
 --echo # end of 10.1 tests
 
+--echo #
+--echo # MDEV-25362: name resolution for subqueries in ON expressions
+--echo #
+
+create table t1 (a int, b int);
+create table t2 (c int, d int);
+create table t3 (e int, f int);
+create table t4 (g int, h int);
+
+--error ER_BAD_FIELD_ERROR
+explain
+select *
+from
+  t1 left join
+   (t2
+    join
+    t3 on
+    (t3.f=t1.a)
+   ) on (t2.c=t1.a );
+
+# This must produce an error:
+--error ER_BAD_FIELD_ERROR
+explain
+select *
+from
+  t1 left join
+   (t2
+    join
+    t3 on
+    (t3.f=(select max(g) from t4 where t4.h=t1.a))
+   ) on (t2.c=t1.a );
+
+drop table t1,t2,t3,t4;
+
+create table t1 (a int);
+insert into t1 values (1),(2);
+create table t2 (b int);
+insert into t2 values (1),(2);
+create table t3 (c int);
+insert into t3 values (1),(2);
+
+--error ER_BAD_FIELD_ERROR
+select * from ( select * from t1 left join t2
+                              on b in (select x from t3 as sq1)
+              ) as sq2;
+
+drop table t1,t2,t3;
+
+--echo # end of 10.2 tests
+
 SET optimizer_switch=@org_optimizer_switch;

sql/sql_derived.cc

@@ -562,6 +562,32 @@ bool mysql_derived_init(THD *thd, LEX *lex, TABLE_LIST *derived)
 }
 
 
+/*
+  @brief
+    Prevent name resolution out of context of ON expressions in derived tables
+
+  @param
+    join_list  list of tables used in from list of a derived
+
+  @details
+    The function sets the Name_resolution_context::outer_context to NULL
+    for all ON expressions contexts in the given join list. It does this
+    recursively for all nested joins the list contains.
+*/
+
+static void nullify_outer_context_for_on_clauses(List<TABLE_LIST>& join_list)
+{
+  List_iterator<TABLE_LIST> li(join_list);
+  while (TABLE_LIST *table= li++)
+  {
+    if (table->on_context)
+      table->on_context->outer_context= NULL;
+    if (table->nested_join)
+      nullify_outer_context_for_on_clauses(table->nested_join->join_list);
+  }
+}
+
+
 /*
   Create temporary table structure (but do not fill it)
 
@@ -695,7 +721,12 @@ bool mysql_derived_prepare(THD *thd, LEX *lex, TABLE_LIST *derived)
   /* prevent name resolving out of derived table */
   for (SELECT_LEX *sl= first_select; sl; sl= sl->next_select())
   {
+    // Prevent it for the WHERE clause
     sl->context.outer_context= 0;
+
+    // And for ON clauses, if there are any
+    nullify_outer_context_for_on_clauses(*sl->join_list);
+
     if (!derived->is_with_table_recursive_reference() ||
         (!derived->with->with_anchor && 
          !derived->with->is_with_prepared_anchor()))

sql/sql_parse.cc

@@ -7418,6 +7418,7 @@ mysql_new_select(LEX *lex, bool move_down)
     DBUG_RETURN(1);
   select_lex->select_number= ++thd->lex->stmt_lex->current_select_number;
   select_lex->parent_lex= lex; /* Used in init_query. */
+  Name_resolution_context *curr_context= lex->context_stack.head();
   select_lex->init_query();
   select_lex->init_select();
   lex->nest_level++;
@@ -7448,7 +7449,8 @@ mysql_new_select(LEX *lex, bool move_down)
       By default we assume that it is usual subselect and we have outer name
       resolution context, if no we will assign it to 0 later
     */
-    select_lex->context.outer_context= &select_lex->outer_select()->context;
+
+    select_lex->context.outer_context= curr_context;
   }
   else
   {