Pin that a widening cast of a key does not carry its dependencies

Author: jayzhan211

datafusion/sqllogictest/test_files/functional_dependencies.slt

@@ -401,13 +401,20 @@ SELECT CAST(x AS INT) k, y FROM t_cast GROUP BY CAST(x AS INT), y ORDER BY k, y;
 query error DataFusion error: Error during planning: Column in SELECT must be in GROUP BY or an aggregate function
 SELECT y, count(*) FROM t_cast GROUP BY CAST(x AS INT);
 
+statement ok
+drop table t_cast;
+
 # 6.5 Only the key column itself carries the dependency, even when the cast
-# keeps distinct values distinct. PostgreSQL and DuckDB reject this too.
+# keeps distinct values distinct, like INT to BIGINT. PostgreSQL and DuckDB
+# reject this too.
+statement ok
+CREATE TABLE t_wide (x INT, y VARCHAR, PRIMARY KEY (x)) AS VALUES (1, 'b'), (2, 'a');
+
 query error DataFusion error: Error during planning: Column in SELECT must be in GROUP BY or an aggregate function
-SELECT y, count(*) FROM t_cast GROUP BY CAST(x AS VARCHAR);
+SELECT y, count(*) FROM t_wide GROUP BY CAST(x AS BIGINT);
 
 statement ok
-drop table t_cast;
+drop table t_wide;
 
 # 6.6 The same with `TRY_CAST` over a `UNIQUE NOT NULL` key: 'bad-a' and
 # 'bad-b' both cast to NULL.

docs/source/library-user-guide/upgrading/56.0.0.md

@@ -887,7 +887,7 @@ expression over the key is now rejected, as in PostgreSQL and DuckDB. Group by
 the key column itself instead:
 
 ```sql
--- `id` is the PRIMARY KEY of `t`
+-- `id` is the INT PRIMARY KEY of `t`
 SELECT name FROM t GROUP BY CAST(id AS BIGINT); -- now an error
 SELECT name FROM t GROUP BY id;                 -- ok
 ```