Fix(Trino): Prevent first_value and last_value from being converted (#4661)

* Fix(Trino): Prevent first_value and last_value from being converted to arbitrary

* address pr review comments

Author: MikeWallis42

sqlglot/dialects/presto.py

@@ -392,7 +392,6 @@ class Generator(generator.Generator):
             exp.Encode: lambda self, e: encode_decode_sql(self, e, "TO_UTF8"),
             exp.FileFormatProperty: lambda self, e: f"FORMAT='{e.name.upper()}'",
             exp.First: _first_last_sql,
-            exp.FirstValue: _first_last_sql,
             exp.FromTimeZone: lambda self,
             e: f"WITH_TIMEZONE({self.sql(e, 'this')}, {self.sql(e, 'zone')}) AT TIME ZONE 'UTC'",
             exp.GenerateSeries: sequence_sql,
@@ -403,7 +402,6 @@ class Generator(generator.Generator):
             exp.Initcap: _initcap_sql,
             exp.JSONExtract: lambda self, e: self.jsonextract_sql(e),
             exp.Last: _first_last_sql,
-            exp.LastValue: _first_last_sql,
             exp.LastDay: lambda self, e: self.func("LAST_DAY_OF_MONTH", e.this),
             exp.Lateral: explode_to_unnest_sql,
             exp.Left: left_to_substring_sql,

tests/dialects/test_presto.py

@@ -1083,6 +1083,9 @@ def test_presto(self):
                 "snowflake": "CURRENT_USER()",
             },
         )
+        self.validate_identity(
+            "SELECT id, FIRST_VALUE(is_deleted) OVER (PARTITION BY id) AS first_is_deleted, NTH_VALUE(is_deleted, 2) OVER (PARTITION BY id) AS nth_is_deleted, LAST_VALUE(is_deleted) OVER (PARTITION BY id) AS last_is_deleted FROM my_table"
+        )
 
     def test_encode_decode(self):
         self.validate_identity("FROM_UTF8(x, y)")