Incorrect DATE_SUB output in BigQuery

[elongl]

Fully reproducible code snippet

query = "SELECT DATE_SUB(DATE '2008-12-25', INTERVAL 5 DAY) AS five_days_ago;"
opt_query = str(sqlglot.optimizer.optimize(query, dialect="bigquery", rules=[sqlglot.optimizer.qualify.qualify_tables]))
print(str(opt_query))

SELECT DATE_SUB(CAST('2008-12-25' AS DATE), 5, DAY) AS five_days_ago

The output DATE_SUB signature is invalid syntax in BigQuery.

[georgesittas]

You need to specify the output dialect using either transpile or the sql method. Calling str on an ast implicitly generates towards the default sqlglot dialect which does not necessarily follow bq's syntax.