[FLINK-13284] Correct some builtin functions' return type inference in Blink planner

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.9.0
• Fix Version/s: 1.9.0
• Component/s: Table SQL / Planner
• Labels: pull-request-available
• Assignee: lincoln lee
• Reporter: lincoln lee
• Created: 16/Jul/19 08:24
• Updated: 06/Feb/23 02:59
• Resolved: 22/Jul/19 06:29

Description

Several builtin functions in Blink planner such as 

DATE_FORMAT

declares 

ReturnTypes.cascade(ReturnTypes.explicit(SqlTypeName.VARCHAR), SqlTypeTransforms.TO_NULLABLE)

which should be 

ReturnTypes.cascade(ReturnTypes.explicit(SqlTypeName.VARCHAR), SqlTypeTransforms.FORCE_NULLABLE)

instead.

Issue Links

• links to: GitHub Pull Request #9146