[FLINK-26053] Fix parser generator warnings

• Type: Sub-task
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.15.0
• Component/s: Table SQL / API
• Labels: pull-request-available
• Release Note: STATEMENT is a reserved keyword now. Use backticks to escape tables, fields and other references.
• Assignee: Francesco Guardiani
• Reporter: Francesco Guardiani
• Created: 09/Feb/22 12:25
• Updated: 28/Feb/22 13:18
• Resolved: 28/Feb/22 13:18

Description

When building flink-sql-parser, the javacc logs a couple of warnings:

Warning: Choice conflict in [...] construct at line 2920, column 5.
         Expansion nested within construct and expansion following construct
         have common prefixes, one of which is: "PLAN"
         Consider using a lookahead of 2 or more for nested expansion.
Warning: Choice conflict involving two expansions at
         line 2930, column 9 and line 2932, column 9 respectively.
         A common prefix is: "STATEMENT"
         Consider using a lookahead of 2 for earlier expansion.
Warning: Choice conflict involving two expansions at
         line 2952, column 9 and line 2954, column 9 respectively.
         A common prefix is: "STATEMENT"
         Consider using a lookahead of 2 for earlier expansion.

Took from https://dev.azure.com/apache-flink/apache-flink/_build/results?buildId=30871&view=logs&j=0c940707-2659-5648-cbe6-a1ad63045f0a&t=075c2716-8010-5565-fe08-3c4bb45824a4&l=3911

We should investigate them, as they're often symptom of some bug in our parser template, which might result in unexpected parsing errors.

Issue Links

• links to: GitHub Pull Request #18764