bug fix: using self-referencing columns in HAVING should not overflow

[systay]

Description

The planner rewrites the HAVING clause in two steps, and in the second part, we were doing the the wrong rewrite, which lead to a cycle in the expression tree. When we then tried to turn the expression back to SQL, we ran into a stack overflow.

Example query that was failing:

select a+2 as a from user having a = 42

Related Issue(s)

Checklist

• "Backport me!" label has been added if this change should be backported
• Tests were added or are not required
• Documentation was added or is not required

[vitess-bot]

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[frouioui]

That looks good to me. It's a good fix!