Re: BUG #19841: SQL/JSON RETURNING coercion to GUC-dependent types (timestamptz etc.) is wrongly judged IMMUTABLE -

Hi

Thanks for the reports. #19840, #19841 and #19850 come from the same
check in contain_mutable_functions_walker(), so the attached patch
fixes all three.

One interesting thing is that existing indexes using these
expressions will fail on restore and pg_upgrade, like in b58a9a97fe7.

I still lean toward 17 and up with a release note, since those indexes can
already
return wrong results.

Thanks,
Shihao