GROUPING SETS syntax incorrect?

[deklanw]

I first noticed this problem when trying to make CVs with GROUPING SETS according to the syntax I saw in the Postgres docs, https://www.postgresql.org/docs/current/queries-table-expressions.html like:

GROUP BY a, CUBE (b, c), GROUPING SETS ((d), (e))

Following along, I put parentheses around the groupings, as above. I got this error with all my queries involving GROUPING SETS:

ERROR: column "_0" has pseudo-type record

Looking at the PipelineDB tests:
https://github.com/pipelinedb/pipelinedb/blob/526a6f4c9a1cc4a054d4efb53cf5c92180979303/src/test/regress/sql/cont_grouping_sets.sql

GROUP BY GROUPING SETS (x), (x, y), (x, y, z), (x, z);

It looks like the outer parentheses are being omitted here. I inserted data into my CV and it definitely isn't working as expected. I'm guessing these are being parsed as records as in https://www.postgresql.org/docs/current/rowtypes.html ?

[huimingxie]

how can fix this bug?