Postgres backend - common table expression as join input is put into parentheses

[lordpretzel]

Postgres does not support putting parentheses around a FROM item and its alias like this:

FROM ((SELECT * FROM "r") AS "f0")

GProM's SQL code generator for Postgres was generating this from for CTEs, e.g.,

WITH "sub" AS (SELECT "id" FROM "student") 
SELECT "x.id" AS "id" FROM "sub" "x" JOIN "sub" "y" ON ("x.id" = "y.id");