BUG #8211: Syntax error when creating index on expression

The following bug has been logged on the website:

Bug reference: 8211
Logged by: Andrey Cizov
Email address: acizov(at)gmail(dot)com
PostgreSQL version: 9.2.3
Operating system: Windows
Description:

CREATE INDEX heuristic ON foos (1 / (a + b))

causes:

ERROR: syntax error at or near "1"
LINE 1: CREATE INDEX heuristic ON foos (1 / (a + b))
^

********** Error **********

ERROR: syntax error at or near "1"
SQL state: 42601
Character: 33

While:

CREATE INDEX heuristic ON foos ((1 / (a + b)))

Execution successful