Error parsing complex mathematical expression

[barrywhart]

Input:

SELECT
    COS(2*ACOS(-1)*2*y/53) AS c2
FROM
    t

Output:

$ sqlfluff lint test1.sql
== [test1.sql] FAIL
L:   2 | P:  10 | L006 | Operators should be preceded by a space.
L:   2 | P:  11 | L006 | Operators should be followed by a space.
L:   2 | P:  15 | ???? | Found unparsable segment @L002P015: '(-1)*2*y/53...'
L:   2 | P:  31 | L014 | Inconsistent capitalisation of unquoted identifiers.
L:   4 | P:   5 | L014 | Inconsistent capitalisation of unquoted identifiers.

Interestingly, adding whitespace around the operators also fixes the parsing error. I wonder if two adjacent tokens are being mistakenly parsed as a single token when spaces are missing.

Here's the same SQL with spaces (and no parsing error):

SELECT
    COS(2 * ACOS(-1) * 2 * y / 53) AS c2
FROM
    t

Output:

$ sqlfluff lint test1.sql
== [test1.sql] FAIL
L:   2 | P:  22 | L006 | Operators should be preceded by a space.

I don't know why there's still a warning about needing space around an operator. Can you look into this as well?

[alanmcruickshank]

Sounds like your hunch is very likely. I worry that it might also be related to a change I made in the parsing of negative numbers too. Great to raise this one. I'll pick it up shortly.

I'll also try and post some of my debugging here so you can can get a better feel for how this part of sqlfluff functions. Hopefully it will be useful.

[alanmcruickshank]

Found the issue. The parser was favouring identifiers over functions. That meant it categorised ACOS as an identifier and then got confused about the brackets. I'm pushing up a fix now.