Suggestion: Don't allow more than 1 consecutive blank line

[nfcampos]

Describe the bug
Currently whitespace around CTEs is preserved sometimes, which for me again isn't desired, but I understand if this is intended and not something you want to change

To Reproduce

with






    line_items as (





        select * from {{ ref("order_line_items__01_with_financials") }}
        
    ),









    gift_cards as (
        
        
        
        select * from {{ ref("gift_cards") }}
    
    
    
    ),







select *
from line_items





union all





select *
from gift_cards

Expected behavior
ie. when new lines exist around CTEs / other things (see the space before union all) then I expect it to be reduced to a single new line. (I personally would even go further and add those single new lines even if they weren't in the input, but I do understand that's probably a minority opinion)

with

    line_items as (

        select * from {{ ref("order_line_items__01_with_financials") }}

    ),

    gift_cards as (select * from {{ ref("gift_cards") }}),

select *
from line_items

union all

select *
from gift_cards

Actual behavior

with
    line_items as (





        select * from {{ ref("order_line_items__01_with_financials") }}

    ),









    gift_cards as (select * from {{ ref("gift_cards") }}),







select *
from line_items





union all
select *
from gift_cards

Additional context
What is the output of sqlfmt --version?
sqlfmt, version 0.10.0

[tconbeer]

Right now we try to leave all blank lines as-is, unless we merge across them. There is a bug I introduced somewhere between 0.8 and 0.10 that eliminates some blank lines for reasons I don't understand (I need to make an issue for that).

I'm not totally comfortable with enforcing a style that is "you can never have more than one consecutive blank line," although in practice I don't think I write queries with more than one blank line in them.

What rule(s) around blank lines should we try to enforce?

[nfcampos]

The opinion of some formatters for other languages

• https://prettier.io/docs/en/rationale.html#empty-lines
• https://black.readthedocs.io/en/stable/the_black_code_style/current_style.html#empty-lines

Both leave empty lines from original format, but collapse them to a standard number of lines (ie. 0 empty lines remain 0, 7 or 6 or 1 empty lines all become eg 1 empty line)

Black goes even further and adds empty lines in some places (which I think you could consider doing eg around CTEs for readability)