Bug 549249

Description Mateusz Matela 2019-07-14 08:46:54 EDT

Looking at bug 212867 and its duplicates, I think a good way to solve them is to first make a general change that will allow any blank lines settings to override the "Number of empty lines to preserve" setting and remove empty lines in respecting positions.
It can probably be useful in other situations.

I considered adding a separate twin setting for each blank line setting, but that would be an unnecessary clutter in the API. Another approach would be to reserve a bit in the setting value and use bit masks to extract the number of lines and the line deletion switch. But in the end I chose an even simpler solution: to declare that any negative value means that line deletion is on and the actual number of blank lines is ~x (bitwise negation).

Turns out that one setting in the formatter already had line deletion feature hardcoded in: blank lines between import groups. To be super strict, we should perform profile migration in the next version and change that setting to ~x to keep the old behavior. But I don't think it's very important. It's hard to notice this feature, and turning it off will not affect previously formatted code.