[SAOC 2023] dfmt rewrite - Weekly update #11

[Prajwal S N]

Hi all,

This week, I completed the pass that enables support for multiple 
brace styles - users can now configure between Allman, K&R, OTBS, 
and Stroustrup. I also ironed out some weird bugs in the 
formatting logic that showed up during the implementation.

One major feature that is still yet to be implemented in dmdfmt 
(this seems like a nice name, so I'll use it to refer to the 
project going forward) is the ability to preserve comments. The D 
parser does not store comment information apart from doc 
comments, and currently does not provide a way to store it in the 
AST either. I've been scouring the parsing logic and seeing how 
this can be added into the DMD library without breaking the 
existing API. Ideally, this change should not require us to make 
any modifications in the compiler itself, or to users of the DMD 
library. The lexer definitely processes comments and spits out a 
`TOK.comment` token. We just need to figure out how that can be 
stored, and what to do when it is not associated with any other 
AST node (a free-standing comment, like in an empty block that 
does not generate an AST node).