[coreboot] [RFC] Deciding on style for multi-line comments

[Julius Werner]

First of all, let's dispel the notion that there was one "correct" and
one "wrong" comment style in coreboot right now.

If we count the amount of multi-line comments in the concise style

> coreboot $ egrep '^\s*/\* [^/]+$' src/ | wc
> 5230 50584 491997

against the amount of multi-line comments in the verbose style

> coreboot $ egrep '^\s*/\*$' src/ | wc
> 16103   18607  827285

and subtract the counts from the FSF license header from that, which
uses the verbose style and is just copy&pasted into every file

> coreboot $ grep 'FITNESS FOR A PARTICULAR PURPOSE' src/ | wc
> 11857  133958 1424055

we find that the concise style is actually more common in coreboot
right now. I find the idea of overruling thousands of instances of
established practice on behalf of some ancient Wiki text that the
author obviously didn't even read before copy&pasting it in there
kinda ridiculous.

Secondly, Linux cannot even decide for itself which comment style they
prefer (as exemplified by their net/ directory exemption, which they
have maintained for years despite the fact that enforcing different
styles in different parts of the repo is truly crazy), so I don't
think "do what Linux does because Linux is obviously always right"
makes much sense here either. As far as I can tell, they also don't
have any reasonable justification for their decision other than "it's
what Linus (and the net/ maintainer) like". If we really wanted to
blindly follow the Linux way here, we'd have to pick one directory
under coreboot/src/ that arbitrarily enforces a different style than
the others for no reason whatsoever.

Look, I'm not saying that we should only be using the concise style.
I'm just saying that both styles have their valid uses and we
shouldn't be forcing one over the other in every possible case. Yes,
the verbose style separates comments and makes them stand out better,
and sometimes that's a good and desirable thing! If you want to put in
a big explanation that applies to a whole code block or something, it
may well be the better choice.

But in other cases you maybe just want to explain a tricky detail
about a single statement in a way that you can't quite fit it on one
line, and forcing people to waste four lines and disrupt the whole
flow of the reader at a point where this wouldn't make sense is not a
good decision in that case. It would be similar to decreeing something
like "there may be at most three statements in a row without a blank
line in between them"... yes, blank lines often increase readability
and are encouraged by our coding style, but only in places that make
sense in the context of the code. Screen real estate is a real thing
and can make an already complicated piece of code way harder to
understand because you can't fit it all on one screen anymore. We'd be
actively making code less readable by forcing such an inflexible
style.

All I'm saying is that the programmer writing the comment and the
surrounding code probably has a better idea about which amount of
blank space would make it most readable and understandable than some
outdated Wiki page, so this decision should be left to them. We're
writing comments with the explicit intention of helping others
understand our code, after all, so we're naturally going to write them
with the style that works best for each individual case. Forcing the
verbose style everywhere would just cause people to unnecessarily
shorten comments to one line when a big 4+ multi-line comment would be
too disruptive to readability, and thus decrease the overall quality
of our comments.