Bring back longer lines

[radix]

Since the change to the "heuristics" model of line length limits, I have been unhappy with the line formatting. I can set my max_width to 100, but many lines that are far below that limit get broken up -- often at something like a 1:4 ratio (!) which leads to a huge increase in vertical size of my code.

@nrc commented that "we'll have to see that the demand from users was there" here: #1984 (comment)

so consider this my input into the demand for more flexible configuration.

[nrc]

Since the change to the "heuristics" model of line length limits

This wasn't really a change we've done this since the very early days. What changed is having a single config option rather than 6 or something. Were you configuring them individually before? Is just turning off the heuristics too coarse an option?

[radix]

sorry, I guess my history is a bit off. Yes, I used to have to set several config options to increase various line-limits, but now those are gone.

By "turning off heuristics", do you mean setting use_small_heuristics to false? If so, no, that's kind of the opposite of what I want (as I understand it, it breaks even more lines up). Or did you mean something else? that's the only "heuristic"-related option I saw in Configurations.md

[nrc]

By "turning off heuristics", do you mean setting use_small_heuristics to false?

Yes

I wonder if we need that to be a three-valued option: prefer short lines, use heuristics, and prefer long lines.

[radix]

@nrc that's an interesting idea. Would "prefer long lines" effectively set all heuristic numbers to equal max_width?

[nrc]

Would "prefer long lines" effectively set all heuristic numbers to equal max_width?

Something like that, yes

[radix]

@nrc I would probably be able to put together a PR for that. I can do a WIP tomorrow. The bikeshed would be whether the option name use_small_heuristics should change, and what the values should be called.

[nrc]

That would be great, thank you!

I would probably change the option name to small_heuristics, but I'm not sure what good names for the options might be.

[radix]

I don't think small_heuristics applies that well, with a tri-state value. I'm thinking something like

line_width: minimum | medium | maximum, where minimum is equivalent to current use_small_heuristics: false, medium is equivalent to use_small_heuristics: true, and maximum is the new option for maximizing line length.

However, line_width seems awfully similar to max_width, so I'm not sure that's a great name, but I think it's better than small_heuristics.

[philipc]

minimum isn't a good name for the setting that disables all heuristics, because it's a mix of making some lines longer and some lines shorter.

[philipc]

Does anyone actually use the current use_small_heuristics: false setting?

[radix]

@philipc said on #2299:

@radix That's now cramming long if statements and structs on one line, so I'd probably go with the default heuristics still.

To be honest, I'm not sure if even I want this behavior. I still need to browse through my code formatted with my proposed behavior and see what I think of it. It might be that I still just want more fine-grained options for line-length formatting again... But anyway, I'm blocking on #2446 right now, so I'm trying to fix that.

[radix]

also, thanks for the note about minimum not making sense, I didn't realize that WidthHeuristics::null() returned usize::max_value() for some options!

[nickolay]

I wonder if we need that to be a three-valued option: prefer short lines, use heuristics, and prefer long lines.

Now that there's use_small_heuristics with Possible values: "Default", "Off", "Max", I'm not sure what this issue is about. The options are far from ideal, as:

• "[theMax option is] now cramming long if statements and structs on one line, so I'd probably go with the default heuristics still"
• Off mixes zero-width and max-width settings as noted in use_small_heuristics = false gives a mix of zero width and max width settings #2299

...but it seems like everyone actually just wants better heuristics, and there's a clearer #2636 about that.

[scampi]

The initial request is done through the Max value of the use_small_heuristics option. Discussion for improving the heuristics will take place in the other opened issues listed by @nickolay