Whitespace for negative integers

[johnthagen]

The style guide currently says Use spaces around binary operators, but what about when - is used as a negation "operator"?

Should it be:

fn main() {
    let x = -1;

    let name = match x {
        -1 => "negative one",
        _ => "other",
    };
}

Or:

fn main() {
    let x = - 1;

    let name = match x {
        - 1 => "negative one",
        _ => "other",
    };
}

Sorry if this is trivially obvious, but I couldn't find it explicitly listed. intellij-rust currently formats the match arm to - 1 like in the bottom example, but I didn't want to report a bug unless I could verify that the first example is indeed what the Rust style guide is preferring.

[regexident]

For the sake of making it easier to "vote":

-1 (no space)

[regexident]

- 1 (space)

[joshtriplett]

@regexident

Sorry if this is trivially obvious, but I couldn't find it explicitly listed.

The style guide currently says "Do not include a space between a unary op and its operand". That applies to the negation operator, too.

I don't think we should change that.

However, if you think some clarification in the style guide's description of unary operators would make it clearer, please feel free to send a PR for that.

[johnthagen]

@joshtriplett Thanks for the info, I had missed that. I think the problem was more a problem of finding the most up-to-date style guide. If you Google "rust style guide":

• First hit https://aturon.github.io/ (old)
• Second hit https://github.com/rust-lang/rust-guidelines (old)
  • This has a link to a rendered: https://doc.rust-lang.org/1.12.0/style/README.html (also old)
  • Third link: https://github.com/rust-lang-nursery/fmt-rfcs (new, but not the actual style guide)
    • If you know to navigate to guide/guide.md then you find the most up-to-date style guide

Now that I've found the current authoritative style guide, I think this issue can be closed, but maybe we could link the guide/guide.md from this repos README to make it a little easier to navigate to. I'll open PRs on the other old projects to try to get people directed to this repo a little easier.

[joshtriplett]

@johnthagen Good idea. Just submitted #46 for that.

[nrc]

Seems clear to me that unary minus is a unary operator and therefore should have to space. I'll leave this open (and FCPed) in case anyone objects, but I expect to close this soon (I believe the style guide does not need further amendment).

[joshtriplett]

Agreed. I wanted to make sure nothing made this unclear in the style guide, but it sounds like the problem in this case arose from "which style guide?".

(Also, I assume you meant "should have no space"?)

[johnthagen]

@nrc @joshtriplett Agreed this can be closed. Thanks all!

For reference I also opened the following:

• Link to new fmt-rfcs repo aturon/aturon.github.io#6
• Remove link to old style guide rust-guidelines#55