Was very surprised to find that spaces are allowed between the minus and the digits in a literal. Neither rustc nor clippy contains. Only found this because I had a horrible typo in an if test:
fn main() {
// Spaces seem to be OK between the minus and the number.
let x = - 3;
// Which can lead to a hellish typo-bug.
let a = 30;
if a >- 150 {
println!("Not what I expected");
}
}
Is this a known thing? Do you think I should report it as a suggested clippy lint?
There's no ambiguity in terms of how the code gets parsed, so it makes sense that it'd be allowed (bear in mind that - is an operator that applies to the literal, it's not part of the literal).
That said, = and - being right next to each other on the keyboard makes this pretty easy to run into, so I could see a Clippy lint maybe being a good idea!
That's a good point @mrec. I hadn't considered how other languages behave. My excuse is that I cannot remember ever making this error before and it took me over an hour to find it in my actual code.
Consider running rustfmt more often -- I know some people have their editors do it on save -- because it will reformat it to if a > -150 { as one would expect, which should make it easier to notice.
Note that the Rust syntax considers -1i8 as an application of the unary minus operator to an integer literal 1i8 , rather than a single integer literal.
^ from rust reference manual.
Either solution from @scottmcm or @17cupsofcoffee should be fine. Especially having rustfmt enabled in editor for every "save".
Yes, this is the pertinent detail. An expression such as -4 is not a single token but two, and like any two tokens, they can be separated by whitespace. It is somewhat surprising, but negative literals don’t actually exist!
and it took me over an hour to find it in my actual code.