[BUG] Rust format might break ranges in specific cases

[PaulDotSH]

In this code snippet

        self.coords.x -= rng.gen_range(-self.radius / 2. .. self.radius / 2.);

Running rust format will change this code to

        self.coords.x -= rng.gen_range(-self.radius / 2...self.radius / 2.);

Which will make rustc unable to compile the file because 2...X is not a valid syntax for ranges, however having the space lets rustc know that 2 is supposed to be a float and the dots represent a range.

Proposed fix:
Either do not remove the spaces in this case, or add a 0 in the case of floats.

[ytmimi]

Thanks for the report!

There's currently a proposal to add an option to rustfmt to always add 0 to the end of float literals (#5834). We've also had similar issues in the past (#5791 for example and #4808 is similarly related), and in those cases we resolved the issue by wrapping the item with the trialing . in parenthesis. We might need to do the same thing here.

In the meantime it probably makes sense to manually add a 0 to work around this issue.

[ytmimi]

I've also realized that we have a spaces_around_ranges option that could also be used to mitigate this issue.