Fix flycheck-error-level-interesting-p function

[benzanol]

Previously, errors below the minimum severity could get marked as interesting even if errors above the minimum severity existed, as long as no errors which were exactly the minimum severity existed.
This means that if you set your minimum navigation severity to warning, and your file had only errors and hints, navigating would still jump to hints even though they are below the minimum severity.

[CLAassistant]

All committers have signed the CLA.

[bbatsov]

Can you illustrate this with some example, so I can understand better the problem you're trying to fix here?

[benzanol]

Can you illustrate this with some example, so I can understand better the problem you're trying to fix here?

Set flycheck-navigation-minimum-level to warning.
Open a file which has errors with level error (more than warning) as well as info (less than warning,) but no warnings.
For example, the following rust code will have an error on 4 and an info on &str:

fn main() {
    let a: &str = 4;
}

flycheck-previous-error and flycheck-next-error will navigate to the info and to the error, when it should just go to the error, because of the minimum navigation level.
This is fixed by the PR.

Hope this helps!

[bbatsov]

Got it. I'd suggest adding some spec covering this, if there are already some tests related to the flycheck-navigation-minimum-level behavior, so we won't run into regressions down the road. The change also needs a changelog entry.

[bbatsov]

I've also noticed that the older #1870 tackles the same problem, so you can check the solution there as before we proceed. (at a glance it seemed pretty similar to me)

[bbatsov]

@benzanol Friendly ping :-)