conflict between prefer-const and no-use-before-define (2.5.0 regression)

What version of ESLint are you using? 2.5.0 (I think my previous version that didn’t fail was 2.4.0, but it could have been a different 2.x) What parser (default, Babel-ESLint, etc.) are you using? Default Please show your full configuration:

{
...
"no-use-before-define": ["error", "nofunc"],
...
 "prefer-const": "error",
}

What did you do? Please include the actual source code causing the issue.

            let interval;
            function checkForWindow() {
                const newFocussed = BrowserWindow.getFocusedWindow();
                if (newFocussed !== currentlyFocussed) {
                    clearInterval(interval);
                    newFocussed.toggleDevTools();
                }
            }
            interval = setInterval(checkForWindow, msIntervalToCheckForWindow);

What did you expect to happen? no warnings What actually happened? Please include the actual, raw output from ESLint. either

  76:13  error  'interval' is never reassigned, use 'const' instead  prefer-const

or if I change it to const after the interval

  72:35  error  'interval' was used before it was defined    no-use-before-define

I see the rule says this is an error

// the initializer is separated.
let a;
a = 0;
console.log(a);

but this is not

let a;
if (true) {
    a = 0;
}
console.log(a);

I would suggest that

let a;
// read or write of a in any sub block (e.g. if or function)
console.log(a);

is not an error?

[mysticatea]

I’m sorry for late response. I will do within next week. I have a vacation in next week!!

[nzakas]

See note on the PR. Option makes sense.