Fix: no-var should fix ForStatement.init

[mysticatea]

What is the purpose of this pull request? (put an "X" next to item)

[X] Bug fix (template)

Tell us about your environment

• ESLint Version: 3.14.1
• Node Version: 6.9.4
• npm Version: 3.8.8

What parser (default, Babel-ESLint, etc.) are you using?

• default

Please show your full configuration:

• nothing

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

for (var i = 0; i < 10; ++i) {
    foo(i)
}

$ eslint test.js --env es6 --rule no-var:error --fix --no-eslintrc --no-ignore

What did you expect to happen?

The var declaration is fixed then no errors.

What actually happened? Please include the actual, raw output from ESLint.

path/to/test.js
  1:6  error  Unexpected var, use let or const instead  no-var

✖ 1 problem (1 error, 0 warnings)

What changes did you make? (Give an overview)

I changed no-var rule to fix var declarations at ForStatement.init.

Is there anything you'd like reviewers to focus on?

Nothing in particular.

[mention-bot]

@mysticatea, thanks for your PR! By analyzing the history of the files in this pull request, we identified @alangpierce, @vitorbal and @not-an-aardvark to be potential reviewers.

[eslintbot]

LGTM

[eslintbot]

LGTM

[not-an-aardvark]

I think the current implementation can change the behavior of some code:

for (var i = 0, i = 0; false;);

// gets fixed to

for (let i = 0, i = 0; false;); // syntax error

var i = 0;
for (var i = 1; false;);
console.log(i); // => 1

// gets fixed to

var i = 0;
for (let i = 1; false;);
console.log(i); // => 0

[mysticatea]

@not-an-aardvark No. This PR does not change those cases. This is a revision of #7962; it removes ForStatement.init from ignored cases that #7962 added.

[not-an-aardvark]

Oh, I see. LGTM then.

I'll look into those cases in a separate PR.

[eslintbot]

LGTM

[mysticatea]

I rebased to resolve conflicts and just added tests for those cases.