Tell us about your environment

• ESLint Version: v4.4.0
• Node Version: 8.2.1
• npm Version: 5.3.0

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

Default parser

Please show your full configuration:

{
    "env": {
        "es6": true,
        "node": true
    },
    "extends": "eslint:recommended",
    "parserOptions": {
        "sourceType": "module"
    },
    "rules": {
        "no-fallthrough": "error"
    }
}

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

let someVar = 0

// This one cause a eslint error because of no break in first `case`
switch (someVar) {
case 0: {
    someVar = 1
}
default: {
    someVar = 2
}
}

// this one is fine, bypass comment added JUST before second `case`
switch (someVar) {
case 0: 
    someVar = 1
    // fall through
default:
    someVar = 2
}

// this one is fine, bypass comment added JUST before second `case`
switch (someVar) {
case 0: {
    someVar = 1
}
// fall through
default: {
    someVar = 2
}
}

// This one cause a eslint error, although bypass comment is added
switch (someVar) {
case 0: {
    someVar = 1
    // fall through
}
default: {
    someVar = 2
}
}

What did you expect to happen?

The last switch example will not cause a lint error.

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

The last switch example does cause a lint error.

> eslint-test@1.0.0 test /home/i7sdream/code/eslint-test
> ./node_modules/eslint/bin/eslint.js .


/home/i7sdream/code/eslint-test/index.js
   8:1  error  Expected a 'break' statement before 'default'  no-fallthrough
  39:1  error  Expected a 'break' statement before 'default'  no-fallthrough

✖ 2 problems (2 errors, 0 warnings)

npm ERR! Test failed.  See above for more details.

some of my views

Maybe the rules now only check if there is a bypass comment in the line JUST before each case, keyword, but I like to enclose around the case code with curly braces, so the rule doesn't recognize the bypass comment.

But, IMHO, when enclose with curly braces, bypass comment written in the last line in the, let's say, BLOCK of the first case is more intuitive. (last example)

So maybe we can change the rule to determine whether the last sentence in the BLOCK of the first case is bypass comment?

This change is backward compatible, because when there is no curly braces, the last sentence of the first case's BLOCK is also the prev line of the second case, because the BLOCK is all sentences of first case, in this situation.

Any comments is welcome, except for "why you like to add braces after case".

:)