Rule Proposal: func-param-newline

[soda0289]

This rule was originally proposed by @jesstelford here: #6074 (comment) I looked through previous issues and did not see any other similar proposals.

Please describe what the rule should do:
This rule would enforce that function parameters or argument each appear on a new line, either always or when separated on multiple lines.

What category of rule is this? (place an "X" next to just one item)

[X] Enforces code style
[ ] Warns about a potential error
[ ] Suggests an alternate way of doing something
[ ] Other (please specify:)

Provide 2-3 code examples that this rule will warn about:
When set to always-multiline

testA('foo', {
  bar: 2,
  baz: 3
}, {error: 'Invalid'});

function testB(foo, bar
baz) { };

testC(
  'string1', 'string2',
  1, 2
);

When set to always

testA('foo', 'bar', baz);

function testB(foo, bar) {}

testC(
  'string1', 'string2',
  1, 2
);

Why should this rule be included in ESLint (instead of a plugin)?
It is very common to have to break up long function argument list on to multiple lines. Either because of max line length rules or for increased readability. This rule would enforce a consistent style in which this should be done. Code can be hard to read when function arguments are not placed on separate lines and when a function takes in multiple JSON objects it can be hard to tell them apart.

This rule would also complement the code style that our current rules already enforce. Such as object-property-newline and object-curly-newline. As well as another proposed rule function-paren-newline #8102

[soda0289]

Is this case covered by #8102?

[soda0289]

I think is cover. I thought it only handled parenthesis but it covers everything inside of them. Sorry for the noise.