[prefer-immutable-types] Doesn't take into consideration ignoreNamePattern with hash symbol

[Clarchik]

Bug Report

Seems like rule does not work as intended.

Expected behavior

Rule below should not produce error for variables which follows # symbol (TS private modifier)

'functional/prefer-immutable-types': [
      'error',
      {
        ignoreNamePattern: ['_', '#']
      }
    ],

Actual behavior

Works for

_anyName variable

But produces error for

#anyName variable

Property should have a readonly modifier eslint [functional/prefer-immutable-types]

Steps to reproduce

Latest version (7.2.0) with the rule snippet above

Proposed changes

[RebeccaStevens]

So the # symbol at the start of a private field's name isn't internally considered part of the name itself.
So ignoreNamePattern: "^mutable" would ignore class Klass { #mutableFoo: string[] = []; }

I could change this in the future to require a # for private fields, but this would be a breaking change.

You could use the ignoreClasses: "fieldsOnly" option, but this will ignore all class fields, not just private ones. Is this suitable for your needs?

[Clarchik]

@RebeccaStevens

You could use the ignoreClasses: "fieldsOnly" option, but this will ignore all class fields, not just private ones. Is this suitable for your needs?

Not sure, need to test it.

I was playing around source code of the lib and found the solution for myself which works, but the question is - is it a breaking change?

Changing this

if (isIdentifier(node) || isPrivateIdentifier(node)) {
 mut_identifierText = node.name;
}

to this

if (isIdentifier(node)) {
 mut_identifierText = node.name;
} else if(isPrivateIdentifier(node)) {
 mut_identifierText = `#${node.name}`;
} 

I found that only hash symbol is recognized as PrivateIdentifier and adding # before var name - makes sense in my case.
What's your opinion on that?

[RebeccaStevens]

After thinking about this for awhile, I believe that yes, that should be the desired behavior. It is a breaking change though.