the rule `func-names` should behave differently depending on parser options

What you did?

ESLint config:

{
  parserOptions: {
    ecmaVersion: 5
  },
  rules: {
    'func-names': [ 'error', 'as-needed' ]
  }
}

The code:

var func = function /* no name here */ () {}

What you would like to happen?

With parserOptions.ecmaVersion set to 5 or below, the option as-needed for rule func-names should behave the same as always, since older versions of ECMAScript won’t automatically infer name for anonymous functions. So as-needed here means you always need to specify the name explicitly.

In other cases (parserOptions.ecmaVersion >= 6), the behavior of option as-needed should maintain status quo.

What actually happened?

ESLint was considering func had an inferred name and therefore complained nothing.

[not-an-aardvark]

Unfortunately that wouldn’t solve the problem. First, some parsers support experimental features, or they might only support some features of a particular ECMAScript version but not other features. In this particular case, there is a larger issue: var foo = function(){} is valid syntax regardless of whether the parser can parse ES5 or ES6. Function name inference happens at runtime, so whether it occurs will depend on the engine that’s executing the code, not the parser. It’s not possible for ESLint to determine what engine will be running the code, or whether that engine supports function name inference.

[riophae]

You’re right. Thanks for your patience!