vue/prop-name-casing false positive reaction

[yekver]

Tell us about your environment

• ESLint version: 6.0.1
• eslint-plugin-vue version: 5.2.3
• Node version: 12.6.0

What did you do?

export default {
  props: {
    $css: { type: Function, default: () => '' },
  }
}

What did you expect to happen?
No warning should be emitted

What actually happened?
Prop "$css" is not in camelCase.eslint(vue/prop-name-casing)

[sirlancelot]

The same is happening for props prefixed with _ as well:

Even worse, the linter is automatically "fixing" this which actually breaks code that would depend on the underscore being there. I'm using the underscore as a way to represent "internal" props which should never be accessed from templates.

For now my workaround is to disable that rule for these lines only:

This should definitely be considered a bug though, as it is changing code in a way that will break things.

[sirlancelot]

Related: #862