Conflicts with prettier-plugin-ember-template-tag + eslint-plugin-prettier when linting gjs/gts files

I had a bug filed on my new project regarding an error being thrown when run via eslint + eslint-plugin-ember + eslint-plugin-prettier: https://github.com/gitKrystan/prettier-plugin-ember-template-tag/issues/20

The further I delve into the issue, the more I think I might need help from this team to solve it, and that possibly the solution might involve changes to this repo rather than mine.

Repro: https://github.com/gitKrystan/simple-gjs-project/pull/2

This is the error thrown:

npm run lint:js                             

> gjs-project@0.0.0 lint:js
> eslint . --cache


Oops! Something went wrong! :(

ESLint: 7.32.0

SyntaxError: Invalid regular expression: /\b[__GLIMMER_\b/: Unterminated character class
    at new RegExp (<anonymous>)
    at /Users/krystanhuffmenne/Code/gjs-project/node_modules/eslint-plugin-ember/lib/preprocessors/glimmer.js:121:34
    at Array.map (<anonymous>)
    at mapRange (/Users/krystanhuffmenne/Code/gjs-project/node_modules/eslint-plugin-ember/lib/preprocessors/glimmer.js:106:20)
    at Linter._verifyWithProcessor (/Users/krystanhuffmenne/Code/gjs-project/node_modules/eslint/lib/linter/linter.js:1339:16)
    at Linter._verifyWithConfigArray (/Users/krystanhuffmenne/Code/gjs-project/node_modules/eslint/lib/linter/linter.js:1273:25)
    at Linter.verify (/Users/krystanhuffmenne/Code/gjs-project/node_modules/eslint/lib/linter/linter.js:1235:25)
    at Linter.verifyAndFix (/Users/krystanhuffmenne/Code/gjs-project/node_modules/eslint/lib/linter/linter.js:1428:29)
    at verifyText (/Users/krystanhuffmenne/Code/gjs-project/node_modules/eslint/lib/cli-engine/cli-engine.js:240:48)
    at CLIEngine.executeOnFiles (/Users/krystanhuffmenne/Code/gjs-project/node_modules/eslint/lib/cli-engine/cli-engine.js:808:28)

First of all, it seems like there should be some escaping happening here: https://github.com/ember-cli/eslint-plugin-ember/blob/db745a3881686d50e486be67d6851d806ac770d6/lib/preprocessors/glimmer.js#L120

Because eslint-plugin-prettier runs Prettier as an ESLint rule, my plugin causes the Prettier ESLint rule to log the following violation message:

{
  ruleId: "prettier/prettier",
  severity: 2,
  message: "Replace `[__GLIMMER_TEMPLATE(`⏎··<h1>···Hello·{{@who}}.·</h1>⏎`,·{·strictMode:·true·})];` with `<template><h1>·Hello·{{@who}}.·</h1></template>`",
  line: 1,
  column: 16,
  nodeType: null,
  messageId: "replace",
  endLine: 3,
  endColumn: 27,
}

Interestingly, the message has the preprocessed [__GLIMMER_TEMPLATE( shenanigans when it probably should not. (Not sure yet if that because of something I am doing or because of something happening in this package).

As a result, the line linked above is generating new RegExp('\b[__GLIMMER_\b') which indeed has an opening [ that the RegExp constructor interprets as the beginning of a character set.

I’ve noticed that this doesn’t always happen. For example, if I use the <template> tag in the “top-level class” position, npm run lint:js works properly (ish…it still has [__GLIMMER_TEMPLATE()] in the message, and I think the line/column numbers might be off):

// works-ish.gjs

import Component from '@glimmer/component';

export default class MyComponent
  extends Component {

        <template>


    <h1>   Hello {{@who}}. </h1>
  </template>
}

npm run lint:js 

> gjs-project@0.0.0 lint:js
> eslint . --cache

Debugger attached.

/Users/krystanhuffmenne/Code/gjs-project/app/components/broken.gjs
  2:1  error  Delete `⏎`                                                                                                                                                        prettier/prettier
  2:1  error  Delete `⏎·`                                                                                                                                                       prettier/prettier
  2:1  error  Replace `⏎········[__GLIMMER_TEMPLATE(`⏎⏎⏎····<h1>···Hello·{{@who}}.·</h1>⏎··`,·{·strictMode:·true·})]` with `··<template><h1>·Hello·{{@who}}.·</h1></template>`  prettier/prettier

✖ 3 problems (3 errors, 0 warnings)

[gitKrystan]

@NullVoxPopuli I just released prettier-plugin-ember-template-tag 0.1.0 which should have all the fixes necessary. I also did a little spike to make sure the fix would actually be helpful for this library:

https://github.com/ember-cli/eslint-plugin-ember/compare/master...gitKrystan:gjs-prettier?expand=1

The tests are still failing, but things are way closer than they were before.

[NullVoxPopuli]

@gitKrystan sounds awesome! once you have that work released, I’ll get going on the fixes for eslint-plugin-ember