Update: fix quotes false negative for string literals as template tags

[not-an-aardvark]

What is the purpose of this pull request? (put an "X" next to item)

[x] Bug fix

Tell us about your environment

• ESLint Version: master
• Node Version: 7.5.0
• npm Version: 4.1.2

What parser (default, Babel-ESLint, etc.) are you using?

default

Please show your full configuration:

rules:
  quotes: error
parserOptions:
  ecmaVersion: 6

What did you do? Please include the actual source code causing the issue.

I absentmindedly spammed ` while working on something else, and I ended up with something like this:

````

This is a tagged template literal, where the tag is the first `` and the quasi is the second ``.

What did you expect to happen?

I expected the first `` to be reported, since it can be in double quotes. Only the second `` needs to be a template literal.

What actually happened? Please include the actual, raw output from ESLint.

No errors were reported.

What changes did you make? (Give an overview)

This fixes a tagged template check in quotes. Since the "literal" of a tagged template literal can't be converted to single/double quotes (e.g. foo`bar`), the rule currently ignores template literals that have a TaggedTemplateLiteral parent. However, it should only ignore these if the template literal is actually the quasi if the parent -- an error should still be reported if the template literal is the tag of the parent.

Is there anything you'd like reviewers to focus on?

Nothing in particular

[mention-bot]

@not-an-aardvark, thanks for your PR! By analyzing the history of the files in this pull request, we identified @mysticatea, @nzakas and @vitorbal to be potential reviewers.

[eslintbot]

LGTM

[mysticatea]

LGTM.

Though, I'm not sure if this is needed since the expression would always throw a run-time error.

[not-an-aardvark]

That's true, but I suppose it's still better for the rule to be correct here.

Now I'm imagining this as a minification strategy 😄:

function foo() {
  throw new TypeError('not implemented yet');
}

// ->

function foo(){
  ````
}

[gyandeeps]

@mysticatea and @not-an-aardvark are we good with this? Also this is a bug fix right?

[ilyavolodin]

This has a very slight potential in resulting in more errors, I think. That's why it's marked as an update.