fix(eslint-plugin): [no-use-before-define] correctly handle typeof type references

[Drakota]

Fixes #2572

The no-use-before-define rule wasn't taking into account type reference that comes from values prefixed by the typeof operator.

Thank you @bradzacher for your help 🙂

[typescript-eslint]

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[codecov]

Codecov Report

Merging #2623 into master will increase coverage by 0.00%.
The diff coverage is 80.00%.

@@           Coverage Diff           @@
##           master    #2623   +/-   ##
=======================================
  Coverage   92.82%   92.83%           
=======================================
  Files         293      294    +1     
  Lines        9619     9673   +54     
  Branches     2697     2714   +17     
=======================================
+ Hits         8929     8980   +51     
- Misses        326      327    +1     
- Partials      364      366    +2     

Flag	Coverage Δ
#unittest	92.83% <80.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...es/eslint-plugin/src/rules/no-use-before-define.ts	92.50% <80.00%> (-1.87%)	⬇️
...es/eslint-plugin/src/rules/no-duplicate-imports.ts	97.77% <0.00%> (ø)

[bradzacher]

You're most of the way there!
A few comments.
Thanks for working on this.

[bradzacher]

almost! but this will only match one case.

We need to match all of these cases, and more:

• typeof a
• typeof a.b
• typeof a.b.c

Instead an easier way to do this would be with a loop.
Based on the defined types for TSTypeQuery, we know that the exprName will either be an Identifier or a TSQualifiedName.

typescript-eslint/packages/types/src/ts-estree.ts

Lines 1669 to 1672 in d7dc108

	export interface TSTypeQuery extends BaseNode {
	type: AST_NODE_TYPES.TSTypeQuery;
	exprName: EntityName;
	}

Based on the defined types for TSQualifiedName, we know the left will always be an Identifier or a TSQualifiedName.

typescript-eslint/packages/types/src/ts-estree.ts

Lines 1572 to 1576 in d7dc108

	export interface TSQualifiedName extends BaseNode {
	type: AST_NODE_TYPES.TSQualifiedName;
	left: EntityName;
	right: Identifier;
	}

This means we can simply loop and look at the parents
The reason I gave you the above is it'll help you constrain the loop so it won't iterate forever

[Drakota]

Fixed!

[bradzacher]

Almost there!

We can constrain this a little more so we don't recursively traverse up the whole tree unnecessarily.
We know that the node must always be either be a TSQualifiedName, Identifier or TSTypeQuery.

switch (node.type) {
  case AST_NODE_TYPES.TSTypeQuery:
    return true;

  case AST_NODE_TYPES.TSQualifiedName:
  case AST_NODE_TYPES.Identifier:
    return referenceContainsTypeQuery(node.parent);

  default:
    // if we find a different node, there's no chance that we're in a TSTypeQuery
    return false;
}

[Drakota]

I see! I wasn't sure of what you meant in your first comment.
I've changed it.

[bradzacher]

LGTM - thanks for your contribution!

[Drakota]

Thank you for guiding me through this @bradzacher, I appreciate it 🙂