Bug: decorators get duplicated in AST for parameter properties

[fisker]

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• I have tried restarting my IDE and the issue persists.
• I have updated to the latest version of the packages.
• I have searched for related issues and found none that matched my issue.
• I have read the FAQ and my problem is not listed.

Relevant Package

parser

Playground Link

https://typescript-eslint.io/play/#ts=4.8.2&sourceType=module&showAST=es&code=MYGwhgzhAECC0G9pgBQAEAm0AOAnAlgG5gAuAptAB4Bc0AdgK4C2ARmbgJSLQC+vQA&eslintrc=N4KABGBEBOCuA2BTAzpAXGYBfEWg&tsconfig=N4KABGBEDGD2C2AHAlgGwKYCcDyiAuysAdgM6QBcYoEEkJemy0eAcgK6qoDCAFutAGsylBm3TgwAXxCSgA

Repro Code

> parse = require("@typescript-eslint/typescript-estree").parse
[Function: parse]
> ast = parse('class A {a (@d private x: number) {}}')
{
  type: 'Program',
  body: [
    {
      type: 'ClassDeclaration',
      id: [Object],
      body: [Object],
      superClass: null
    }
  ],
  sourceType: 'script'
}
> ast.body[0].body.body[0].value.params[0].decorators[0]
{ type: 'Decorator', expression: { type: 'Identifier', name: 'd' } }
> ast.body[0].body.body[0].value.params[0].parameter.decorators[0]
{ type: 'Decorator', expression: { type: 'Identifier', name: 'd' } }

ESLint Config

N/A

tsconfig

N/A

Expected Result

Not duplicate the decorator

Actual Result

the decorator get duplicate

Additional Info

No response

Versions

package	version
@typescript-eslint/parser	5.36.1
node	18.8.0

[bradzacher]

I believe that this specific code isn't required.

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

Lines 1672 to 1675 in f7c5deb

	const decorators = getDecorators(node);
	if (decorators) {
	parameter.decorators = decorators.map(d => this.convertChild(d));
	}

This block was added in #5551 (https://github.com/typescript-eslint/typescript-eslint/pull/5551/files#diff-341d9ffb40c62139c7da69b49d5081cbce7eabce79b58fe569de987a91e63c14R1676-R1679).

We should also add a fixture for this to prevent future regressions.