jquery / jquery/esprima

Dangling comment not attach to any ast node

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Dominant language
TypeScript
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Description

Steps to reproduce
esprima.parse('function foo() {return /*comment*/;}', { comment: true })
Expected output
{
  "type": "Program",
  "body": [
    {
      "type": "FunctionDeclaration",
      "id": {
        "type": "Identifier",
        "name": "foo"
      },
      "params": [],
      "body": {
        "type": "BlockStatement",
        "body": [
          {
            "type": "ReturnStatement",
            "argument": null,
            "danglingComments": ["comment"],  // attach to ReturnStatement ast node 
          }
        ]
      },
      "generator": false,
      "expression": false,
      "async": false
    }
  ],
  "sourceType": "script",
  "comments": [
    {
      "type": "Block",
      "value": "comment"
    }
  ]
}
Actual output
{
  "type": "Program",
  "body": [
    {
      "type": "FunctionDeclaration",
      "id": {
        "type": "Identifier",
        "name": "foo"
      },
      "params": [],
      "body": {
        "type": "BlockStatement",
        "body": [
          {
            "type": "ReturnStatement",
            "argument": null
          }
        ]
      },
      "generator": false,
      "expression": false,
      "async": false
    }
  ],
  "sourceType": "script",
  "comments": [
    {
      "type": "Block",
      "value": "comment"
    }
  ]
}

Here "comment" become a "dangling comment".

Relevant references
ReturnStatement:
    return ;

In this case, it's true that "comment" is out of both the leading and trailing range of ReturnStatement according to the specification but it will be more convenient if this comment be attached to the ast node.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the supplied esprima.parse call and compare its actual AST with the requested ReturnStatement attachment for the comment. Determine the parser behavior for comments outside a node's leading or trailing range, then add coverage showing the comment is retained in the AST as requested.

Written by the indexing model from the issue text.

Assessment

Tech stack
javascript, typescript
Domain
compilers
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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