Comments in JSX jump inside braces

[fhammerschmidt]

<div>
  // Execute "format" and this comment will jump inside the braces
  {React.string("Hello, World!")}
</div>

turns into

<div>
  {// Execute "format" and this comment will jump inside the braces
  React.string("Hello, World!")}
</div>

I would expect it to stay where it is.

Playground example

[IwanKaramazow]

Thanks for the bug report. Comments surrounding braces are indeed not implemented. Added to my TODO list

[cknitt]

@IwanKaramazow Do I see this correctly?

We have a braced expression as follows:

expression (Test.res[3,73+3]..[3,73+32])
    attribute "ns.braces"
        []
    Pexp_apply
    expression (Test.res[3,73+3]..[3,73+15])
        Pexp_ident "React.string" (Test.res[3,73+3]..[3,73+15])
    [
        <arg>
        Nolabel
        expression (Test.res[3,73+16]..[3,73+31])
            Pexp_constant PConst_string ("Hello, World!",Some "js")
    ]

with a leading comment at the same location:

leading comments:
  [3:3-3:32]
     Execute "format" and this comment will jump inside the braces

But the AST does not tell us whether the comment originally was inside or outside the braces. So there is no way to solve this currently?

I mean we could always print the comment outside of the braces, but that's just as wrong as always printing it inside the braces.

[IwanKaramazow]

Braces are indeed not a part of the AST, we currently parse them into the attribute "ns.braces". The location of the "braces" are part of the attribute, so you have perfect knowledge of where they should be placed.

The work:

• res_comments_table: modify walkExpr to attach comments to the location of the "ns.braces" if relevant and present
• res_printer: whenever braces are printed, we now also need to print attached comments.

[cknitt]

Right, I now modified printast.ml to be able to see the attribute location, and indeed it's different from the expression location:

expression (Test.res[3,73+3]..[3,73+32])
    attribute "ns.braces" (Test.res[3,73+2]..[3,73+33])
    []