PPX attribute vanishes when the propValue variable has the exact name of the prop

[pedrobslisboa]

Description

I was trying to use ppx attributes on prop variables with the exact name of the prop itself, but the refmt converts it to a shorthand value

<button onFocus={onFocus} onClick={[@foo] onClick} /> becomes <button onFocus onClick/>

The same happens to long records

// This is the initial code
let foo = {a: [@hey] a};
let foo = {a:a, b:b, c:c, d: [@hey] d};

// Turns into the below after refmt
let foo = {d: [@hey] d};
let foo = {
  a,
  b,
  c,
  d,
};

We can see that it happens only on reason:

• Access this playground sample

• Click on format

• Check the refmt makes baz as shorthand on both components and the long record.

• Access the ocaml version of this code

• Click on format

• Check that nothing happens.

Solution

On those cases, I think we can keep the prop without shorthand:

// This is the initial code
let bar = <button onFocus={onFocus} onClick={[@foo] onClick} />
let foo = {a:a, b:b, c:c, d: [@hey] d}

// Turns into the below after refmt
let bar = <button onFocus onClick={[@foo] onClick} />
let foo = {
  a,
  b,
  c,
  d: [@hey] d
};

Record

Gravacao.de.Tela.2025-01-06.as.11.46.17.mov

[EmileTrotignon]

ocamlformat would never do such a thing, it checks that you get the same AST before and after formatting (ignoring locations). Such a bug would be possible, but it would result in ocamlformat crashing. Maybe the same needs to be added to refmt ?

[anmonteiro]

it makes sense to fix this issue and open a new one for the AST check.