Ugly formatting

[so1ve]

Prettier 3.0.1 Playground link

--parser typescript
--trailing-comma es5

Input:

export type Equals<X, Y> =
  (<T>() => T extends X ? 1 : 2) extends
  (<T>() => T extends Y ? 1 : 2)
    ? true
    : false;

Output:

export type Equals<X, Y> = (<T>() => T extends X ? 1 : 2) extends <
  T,
>() => T extends Y ? 1 : 2
  ? true
  : false;

Expected behavior:

Should be the same as the input, or something better

[shaiallseated]

i agree very ugly yikes 😣😣😣😣😣😣😣

[seiyab]

Just for information: I think this output has multiple different problems.

• The layout break-after-operator looks more suitable (same problem as https://github.com/prettier/prettier/issues/15292)
• The extendsType (type between extends and ?) looks better to have parens in this case
• It looks slightly better to have line after extends in this case

[so1ve]

Thanks for your investigation ❤️

[seiyab]

Prettier 3.2.4 Playground link

--parser typescript
--trailing-comma es5

Input:

export type Equals<X, Y> =
  (<T>() => T extends X ? 1 : 2) extends
  (<T>() => T extends Y ? 1 : 2)
    ? true
    : false;

Output:

export type Equals<X, Y> =
  (<T>() => T extends X ? 1 : 2) extends <T>() => T extends Y ? 1 : 2
    ? true
    : false;