inconsistent and unstable formatting of nested arrow functions

[adrian-gierakowski]

Describe the bug

dprint-plugin-typescript version: 0.95.12

using following config:

  "typescript": {
    "lineWidth": 80,
    "memberExpression.linePerExpression": true,
    "semiColons": "asi"
  }

I will start by showing 2 examples of code which is formatted correctly (at least according to my preference):

Example 1:

const func =
  (arg1: { a: number; b: number }) =>
  (arg2: { c: number }) =>
  (arg3: undefined): undefined => arg3

Example 2:

const func =
  (arg1: { a: number; b: number }): (a: any) => (a: any) => undefined =>
  (arg2: { c: number }) =>
  (arg3: undefined): undefined => arg3

Now if I change example 1 by splitting the arg1's type into multiple lines, the entire block gets reformatted in a wired way:

Input Code

const func =
  (arg1: {
    a: number; b: number}) =>
  (arg2: { c: number }) =>
  (arg3: undefined): undefined => arg3

Expected Output

const func =
  (arg1: { 
    a: number; 
    b: number 
  }) =>
  (arg2: { c: number }) =>
  (arg3: undefined): undefined => arg3

Actual Output

const func = (arg1: {
  a: number
  b: number
}) =>
(arg2: { c: number }) =>
(arg3: undefined): undefined => arg3

Example 2 shows unstable formatting which needs a couple of passes to arrive at a stable formatting. I first modify the first line to be longer than line character limit (by adding return time to the first arrow function):

const func =
  (arg1: { a: number; b: number }): (a: { c: number }) => (a: undefined) => undefined =>
  (arg2: { c: number }) =>
  (arg3: undefined): undefined => arg3

which on first pass generates the following (which is fine):

Input Code

const func =
  (
    arg1: { a: number; b: number },
  ): (a: { c: number }) => (a: undefined) => undefined =>
  (arg2: { c: number }) =>
  (arg3: undefined): undefined => arg3

Expected Output

const func =
  (
    arg1: { a: number; b: number },
  ): (a: { c: number }) => (a: undefined) => undefined =>
  (arg2: { c: number }) =>
  (arg3: undefined): undefined => arg3

Actual Output

const func = (
  arg1: { a: number; b: number },
): (a: { c: number }) => (a: undefined) => undefined =>
(arg2: { c: number }) =>
(arg3: undefined): undefined => arg3

The Actual Output is a result of two passes of formatting.