Flow choosing incorrect overload.

[JohnLouderback]

Given this code defined in a library:

  /**
   * Get the value of style properties for the first element in the set of matched elements.
   *
   * @param propertyName A CSS property.
   */
  css(propertyName: string): string;
  /**
   * Set one or more CSS properties for the set of matched elements.
   *
   * @param propertyName A CSS property name.
   * @param value A value to set for the property.
   */
  css(propertyName: string, value: string | number): JQuery;
  /**
   * Set one or more CSS properties for the set of matched elements.
   *
   * @param propertyName A CSS property name.
   * @param value A function returning the value to set. this is the current element. Receives the index position of the element in the set and the old value as arguments.
   */
  css(propertyName: string, value: (index: number, value: string) => string | number): JQuery;
  /**
   * Set one or more CSS properties for the set of matched elements.
   *
   * @param properties An object of property-value pairs to set.
   */
  css(properties: Object): JQuery;

And this code leveraging that method:

$this.css('max-height', folderClosedMaxHeight + 'px')
     .addClass('is-folder')
     .after('<div class="show-more">Show More</div>');

I get the error: property addClass Property not found in String

Since there is two arguments being passed, there's no good reason it should choose an overload that only has one parameter.

[gcanti]

You can either

1. sort the overloadings by the number of arguments desc

Bad

declare function f(a: string): number;
declare function f(a: string, b: string): string

f('a', 'b').trim() // <= error property `trim`. Property not found in Number

Good

declare function f(a: string, b: string): string
declare function f(a: string): number;

f('a', 'b').trim() // <= ok

2. add a fake rest argument

declare function f(a: string, ...rest: Array<void>): number;
declare function f(a: string, b: string, ...rest: Array<void>): string

f('a', 'b').trim() // <= ok

[JohnLouderback]

Option 1 seems to do the trick. I understand why Flow does this (kind of), but wouldn't it make more sense to need to explicitly define rest parameters rather than "block" them as above? It seems to defeat the purpose of strict typing and other specifications.

[SamChou19815]

The issue seemed to be fixed a long time ago.