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Spread operator should work with generic types #13557

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Spread operator should work with generic types#13557
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Description

@falsandtru
falsandtru (falsandtru)
opened on Jan 18, 2017

TypeScript Version: master

Code

function f<a extends Object>() {
	return {...<a>{}};
}
function g<a extends object>() {
	return {...<a>{}};
}

Expected behavior:

ok

Actual behavior:

index.ts(2,10): error TS2698: Spread types may only be created from object types.
index.ts(5,10): error TS2698: Spread types may only be created from object types.

Activity

  1. HerringtonDarkholme commented on Jan 18, 2017

    @HerringtonDarkholme
    Herrington Darkholme (HerringtonDarkholme)
    on Jan 18, 2017
    Contributor

    Another example, it's quite hard for TypeScript to prove a type constraint is spreadable given structural typing

    class NonPrimitive {
    private cannotBePrimitiveBrand
}
function t<T extends NonPrimitive>(a: T, b: NonPrimitive) {
    var c = { ...a }
    var d = { ...b }
}

    #2103 (comment)

  2. billba commented on Apr 24, 2017

    @billba
    Bill Barnes (billba)
    on Apr 24, 2017
    Member

    Another example:

    interface Foo {
    foo: string;
}

const addBar = <F extends Foo>(input: F) => ({
    ... input,
    bar: 5
});

    Build 2.3.0-dev.20170424 gives error TS2698: Spread types may only be created from object types. on ...input,

  3. mhegazy commented on Apr 24, 2017

    @mhegazy
    Mohamed Hegazy (mhegazy)
    on Apr 24, 2017
    Contributor

    Duplicate of #10727. Fixed by #13288

  4. Mohamed Hegazy (mhegazy)
    closed this as completedon Apr 24, 2017
  5. Mohamed Hegazy (mhegazy)
    added
    DuplicateAn existing issue was already created
    on Apr 24, 2017

  6. billba commented on Apr 24, 2017

    @billba
    Bill Barnes (billba)
    on Apr 24, 2017
    Member

    Mohamed Hegazy (@mhegazy) This is still happening in the current build.

  7. mhegazy commented on Apr 24, 2017

    @mhegazy
    Mohamed Hegazy (mhegazy)
    on Apr 24, 2017
    Contributor

    yes. #13288 is not merged yet. we do not have an ETA at the moment.

  8. billba commented on Apr 24, 2017

    @billba
    Bill Barnes (billba)
    on Apr 24, 2017
    Member

    Aha, thanks.

  9. LKay commented on Apr 25, 2017

    @LKay
    Karol Janyst (LKay)
    on Apr 25, 2017

    When it will be fixed finally? The problem persists and it's breaking code all over the place!

  10. devlato commented on Apr 20, 2018

    @devlato
    Denis Tokarev (devlato)
    on Apr 20, 2018

    Any plans fixing this?

  11. massimonewsuk commented on May 3, 2018

    @massimonewsuk
    massimonewsuk
    on May 3, 2018

    Is there a milestone or version that we can expect this to be fixed in?

  12. nblavoie commented on May 12, 2018

    @nblavoie
    Nicolas Boulet-Lavoie (nblavoie)
    on May 12, 2018

    Count me in !

  13. mcamou commented on Jul 23, 2018

    @mcamou
    Mario Camou (mcamou)
    on Jul 23, 2018

    Any news on when/whether #13288 will be merged? This bug has been open for over a year now.

  14. ivansky commented on Aug 23, 2018

    @ivansky
    Ivan Martianov (ivansky)
    on Aug 23, 2018

    Mohamed Hegazy (@mhegazy)
    It's not a duplicate! I am interested in fixing too.
    Could you remove label and reopen the issue?

  15. RyanCavanaugh commented on Aug 24, 2018

    @RyanCavanaugh
    Ryan Cavanaugh (RyanCavanaugh)
    on Aug 24, 2018
    Member

    Please read #13288 (comment)

  16. microsoft
    locked as resolved and limited conversation to collaborators on Aug 24, 2018
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