Ionic-framework: Compilation fails with TypeScript 2.4.x

[RoopeHakulinen]

Ionic version: (check one with "x")
[ ] 1.x (For Ionic 1.x issues, please use https://github.com/ionic-team/ionic-v1)
[ ] 2.x
[x] 3.x

I'm submitting a ... (check one with "x")
[x] bug report
[ ] feature request
[ ] support request => Please do not submit support requests here, use one of these channels: https://forum.ionicframework.com/ or http://ionicworldwide.herokuapp.com/

Current behavior:

App does not compile with TypeScript 2.4.x since

typescript: ...ments/GitHub/Helvar/AA-mobile/node_modules/ionic-angular/components/nav/nav.d.ts, line: 47 
            Class 'Nav' incorrectly extends base class 'NavControllerBase'. Types of property 'goToRoot' are
            incompatible. Type '(opts: NavOptions) => Promise<any>' is not assignable to type '(opts: NavOptions) =>
            Promise<never>'. Type 'Promise<any>' is not assignable to type 'Promise<never>'. Type 'any' is not
            assignable to type 'never'.

      L47:  export declare class Nav extends NavControllerBase implements AfterViewInit, RootNode, INav {
      L48:      private _root;

[18:44:08]  typescript: ...ents/GitHub/Helvar/AA-mobile/node_modules/ionic-angular/components/tabs/tab.d.ts, line: 121 
            Class 'Tab' incorrectly extends base class 'NavControllerBase'. Types of property 'goToRoot' are
            incompatible. Type '(opts: NavOptions) => Promise<any>' is not assignable to type '(opts: NavOptions) =>
            Promise<never>'. Type 'Promise<any>' is not assignable to type 'Promise<never>'.

     L121:  export declare class Tab extends NavControllerBase implements ITab {
     L122:      private _cd;

Expected behavior:

Steps to reproduce:

Related code:

insert any relevant code here

Other information:

Ionic info: (run ionic info from a terminal/cmd prompt and paste output below):

insert the output from ionic info here

[RoopeHakulinen]

This is caused by Promise.reject returned from _NavControllerBase_'s method _goToRoot_. I'll take a look at fix and possibly submit a PR.

[RoopeHakulinen]

PR #12235 fixes this by explicitly typing the promise.

[jgw96]

Hello @RoopeHakulinen , thanks for using Ionic and thanks for the PR! We will look into getting this merged.

[vascofernandes]

add this to tsconfig.json temporarily until the issue is fixed:

 "compilerOptions": {
     ....
    "skipLibCheck": true,
    "noStrictGenericChecks": true,
    .....

[ssalasgx]

Hi, i suddenly had a problem like that, and i didn't know why, i will share the screen

I checked ionic info:

And i try the solution from vascofernandes and it works, please can you explain how does it work?

Best regards!

[RoopeHakulinen]

It works because in TS 2.4 there was an addition to the compiler that improves generics checking. In this case it relates to checking the generic Promise<T> better. The problem is that the base class' (NavControllerBase) method returns Promise<never> while the child class' (NavController) overrides this method and returns Promise<any>. These two types are different starting from TS 2.4 and thus the compilation error.

[fiznool]

Would love to see this PR merged soon! tslint is causing a load of erroneous warnings with ts 2.3.4 due to this issue.

[mburger81]

@RoopeHakulinen is it save to use TS 2.4.2 on [email protected], we have som libs which requires >2.4 but I saw ionic is for example reverting TS from 2.5.x back again to 2.3.4 so it seems > 2.3.4 should not work properly?

[RoopeHakulinen]

I haven't had a chance to update yet myself so unfortunately can't tell you that :( @jgw96 probably knows

[nour05]

it still does not work for me what I have to do!!

[ionitron-bot[bot]]

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