User/docker tests broken with duplicate identifier IteratorResult

[sandersn]

#32324 shows some errors in the user tests with duplicate identifier IteratorResult between the es2015 lib and @types/node. The docker tests also fail, probably for a similar reason.

#32303 should fix some of these errors; we should make sure that the docker tests compile without error since those are open source partner teams in microsoft. Not sure if the fix will be in our code or theirs.

[eamodio]

I'm seeing the same thing when I tried to move to 3.6.1-rc

    ERROR in C:/Users/Eric/code/vscode-gitlens/node_modules/@types/node/index.d.ts
    ERROR in C:/Users/Eric/code/vscode-gitlens/node_modules/@types/node/index.d.ts(177,11):
    TS2300: Duplicate identifier 'IteratorResult'.

    ERROR in C:/Users/Eric/code/vscode-gitlens/node_modules/typescript/lib/lib.es2015.iterable.d.ts
    ERROR in C:/Users/Eric/code/vscode-gitlens/node_modules/typescript/lib/lib.es2015.iterable.d.ts(41,6):
    TS2300: Duplicate identifier 'IteratorResult'.

[rbuckton]

@eamodio You need to update the version of @types/node you are using as this has already been addressed in that types package.

[eamodio]

@rbuckton Excellent -- that worked! Thank you!

[JontyMC]

I upgraded to typescript 3.7.2 today and now am seeing the same error:

node_modules\@types\node\index.d.ts(72,11): error TS2300: Duplicate identifier 'IteratorResult'

I have upgraded @types\node to latest (12.12.6), but still getting the error. Any suggestions?

[guyellis]

@JontyMC where is the other location that it is defined? I just ran into that issue as well:

node_modules/@types/node/index.d.ts:169:11 - error TS2300: Duplicate identifier 'IteratorResult'.

169 interface IteratorResult<T> { }
              ~~~~~~~~~~~~~~

  node_modules/typescript/lib/lib.es2015.iterable.d.ts:41:6
    41 type IteratorResult<T, TReturn = any> = IteratorYieldResult<T> | IteratorReturnResult<TReturn>;
            ~~~~~~~~~~~~~~
    'IteratorResult' was also declared here.

However, for me it was because I didn't have @types/node installed in that project. For you I see that you already have this installed. Could it be a reference in your tsconfig lib prop that's causing this? What do you have listed in there?

[JontyMC]

Yeah, that was the issue, thanks. I had:

"./node_modules/@types/**/*.d.ts"

If this helps anyone else, I'm using Aurelia, and had to remove the above from aurelia.json in transpiler > dtsSource.

Here's a good post that explains how type definitions work https://blog.angular-university.io/typescript-2-type-system-how-do-type-definitions-work-in-npm-when-to-use-types-and-why-what-are-compiler-opt-in-types/

[nealeu]

@eamodio You need to update the version of @types/node you are using as this has already been addressed in that types package.

@rbuckton Exactly where is this addressed already? IteratorResult is still there at: https://github.com/DefinitelyTyped/DefinitelyTyped/blob/master/types/node/index.d.ts#L72

[nealeu]

@rbuckton we need a flag to disable this error. The release notes say we need to fix this on case-by-case basis, but we cannot fix it for libraries that we cannot control, so due to this one feature we cannot adopt Typescript 3.7.

Why can't we opt in to this behaviour as has been the case with other stricter checking changes?

[rbuckton]

@nealeu this is handled by the "typesVersions" entry in package.json: https://github.com/DefinitelyTyped/DefinitelyTyped/blob/50adc95acf873e714256074311353232fcc1b5ed/types/node/package.json#L4-L10

When the TypeScript compiler searches for types (either using the "types" entry in your compiler options or automatic type directive detection when an "types" is not present), it will search in node_modules/@types/node and encounter this package.json. This informs the compiler to redirect the request for node_modules/@types/node/index.d.ts to node_modules/@types/node/ts3.2/index.d.ts, which does not contain IteratorResult.

However, if your build is configured such that you are explicitly adding node_modules/@types/node/index.d.ts (either via "files" or "includes" in your tsconfig.json), the compiler does not perform this redirection.

[weswigham]

The latest versions of the node declarations directly include the required lib, rather than forward declaring anything - are you sure? The latest version of node declarations quite literally do not include IteratorResult.

[ik-kaseya]

@weswigham One of the submodules stored the old version of @types/node. Updated it as well and error's gone. Thanks for your help!

[mprinc]

Whow?! That really hearts! :)

I had an issue with obsoleted @types/nodes in the parent folder

Nevertheless, thanks @rbuckton and @weswigham to this issue thread was REALLY useful to track all possible scenarios of this really painful and recurring issue.

I would really love to see this extracted into a separate troubleshooting document :)

[danieldanielecki]

@eamodio You need to update the version of @types/node you are using as this has already been addressed in that types package.

This issue can be closed, the StackOverflow question also suggests that it resolves this issue.

[rbuckton]

As mentioned, please refer to https://stackoverflow.com/questions/57331779/typescript-duplicate-identifier-iteratorresult if you are still experiencing problems.

[ankita219819]

I used type/node version 17.0.3
I still get the same error. Can you specify which version can be better.

Version:
npm : 6.13.4
angular: 8
node: v10.19.0
storybook angular: 6.0.12

[ankita219819]

I have used 17.0.3 version of type/node. The issue still persist. Can you specify which can be the best version to be used. Please help me out. Its urgent.

Version:
npm : 6.13.4
angular: 8
node: v10.19.0
storybook angular: 6.0.12