When an enum is imported and used only as a type with "verbatimModuleSyntax" enabled, an error is not being shown

[lsalazarm99]

🔎 Search Terms

"verbatimModuleSyntax", "enum"

🕗 Version & Regression Information

• This is the behavior in every version I tried, and I reviewed the FAQ for entries about "verbatimModuleSyntax" (there wasn't any) and "enums".

⏯ Playground Link

https://www.typescriptlang.org/dev/bug-workbench/?verbatimModuleSyntax=true&ts=5.0.4#code/PTAEAEDcFMCcCMCGAXAlgWwLIHsAmBXAG2gGUBPAO2UQA8AuUZWfaAKFZAgDNViLF00Bj2IBaAO6pkAC1HQaAB2yxkAOmQBnVvKUrQ0CvnSgA6stwbQAb1ag7oAIKgAvKABEDtwBpb9gEIu7n7erAC+7DrKyIxkCtCm5oEaTKgUAOYA3Oyc4CIGAkKgqbjy6loYutFWCbAWXjW4oKGgXLDYxm6qwHkSUrKRKm7sxNGIDGa1WSOgiBRkE7jj5hoZQA

💻 Code

// @verbatimModuleSyntax: true

// @filename: file-with-export.ts
export enum Words {
    A = "A",
    B = "B",
}

export type Word = string;

// @filename: index.ts
import { Words, Word } from "./file-with-export"

let a: Word;
let anyWord: Words;

🙁 Actual behavior

The import of the Words enum doesn't show any errors.

🙂 Expected behavior

The import of the Words enum should show a 1484 error.

Additional information about the issue

The mentioned import should show an error because it's being used only as a type and the "verbatimModuleSyntax" flag is enabled.

[fatcerberus]

It’s being used only as a type, but it’s a valid runtime import, so I don’t see why this would be an error.

[lsalazarm99]

🤔 I understand your point, and I think you are right. In that case, how can I get the effects of the "importsNotUsedAsValues" flag when marked as "error"? Since it's going to be deprecated in favor of "verbatimModuleSyntax", I would expect the latter to handle its functionality.

[MartinJohns]

Since it's going to be deprecated

Where did you read that?

[lsalazarm99]

It's in the documentation of the rule, here. Actually, it's already deprecated. 😅

[lsalazarm99]

Also "tsc" says it when I use the flag:

error TS5101: Option 'importsNotUsedAsValues' is deprecated and will stop functioning in TypeScript 5.5. Specify compilerOption '"ignoreDeprecations": "5.0"' to silence this error.

I can't use both flags at the same time neither because "tsc" shows this error:

error TS5104: Option 'importsNotUsedAsValues' is redundant and cannot be specified with option 'verbatimModuleSyntax'.

[MartinJohns]

Thank you. I completely skipped that information when reading the documentation.

[RyanCavanaugh]

There isn't a new configuration that corresponds to the old behavior of erroring here, since no "problem" per se has occurred (only a style violation). #52203 (comment)

[jakebailey]

If the output JS had this import removed, that'd be a bug, but the flag doesn't tell you that you could switch an import to a type import because it's only used in type positions. verbatimModuleSyntax means "only type annotated imports are removed" and that's it.

If you want to be told to use a type import when possible, you need: https://typescript-eslint.io/rules/no-import-type-side-effects/

[fatcerberus]

verbatimModuleSyntax means "only type annotated imports are removed" and that's it.

Hmm, shouldn’t the unannotated import of Word (not Words) be an error then, since that’s a pure type and thus can’t be imported at runtime?

[RyanCavanaugh]

Hmm, shouldn’t the unannotated import of Word (not Words) be an error then

It is

[jakebailey]

It is:

[RyanCavanaugh]

My cropping is better

[jakebailey]

I had a colon

[MartinJohns]

@jakebailey I hope you still have a colon.

[fatcerberus]

It is

Ah okay, good. I wasn’t sure because the OP only mentioned the “missing” error on Words so I just assumed the rest of the repro code was legal. I probably should have clicked the playground link before commenting 😅

[lsalazarm99]

Got it! Thank you all for your help! I think the new flag is still a bit confusing. I was expecting it to be able to do the same things that the deprecated flag does with the "error" option.

As @jakebailey said, @typescript-eslint has the situation covered. By the way, I think you were talking about the @typescript-eslint/consistent-type-imports rule, since it is the one that makes the expected error be shown.

[jakebailey]

Some combo of those rules, sure. You do probably want the rule I mentioned if you want to be warned that import { type A } from "..." will turn into import {} from "..." at runtime.

[typescript-bot]

This issue has been marked as "Question" and has seen no recent activity. It has been automatically closed for house-keeping purposes.