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importsNotUsedAsValues in JS files elides imports incorrectly #38412
Description
TypeScript Version: 4.0.0-dev.20200508
Search Terms:
importsNotUsedAsValues
import eliding
Code
In TypeScript 3.8, a new importsNotUsedAsValues feature/compilerOption was added. This, however is producing different output based on if the file is .ts or .js.
tsconfig.json
{
"compilerOptions": {
"allowJs": true,
"noResolve": true,
"importsNotUsedAsValues": "preserve",
"target": "ES2015",
"outDir": "./out",
"types": []
}
}test.js
// @ts-nocheck
import * as moment from 'moment';
import rollupMoment__default from 'moment';
export const moment = rollupMoment__default || moment;Output
// @ts-nocheck
import * as moment from 'moment';
import 'moment';
export const moment = rollupMoment__default || moment;Removing the importsNotUsedAsValues option, which is equivalent of having the value of remove will produce:
// @ts-nocheck
import * as moment from 'moment';
export const moment = rollupMoment__default || moment;Changing the file extension from .js to .ts will produce the correct output for both cases
// @ts-nocheck
import * as moment from 'moment';
import rollupMoment__default from 'moment';
export const moment = rollupMoment__default || moment;Expected behavior:
- Used imports are not elided.
- Given the same input it should produce the same output, irrespective of the file extension.
Actual behavior:
- Given a JS input the import is elided incorrectly.
Playground Link: Playground doesn't have the importsNotUsedAsValues options.
Related Issues: None that I can find.
Activity
alan-agius4 commentedon May 8, 2020
Note: this bug is also present in 3.8 & 3.9.
build: vendor typescript 3.6 in build optimizer
refactor(elements): add accessor workaround for build-optimizer (#37456)
refactor(elements): add accessor workaround for build-optimizer (#37456)
refactor(elements): add accessor workaround for build-optimizer (angu…
refactor(elements): add accessor workaround for build-optimizer (angu…
milahu commentedon Apr 15, 2021
https://codesandbox.io/s/typescript-importsnotusedasvalues-preserve-bug-demo-qm23x
andrewbranch commentedon Apr 15, 2021
milahu would you mind opening a new issue?
milahu commentedon Apr 15, 2021
#43693 (sorry for the noise)