Discrepancy with TS compiler in import elision with preserveValueImports:true

[AlexandreBonaventure]

Hello,

I'm copying the comment from @sapphi-red found in this vite issue: vitejs/vite#8339 (comment)

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Repro

import { type Map } from 'mapbox-gl';

let MyMap:Map

When preserveValueImports is true, the output behavior differs from TypeScript compiler. I thought a bit strange about the TS compiler's behavior at first, but it seems intended.

Esbuild

import {} from "mapbox-gl";
let MyMap;

TS compiler remove the import line

let MyMap;

"preserveValueImports":true (esbuild repl) "preserveValueImports":true (ts playground)

Expected behaviour

Esbuild should probably behave like TS compiler in this case and remove the whole unused import line, otherwise it is keeping an empty import line which breaks tree-shaking/code-splitting in bundlers using esbuild like vite

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When preserveValueImports is false, no discrepancies, it becomes:

let MyMap;

"preserveValueImports":false (esbuild repl) "preserveValueImports":false (ts playground)

[evanw]

Thanks for the report. I can confirm the issue, and will fix this in the next release.