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Fix esModuleInterop not being respected for JS CommonJS imports#2693

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Fix esModuleInterop not being respected for JS CommonJS imports#2693
Copilot wants to merge 2 commits intomainfrom
copilot/fix-tsgo-esmodule-interop-issue

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Copilot AI commented Feb 5, 2026 •
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tsgo reports TS2497 when importing named exports from CommonJS JavaScript files even when esModuleInterop: true is set. tsc allows these imports without error.

// tsconfig.json: { "allowJs": true, "esModuleInterop": true }

// shared.vars.js
module.exports = { foo };

// index.ts - tsgo incorrectly errors here with TS2497
import { foo } from "./shared.vars";

Root Cause

The Go binder creates an export= symbol with SymbolFlagsProperty for module.exports = { ... }, while TypeScript exports each shorthand property directly. The property symbol lacks SymbolFlagsModule | SymbolFlagsVariable, triggering the interop error check in resolveESModuleSymbol.

Changes

  • internal/checker/checker.go: Skip TS2497 for JavaScript files when ESModuleInterop.IsTrue() (uses tristate, not the deprecated always-true GetESModuleInterop())
  • testdata/tests/cases/compiler/esModuleInteropJsCommonJsImport.ts: Test case reproducing the issue
Original prompt

This section details on the original issue you should resolve

<issue_title>tsgo does not respect esModuleInterop in certain cases</issue_title>
<issue_description>## Steps to reproduce

When importing named exports from a CommonJS JavaScript file (with allowJs: true), tsgo reports TS2497 even though esModuleInterop: true is set in tsconfig.json.

tsc allows this import without error.

Reproduction: https://github.com/psm14/tsgo-esmodule-interop-reproduction

Behavior with typescript@5.9

❯ npm run build:tsc

> tsgo-esmodule-interop-repro@1.0.0 build:tsc
> tsc --noEmit

Behavior with tsgo

❯ npm run build:tsgo

> tsgo-esmodule-interop-repro@1.0.0 build:tsgo
> tsgo --noEmit

src/index.ts:3:32 - error TS2497: This module can only be referenced with ECMAScript imports/exports by turning on the 'esModuleInterop' flag and referencing its default export.

3 import { helper, format } from './utils';
                                 ~~~~~~~~~


Found 1 error in src/index.ts:3
```</issue_description>

<agent_instructions>Create a test case lot of the linked repo that shows the bug, and commit that. Then fix the issue.</agent_instructions>

## Comments on the Issue (you are @copilot in this section)

<comments>
<comment_new><author>@jakebailey</author><body>
Feels like https://github.com/microsoft/typescript-go/issues/1054, potentially </body></comment_new>
</comments>

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@jakebailey
Fix esModuleInterop not being respected for JS CommonJS imports
7394105 
For JavaScript CommonJS modules with `module.exports = { ... }`,
the binder creates an export= symbol with SymbolFlagsProperty, not
SymbolFlagsValueModule. This was causing TS2497 to be emitted even
when esModuleInterop was enabled.

The fix adds a check in resolveESModuleSymbol to skip the error for
JavaScript files when esModuleInterop is explicitly enabled.

Fixes #1124 and related issue #1054

Co-authored-by: jakebailey <5341706+jakebailey@users.noreply.github.com>
Copilot AI changed the title [WIP] Fix tsgo not respecting esModuleInterop in certain cases Fix esModuleInterop not being respected for JS CommonJS imports Feb 5, 2026
Copilot AI requested a review from jakebailey February 5, 2026 16:35
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tsgo does not respect esModuleInterop in certain cases

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