TsImportEquals causes program to be considered a module. Should it?

[dsherret]

The prescence of a TsImportEquals causes a script to be considered a module.

import test = require("asdf");

Playground link (notice source type is "unknown" and the AST shows as "module" instead of "script"):

https://play.swc.rs/?version=1.7.40&code=H4sIAAAAAAAAA8vMLcgvKlEoSS0uUbBVKEotLM0sStVQSixOSVPStOblAgBnhfLXIAAAAA%3D%3D&config=H4sIAAAAAAAAA1WQMW7DMAxF95zC4BzUhcesLbJ16gkEhW6USqRAUmiNwHev5MRxupHv8%2FODvO66Di7q4dBda1mb7ERRHn0lOpG530rApozqJWSD%2FaqaNsmk4ELmmwDm5AutmVCH12GAlYsjHVnSc0JRfMcxEB5Z3qJTPQaMJ73vfUQJOm9PvopCyiz2yUU8trCzWdZD36OmFz33%2BWbZbwYpZCEts64YJ2fBw12e%2F10QmbXNjS5qu23hkPhUIm7vai9pyzynxHRR2CYDhXFaFywo6Mdqh0LfxD8Eu%2FkPEPbTUoQBAAA%3D

Is this expected behaviour? I understand that TsImportEquals are only included in the ModuleDecl enum.

[dsherret]

I think probably this one is not worth fixing given this stuff is legacy? I can compute if a program is actually a script another way

[kdy1]

@swc-project/core-es Do you have any opinion?
I expect the fix to be trivial so not sure.

We would only need to check for ModuleDecl::xxx while matching ModuleItem::ModuleDecl

[magic-akari]

We have already handled a similar issue

• fix(es/typescript): Correctly handle ESM context #9490

However, this time it needs to be processed in the parser.

Technically speaking, TsImportEquals is a module declaration that is part of the syntax and must appear at the top of the file. This declaration allows TypeScript to perform static analysis on CommonJS, similar to the import declaration in ESM.

In SWC, a module only represents an ECMAScript module and does not refer any other module system.
Therefore, I support this change.

[magic-akari]

There is a special case that complicates the issue.
In TypeScript, the module: nodenext turns TsImportEquals into a related call to _createRequire.

https://www.typescriptlang.org/play/?target=99&moduleResolution=99&module=199#code/PTAEAEFsHsBMFcA2BTAXKAdnZHkA8AXAKBAgIEMAnAc2QPWQGddCiBLSAB2koNElABeUJWQBHeG1EAKAEQwEKWQEoA3ESIBjaBkbQUAOkTRq0yAYCycJMmVA