Importing large export assignment object causes Maximum call stack size exceeded

TypeScript Version: 3.5.1

Search Terms: import, export assignment, export =, call stack

Code

This crashes tsc,

//npm install --save type-mapping@1.1.2
//`ts-node ./index.ts` works fine
//`tsc` gives `Maximum call stack size exceeded`
//`"type-mapping/fluent"` is a file that uses `export =`
//to export an object with many properties
import * as tm from "type-mapping/fluent";
console.log(tm);

This works fine,

//npm install --save type-mapping@1.1.2
//`ts-node ./index.ts` works fine
//`tsc` also works fine
//`"type-mapping"` is a file that uses `export *`
//to export many objects, even more than "type-mapping/fluent"
import * as tm from "type-mapping";
console.log(tm);

Expected behavior:

tsc should compile fine in both cases.

"type-mapping/fluent" uses export = to export a single object with many properties (141 properties).

However, the number of "things" exported is less than the amount exported
by "type-mapping", which uses export * (178, excluding interfaces and typedefs).

So, this makes me suspect that the problem is export =.
However, I simply have to use export = because "type-mapping/fluent" is generating these properties during run-time. (During compile-time, the export is a mapped object type)

Actual behavior:

Maximum call stack size exceeded with "type-mapping/fluent" and export =.

Works fine with "type-mapping" and export *

Related Issues: Not that I could find

The export is created here,
https://github.com/AnyhowStep/type-mapping/blob/1a999792f00fe25d2d3d1038d48b857a82b94219/src/fluent-lib/non-generic.ts

It is exported here,
https://github.com/AnyhowStep/type-mapping/blob/1a999792f00fe25d2d3d1038d48b857a82b94219/src/fluent-lib/index.ts

And here,
https://github.com/AnyhowStep/type-mapping/blob/1a999792f00fe25d2d3d1038d48b857a82b94219/fluent.d.ts

If I want to convert this to export *, I have to manually copy-paste code (and tweak) for possibly 100+ functions.

I've also noticed that when I use import * as tm from "type-mapping/fluent";, VS code will hang for a bit at times. And then I get an error saying the TS extension has crashed.

Restarting VS code lets it run fine again for a while before crashing again.

I just made a workaround for large export = objects causing tsc to crash.

I wrote a script to generate a file that uses export *, instead of export =

https://github.com/AnyhowStep/type-mapping/blob/13d9a96241d91d0e486ee4e8194ad163cce3986c/script/src/generate-fluent-lib-export.ts

So, fluent-lib/non-generic.ts still does its run-time wrapping of 100+ functions, and uses export =

But fluent-lib/index.ts uses export {/*list of function names*/} from "./non-generic";.

This way, I side-step the issue

I just published as version 1.1.5 and tested it and it seems to work without crashing now.
I'll have to test some more and see if there are any lingering side-effects.

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Importing large export assignment object causes Maximum call stack size exceeded #31824

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Importing large export assignment object causes Maximum call stack size exceeded #31824

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AnyhowStep commented on Jun 8, 2019

AnyhowStep commented on Jun 8, 2019

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