runtime exception: `Class constructor GAstVisitor cannot be invoked without 'new'`

[mshima]

ERROR! Class constructor GAstVisitor cannot be invoked without 'new'
TypeError: Class constructor GAstVisitor cannot be invoked without 'new'
    at new DslMethodsCollectorVisitor (/Users/mshima/aplicacoes/default/node_modules/chevrotain/lib/src/parse/parser/traits/looksahead.js:107:47)
    at Object.<anonymous> (/Users/mshima/aplicacoes/default/node_modules/chevrotain/lib/src/parse/parser/traits/looksahead.js:148:24)
    at Module._compile (node:internal/modules/cjs/loader:1105:14)
    at Object.Module._extensions..js (node:internal/modules/cjs/loader:1159:10)
    at Module.load (node:internal/modules/cjs/loader:981:32)
    at Function.Module._load (node:internal/modules/cjs/loader:822:12)
    at Module.require (node:internal/modules/cjs/loader:1005:19)
    at require (node:internal/modules/cjs/helpers:102:18)
    at Object.<anonymous> (/Users/mshima/aplicacoes/default/node_modules/chevrotain/lib/src/parse/parser/parser.js:34:20)
    at Module._compile (node:internal/modules/cjs/loader:1105:14)

Reproducing:

npx generator-jhipster@latest jdl bug-tracker.jh

Related to https://github.com/jhipster/generator-jhipster/pull/19483

[bd82]

Hello @mshima

I'm not seeing any issues in a small example consuming latest (10.2.0) chevrotain via commonjs. Nor am I spotting anything (e.g cyclic dependencies related to GAstVisitor) by looking at the code.

Also the latest tag of generator-jhipster is 7.9.2 and this seems to be using 10.1.2 (locked) version of Chevrotain. So I'm not sure how the update to 10.2.0 is related to breakage in 7.9.2 (latest)...

• via npx generator-jhipster@latest jdl bug-tracker.jh

Can you provide a way for me to debug this?

• I'm not sure how to debug via npx...
• e.g a package.json with a local (not npx) script to trigger a flow that causes an error

[mshima]

You can install jhipster locally and run it.

npm install generator-jhipster@7.9.2
npx jhipster jdl bug-tracker.jh

Updating to chevrotain@10.2.0 fails too: https://github.com/jhipster/generator-jhipster/pull/19487

git clone https://github.com/jhipster/generator-jhipster.git
cd generator-jhipster
npm install
npm install chevrotain@latest
npx mocha test/jdl --no-parallel # test/jdl is where chevrotain is used.

This is a big issue for jhipster since it breaks every new installation. https://github.com/jhipster/generator-jhipster/issues/19486

I probably won't manage to debug this today.

[bd82]

I wonder if this is somehow related to how npx runs things. Because with yeoman directly it works properly:

{
  "name": "blah",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "yo": "yo jhipster jdl bug-tracker.jh",
    "npx": "npx jhipster jdl bug-tracker.jh"

  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "generator-jhipster": "7.9.2"
  }
}

Unless these two commands are not equivalent?

[bd82]

Actually these two commands may not be equivalent, I am not sure if yeoman does a local lookup in closest node_modules... but when I did npm install -g generator-jhipster before hand the scenario without npx still worked.

I am not sure if the arguments part is equivalent though...

[mshima]

At package.json scripts npx is not required, use plain jhipster jdl bug-tracker.jh

In this case, npx is just a wrapper for the local node_modules bin. So it’s just like

node_modules/.bin/jhipster jdl bug-tracker.jh

You can install globally. I’m just used to install locally.

The jhipster bin is required. Yo will not work.

[bd82]

Okay I realize why 6months old version 10.1.2 suddenly broke in generator-jhipster

Basically chevrotain 10.1.2 was depending on @chevrotain/gast ^10.1.2 (with ^ minor range). So once chevrotain 10.2.0 was released installing chevrotain@10.1.2 would pull @chevrotain/gast@10.2.0 as a dependency, but between these two versions the TypeScript compilation target changed (es5 --> ES2015) so the inheritance system is incompatible between these two versions.

There are a few solutions:

1. add a shrinkwrap file to generator-jhipster
2. release 10.2.1 version of chevrotain with the es5 compilation target and then release version 11.0.0 with the new compilation target.

I will try to implement #2 but if you can't wait you may want to implement the first one.

I still don't know why you encountered issues with 10.2.0...

[mshima]

I did some debug and the update to 10.2.0 broke because of this change: https://github.com/Chevrotain/chevrotain/commit/a4caf4db21fc334d1733bdc946ff656f3d94bdc0#diff-3130c8a9d16f6271d9c85f52d411bf95164c311adf5c8c3283c0a716a4effb3c

Operators for...in and getOwnPropertyNames are quite different, so some methods were not checked before: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Enumerability_and_ownership_of_properties#traversing_object_properties

Removing validateVisitor here makes the problem go await: https://github.com/jhipster/generator-jhipster/blob/045e1841226e237aa62aeae631b0a8a559266fca/jdl/parsing/validator.js#L336

But I have not clue if that's the correct approach.

[bd82]

It is safe to remove the validateVisitor it is an optional flow.

I am evaluating removing it as it seems fragile and I suspect it should be something an end user implements according to their needs and specific flavor of class syntax (ES5/ES2015/mixings/other)

[bd82]

I've released version 10.3.0 with ES5 artifacts and locked semver versions.

[bd82]

The problem was resolved for me on the local package.json + npx scenario (after rm -rf node_modules && rm package-lock).

I still get an error with running directly with global npx package install, but I am guessing that is because chevrotain does not get reinstalled on every npx generator-jhipster@latest jdl bug-tracker.jh invocation (is there a clean flag?).

perhaps it would be a good safe practice to also release a new patch version of jhipster...

[mshima]

Transitional dependencies merged at https://github.com/jhipster/generator-jhipster/pull/19483. And 10.3.0 merged at https://github.com/jhipster/generator-jhipster/pull/19490.

Thanks @bd82

[bd82]

hip hip hurray 😸