Terser: [Regression] "Maximum call stack size exceeded"

[nifgraup]

Bug report or Feature request?
Regression bug.

Version (complete output of terser -V or specific git commit)
Regression point:

commit 2889744e409fa919abae195d00da926f51e980fb
Author: Fábio Santos <[email protected]>
Date:   Mon Dec 23 00:41:36 2019 +0000

    improve inlining

Complete CLI command or minify() options used

# apply pull request #542 to get fuzz.js working after Acorn 7 upgrade
npm run build
node test/fuzz.js

terser output or error
Example run:

$ node test/fuzz.js 
"";
">6";
export default class ohgoxshajhn {
  static set [null] ([, [], , ...p] = (super[new.target] <<= new.target) == "F") {
    class k {
      static [/k\u457d\B/giuy]() {}
      static get [(0)]() {}
      static set [k] (v) {
        "use strict";
      }
      static get [""]() {}
    }
  }
  static [2e308](ptbewuqujkw, iqlnwhrnf, jhtxfhxljwlrmv, sypkxlsjs) {
    "&ìáT"
    "x";
    "use strict"
    debugger;
    return;
  }
}
import udyiif,  * as pavhomwljuu from "îÑ]";
export {}
/terser/test/fuzz.js:56
    throw result.error;
    ^

RangeError: Maximum call stack size exceeded
    at Tn.before (/terser/dist/bundle.min.js:1:178002)
    at AST_SymbolDefClass.transform (/terser/dist/bundle.min.js:1:79151)
    at /terser/dist/bundle.min.js:1:82505
    at AST_ClassExpression.transform (/terser/dist/bundle.min.js:1:79182)
    at /terser/dist/bundle.min.js:1:82415
    at AST_ObjectSetter.transform (/terser/dist/bundle.min.js:1:79182)
    at /terser/dist/bundle.min.js:1:79313
    at l (/terser/dist/bundle.min.js:1:931)
    at e (/terser/dist/bundle.min.js:1:1251)
    at Mn (/terser/dist/bundle.min.js:1:79287)

Expected result
node test/fuzz.js should run forever.

[nifgraup]

Minimal repro:

maximum-callstack-size-exceeded.js:

class a {
  set() {
    class b {
      set [b] (c) {}
    }
  }
}

cat maximum-callstack-size-exceeded.js  | bin/terser -c
ERROR: Maximum call stack size exceeded
    at Function.[Symbol.hasInstance] (<anonymous>)
    at Tn.self [as before] (/terser/lib/compress/index.js:4125:22)
    at AST_ClassExpression.transform (/terser/lib/transform.js:94:20)
    at properties (/terser/lib/transform.js:267:36)
    at AST_ObjectSetter.transform (/terser/lib/transform.js:98:9)
    at tw (/terser/lib/transform.js:106:9)
    at l (/terser/lib/utils/index.js:90:11)
    at i (/terser/lib/utils/index.js:115:38)
    at in_list (/terser/lib/transform.js:102:57)
    at tw (/terser/lib/transform.js:278:52)

Fine with 2889744e409fa919abae195d00da926f51e980fb reverted.

[fabiosantoscode]

Awesome, thanks for this report!

[eamodio]

I'm seeing the same behavior when upgrading my project to use 4.5.1

[fabiosantoscode]

I haven't gotten to this yet since it seems a bit far fetched. @eamodio can you please provide a minimal reproduction? Would be good to know what other things can cause this bug.

[eamodio]

Unfortunately I don't have a minimal repo, but it can be easily reproduced with GitLens.

1. Clone https://github.com/eamodio/vscode-gitlens
2. Switch to the develop branch
3. Run yarn
4. Run yarn upgrade -- which will update the version of Terser from 4.4.3 to 4.5.1
5. Run yarn run bundle -- builds the project and will fail with the latest Terser

Here is what I see when I run yarn run bundle:

yarn run bundle
yarn run v1.21.1
$ webpack --env.production
dist-web/index.js
Rewrote universal-user-agent's package.json module field to `dist-node/index.js`
Optimizing images (src/webviews/apps/images/settings/*.png)...
Starting type checking service...
Starting type checking service...
Child extension:
    Time: 11280ms
    Built at: 01/05/2020 5:55:01 PM
     5 assets

    ERROR in extension.js from Terser
    RangeError: Maximum call stack size exceeded
        at AST_Dot.transform (C:\Users\Eric\code\eamodio\vscode-gitlens\node_modules\terser\dist\bundle.min.js:1:79101)
        at C:\Users\Eric\code\eamodio\vscode-gitlens\node_modules\terser\dist\bundle.min.js:1:82445
        at AST_ObjectKeyVal.transform (C:\Users\Eric\code\eamodio\vscode-gitlens\node_modules\terser\dist\bundle.min.js:1:79182)
        at C:\Users\Eric\code\eamodio\vscode-gitlens\node_modules\terser\dist\bundle.min.js:1:79313
        at l (C:\Users\Eric\code\eamodio\vscode-gitlens\node_modules\terser\dist\bundle.min.js:1:931)
        at e (C:\Users\Eric\code\eamodio\vscode-gitlens\node_modules\terser\dist\bundle.min.js:1:1251)
        at Mn (C:\Users\Eric\code\eamodio\vscode-gitlens\node_modules\terser\dist\bundle.min.js:1:79287)
        at C:\Users\Eric\code\eamodio\vscode-gitlens\node_modules\terser\dist\bundle.min.js:1:82338
        at AST_Object.transform (C:\Users\Eric\code\eamodio\vscode-gitlens\node_modules\terser\dist\bundle.min.js:1:79182)
        at C:\Users\Eric\code\eamodio\vscode-gitlens\node_modules\terser\dist\bundle.min.js:1:79313
Child webviews:
    Time: 8161ms
    Built at: 01/05/2020 5:54:58 PM
              Asset       Size  Chunks             Chunk Names
    main-styles.css   22.6 KiB       0  [emitted]  main-styles
     main-styles.js  990 bytes       0  [emitted]  main-styles
      settings.html    104 KiB          [emitted]
        settings.js     24 KiB       1  [emitted]  settings
       welcome.html   38.6 KiB          [emitted]
         welcome.js   20.4 KiB       2  [emitted]  welcome
error Command failed with exit code 2.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

[fabiosantoscode]

Of that repo, I ended up with a pretty simple reproduction:

class x {            
    constructor() {  
        x();         
    }                
}                    

I've recorded a video of doing this, so it might help people come up with minimal reproducible issues.