Parcel: Parcel 2: Unexpected token: punc (.)

[Banou26]

🐛 bug report

Build error when using targets in a monorepo, same config as https://github.com/parcel-bundler/parcel/issues/4392

🚨 Build failed.
@parcel/optimizer-terser: Unexpected token: punc (.)
SyntaxError: Unexpected token: punc (.)
    at ee (/home/banou/dev/test/node_modules/terser/dist/bundle.min.js:1:19391)
    at c (/home/banou/dev/test/node_modules/terser/dist/bundle.min.js:1:27867)
    at l (/home/banou/dev/test/node_modules/terser/dist/bundle.min.js:1:27958)
    at f (/home/banou/dev/test/node_modules/terser/dist/bundle.min.js:1:28011)
    at G (/home/banou/dev/test/node_modules/terser/dist/bundle.min.js:1:41825)
    at De (/home/banou/dev/test/node_modules/terser/dist/bundle.min.js:1:48112)
    at /home/banou/dev/test/node_modules/terser/dist/bundle.min.js:1:48992
    at ye (/home/banou/dev/test/node_modules/terser/dist/bundle.min.js:1:49007)
    at ze (/home/banou/dev/test/node_modules/terser/dist/bundle.min.js:1:50261)
    at qe (/home/banou/dev/test/node_modules/terser/dist/bundle.min.js:1:50493)
error Command failed with exit code 1.

I managed to workaround the bug by removing the engines property in the target

  "targets": {
-    "appModern": {
-      "engines": {
-        "browsers": [
-          "last 1 chrome version"
-        ]
-      }
-    },
+    "appModern": {},
  },

Using ^2.0.0-nightly.180.

[mischnic]

I guess this is because terser doesn't support optional chaining

echo " export function f(){return x?.y; }" | terser -mc --module
Parse error at 0:1,30
 export function f(){return x?.y; }
                              ^
ERROR: Unexpected token: punc (.)

We should definitely add a codeframe to that error.

For the cause itself:

• would you understand that terser doesn't support that syntax and that you need to change your babelrc/browserslist?
• or should we add a hint like "Terser might not support this syntax yes"

[Banou26]

I mean, my .babelrc does contains @babel/plugin-proposal-optional-chaining, shouldn't it be okay ?

[mischnic]

Yes, but if removing targets.appModern.engines changes the behaviour of babel, then your .babelrc isn't actually being used.

[mischnic]

This is what the codeframe would look like without using source maps (this is potentially more correct since the unsupported syntax could have been inserted by a build step)

On the other hand, it's a lot prettier displaying the source in this case:

[Banou26]

Why not both ? :)
Just kidding.

Maybe have the source display as normal log level, and the final result when using the verbose log level ?

[mischnic]

Great idea.

(I'm not entirely happy with the formatting of these diagnostics but we have bigger priorities right now.)

Will open a PR once https://github.com/parcel-bundler/source-map/issues/15 is resolved.

[lukejagodzinski]

I've just encountered this problem. I'm targeting newest Chrome browser which already has optional chaining. It's no longer proposal. Shouldn't this be just ignored?