JSON fails to parse with a trailing comment at the end of an array

[elibarzilay]

Windows Terminal version (or Windows build number)

1.10.2714.0

Other Software

No response

Steps to reproduce

In the settings file, put a comment at the end of an object with a comma after it.

This fails:

"actions": [
  {},
  // ...
],

Dropping either the , or the comment makes it work.

Expected Behavior

Should be parsed as usual since both terminating commas and comments are allowed, or forbid trailing commas (assuming that comments are a desired feature).

Actual Behavior

Settings could not be loaded from file. Check for syntax errors, including trailing commas.

[zadjii-msft]

I suspect this is a jsoncpp bug. I know that they don't support a "trailing" comment, the comment has to be before some real value that it can attach the comment too. That being said, there's nothing open on their repo (or maybe I'm just bad at searching). We should probably drum up a minimal repro without the Terminal involved and post this upstream

[jamespack]

I have a minimal repro example ready to go to file a bug at jsoncpp. But before I did, I did some searching and I cant find where trailing commas are permitted by the spec and most searches on StackOverflow indicate that they are not permitted.

https://stackoverflow.com/questions/201782/can-you-use-a-trailing-comma-in-a-json-object

From MDN:

Maybe a better error message could be produced?

[jamespack]

Still happy to open the issue if you think it'd be prudent :)

[lhecker]

Many JSON parsers allow trailing commas as an extension to the spec, including jsoncpp with the allowTrailingCommas option. This is helpful, because trailing commas make editing and diffing JSON files easier.

[jamespack]

Right on. I will open an with them today then. Thanks for the clarification!

[jamespack]

Here you go

open-source-parsers/jsoncpp#1500

[sba923]

Many JSON parsers allow trailing commas as an extension to the spec, including jsoncpp with the allowTrailingCommas option. This is helpful, because trailing commas make editing and diffing JSON files easier.

VScode doesn't like Windows Terminal's defaults.json:

@nguyen-dows does this deserve an issue?