congo-cc
jsonc needs to support trailing commas
Fixing this will probably need to avoid including the JSON.ccc file in JSONC.ccc, but rather copying its contents and changing the grammar to allow trailing commas. Also, JSONC allows bare identifiers as keys, which would need to be catered for - that's not mentioned in the title of this issue.
Well, generally speaking, these JSON and JSONC grammars are pretty trivial examples that are provided potentially as a starting point, though they can be useful as-is too, depending on your case. But if you want something slightly different, it should not be very hard to modify the grammar to do what you need.
This is over two years old, so I'm closing it. Hopefully the OP finally understood that the JSON grammars are just examples that you can use as a starting point.