YAMLConfiguration handles trailing comma not as expected

[pgeier]

What happened?

I've got a json file with the following structure

{"rules": [
  {...}, 
  {...},
   ..., 
  {...},
]}

The file is read with eckit::LocalConfiguration{eckit::YAMLConfiguration{eckit::PathName{...}}}
and accessed with .getSubConfigurations("rules"), which returns a std::vector<eckit::LocalConfiguration>.

Now, because of the trailing comma, the vector contains an additional element which is printed as LocalConfiguration[root=].
This element is not expected.

For a formal JSON, the trailing comma would not be allowed. In a YAML file it should (AFAIK - maybe compare with this closed issue on the YAML formatter prettier: prettier/prettier#7452)

What are the steps to reproduce the bug?

Create an additional test that parses a list with trailing comma.

Version

1.30.0

Platform (OS and architecture)

Atos

Relevant log output

There are just followup errors when accessing keys in the subdictionary.
Explicitly printing the last entry shows `LocalConfiguration[root=]`.

Accompanying data

No response

Organisation

ECMWF

[wdeconinck]

Hi @pgeier I don't know who would have time to look into this.
It does not seem like anything with priority, especially if this is a yaml file that you created yourself...? In which case you could remove the trailing comma.

[Ozaq]

Trailing commas are not allowed in JSON, see https://www.json.org/json-en.html. Further they are also not supported in YAML.