Consider this input:

std.parseYaml("0777")

cpp-jsonnet outputs:

Something went wrong during jsonnet_evaluate_snippet, please report this: [json.exception.parse_error.101] parse error at line 1, column 5: syntax error while parsing array - unexpected number literal; expected ']'
Segmentation fault

go-jsonnet outputs:

511

jrsonnet outputs:

511

sjsonnet outputs:

sjsonnet.Error: Internal error: scala.MatchError: null
Caused by: scala.MatchError: null

But this is caused by sjsonnet only supporting objects in parseYaml, so std.parseYaml("a: 0777") works:

{
   "a": 511
}

Why does it happens?
Well, there is two yaml specs: yaml 1.1, and yaml 1.2, and even if it is a minor update by semver... It isn't a semver.
The one breaking change in yaml 1.2, is that octal literals in 0777 form are now forbidden, 0o777 should be used instead.

However, many yaml implementations are not following the spec, especially golang, which will even output octals in 0777 format: go-yaml/yaml#420

For jrsonnet, I had to modify serde-yaml rust library to also accept this input: dtolnay/serde-yaml#225

And rapidyaml did not implemented this compatibility feature: biojppm/rapidyaml#291