Round-trip failure with certain unsigned int64 values

[beojan]

Jsonnet produces surprising output for certain unsigned int64 values. For example, with this test.jsonnet:

{
    a_uint: 18446744073709551615,
    b_uint: 9223372036854775807
}

jsonnet test.jsonnet produces this output:

{
   "a_uint": 18446744073709551616,
   "b_uint": 9223372036854775808
}

Tagging Framework-R-D/phlex#243.

EDIT: Evidently this is because all numbers are 64-bit floats in Jsonnet.

[johnbartholomew]

EDIT: Evidently this is because all numbers are 64-bit floats in Jsonnet

Yes, I think you've found the reason. It is mentioned in the reference (https://jsonnet.org/ref/language.html#number which notes the limited range of safely representable integers) but it's still not ideal that inputs like your example here silently fail to round-trip properly.

There will always be non-representable numbers unless we go to a full arbitrary precision representation, which I'm hesitant to do. But given the use of JSON for things involving, eg, machine configuration, 64-bit integers are pretty common (e.g., https://github.com/opencontainers/runtime-spec/blob/d64c1d945da7cf6970061c7c9ff4391fafdf2a15/schema/defs.json#L19-L22) so it would be good to cope with them more gracefully.