How does CUE parse value supplied to its "--inject" flag?

[seh]

Moving here from the "general" channel in the "CUE" Slack workspace, I have a CUE file with a @tag attribute defined like this:

built_at: int @tag(builtat,type=int)

If I run cue export file.cue --inject builtat=1, it works as expected.
If I run cue export file.cue --inject builtat=x, it fails with this message:

built_at: reference "x" not found:
    builtat:1:1

That sort of makes sense, though I’m not sure what it means by “reference” there. With what is CUE trying to match the string “x”?

Also interesting: If I instead run cue export file.cue --inject ’builtat={x}’, with curly braces around “x,” it fails with the same message, having “unwrapped” the value “{x}“:

built_at: reference "x" not found:
    builtat:1:2

Is there some syntax for the right-hand side of that equals sign that CUE is parsing? The documentation in cue injection doesn’t mention anything elaborate.

[myitcv]

@seh - sincere apologies for being slow at replying to this (and thank you for raising it as a discussion from Slack in the first place).

This looks like a bug to me: injected values can only be concrete. AFAICT, that error comes from the compiler, and if the injection has got that far without being detected as a type error. Hence I've raised: #1010

But in investigating this I stumbled across another issue that looks like a typo/copy paste bad error message, raised as: #1011

[cueckoo]

This discussion has been migrated to cue-lang/cue#932.

For more details about CUE's migration to a new home, please see cue-lang/cue#1078.