"field is required but not present" never surfaces data files as positions

[vytstank]

What version of CUE are you using (cue version)?

$ podman run -ti --rm cuelang/cue:latest version
cue version v0.15.4

CUE language version v0.15.4

Go version go1.25.6
      -buildmode exe
       -compiler gc
       -trimpath true
     CGO_ENABLED 0
          GOARCH arm64
            GOOS linux
         GOARM64 v8.0

Does this issue reproduce with the latest stable release?

Yes

What did you do?

Trying out some validation patterns to create schemas. Not sure if this is a bug or expected behavior, but sharing the case.

$ cat demo.yaml
type: cat
diet: chicken

$ cat demo.cue
name!:   string // All animals have a name.
type!:   string // Every animal must have a type.
height?: int    // Optional, as we haven't managed to measure *every* animal just yet.

$  podman run -ti --rm -v $(pwd):/workspace -w /workspace cuelang/cue:latest vet -c demo.cue demo.yaml
name: field is required but not present:
    ./demo.cue:1:1

What did you expect to see?

./demo.yaml: somewhere in addition to demo.cue

What did you see instead?

name: field is required but not present:
    ./demo.cue:1:1

[mvdan]

Hello again, and thanks for stopping by our booth at CfgMgmtCamp :)

I see what's happening now, thanks for the example. "field is required but not present" is a type of error which relates to a required field not having been unified with a regular field which satisfies it. So in that sense, the error is correct in only showing a position for the CUE file; no other source or data file contributed to that field or its value.

From a UX perspective and given your example, I can understand how this is not desirable, though. I'll have a think about this and get back to you tomorrow.

[mvdan]

For context, here's the reproducer in testscript form:

exec cue vet -c in.cue data.yaml

-- in.cue --
name!:   string
type!:   string
height?: int
-- data.yaml --
type: cat
diet: chicken

> exec cue vet -c in.cue data.yaml
[stderr]
name: field is required but not present:
    ./in.cue:1:1
[exit status 1]