importing an empty yaml file as a list panics

[uhthomas]

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

$ cue version

e1ceed4

Does this issue reproduce with the latest stable release?

Yes.

What did you do?

❯ touch empty.yaml
❯ cue import --list empty.yaml
panic: unreachable [recovered]
        panic: unreachable

goroutine 1 [running]:
cuelang.org/go/cmd/cue/cmd.recoverError(0xc0004fbe78)
        cuelang.org/go/cmd/cue/cmd/root.go:318 +0x76
panic({0x56236702db60?, 0x56236714b500?})
        runtime/panic.go:914 +0x21f
cuelang.org/go/cmd/cue/cmd.placeOrphans(0xc000299790, 0xc0001d5290, {0x0, 0x0}, {0x0, 0x0, 0x0?})
        cuelang.org/go/cmd/cue/cmd/orphans.go:299 +0xe3d
cuelang.org/go/cmd/cue/cmd.(*buildPlan).placeOrphans(0xc000299790, 0xc0002ca780, {0xc000120170, 0x1, 0x5623666a1488?})
        cuelang.org/go/cmd/cue/cmd/orphans.go:141 +0x5ad
cuelang.org/go/cmd/cue/cmd.parseArgs(0xc000428750, {0xc00041f180, 0x1, 0x2}, 0xc00034edc0)
        cuelang.org/go/cmd/cue/cmd/common.go:655 +0xfac
cuelang.org/go/cmd/cue/cmd.runImport(0xc000428750?, {0xc00041f180, 0x1, 0x2})
        cuelang.org/go/cmd/cue/cmd/import.go:314 +0x786
cuelang.org/go/cmd/cue/cmd.newImportCmd.mkRunE.func1(0xc000434600?, {0xc00041f180, 0x1, 0x2})
        cuelang.org/go/cmd/cue/cmd/root.go:87 +0xab
github.com/spf13/cobra.(*Command).execute(0xc000437200, {0xc00041f160, 0x2, 0x2})
        github.com/spf13/cobra@v1.7.0/command.go:940 +0x87c
github.com/spf13/cobra.(*Command).ExecuteC(0xc000005200)
        github.com/spf13/cobra@v1.7.0/command.go:1068 +0x3a5
github.com/spf13/cobra.(*Command).Execute(...)
        github.com/spf13/cobra@v1.7.0/command.go:992
cuelang.org/go/cmd/cue/cmd.(*Command).Run(0xc000428750, {0x3?, 0x3?})
        cuelang.org/go/cmd/cue/cmd/root.go:303 +0x65
cuelang.org/go/cmd/cue/cmd.Main()
        cuelang.org/go/cmd/cue/cmd/root.go:231 +0x72
main.main()
        cuelang.org/go/cmd/cue/main.go:24 +0x13

What did you expect to see?

An empty list.

empty.cue

[]

What did you see instead?

See above.

[mvdan]

Duplicate of #1790 and possibly #2714 too, I think.

[mvdan]

Hm, I actually take that back for now, because the panic doesn't look the same. It might not be an exact duplicate.

[uhthomas]

Seems to be this:

cue/cmd/cue/cmd/orphans.go

Line 299 in e1ceed4

panic("unreachable")

I can push a fix I think.

[uhthomas]

https://review.gerrithub.io/c/cue-lang/cue/+/1173072