cmd/cue: get go generates invalid CUE from byte type

[james-maloney]

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

$ cue version
cue version v0.4.0 darwin/amd64

Does this issue reproduce with the latest release?

Yes

What did you do?

package cuego

import "github.com/google/uuid"

type Bar struct {
    ID uuid.UUID
}

Generate Cue from Go package

cue get go cuego

Output:

$cat cuego/types_go_gen.cue

// Code generated by cue get go. DO NOT EDIT.

//cue:generate cue get go cuego

package cuego

import "github.com/google/uuid"

#Bar: ID: uuid.#UUID

Vet

cue vet gen/cuego/types_go_gen.cue
#Domain: reference "byte" not found:
    ./gen/github.com/google/uuid/dce_go_gen.cue:8:10
#Version: reference "byte" not found:
    ./gen/github.com/google/uuid/uuid_go_gen.cue:12:11
#Variant: reference "byte" not found:
    ./gen/github.com/google/uuid/uuid_go_gen.cue:15:11

What did you expect to see?

A valid cue file generated from the Go package

What did you see instead?

An invalid cue file using an un-known byte type

// Code generated by cue get go. DO NOT EDIT.

//cue:generate cue get go github.com/google/uuid

package uuid

// A Domain represents a Version 2 domain
#Domain: byte // #enumDomain

#enumDomain:
	#Person |
	#Group |
	#Org

#values_Domain: {
	Person: #Person
	Group:  #Group
	Org:    #Org
}

#Person: #Domain & 0
#Group:  #Domain & 1
#Org:      #Domain & 2

[slewiskelly]

In Go, but not in CUE, a byte is an alias for uint8.

Using uint8 in place of byte works as expected, so (naively) assume a similar translation needs to occur?

The only documentation I see about byte or bytes is when translating arrays or slices:

• slices and arrays convert to CUE lists, except when the element type is byte, in which case it translates to the CUE bytes type.

However, there is a note here which mentions why there is no byte builtin:

Do not include an alias for "byte", as it would be too easily confused with the builtin "bytes".

[myitcv]

Thanks for the report, @james-maloney.

Confirmed with e8550b8:

exec cue get go --local .
exec cue eval

-- go.mod --
module mod.com

go 1.16
-- main.go --
package cuego

type Bar byte
-- main_go_gen.cue --
// Code generated by cue get go. DO NOT EDIT.

//cue:generate cue get go mod.com

package cuego

#Bar: byte

gives:

> exec cue eval
[stderr]
#Bar: reference "byte" not found:
    ./main_go_gen.cue:7:7
[exit status 1]
FAIL: /tmp/testscript009373651/repro.txt/script.txt:2: unexpected command failure