cmd/cue: tool/exec.Run doesn't handle lists of environment variables

[nickfiggins]

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

$ cue version
cue version v0.7.0

go version go1.21.5
      -buildmode exe
       -compiler gc
       -trimpath true
     CGO_ENABLED 0
          GOARCH amd64
            GOOS darwin
         GOAMD64 v1

Does this issue reproduce with the latest stable release?

yes

What did you do?

exec cue cmd envFromList
stdout FOO=BAR
-- a_tool.cue --
package p

import "tool/exec"

command: envFromList: exec.Run & {
	cmd: "env"
	env: ["FOO=BAR"]
}

What did you expect to see?

A passing test (as a result of FOO=BAR populated in the command output).

What did you see instead?

> exec cue cmd envFromList
            [stderr]
            command.envFromList.env: conflicting values ["FOO=BAR"] and {[string]:(string|[...=~"="])} (mismatched types list and struct):
                ./a_tool.cue:5:23
                ./a_tool.cue:7:7
                tool/exec:6:8
            [exit status 1]
            FAIL: testdata/script/cmd_execenv.txtar:1: unexpected command failure

Per the docs (and implementation), it seems like this usage of env is meant to be supported. It seems like this just may be due to the order of operations in the env definition which leads to this schema being generated

[mvdan]

Thanks - this looks like a mistake in the schema. I think env: [string]: string | [...=~"="] should be env: {[string]: string} | [...=~"="] so that the disjunction applies to the entire [string]: string, otherwise it applies to just string on the left side. See: https://tip.cuelang.org/play/?id=Q2sENh20fvy#cue@export@cue