evaluator: logical operator ! should not be allowed on a disjunction

[myitcv]

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

$ cue version
cue version v0.0.0-20231020094642-eddccfc72316

go version go1.21.3
      -buildmode exe
       -compiler gc
  DefaultGODEBUG panicnil=1
     CGO_ENABLED 1
          GOARCH arm64
            GOOS linux
             vcs git
    vcs.revision eddccfc72316a648971d9684ac5dcd003ee26385
        vcs.time 2023-10-20T09:46:42Z
    vcs.modified false

Does this issue reproduce with the latest release?

Yes

What did you do?

! exec cue eval x1.cue
cmp stderr stderr.golden

! exec cue eval x2.cue
stderr 'invalid operation'

-- x1.cue --
x: ! (4)

-- x2.cue --
x: ! (4 | 5)

-- stderr.golden --
x: invalid operation !4 (! int):
    ./x1.cue:1:4

What did you expect to see?

Passing test

What did you see instead?

> ! exec cue eval x1.cue
[stderr]
x: invalid operation !4 (! int):
    ./x1.cue:1:4
[exit status 1]
> cmp stderr stderr.golden
> ! exec cue eval x2.cue
[stdout]
x: !(4 | 5)
FAIL: /tmp/testscript2702638972/repro.txtar/script.txtar:4: unexpected command success

The intent here was to use ! as if we had implemented not().

We should disallow the use of ! in this way, ahead of introducing not().

[rogpeppe]

As another data point, ! bool correctly fails:

x: invalid operand bool ('!' requires concrete value):

but ! (true | false) (exactly equivalent AIUI) does not.