internal: remove MakeInstance

Its last use was in internal/encoding and removed in
https://cuelang.org/cl/1193586, which fixed its deprecation warnings.

This removes the close dependency between the cue and internal packages,
which is a good step as it was a bit of a hack.

Signed-off-by: Daniel Martí <mvdan@mvdan.cc>
Change-Id: I449eb6ddad58da256c4ff7eb64d134a73d1cfa27
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1193598
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>
Reviewed-by: Roger Peppe <rogpeppe@gmail.com>
Unity-Result: CUE porcuepine <cue.porcuepine@gmail.com>

cue/instance.go

@@ -18,7 +18,6 @@ import (
 	"cuelang.org/go/cue/ast"
 	"cuelang.org/go/cue/build"
 	"cuelang.org/go/cue/errors"
-	"cuelang.org/go/internal"
 	"cuelang.org/go/internal/core/adt"
 	"cuelang.org/go/internal/core/compile"
 	"cuelang.org/go/internal/core/runtime"
@@ -138,21 +137,6 @@ func getImportFromPath(x *runtime.Runtime, id string) *Instance {
 	return inst
 }
 
-func init() {
-	internal.MakeInstance = func(value interface{}) interface{} {
-		v := value.(Value)
-		x := v.eval(v.ctx())
-		st, ok := x.(*adt.Vertex)
-		if !ok {
-			st = &adt.Vertex{}
-			st.AddConjunct(adt.MakeRootConjunct(nil, x))
-		}
-		return addInst(v.idx, &Instance{
-			root: st,
-		})
-	}
-}
-
 // newInstance creates a new instance. Use Insert to populate the instance.
 func newInstance(x *runtime.Runtime, p *build.Instance, v *adt.Vertex) *Instance {
 	// TODO: associate root source with structLit.

internal/internal.go

@@ -90,9 +90,6 @@ func (c Context) Sqrt(d, x *apd.Decimal) (apd.Condition, error) {
 // incomplete.
 var ErrIncomplete = errors.New("incomplete value")
 
-// MakeInstance makes a new instance from a value.
-var MakeInstance func(value interface{}) (instance interface{})
-
 // BaseContext is used as CUE's default context for arbitrary-precision decimals.
 var BaseContext = Context{*apd.BaseContext.WithPrecision(34)}