pkg/encoding/yaml: validate concreteness instead of instance of for Validate

This makes the checks more permissive. Subsumption will
no longer be a part of the new evaluator, so we need to use
something different. Ultimately, the use of Subsumption here
is not ideal anyway, instead users should be able to specify
underspecified values in the type definitions itself.

Change-Id: I852bd4ebda805de3536ca33d4950dedcd379d835
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/6462
Reviewed-by: CUE cueckoo <[email protected]>
Reviewed-by: Marcel van Lohuizen <[email protected]>

Author: mpvl

cmd/cue/cmd/testdata/script/vet_yaml.txt

@@ -2,11 +2,9 @@
 cmp stderr expect-stderr
 
 -- expect-stderr --
-phrases: error in call to encoding/yaml.Validate: missing field "text":
+phrases: error in call to encoding/yaml.Validate: phrases.quote1.text: incomplete value (!=""):
     ./yaml.cue:19:10
-    ./yaml.cue:4:11
     ./yaml.cue:11:17
-    yaml.Validate:4:6
 -- yaml.cue --
 import "encoding/yaml"
 

cue/builtin_test.go

@@ -115,13 +115,13 @@ func TestBuiltins(t *testing.T) {
 		`_|_(error in call to encoding/json.Validate: a: invalid value 10 (out of bound <3))`,
 	}, {
 		test("encoding/yaml", `yaml.Validate("a: 2\n---\na: 4", {a:<3})`),
-		`_|_(error in call to encoding/yaml.Validate: invalid value 4 (out of bound <3))`,
+		`_|_(error in call to encoding/yaml.Validate: a: invalid value 4 (out of bound <3))`,
 	}, {
 		test("encoding/yaml", `yaml.Validate("a: 2\n---\na: 4", {a:<5})`),
 		`true`,
 	}, {
 		test("encoding/yaml", `yaml.Validate("a: 2\n", {a:<5, b:int})`),
-		`_|_(error in call to encoding/yaml.Validate: value not an instance)`,
+		`_|_(error in call to encoding/yaml.Validate: b: incomplete value (int))`,
 	}, {
 		test("encoding/yaml", `yaml.ValidatePartial("a: 2\n---\na: 4", {a:<3})`),
 		`_|_(error in call to encoding/yaml.ValidatePartial: a: invalid value 4 (out of bound <3))`,

cue/builtins.go

@@ -94,9 +94,23 @@ func Validate(b []byte, v cue.Value) (bool, error) {
 			return false, err
 		}
 
-		if err := v.Subsume(inst.Value(), cue.Final()); err != nil {
+		// TODO: consider using subsumption again here.
+		// Alternatives:
+		// - allow definition of non-concrete list,
+		//   like list.Of(int), or []int.
+		// - Introduce ! in addition to ?, allowing:
+		//   list!: [...]
+		// if err := v.Subsume(inst.Value(), cue.Final()); err != nil {
+		// 	return false, err
+		// }
+		x := v.Unify(inst.Value())
+		if err := x.Err(); err != nil {
 			return false, err
 		}
+		if err := x.Validate(cue.Concrete(true)); err != nil {
+			return false, err
+		}
+
 	}
 }