cue: Value.Equal should not only consider values

It is verified that this is the same behavior as v0.2.2.
So this brings v0.3 closer to v0.2.

This also fixes builtins that still relied on the old
behavior.

Fixes #784

Change-Id: I80714da319f91bc09d2d6c3495deaa369d80c9d6
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/8901
Reviewed-by: CUE cueckoo <cueckoo@gmail.com>
Reviewed-by: Marcel van Lohuizen <mpvl@golang.org>

cue/types.go

@@ -1831,7 +1831,7 @@ func (v Value) Equals(other Value) bool {
 	if v.v == nil || other.v == nil {
 		return false
 	}
-	return adt.Equal(v.ctx().opCtx, v.v, other.v, adt.CheckStructural)
+	return adt.Equal(v.ctx().opCtx, v.v, other.v, 0)
 }
 
 // Format prints a debug version of a value.

cue/types_test.go

@@ -1493,6 +1493,21 @@ func TestEquals(t *testing.T) {
 			a: "foo",
 		}`,
 		false,
+	}, {
+		// Ignore closedness
+		`{ #Foo: { k: 1 }, a: #Foo }`,
+		`{ #Foo: { k: 1 }, a: { k: 1 } }`,
+		true,
+	}, {
+		// Ignore optional fields
+		`{ #Foo: { k: 1 }, a: #Foo }`,
+		`{ #Foo: { k: 1 }, a: { #Foo, i?: 1 } }`,
+		true,
+	}, {
+		// Treat embedding as equal
+		`{ a: 2, b: { 3 } }`,
+		`{ a: { 2 }, b: 3 }`,
+		true,
 	}}
 	for _, tc := range testCases {
 		t.Run("", func(t *testing.T) {

internal/core/adt/equality.go

@@ -57,11 +57,13 @@ func equalVertex(ctx *OpContext, x *Vertex, v Value, flags Flag) bool {
 	}
 
 	// TODO: this really should be subsumption.
-	if x.IsClosed(ctx) != y.IsClosed(ctx) {
-		return false
-	}
-	if flags != 0 && !equalClosed(ctx, x, y, flags) {
-		return false
+	if flags != 0 {
+		if x.IsClosed(ctx) != y.IsClosed(ctx) {
+			return false
+		}
+		if !equalClosed(ctx, x, y, flags) {
+			return false
+		}
 	}
 
 loop1: