hcldec: ImpliedSchema must visit deep specs

Previously, due to a bug, it was only visiting the first two levels of
specifications, missing anything referenced at lower levels.

hcldec/public_test.go

@@ -86,6 +86,23 @@ func TestDecode(t *testing.T) {
 			cty.NumberIntVal(10),
 			0,
 		},
+		{
+			"a = 1\n",
+			ObjectSpec{
+				"foo": &DefaultSpec{
+					Primary: &AttrSpec{
+						Name: "a",
+						Type: cty.Number,
+					},
+					Default: &LiteralSpec{
+						Value: cty.NumberIntVal(10),
+					},
+				},
+			},
+			nil,
+			cty.ObjectVal(map[string]cty.Value{"foo": cty.NumberIntVal(1)}),
+			0,
+		},
 		{
 			"a = \"1\"\n",
 			&AttrSpec{

hcldec/schema.go

@@ -14,7 +14,8 @@ func ImpliedSchema(spec Spec) *hcl.BodySchema {
 	// visitSameBodyChildren walks through the spec structure, calling
 	// the given callback for each descendent spec encountered. We are
 	// interested in the specs that reference attributes and blocks.
-	visit := func(s Spec) {
+	var visit visitFunc
+	visit = func(s Spec) {
 		if as, ok := s.(attrSpec); ok {
 			attrs = append(attrs, as.attrSchemata()...)
 		}
@@ -22,10 +23,11 @@ func ImpliedSchema(spec Spec) *hcl.BodySchema {
 		if bs, ok := s.(blockSpec); ok {
 			blocks = append(blocks, bs.blockHeaderSchemata()...)
 		}
+
+		s.visitSameBodyChildren(visit)
 	}
 
 	visit(spec)
-	spec.visitSameBodyChildren(visit)
 
 	return &hcl.BodySchema{
 		Attributes: attrs,