encoding/gocode: make work for definitions

The Go code could only be correlated with
values so far. Allow either.

Change-Id: I3ebf8fd532a66eb11fe933f8e40a8e28b8eb5c42
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/4981
Reviewed-by: Marcel van Lohuizen <mpvl@golang.org>

encoding/gocode/generator.go

@@ -139,7 +139,7 @@ func Generate(pkgPath string, inst *cue.Instance, c *Config) (b []byte, err erro
 		pkgName = g.pkg.Name
 
 		for _, obj := range g.pkg.TypesInfo.Defs {
-			if obj == nil || obj.Pkg() != g.pkg.Types {
+			if obj == nil || obj.Pkg() != g.pkg.Types || obj.Parent() == nil {
 				continue
 			}
 			g.typeMap[obj.Name()] = obj.Type()
@@ -152,7 +152,7 @@ func Generate(pkgPath string, inst *cue.Instance, c *Config) (b []byte, err erro
 		"pkgName": pkgName,
 	})
 
-	iter, err := inst.Value().Fields()
+	iter, err := inst.Value().Fields(cue.Definitions(true))
 	g.addErr(err)
 
 	for iter.Next() {
@@ -231,7 +231,10 @@ func (g *generator) decl(name string, v cue.Value) {
 
 	zero := "nil"
 
-	typ := g.typeMap[goTypeName]
+	typ, ok := g.typeMap[goTypeName]
+	if !ok && !mappedGoTypes(goTypeName) {
+		return
+	}
 	if goType == "" {
 		goType = goTypeName
 		if typ != nil {
@@ -276,3 +279,13 @@ func strValue(have, fallback string) string {
 	}
 	return have
 }
+
+func mappedGoTypes(s string) bool {
+	switch s {
+	case "bool", "float32", "float64",
+		"int", "int8", "int16", "int32", "int64", "string",
+		"uint", "uint8", "uint16", "uint32", "uint64":
+		return true
+	}
+	return false
+}

encoding/gocode/templates.go

@@ -19,7 +19,7 @@ import "text/template"
 // Inputs:
 // .pkgName  the Go package name
 var headerCode = template.Must(template.New("header").Parse(
-	`// Code generated by gogen.Generate; DO NOT EDIT.
+	`// Code generated by gocode.Generate; DO NOT EDIT.
 
 package {{.pkgName}}
 
@@ -80,10 +80,11 @@ var {{.prefix}}Codec, {{.prefix}}Instance = func() (*gocodec.Codec, *cue.Instanc
 // {{.prefix}}Make is called in the init phase to initialize CUE values for
 // validation functions.
 func {{.prefix}}Make(name string, x interface{}) cue.Value {
-	v := {{.prefix}}Instance.Lookup(name)
-	if !v.Exists() {
+	f, err := {{.prefix}}Instance.LookupField(name)
+	if err != nil {
 		panic(fmt.Errorf("could not find type %q in instance", name))
 	}
+	v := f.Value
 	if x != nil {
 		w, err := {{.prefix}}Codec.ExtractType(x)
 		if err != nil {

encoding/gocode/testdata/pkg1/instance.cue

@@ -22,6 +22,8 @@ String: !="" @go(,validate=ValidateCUE)
 
 SpecialString: =~"special" @go(,type=string)
 
+IgnoreThis: =~"foo" // No corresponding Go type
+
 Omit: int @go(-)
 
 // NonExisting will be omitted as there is no equivalent Go type.