envoyproxy#GH-585 fix generated enum type name

Signed-off-by: Elliot Jackson <[email protected]>

templates/go/file.go

@@ -41,7 +41,7 @@ var (
 	_ = sort.Sort
 
 	{{ range $pkg, $path := enumPackages (externalEnums .) }}
-	_ = {{ $pkg }}.{{ enumName (index (externalEnums $) 0) }}(0)
+		_ = {{ $pkg }}.{{ enumType (index (externalEnums $) 0) }}(0)
 	{{ end }}
 )
 

templates/goshared/register.go

@@ -50,6 +50,7 @@ func Register(tpl *template.Template, params pgs.Parameters) {
 		"externalEnums": fns.externalEnums,
 		"enumName":      fns.enumName,
 		"enumPackages":  fns.enumPackages,
+		"enumType":      fns.enumType,
 	})
 
 	template.Must(tpl.New("msg").Parse(msgTpl))
@@ -365,6 +366,25 @@ func (fns goSharedFuncs) enumPackages(enums []pgs.Enum) map[pgs.Name]pgs.FilePat
 	return out
 }
 
+// recursively walks up the parents of the enum until it reaches the root file
+// prepends 'Message_' for each message it sees on the way. This builds up the generated enum type name.
+//
+// intended to be used by the enumType function to build the generate type name.
+func walkEnumParents(parent pgs.ParentEntity, name string) string {
+	switch t := parent.(type) {
+	case pgs.Message:
+		return walkEnumParents(t.Parent(), string(t.Name())+"_"+name)
+	case pgs.File:
+		return name
+	default:
+		panic("enum parent can only resolve to message or file")
+	}
+}
+
+func (fns goSharedFuncs) enumType(enum pgs.Enum) string {
+	return walkEnumParents(enum.Parent(), string(enum.Name()))
+}
+
 func (fns goSharedFuncs) snakeCase(name string) string {
 	return strcase.ToSnake(name)
 }