2 files changed, 17 insertions, 0 deletions
diff --git a/vendor/github.com/alecthomas/go-check-sumtype/decl.go b/vendor/github.com/alecthomas/go-check-sumtype/decl.go
index ea2cd06df..9dec9eefd 100644
--- a/vendor/github.com/alecthomas/go-check-sumtype/decl.go
+++ b/vendor/github.com/alecthomas/go-check-sumtype/decl.go
@@ -57,6 +57,7 @@ func findSumTypeDecls(pkgs []*packages.Package) ([]sumTypeDecl, error) {
 					}
 					pos = pkg.Fset.Position(tspec.Pos())
 					decl := sumTypeDecl{Package: pkg, TypeName: tspec.Name.Name, Pos: pos}
+					debugf("found sum type decl: %s.%s", decl.Package.PkgPath, decl.TypeName)
 					decls = append(decls, decl)
 					break
 				}
diff --git a/vendor/github.com/alecthomas/go-check-sumtype/def.go b/vendor/github.com/alecthomas/go-check-sumtype/def.go
index 811b98f98..24729ac01 100644
--- a/vendor/github.com/alecthomas/go-check-sumtype/def.go
+++ b/vendor/github.com/alecthomas/go-check-sumtype/def.go
@@ -1,11 +1,21 @@
 package gochecksumtype
 
 import (
+	"flag"
 	"fmt"
 	"go/token"
 	"go/types"
+	"log"
 )
 
+var debug = flag.Bool("debug", false, "enable debug logging")
+
+func debugf(format string, args ...interface{}) {
+	if *debug {
+		log.Printf(format, args...)
+	}
+}
+
 // Error as returned by Run()
 type Error interface {
 	error
@@ -107,6 +117,7 @@ func newSumTypeDef(pkg *types.Package, decl sumTypeDecl) (*sumTypeDef, error) {
 		Decl: decl,
 		Ty:   iface,
 	}
+	debugf("searching for variants of %s.%s\n", pkg.Path(), decl.TypeName)
 	for _, name := range pkg.Scope().Names() {
 		obj, ok := pkg.Scope().Lookup(name).(*types.TypeName)
 		if !ok {
@@ -116,7 +127,12 @@ func newSumTypeDef(pkg *types.Package, decl sumTypeDecl) (*sumTypeDef, error) {
 		if types.Identical(ty.Underlying(), iface) {
 			continue
 		}
+		// Skip generic types.
+		if named, ok := ty.(*types.Named); ok && named.TypeParams() != nil {
+			continue
+		}
 		if types.Implements(ty, iface) || types.Implements(types.NewPointer(ty), iface) {
+			debugf("  found variant: %s.%s\n", pkg.Path(), obj.Name())
 			def.Variants = append(def.Variants, obj)
 		}
 	}