Fix up the MapWalk function so that it properly handles nested map[interface{}]interface{} (#5774)

go.mod

@@ -95,7 +95,7 @@ require (
 	github.com/mitchellh/go-testing-interface v1.0.0
 	github.com/mitchellh/hashstructure v0.0.0-20170609045927-2bca23e0e452
 	github.com/mitchellh/mapstructure v1.1.2
-	github.com/mitchellh/reflectwalk v0.0.0-20170726202117-63d60e9d0dbc
+	github.com/mitchellh/reflectwalk v1.0.1
 	github.com/oklog/run v0.0.0-20180308005104-6934b124db28 // indirect
 	github.com/onsi/gomega v1.4.2 // indirect
 	github.com/opencontainers/go-digest v1.0.0-rc1 // indirect

go.sum

@@ -256,8 +256,8 @@ github.com/mitchellh/iochan v1.0.0/go.mod h1:JwYml1nuB7xOzsp52dPpHFffvOCDupsG0Qu
 github.com/mitchellh/mapstructure v0.0.0-20160808181253-ca63d7c062ee/go.mod h1:FVVH3fgwuzCH5S8UJGiWEs2h04kUh9fWfEaFds41c1Y=
 github.com/mitchellh/mapstructure v1.1.2 h1:fmNYVwqnSfB9mZU6OS2O6GsXM+wcskZDuKQzvN1EDeE=
 github.com/mitchellh/mapstructure v1.1.2/go.mod h1:FVVH3fgwuzCH5S8UJGiWEs2h04kUh9fWfEaFds41c1Y=
-github.com/mitchellh/reflectwalk v0.0.0-20170726202117-63d60e9d0dbc h1:gqYjvctjtX4GHzgfutJxZpvZ7XhGwQLGR5BASwhpO2o=
+github.com/mitchellh/reflectwalk v1.0.1 h1:FVzMWA5RllMAKIdUSC8mdWo3XtwoecrH79BY70sEEpE=
-github.com/mitchellh/reflectwalk v0.0.0-20170726202117-63d60e9d0dbc/go.mod h1:mSTlrgnPZtwu0c4WaC2kGObEpuNDbx0jmZXqmk4esnw=
+github.com/mitchellh/reflectwalk v1.0.1/go.mod h1:mSTlrgnPZtwu0c4WaC2kGObEpuNDbx0jmZXqmk4esnw=
 github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd h1:TRLaZ9cD/w8PVh93nsPXa1VrQ6jlwL5oN8l14QlcNfg=
 github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd/go.mod h1:6dJC0mAP4ikYIbvyc7fijjWJddQyLn8Ig3JB5CqoB9Q=
 github.com/modern-go/reflect2 v1.0.1 h1:9f412s+6RmYXLWZSEzVVgPGK7C2PphHj5RJrvfx9AWI=

lib/map_walker.go

@@ -95,8 +95,31 @@ func (w *mapWalker) Map(m reflect.Value) error {
 func (w *mapWalker) MapElem(m, k, v reflect.Value) error {
 	w.csData = k
 	w.csKey = append(w.csKey, k)
-
 	w.lastValue = v
+
+	// We're looking specifically for map[interface{}]interface{}, but the
+	// values in a map could be wrapped up in interface{} so we need to unwrap
+	// that first. Therefore, we do three checks: 1.) is it valid? so we
+	// don't panic, 2.) is it an interface{}? so we can unwrap it and 3.)
+	// after unwrapping the interface do we have the map we expect?
+	if !v.IsValid() {
+		return nil
+	}
+
+	if v.Kind() != reflect.Interface {
+		return nil
+	}
+
+	if inner := v.Elem(); inner.Type() == typMapIfaceIface {
+		// map[interface{}]interface{}, attempt to weakly decode into string keys
+		var target map[string]interface{}
+		if err := mapstructure.WeakDecode(v.Interface(), &target); err != nil {
+			return err
+		}
+
+		m.SetMapIndex(k, reflect.ValueOf(target))
+	}
+
 	return nil
 }
 

lib/map_walker_test.go

@@ -38,20 +38,21 @@ func TestMapWalk(t *testing.T) {
 			},
 			unexpected: true,
 		},
-		// TODO(banks): despite the doc comment, MapWalker doesn't actually fix
+		// ensure nested maps get processed correctly
-		// these cases yet. Do that in a later PR.
+		"nested": tcase{
-		// "map iface": tcase{
+			input: map[string]interface{}{
-		//  input: map[string]interface{}{
+				"foo": map[interface{}]interface{}{
-		//    "foo": map[interface{}]interface{}{
+					"bar": []uint8("baz"),
-		//      "bar": "baz",
+				},
-		//    },
+				"bar": []uint8("baz"),
-		//  },
+			},
-		//  expected: map[string]interface{}{
+			expected: map[string]interface{}{
-		//    "foo": map[string]interface{}{
+				"foo": map[string]interface{}{
-		//      "bar": "baz",
+					"bar": "baz",
-		//    },
+				},
-		//  },
+				"bar": "baz",
-		// },
+			},
+		},
 	}
 
 	for name, tcase := range cases {

vendor/github.com/mitchellh/reflectwalk/go.mod

@@ -0,0 +1 @@
+module github.com/mitchellh/reflectwalk

vendor/github.com/mitchellh/reflectwalk/reflectwalk.go

@@ -230,7 +230,8 @@ func walkMap(v reflect.Value, w interface{}) error {
 			ew.Enter(MapValue)
 		}
 
-		if err := walk(kv, w); err != nil {
+		// get the map value again as it may have changed in the MapElem call
+		if err := walk(v.MapIndex(k), w); err != nil {
 			return err
 		}
 

vendor/modules.txt

@@ -377,7 +377,7 @@ github.com/mitchellh/go-testing-interface
 github.com/mitchellh/hashstructure
 # github.com/mitchellh/mapstructure v1.1.2
 github.com/mitchellh/mapstructure
-# github.com/mitchellh/reflectwalk v0.0.0-20170726202117-63d60e9d0dbc
+# github.com/mitchellh/reflectwalk v1.0.1
 github.com/mitchellh/reflectwalk
 # github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd
 github.com/modern-go/concurrent