shell completion --format: work with pointer functions

The completion logic currently suggest also the functions that are
defined for this type. However this did not work correctly when it was
defined as pointer to that type on not the actual type.

This commit fixes that problem. To test you can compare the difference
between `podman stats --format {{.[TAB]` with and without this commit.

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

2 files changed, 24 insertions, 15 deletions

diff --git a/cmd/podman/common/completion.go b/cmd/podman/common/completion.go
index 6149a4465..e07e28dab 100644
--- a/cmd/podman/common/completion.go
+++ b/cmd/podman/common/completion.go
@@ -992,13 +992,6 @@ func AutocompleteFormat(o interface{}) func(cmd *cobra.Command, args []string, t
 		fields := strings.Split(field[len(field)-1], ".")
 		f := reflect.ValueOf(o)
 		for i := 1; i < len(fields); i++ {
-			val := getActualStructType(f)
-			if val == nil {
-				// no struct return nothing to complete
-				return nil, cobra.ShellCompDirectiveNoFileComp
-			}
-			f = *val
-
 			// last field get all names to suggest
 			if i == len(fields)-1 {
 				suggestions := getStructFields(f, fields[i])
@@ -1008,6 +1001,14 @@ func AutocompleteFormat(o interface{}) func(cmd *cobra.Command, args []string, t
 				toComplete = strings.Join(toCompArr, ".")
 				return prefixSlice(toComplete, suggestions), cobra.ShellCompDirectiveNoSpace | cobra.ShellCompDirectiveNoFileComp
 			}
+
+			val := getActualStructType(f)
+			if val == nil {
+				// no struct return nothing to complete
+				return nil, cobra.ShellCompDirectiveNoFileComp
+			}
+			f = *val
+
 			// set the next struct field
 			f = f.FieldByName(fields[i])
 		}
@@ -1038,12 +1039,15 @@ func getActualStructType(f reflect.Value) *reflect.Value {
 
 // getStructFields reads all struct field names and method names and returns them.
 func getStructFields(f reflect.Value, prefix string) []string {
-	suggestions := []string{}
+	var suggestions []string
+	if f.IsValid() {
+		suggestions = append(suggestions, getMethodNames(f, prefix)...)
+	}
 
 	val := getActualStructType(f)
 	if val == nil {
 		// no struct return nothing to complete
-		return nil
+		return suggestions
 	}
 	f = *val
 
@@ -1069,7 +1073,11 @@ func getStructFields(f reflect.Value, prefix string) []string {
 			suggestions = append(suggestions, fname+suffix)
 		}
 	}
+	return suggestions
+}
 
+func getMethodNames(f reflect.Value, prefix string) []string {
+	suggestions := make([]string, 0, f.NumMethod())
 	for j := 0; j < f.NumMethod(); j++ {
 		fname := f.Type().Method(j).Name
 		if strings.HasPrefix(fname, prefix) {
@@ -1077,7 +1085,6 @@ func getStructFields(f reflect.Value, prefix string) []string {
 			suggestions = append(suggestions, fname+"}}")
 		}
 	}
-
 	return suggestions
 }
 
diff --git a/cmd/podman/common/completion_test.go b/cmd/podman/common/completion_test.go
index ae117a173..13f45a662 100644
--- a/cmd/podman/common/completion_test.go
+++ b/cmd/podman/common/completion_test.go
@@ -25,7 +25,9 @@ func (c Car) Type() string {
 	return ""
 }
 
-func (c Car) Color() string {
+// Note: It is important that this function is *Car and the Type one is just Car.
+// The reflect logic behaves differently for these cases so we have to test both.
+func (c *Car) Color() string {
 	return ""
 }
 
@@ -94,7 +96,7 @@ func TestAutocompleteFormat(t *testing.T) {
 		{
 			"second level struct field name",
 			"{{ .Car.",
-			[]string{"{{ .Car.Brand}}", "{{ .Car.Stats.", "{{ .Car.Extras}}", "{{ .Car.Color}}", "{{ .Car.Type}}"},
+			[]string{"{{ .Car.Color}}", "{{ .Car.Type}}", "{{ .Car.Brand}}", "{{ .Car.Stats.", "{{ .Car.Extras}}"},
 		},
 		{
 			"second level struct field name",
@@ -104,7 +106,7 @@ func TestAutocompleteFormat(t *testing.T) {
 		{
 			"second level nil struct field name",
 			"{{ .Car2.",
-			[]string{"{{ .Car2.Brand}}", "{{ .Car2.Stats.", "{{ .Car2.Extras}}", "{{ .Car2.Color}}", "{{ .Car2.Type}}"},
+			[]string{"{{ .Car2.Color}}", "{{ .Car2.Type}}", "{{ .Car2.Brand}}", "{{ .Car2.Stats.", "{{ .Car2.Extras}}"},
 		},
 		{
 			"three level struct field name",
@@ -134,8 +136,8 @@ func TestAutocompleteFormat(t *testing.T) {
 		{
 			"two variables struct field name",
 			"{{ .Car.Brand }} {{ .Car.",
-			[]string{"{{ .Car.Brand }} {{ .Car.Brand}}", "{{ .Car.Brand }} {{ .Car.Stats.", "{{ .Car.Brand }} {{ .Car.Extras}}",
-				"{{ .Car.Brand }} {{ .Car.Color}}", "{{ .Car.Brand }} {{ .Car.Type}}"},
+			[]string{"{{ .Car.Brand }} {{ .Car.Color}}", "{{ .Car.Brand }} {{ .Car.Type}}", "{{ .Car.Brand }} {{ .Car.Brand}}",
+				"{{ .Car.Brand }} {{ .Car.Stats.", "{{ .Car.Brand }} {{ .Car.Extras}}"},
 		},
 		{
 			"only dot without variable",