Add DestinationPointer for flags generator

In this commit I added a DestinationPointer variable that should be set
if the `Destination` should be configured as a pointer for a specific
flag type. It is expected that Generic type which is an interface will
not be a pointer but a struct. Before this change the code compilation
was failing with `type *Generic is pointer to interface, not interface`.

See https://github.com/urfave/cli/issues/1441

cmd/urfave-cli-genflags/generated.gotmpl

@@ -17,7 +17,11 @@ type {{.TypeName}} struct {
   HasBeenSet bool
 
   Value {{if .ValuePointer}}*{{end}}{{.GoType}}
+<<<<<<< HEAD:cmd/urfave-cli-genflags/generated.gotmpl
   Destination {{if .NoDestinationPointer}}{{else}}*{{end}}{{.GoType}}
+=======
+  Destination {{if .DestinationPointer}}*{{end}}{{.GoType}}
+>>>>>>> Add DestinationPointer for flags generator:internal/genflags/generated.gotmpl
 
   Aliases []string
   EnvVars []string

cmd/urfave-cli-genflags/main_test.go

@@ -80,8 +80,9 @@ func genFlagType() *main.FlagType {
 					Type: "bool",
 				},
 			},
-			TypeName:     "YeOldeBlerfFlag",
-			ValuePointer: true,
+			TypeName:           "YeOldeBlerfFlag",
+			ValuePointer:       true,
+			DestinationPointer: true,
 		},
 	}
 }
@@ -115,6 +116,21 @@ func TestFlagType_ValuePointer(t *testing.T) {
 	}
 }
 
+func TestFlagType_DestinationPointer(t *testing.T) {
+	ft := genFlagType()
+
+	if !ft.DestinationPointer() {
+		t.Errorf("expected DestinationPointer to be true")
+		return
+	}
+
+	ft.Config = nil
+
+	if ft.DestinationPointer() {
+		t.Errorf("expected DestinationPointer to be false")
+	}
+}
+
 func TestFlagType_GenerateFmtStringerInterface(t *testing.T) {
 	ft := genFlagType()
 

flag-spec.yaml

@@ -2,6 +2,7 @@
 # ./cmd/urfave-cli-genflags/main.go which uses the
 # `Spec` type that maps to this file structure.
 flag_types:
+<<<<<<< HEAD
   bool:
     struct_fields:
       - name: Count
@@ -13,8 +14,30 @@ flag_types:
     struct_fields:
       - name: Action
         type: "func(*Context, float64) error"
+=======
+  bool: {}
+  float64: {}
+  int64: {}
+  int: {}
+  time.Duration: {}
+  uint64: {}
+  uint: {}
+
+  string:
+    destination_pointer: true
+    struct_fields:
+      - { name: TakesFile, type: bool }
+  Generic:
+    struct_fields:
+      - { name: TakesFile, type: bool }
+  Path:
+    destination_pointer: true
+    struct_fields:
+      - { name: TakesFile, type: bool }
+>>>>>>> Add DestinationPointer for flags generator
   Float64Slice:
     value_pointer: true
+    destination_pointer: true
     skip_interfaces:
       - fmt.Stringer
     struct_fields:
@@ -41,6 +64,7 @@ flag_types:
         type: "func(*Context, int64) error"
   Int64Slice:
     value_pointer: true
+    destination_pointer: true
     skip_interfaces:
       - fmt.Stringer
     struct_fields:
@@ -54,6 +78,7 @@ flag_types:
         type: "func(*Context, uint) error"
   UintSlice:
     value_pointer: true
+    destination_pointer: true
     skip_interfaces:
       - fmt.Stringer
     struct_fields:
@@ -80,6 +105,7 @@ flag_types:
         type: "func(*Context, string) error"
   StringSlice:
     value_pointer: true
+    destination_pointer: true
     skip_interfaces:
       - fmt.Stringer
     struct_fields:
@@ -93,6 +119,7 @@ flag_types:
         type: "func(*Context, time.Duration) error"
   Timestamp:
     value_pointer: true
+    destination_pointer: true
     struct_fields:
       - name: Layout
         type: string

internal/genflags/spec.go

@@ -0,0 +1,117 @@
+package genflags
+
+import (
+	"sort"
+	"strings"
+)
+
+type Spec struct {
+	FlagTypes              map[string]*FlagTypeConfig `yaml:"flag_types"`
+	PackageName            string                     `yaml:"package_name"`
+	TestPackageName        string                     `yaml:"test_package_name"`
+	UrfaveCLINamespace     string                     `yaml:"urfave_cli_namespace"`
+	UrfaveCLITestNamespace string                     `yaml:"urfave_cli_test_namespace"`
+}
+
+func (gfs *Spec) SortedFlagTypes() []*FlagType {
+	typeNames := []string{}
+
+	for name := range gfs.FlagTypes {
+		if strings.HasPrefix(name, "[]") {
+			name = strings.TrimPrefix(name, "[]") + "Slice"
+		}
+
+		typeNames = append(typeNames, name)
+	}
+
+	sort.Strings(typeNames)
+
+	ret := make([]*FlagType, len(typeNames))
+
+	for i, typeName := range typeNames {
+		ret[i] = &FlagType{
+			GoType: typeName,
+			Config: gfs.FlagTypes[typeName],
+		}
+	}
+
+	return ret
+}
+
+type FlagTypeConfig struct {
+	SkipInterfaces     []string           `yaml:"skip_interfaces"`
+	StructFields       []*FlagStructField `yaml:"struct_fields"`
+	TypeName           string             `yaml:"type_name"`
+	ValuePointer       bool               `yaml:"value_pointer"`
+	DestinationPointer bool               `yaml:"destination_pointer"`
+}
+
+type FlagStructField struct {
+	Name string
+	Type string
+}
+
+type FlagType struct {
+	GoType string
+	Config *FlagTypeConfig
+}
+
+func (ft *FlagType) StructFields() []*FlagStructField {
+	if ft.Config == nil || ft.Config.StructFields == nil {
+		return []*FlagStructField{}
+	}
+
+	return ft.Config.StructFields
+}
+
+func (ft *FlagType) ValuePointer() bool {
+	if ft.Config == nil {
+		return false
+	}
+
+	return ft.Config.ValuePointer
+}
+
+func (ft *FlagType) DestinationPointer() bool {
+	if ft.Config == nil {
+		return false
+	}
+
+	return ft.Config.DestinationPointer
+}
+
+func (ft *FlagType) TypeName() string {
+	return TypeName(ft.GoType, ft.Config)
+}
+
+func (ft *FlagType) GenerateFmtStringerInterface() bool {
+	return ft.skipInterfaceNamed("fmt.Stringer")
+}
+
+func (ft *FlagType) GenerateFlagInterface() bool {
+	return ft.skipInterfaceNamed("Flag")
+}
+
+func (ft *FlagType) GenerateRequiredFlagInterface() bool {
+	return ft.skipInterfaceNamed("RequiredFlag")
+}
+
+func (ft *FlagType) GenerateVisibleFlagInterface() bool {
+	return ft.skipInterfaceNamed("VisibleFlag")
+}
+
+func (ft *FlagType) skipInterfaceNamed(name string) bool {
+	if ft.Config == nil {
+		return true
+	}
+
+	lowName := strings.ToLower(name)
+
+	for _, interfaceName := range ft.Config.SkipInterfaces {
+		if strings.ToLower(interfaceName) == lowName {
+			return false
+		}
+	}
+
+	return true
+}