Allow disabling SliceFlag separator altogether

app.go

@@ -107,6 +107,8 @@ type App struct {
 	CustomAppHelpTemplate string
 	// SliceFlagSeparator is used to customize the separator for SliceFlag, the default is ","
 	SliceFlagSeparator string
+	// DisableSliceFlagSeparator is used to disable SliceFlagSeparator, the default is false
+	DisableSliceFlagSeparator bool
 	// Boolean to enable short-option handling so user can combine several
 	// single-character bool arguments into one
 	// i.e. foobar -o -v -> foobar -ov
@@ -264,6 +266,8 @@ func (a *App) Setup() {
 	if len(a.SliceFlagSeparator) != 0 {
 		defaultSliceFlagSeparator = a.SliceFlagSeparator
 	}
+
+	disableSliceFlagSeparator = a.DisableSliceFlagSeparator
 }
 
 func (a *App) newRootCommand() *Command {

flag.go

@@ -15,7 +15,10 @@ import (
 
 const defaultPlaceholder = "value"
 
-var defaultSliceFlagSeparator = ","
+var (
+	defaultSliceFlagSeparator = ","
+	disableSliceFlagSeparator = false
+)
 
 var (
 	slPfx = fmt.Sprintf("sl:::%d:::", time.Now().UTC().UnixNano())
@@ -380,5 +383,9 @@ func flagFromEnvOrFile(envVars []string, filePath string) (value string, fromWhe
 }
 
 func flagSplitMultiValues(val string) []string {
+	if disableSliceFlagSeparator {
+		return []string{val}
+	}
+
 	return strings.Split(val, defaultSliceFlagSeparator)
 }

flag_test.go

@@ -3402,3 +3402,19 @@ func TestCustomizedSliceFlagSeparator(t *testing.T) {
 		}
 	}
 }
+
+func TestFlagSplitMultiValues_Disabled(t *testing.T) {
+	disableSliceFlagSeparator = true
+	defer func() {
+		disableSliceFlagSeparator = false
+	}()
+	opts := []string{"opt1", "opt2", "opt3,op", "opt4"}
+	ret := flagSplitMultiValues(strings.Join(opts, ","))
+	if len(ret) != 1 {
+		t.Fatalf("failed to disable split slice flag, want: 1, but got: %d", len(ret))
+	}
+
+	if ret[0] != strings.Join(opts, ",") {
+		t.Fatalf("failed to disable split slice flag, want: %s, but got: %s", strings.Join(opts, ","), ret[0])
+	}
+}