fish.go: support PathFlag.TakesFile [#1156]

fish.go

@@ -171,6 +171,10 @@ func fishAddFileFlag(flag Flag, completion *strings.Builder) {
 		if f.TakesFile {
 			return
 		}
+	case *PathFlag:
+		if f.TakesFile {
+			return
+		}
 	}
 	completion.WriteString(" -f")
 }

fish_test.go

@@ -7,6 +7,10 @@ import (
 func TestFishCompletion(t *testing.T) {
 	// Given
 	app := testApp()
+	app.Flags = append(app.Flags, &PathFlag{
+		Name:      "logfile",
+		TakesFile: true,
+	})
 
 	// When
 	res, err := app.ToFishCompletion()

testdata/expected-fish-full.fish

@@ -12,6 +12,7 @@ end
 complete -c greet -n '__fish_greet_no_subcommand' -l socket -s s -r -d 'some \'usage\' text'
 complete -c greet -n '__fish_greet_no_subcommand' -f -l flag -s fl -s f -r
 complete -c greet -n '__fish_greet_no_subcommand' -f -l another-flag -s b -d 'another usage text'
+complete -c greet -n '__fish_greet_no_subcommand' -l logfile -r
 complete -c greet -n '__fish_greet_no_subcommand' -f -l help -s h -d 'show help'
 complete -c greet -n '__fish_greet_no_subcommand' -f -l version -s v -d 'print the version'
 complete -c greet -n '__fish_seen_subcommand_from config c' -f -l help -s h -d 'show help'