panic when using named non-struct types

[niaow]

While attempting to use a wrapped version of time.Duration, I ran into a crash when using commandeer.

commandeer/com.go

Lines 274 to 358 in 07c6265

	case reflect.String:
	p := f.Addr().Interface().(*string)
	flags.string(p, flagName, shorthand, f.String(), flagHelp(ft))
	case reflect.Bool:
	p := f.Addr().Interface().(*bool)
	flags.bool(p, flagName, shorthand, f.Bool(), flagHelp(ft))
	case reflect.Int:
	p := f.Addr().Interface().(*int)
	val := int(f.Int())
	flags.int(p, flagName, shorthand, val, flagHelp(ft))
	case reflect.Int64:
	p := f.Addr().Interface().(*int64)
	flags.int64(p, flagName, shorthand, f.Int(), flagHelp(ft))
	case reflect.Float64:
	p := f.Addr().Interface().(*float64)
	flags.float64(p, flagName, shorthand, f.Float(), flagHelp(ft))
	case reflect.Uint:
	p := f.Addr().Interface().(*uint)
	val := uint(f.Uint())
	flags.uint(p, flagName, shorthand, val, flagHelp(ft))
	case reflect.Uint64:
	p := f.Addr().Interface().(*uint64)
	flags.uint64(p, flagName, shorthand, f.Uint(), flagHelp(ft))
	case reflect.Slice:
	if !flags.pflag {
	return fmt.Errorf("cannot support slice field at '%v' with stdlib flag pkg.", flagName)
	}
	switch ft.Type.Elem().Kind() {
	case reflect.String:
	p := f.Addr().Interface().(*[]string)
	flags.stringSlice(p, flagName, shorthand, *p, flagHelp(ft))
	case reflect.Bool:
	p := f.Addr().Interface().(*[]bool)
	flags.boolSlice(p, flagName, shorthand, *p, flagHelp(ft))
	case reflect.Int:
	p := f.Addr().Interface().(*[]int)
	flags.intSlice(p, flagName, shorthand, *p, flagHelp(ft))
	case reflect.Uint:
	p := f.Addr().Interface().(*[]uint)
	flags.uintSlice(p, flagName, shorthand, *p, flagHelp(ft))
	default:
	return fmt.Errorf("encountered unsupported slice type/kind: %#v at %s", f, prefix)
	}
	case reflect.Float32:
	if !flags.pflag {
	return fmt.Errorf("cannot support float32 field at '%v' with stdlib flag pkg.", flagName)
	}
	p := f.Addr().Interface().(*float32)
	flags.float32(p, flagName, shorthand, *p, flagHelp(ft))
	case reflect.Int16:
	if !flags.pflag {
	return fmt.Errorf("cannot support int16 field at '%v' with stdlib flag pkg.", flagName)
	}
	p := f.Addr().Interface().(*int16)
	flags.int16(p, flagName, shorthand, *p, flagHelp(ft))
	case reflect.Int32:
	if !flags.pflag {
	return fmt.Errorf("cannot support int32 field at '%v' with stdlib flag pkg.", flagName)
	}
	p := f.Addr().Interface().(*int32)
	flags.int32(p, flagName, shorthand, *p, flagHelp(ft))
	case reflect.Uint16:
	if !flags.pflag {
	return fmt.Errorf("cannot support uint16 field at '%v' with stdlib flag pkg.", flagName)
	}
	p := f.Addr().Interface().(*uint16)
	flags.uint16(p, flagName, shorthand, *p, flagHelp(ft))
	case reflect.Uint32:
	if !flags.pflag {
	return fmt.Errorf("cannot support uint32 field at '%v' with stdlib flag pkg.", flagName)
	}
	p := f.Addr().Interface().(*uint32)
	flags.uint32(p, flagName, shorthand, *p, flagHelp(ft))
	case reflect.Uint8:
	if !flags.pflag {
	return fmt.Errorf("cannot support uint8 field at '%v' with stdlib flag pkg.", flagName)
	}
	p := f.Addr().Interface().(*uint8)
	flags.uint8(p, flagName, shorthand, *p, flagHelp(ft))
	case reflect.Int8:
	if !flags.pflag {
	return fmt.Errorf("cannot support int8 field at '%v' with stdlib flag pkg.", flagName)
	}
	p := f.Addr().Interface().(*int8)
	flags.int8(p, flagName, shorthand, *p, flagHelp(ft))

All of these type assertions will panic if the type is named.