Atomic String Swap panics if created with empty string

[KromDaniel]

Hey,

I've encountered the following issue with atomic.String

atomicStr := atomic.NewString("")
atomicStr.Swap("string")

error

panic: interface conversion: interface {} is nil, not string [recovered]
	panic: interface conversion: interface {} is nil, not string
	
go.uber.org/atomic.(*String).Swap(...)
	/Users/dkrom/Dev/gonzo/pkg/mod/go.uber.org/atomic@v1.10.0/string.go:64

I guess its because NewString condition

func NewString(val string) *String {
	x := &String{}
	if val != _zeroString {
		x.Store(val)
	}
	return x
}

I'm not sure if its by design or not?

go version go1.19.4 darwin/arm64
atomic @v1.10.0

Thanks a lot!

[eNV25]

Needs fixing in Swap method to match Load.

atomic/internal/gen-atomicwrapper/wrapper.tmpl

Lines 94 to 100 in 78a3b8e

	func (x *{{ .Name }}) Swap(val {{ .Type }}) (old {{ .Type }}) {
	{{ if .Pack -}}
	return {{ .Unpack }}(x.v.Swap({{ .Pack }}(val)))
	{{- else -}}{{- /* assume go.uber.org/atomic.Value */ -}}
	return x.v.Swap(val).({{ .Type }})
	{{- end }}
	}