Hi Ian, Thank you for the explanation. That makes perfect sense.
OTOH, in my quest to provide the simplest example I could, I provided an example that does not expose the use-case I was interested in exploring, unfortunately. Let me instead present some real code from my current project, specifically the variable declarations on the lines 35-36 of the `Process()` method of `*FileProcessor` where the variables declared at the top are not referenced after the label: https://github.com/newclarity/wpfr/blob/88d1289a90646f59ec4233eed0e421f1eae36332/pkg/wpfr.go#L34-L75 However, your links to https://go.dev/issue/27165 and https://go.dev/issue/26058 <https://go.dev/issue/26058> seems to be addressing exactly the concern, so I will follow up with use-cases on those tickets after spending enough time with them to determine which one addresses my use-cases better. Again, thank you. -Mike > On Aug 26, 2023, at 7:00 PM, Ian Lance Taylor <i...@golang.org> wrote: > > On Sat, Aug 26, 2023 at 2:11 PM Mike Schinkel <m...@newclarity.net> wrote: >> >> Question about disallowing `goto <label>` jumping over a variable >> declaration? >> >> >> And please, before bikeshedding opinions about the use of `goto` pro or con >> — note that the Go standard library uses `goto` in some places — this >> question is purely for me to gain better understanding the choices made with >> the Go compiler. >> >> >> Question. Was it: >> >> >> 1. Somehow logically required by the compiler, and if so can you elaborate >> why? >> >> 2. A design decision made, and if so what what the rationale for the design >> decision? >> >> 3. A limitation place on GoLang for some other reason, and if so, what and >> why? >> >> >> I have prepared an example showing use of `goto` that compiles and one that >> does not at this playground URL: >> >> >> https://goplay.tools/snippet/tSAbWhmiCZK >> >> >> Hoping to hear from someone who actually knows why the decision was made as >> opposed to someone who might just be guessing at the reason. > > Consider a function like > > func F() { > goto lab > x := 1 > lab: > fmt.Println(x) > } > > This function is forbidden today. If it were permitted, what should it print? > > If the answer to that question seems obvious, what about a case like > > func F() { > goto lab > x := func() int { > fmt.Println("setting x") > return 1 > }() > lab: > fmt.Println(x) > } > > Should that print "setting x"? > > Rather than attempt to answer these kinds of questions, Go simply > forbids cases like this. > > Note that Go is not the only language with this restriction. This > similar C++ function is invalid, because the goto crosses the > initialization of the variable. > > int f() { > goto lab; > int x = 1; > lab: > std::cout << x; > return 0; > } > > If you are interested in this topic you may be interested in > https://go.dev/issue/27165 and https://go.dev/issue/26058. > > Ian -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/B066901D-A60A-4F08-A1BF-D2C307910548%40newclarity.net.
