For language change proposals, please fill out the template at https://go.googlesource.com/proposal/+/refs/heads/master/go2-language-changes.md .

When you are done, please reply to the issue with @gopherbot please remove label WaitingForInfo.

Thanks!

I feel a little unsure what exactly this proposal means by "tuple". Given the use of indexing syntax I guessed an array, but I don't think that's a correct guess because in that case both of the presented examples compile and are functionally equivalent:

package main

import "fmt"

func returnTuple() [2]string {
	return [...]string{"a", "b"}
}

func anyFunction(v string) {
	fmt.Printf("anyFunction(%#v)\n", v)
}

func main() {
	tuple := returnTuple()
	anyFunction(tuple[0])

	anyFunction(returnTuple()[0])
}

(Playground)

The Go spec uses "tuple" only in the concept of "tuple assignment" to refer to the idea of assigning multiple return values to multiple symbols, and so I suspect that's probably what you actually meant but note that the first example you provided is not correct if that's the interpretation you intended, because if would be forbidden to assign two function results to a single symbol like that:

package main

import "fmt"

func returnTuple() (string, string) {
	return "a", "b"
}

func anyFunction(v string) {
	fmt.Printf("anyFunction(%#v)\n", v)
}

func main() {
	// Error: assignment mismatch: 1 variable but returnTuple returns 2 values
	tuple := returnTuple()
	anyFunction(tuple[0])
}

I suspect this'll be clearer once you've completed the language changes template! 😀 But if your intent is to propose making multiple return values be usable as a single value of some new tuple type then you may wish to refer to #32941 first to consider how your proposal differs from that earlier one on a similar topic. There are some other related proposals linked later in the history of that issue which you may wish to consider too.

Timed out in state WaitingForInfo. Closing.

(I am just a bot, though. Please speak up if this is a mistake or you have the requested information.)