Support Go 1.17 slice-to-array conversion

[ainar-g]

$ go version
  go version go1.17beta1 linux/amd64

$ more ./go/tmp/main.go 
  package main

  import (
  	"fmt"
  )

  func main() {
  	s := []int{1, 2, 3, 4}
  	fmt.Println(*(*[4]int)(s))
  }

$ go run ./go/tmp/main.go 
  [1 2 3 4]

$ unparam ./go/tmp/main.go 
  panic: in command-line-arguments.main: cannot convert *t0 ([]int) to *[4]int
  [...]

This is using latest unparam from master. I'm ready to provide any additional details.

[mvdan]

I wonder if simply upgrading the version of x/tools would solve this error, as we use the ssa package.

[ainar-g]

I've tried upgrading to golang.org/x/tools@v0.1.5-0.20210629191230-72e4d1bb8d47, but it seems to have no effect. And also, nilness, another SSA-based analyser, is panicking as well. I guess it's an upstream issue then?

[mvdan]

Seems like it, yup.

[ainar-g]

@mvdan, the bug seems to be fixed in golang.org/x/tools. Should I close this issue, or should I wait for the next tag in that module and make a PR updating the dependency?

[mvdan]

I don't have a problem with using x/tools from master; happy to receive a PR to update it.