Is this an ssa optimization to use a global untyped nil interface and avoid constructing it? If so, how do I go about finding out the rule for it?

When var i interface{} = nil:

func main():
0:                                                                entry P:0 S:0
        return

When var i interface{} = 555:

func main():
0:                                                                entry P:0 S:0
        t0 = make interface{} <- int (555:int)                      interface{}
        return

I realized I could build the naive SSA form using -N

func main():
0:                                                                entry P:0 S:0
        t0 = local interface{} (i)                                 *interface{}
        *t0 = nil:interface{}
        t1 = *t0                                                    interface{}
        rundefers
        return

I'm exploring the code and slowing getting there lol

Okay, got it. All I had to do was add ssa.NaiveForm

prog := ssautil.CreateProgram(lprog, ssa.GlobalDebug|ssa.NaiveForm)

Now guru pointsto's message is a lot better (for my use):

this interface{} cannot contain any dynamic types.

I am still interested in being able to only partially enable ssa.NaiveForm, so that I don't miss other useful features of the non-naive form.

/cc @golang/tools-team

@siadat: We welcome any patches if you're interested in contributing, but guru is largely unmaintained so we won't work on making any changes ourselves.

Thank you for the replies! :) Is guru being replaced by something else? gopls comes to mind which (if I'm not mistaken) uses analyzers from github.com/dominikh/go-tools. So, would it be correct to say the focus from guru is shifted to gopls plus github.com/dominikh/go-tools?

EDIT: okay, I found the implementation doc :)

Regarding this issue: I'd love to help! :) Enabling ssa.NaiveForm in guru will change the output of the pointsto subcommand for inputs other than the one reported in this issue. (I can write an example if needed.) So, I think a good fix would follow one of these two approaches:

• patch the ssa.lift func so that the nil empty interface is not lifted but other things are, or;
• add a -N flag to guru to enable ssa.NaiveForm. It is analogous to ssadump's -N. In the error message we could replace the error message (dead code?) with a suggestion to use -N: (dead code? try running guru with -N)

Let me know what you think :)