Erroring related to top-level variables in p/

[leohhhn]

Description

Packages under p/ are not supposed to have top-level variables - they are supposed to be stateless. Packages can have top-level variables and they can be initialized, but cannot be later modified. Erroring related to this is non-existent - modifying these variables will not work as expected. Replicate the following example locally:

In root of Gno repo, run

mkdir examples/gno.land/p/demo/tt

Add following files:

p/demo/tt/gno.mod:

module gno.land/p/demo/tt

p/demo/tt/tt.gno:

package tt

var toplevelvar string

func init() {
	toplevelvar = "initialized"
}

func GetVar() string {
	return toplevelvar
}

func SetVar(arg string) {
	toplevelvar = arg
}

• Deployment of this will pass normally when running the chain.
• Calling GetVar with gnokey will successfully access the variable

> gnokey maketx call -pkgpath gno.land/p/demo/tt --func GetVar --gas-fee 10000000ugnot --gas-wanted 800000 --broadcast dev  

Enter password.

("initialized" string)
OK!
GAS WANTED: 800000
GAS USED:   67444

• Calling SetVar will not error in any way, but toplevelvar will not be updated:

> gnokey maketx call -pkgpath gno.land/p/demo/tt --func SetVar --args "changed" --gas-fee 10000000ugnot --gas-wanted 800000 --broadcast dev

Enter password.

OK!
GAS WANTED: 800000
GAS USED:   70271

> gnokey maketx call -pkgpath gno.land/p/demo/tt --func GetVar --gas-fee 10000000ugnot --gas-wanted 800000 --broadcast dev                           

Enter password.
("initialized" string)
OK!
GAS WANTED: 800000
GAS USED:   70081

Not sure if this is a feature or a bug, but we should be clear on erroring related to this, since we are pushing the "packages are stateless" narrative.

Also, should we allow for init() in p/?

EDIT: Top-level variables in packages is indeed a feature. Packages can define top-level variables and have them initialized in init(). However, they are not to be modified, and we do not have erroring related to that, as you can see in the previous CLI block.

[thehowl]

I'll tell you something even funnier: you can actually maketx call stdlibs! 😂

$ gnokey maketx call -broadcast -pkgpath strconv -gas-wanted 10000000 -gas-fee 1000000ugnot -func Itoa -args 11 gentest
Enter password.
("11" string)
OK!
GAS WANTED: 10000000
GAS USED:   77386

I think the action here is to restrict maketx call to work exclusively on gno.land/r. wdyt @moul @jaekwon?