Backward compatibility - Native function implementations

[Kouteki]

Description

Originally referenced in #1896

Context

It's important to be aware that all native functions could have backward compatibility issues when we update their native implementation. This is not introduced by the new binding solution; instead, it makes the potential issue more apparent.

During contract execution, the functionValue.nativeBody,

gno/gnovm/pkg/gnolang/op_call.go

Line 63 in 831bb6f

fv.nativeBody = m.Store.GetNative(fv.NativePkg, fv.NativeName)

which is a func(*Machine) returned from iterating through nativeFuncs in stdlibs/native.go, by finding matching package and names,

gno/gnovm/stdlibs/native.go

Line 26 in 831bb6f

var nativeFuncs = [...]nativeFunc{

returns a matching func(*Machine) when the VM executes the contract.

For example, in the standard contract stdlib/std/native.gno, PrevRealm() > getRealm(1), the nativeFuncs links Gno's getRealm(1)

gno/gnovm/stdlibs/std/native.gno

Line 57 in 831bb6f

func getRealm(height int) (address string, pkgPath string)

with the native implementation of X_getRealm().

gno/gnovm/stdlibs/std/native.go

Line 70 in 831bb6f

func X_getRealm(m *gno.Machine, height int) (address string, pkgPath string) {

gno/gnovm/stdlibs/native.go

Line 535 in 831bb6f

r0, r1 := libs_std.X_getRealm(

Backward compatibility issues:

updating the logic in stdlibs/std/native.go could cause existing contracts to fail to execute if contract developers assume the behaviors of PrevRealm have changed in a new release.