gnovm/pkg/gnolang: Gno permits invalid compiler directive placements: Go rejects invalid compiler directives affixed as comments on statements but Gno accepts such

[odeke-em]

Description

This code

package main //go:generate say "Pwned"

func main() {}

is invalid in Go because it doesn't match the rules per https://pkg.go.dev/cmd/compile#hdr-Compiler_Directives

but it successfully compiles and runs in Gno.

Implications

Allowing compiler directives in misplaced positions can result in a security vector whereby security and static analysis tools won't be able to detect such entirely for Gno and then later be used to run arbitrary code.