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fix(preprocess): using iota outside constant declaration #5822

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fix(preprocess): using iota outside constant declaration #5822

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fix(preprocess): using iota outside constant declaration
Villaquiranm Jun 12, 2026
35fdab4
remove Go mentions
Villaquiranm Jun 12, 2026
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5 changes: 5 additions & 0 deletions gnovm/pkg/gnolang/preprocess.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1297,6 +1297,11 @@ func preprocess1(store Store, ctx BlockNode, n Node) Node {
return n, TRANS_CONTINUE
case "iota":
pd := lastDecl(ns)
valueDecl, ok := pd.(*ValueDecl)
if !ok || !valueDecl.Const {
panic("cannot use iota outside constant declaration")

@davd-gzl davd-gzl Jun 12, 2026

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Not directly related. Declaring a variable name iota := 0 is legal in Go (https://go.dev/play/p/FP9F1VlxwAt), and is now returning "cannot use iota outside constant declaration".

Either we should copy Go behavior, or set builtin identifiers cannot be shadowed: iota. like it is done for const iota = 5

}

io := pd.GetAttribute(ATTR_IOTA).(int)
cx := constUntypedBigint(n, int64(io))
return cx, TRANS_CONTINUE
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17 changes: 17 additions & 0 deletions gnovm/tests/files/iota_outside_const.gno
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Original file line number Diff line number Diff line change
@@ -0,0 +1,17 @@
package main

const X = iota

func f(x int) {}

func main() {
f(X)
f(iota) // ERROR "iota"
f(X)
}

// Error:
// main/iota_outside_const.gno:9:4-8: cannot use iota outside constant declaration

// TypeCheckError:
// main/iota_outside_const.gno:9:4: cannot use iota outside constant declaration
18 changes: 18 additions & 0 deletions gnovm/tests/files/iota_outside_const_2.gno
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Original file line number Diff line number Diff line change
@@ -0,0 +1,18 @@
package main

const X = iota

func f(x int) {}

func main() {
f(X)
var a = iota // ERROR "iota"
_ = a
f(X)
}

// Error:
// main/iota_outside_const_2.gno:9:10-14: cannot use iota outside constant declaration

// TypeCheckError:
// main/iota_outside_const_2.gno:9:10: cannot use iota outside constant declaration