package main
const X = 3
func main() {
const (
X = X + X
Y
)
println(X, Y)
}
Choices:
Answer: 6 12
Run it on Go play.
Key points:
The consntant declaration in the quiz code is equivalent to the following one:
const (
X = X + X // here the two "X" are both the global one
Y = X + X // here the two "X" are both the local one
)
The local X is evaluated as 6 at compile time,
so the constant Y is evaluaed as 12 (also at compile time).
Please note that, the output result was 6 6 when using Go toolchain v1.17-.
The bug has been fixed since Go toochain v1.18.
Similarly, since Go toolchain 1.18, the following program prints 0 0.
Before Go toolchain 1.18, it printed 1 2 (a bug).
package main
func main() {
const (
iota = iota
X
Y
)
println(X, Y)
}
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