What does the keyword exhaustive do?

[ghost]

I remember I have read about it somewhere on this repository but can't find it now!

[IsaacShelton]

exhaustive has two uses.

• The most common is requiring a switch statement to have all its cases specified.

exhaustive switch car_color {
case ::BLACK, print("A nice black car!")
case ::GREY,  print("An awesome grey car!")
case ::WHITE, print("A clean white car!")
case ::RED,   print("A fierce red car!")
}

• And the lesser bizarre case is using it to mark a function as no-discard, so that the return value must be used.

import basics

func getName() exhaustive String = "Not using this return value is a compile-time error"

func main {
    getName() // Compile Time Error!
}