tests/ui/rfc-2008-non-exhaustive/uninhabited/coercions.rs

   1 // aux-build:uninhabited.rs
   2 #![feature(never_type)]
   3
   4 extern crate uninhabited;
   5
   6 use uninhabited::{
   7     UninhabitedEnum,
   8     UninhabitedStruct,
   9     UninhabitedTupleStruct,
  10     UninhabitedVariants,
  11 };
  12
  13 // This test checks that uninhabited non-exhaustive types cannot coerce to any type, as the never
  14 // type can.
  15
  16 struct A;
  17
  18 fn can_coerce_never_type_to_anything(x: !) -> A {
  19     x
  20 }
  21
  22 fn cannot_coerce_empty_enum_to_anything(x: UninhabitedEnum) -> A {
  23     x //~ ERROR mismatched types
  24 }
  25
  26 fn cannot_coerce_empty_tuple_struct_to_anything(x: UninhabitedTupleStruct) -> A {
  27     x //~ ERROR mismatched types
  28 }
  29
  30 fn cannot_coerce_empty_struct_to_anything(x: UninhabitedStruct) -> A {
  31     x //~ ERROR mismatched types
  32 }
  33
  34 fn cannot_coerce_enum_with_empty_variants_to_anything(x: UninhabitedVariants) -> A {
  35     x //~ ERROR mismatched types
  36 }
  37
  38 fn main() {}