src/test/ui/rfc-2008-non-exhaustive/uninhabited/coercions_same_crate.rs

   1 #![feature(never_type)]
   2
   3 #[non_exhaustive]
   4 pub enum UninhabitedEnum {
   5 }
   6
   7 #[non_exhaustive]
   8 pub struct UninhabitedTupleStruct(!);
   9
  10 #[non_exhaustive]
  11 pub struct UninhabitedStruct {
  12     _priv: !,
  13 }
  14
  15 pub enum UninhabitedVariants {
  16     #[non_exhaustive] Tuple(!),
  17     #[non_exhaustive] Struct { x: ! }
  18 }
  19
  20 struct A;
  21
  22 // This test checks that uninhabited non-exhaustive types defined in the same crate cannot coerce
  23 // to any type, as the never type can.
  24
  25 fn can_coerce_never_type_to_anything(x: !) -> A {
  26     x
  27 }
  28
  29 fn cannot_coerce_empty_enum_to_anything(x: UninhabitedEnum) -> A {
  30     x //~ ERROR mismatched types
  31 }
  32
  33 fn cannot_coerce_empty_tuple_struct_to_anything(x: UninhabitedTupleStruct) -> A {
  34     x //~ ERROR mismatched types
  35 }
  36
  37 fn cannot_coerce_empty_struct_to_anything(x: UninhabitedStruct) -> A {
  38     x //~ ERROR mismatched types
  39 }
  40
  41 fn cannot_coerce_enum_with_empty_variants_to_anything(x: UninhabitedVariants) -> A {
  42     x //~ ERROR mismatched types
  43 }
  44
  45 fn main() {}