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Diffstat (limited to '')
-rw-r--r-- | src/test/ui/generics/issue-61631-default-type-param-cannot-reference-self.rs | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/src/test/ui/generics/issue-61631-default-type-param-cannot-reference-self.rs b/src/test/ui/generics/issue-61631-default-type-param-cannot-reference-self.rs new file mode 100644 index 000000000..12db143e4 --- /dev/null +++ b/src/test/ui/generics/issue-61631-default-type-param-cannot-reference-self.rs @@ -0,0 +1,45 @@ +#![crate_type="lib"] + +// rust-lang/rust#61631: Uses of `Self` in the defaults of generic +// types for ADT's are not allowed. We justify this because the `Self` +// type could be considered the "final" type parameter, that is only +// well-defined after all of the other type parameters on the ADT have +// been instantiated. +// +// These were previously were ICE'ing at the usage point anyway (see +// `demo_usages` below), so there should not be any backwards +// compatibility concern. + +struct Snobound<'a, P = Self> { x: Option<&'a P> } +//~^ ERROR generic parameters cannot use `Self` in their defaults [E0735] + +enum Enobound<'a, P = Self> { A, B(Option<&'a P>) } +//~^ ERROR generic parameters cannot use `Self` in their defaults [E0735] + +union Unobound<'a, P = Self> { x: i32, y: Option<&'a P> } +//~^ ERROR generic parameters cannot use `Self` in their defaults [E0735] + +// Disallowing `Self` in defaults sidesteps need to check the bounds +// on the defaults in cases like these. + +struct Ssized<'a, P: Sized = [Self]> { x: Option<&'a P> } +//~^ ERROR generic parameters cannot use `Self` in their defaults [E0735] + +enum Esized<'a, P: Sized = [Self]> { A, B(Option<&'a P>) } +//~^ ERROR generic parameters cannot use `Self` in their defaults [E0735] + +union Usized<'a, P: Sized = [Self]> { x: i32, y: Option<&'a P> } +//~^ ERROR generic parameters cannot use `Self` in their defaults [E0735] + +fn demo_usages() { + // An ICE means you only get the error from the first line of the + // demo; comment each out to observe the other ICEs when trying + // this out on older versions of Rust. + + let _ice: Snobound; + let _ice: Enobound; + let _ice: Unobound; + let _ice: Ssized; + let _ice: Esized; + let _ice: Usized; +} |