diff options
Diffstat (limited to 'src/test/ui/never_type/try_from.rs')
-rw-r--r-- | src/test/ui/never_type/try_from.rs | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/src/test/ui/never_type/try_from.rs b/src/test/ui/never_type/try_from.rs new file mode 100644 index 000000000..50451576f --- /dev/null +++ b/src/test/ui/never_type/try_from.rs @@ -0,0 +1,37 @@ +// run-pass +// This test relies on `TryFrom` being blanket impl for all `T: Into` +// and `TryInto` being blanket impl for all `U: TryFrom` + +// This test was added to show the motivation for doing this +// over `TryFrom` being blanket impl for all `T: From` + +#![feature(never_type)] + +use std::convert::{TryInto, Infallible}; + +struct Foo<T> { + t: T, +} + +// This fails to compile due to coherence restrictions +// as of Rust version 1.32.x, therefore it could not be used +// instead of the `Into` version of the impl, and serves as +// motivation for a blanket impl for all `T: Into`, instead +// of a blanket impl for all `T: From` +/* +impl<T> From<Foo<T>> for Box<T> { + fn from(foo: Foo<T>) -> Box<T> { + Box::new(foo.t) + } +} +*/ + +impl<T> Into<Vec<T>> for Foo<T> { + fn into(self) -> Vec<T> { + vec![self.t] + } +} + +pub fn main() { + let _: Result<Vec<i32>, Infallible> = Foo { t: 10 }.try_into(); +} |