Closed
Description
I tried this code:
fn get_numbers<T>() -> impl Iterator<Item=Result<i32, String>>
{
unimplemented!()
}I expected to see this happen: compile success
Instead, this happened:
error[E0277]: `()` is not an iterator
--> src\main.rs:68:24
|
68 | fn get_numbers<T>() -> impl Iterator<Item=Result<i32, String>>
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `()` is not an iterator
69 | {
70 | unimplemented!()
| ---------------- this returned value is of type `!`
|
= help: the trait `std::iter::Iterator` is not implemented for `()`
= note: the return type of a function must have a statically known size
Meta
rustc --version --verbose:
rustc 1.45.0-nightly (fe10f1a49 2020-06-02)
binary: rustc
commit-hash: fe10f1a49f5ca46e57261b95f46f519523f418fe
commit-date: 2020-06-02
host: x86_64-pc-windows-gnu
release: 1.45.0-nightly
LLVM version: 10.0
If you use templates then compile success.
fn get_numbers<T>() -> T
where T: Iterator<Item=Result<i32, String>>
{
unimplemented!()
}