Closed
Description
Cross-crate
I tried this code:
a/src/lib.rs
#![feature(return_position_impl_trait_in_trait)]
pub trait A {
fn get_iter(&self) -> impl Iterator<Item = ()>;
}b/src/lib.rs
use a::A;
pub fn b(a: &impl A) -> usize {
a.get_iter().count()
}Compiled fine with 1.72.0-nightly (5ea666864 2023-06-27), but gives the following error with 1.72.0-nightly (5bd28f5ea 2023-06-28):
error[E0599]: `impl ?Sized` is not an iterator
--> src/lib.rs:6:18
|
4 | a.get_iter().count()
| ^^^^^ `impl ?Sized` is not an iterator
|
= note: the following trait bounds were not satisfied:
`impl ?Sized: Iterator`
which is required by `&mut impl ?Sized: Iterator`
For more information about this error, try `rustc --explain E0599`.
error: could not compile `b` (lib) due to previous error
Single crate
My initial attempt at minimizing the case shown that the single-crate equivalent:
c/src/lib.rs
#![feature(return_position_impl_trait_in_trait)]
pub trait A {
fn get_iter(&self) -> impl Iterator<Item = ()>;
}
pub fn b(a: &impl A) -> usize {
a.get_iter().count()
}compiles just fine.
Meta
rustc --version --verbose:
rustc 1.72.0-nightly (5bd28f5ea 2023-06-28)
binary: rustc
commit-hash: 5bd28f5eac1ba3569bfa8d49ec3f5acbdfdff7a0
commit-date: 2023-06-28
host: x86_64-unknown-linux-gnu
release: 1.72.0-nightly
LLVM version: 16.0.5
EDIT: Reduced reproduction code.