1 // check-pass
2 // run-rustfix
3 // edition 2018
4 #![warn(rust_2021_prelude_collisions)]
5 
6 trait MyTrait<A> {
from_iter(x: Option<A>)7     fn from_iter(x: Option<A>);
8 }
9 
10 impl<T> MyTrait<()> for Vec<T> {
from_iter(_: Option<()>)11     fn from_iter(_: Option<()>) {}
12 }
13 
main()14 fn main() {
15     <Vec<i32>>::from_iter(None);
16     //~^ WARNING trait-associated function `from_iter` will become ambiguous in Rust 2021
17     //~^^ WARNING this is accepted in the current edition
18 }
19