Open
Description
no error case:
pub fn true_pred<T>(_: T) -> bool {
true
}
pub fn foo<T, F>(ele: &T, mut f: F) -> Option<& T>
where F: FnMut(&T) -> bool,
{
[ele].into_iter()
.fold(None, |acc, _| {
acc.filter(|min| f(min))
})
//.filter(true_pred) // error!
}
error case:
pub fn true_pred<T>(_: T) -> bool {
true
}
pub fn foo<T, F>(ele: &T, mut f: F) -> Option<& T>
where F: FnMut(&T) -> bool,
{
[ele].into_iter()
.fold(None, |acc, _| {
acc.filter(|min| f(min))
})
.filter(true_pred) // error!
}
cargo check output:
error[E0308]: mismatched types
--> src/lib.rs:8:5
|
5 | pub fn foo<T, F>(ele: &T, mut f: F) -> Option<& T>
| - found this type parameter ----------- expected `Option<&T>` because of return type
...
8 | / [ele].into_iter()
9 | | .fold(None, |acc, _| {
10 | | acc.filter(|min| f(min))
11 | | })
12 | | .filter(true_pred) // error!
| |__________________________^ expected `Option<&T>`, found `Option<T>`
|
= note: expected enum `Option<&_>`
found enum `Option<_>`
help: try using `.as_ref()` to convert `Option<T>` to `Option<&T>`
|
12 | .filter(true_pred).as_ref() // error!
| +++++++++
For more information about this error, try `rustc --explain E0308`.
error: could not compile `test1` (lib) due to 1 previous error
rustc version:
rustc 1.82.0-nightly (1f12b9b0f 2024-08-27)
binary: rustc
commit-hash: 1f12b9b0fdbe735968ac002792a720f0ba4faca6
commit-date: 2024-08-27
host: aarch64-unknown-linux-gnu
release: 1.82.0-nightly
LLVM version: 19.1.0