bjoernager/rust
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Consider lifetimes when comparing assoc types in method chain

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Do not say "Type changed to X here" when the only difference is caused
by lifetimes.
This commit is contained in:
Esteban Küber 2022-12-13 18:00:24 -08:00
parent 3b938f73f3
commit 2492235c32
3 changed files with 44 additions and 14 deletions
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2
compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
View file

@ -3333,7 +3333,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
let ty_str = with_forced_trimmed_paths!(self.ty_to_string(ty));
let assoc = with_forced_trimmed_paths!(self.tcx.def_path_str(assoc));
if ty != *prev_ty {
if self.can_eq(param_env, ty, *prev_ty).is_err() {
if type_diffs.iter().any(|diff| {
let Sorts(expected_found) = diff else { return false; };
self.can_eq(param_env, expected_found.found, ty).is_ok()

12
src/test/ui/iterators/invalid-iterator-chain.rs
View file

@ -1,3 +1,11 @@
use std::collections::hash_set::Iter;
use std::collections::HashSet;
fn iter_to_vec<'b, X>(i: Iter<'b, X>) -> Vec<X> {
let i = i.map(|x| x.clone());
i.collect() //~ ERROR E0277
}
fn main() {
let scores = vec![(0, 0)]
.iter()
@ -38,4 +46,8 @@ fn main() {
});
let f = e.filter(|_| false);
let g: Vec<i32> = f.collect(); //~ ERROR E0277
let mut s = HashSet::new();
s.insert(1u8);
println!("{:?}", iter_to_vec(s.iter()));
}

44
src/test/ui/iterators/invalid-iterator-chain.stderr
View file

@ -1,5 +1,23 @@
error[E0277]: a value of type `Vec<X>` cannot be built from an iterator over elements of type `&X`
--> $DIR/invalid-iterator-chain.rs:6:7
|
LL | i.collect()
| ^^^^^^^ value of type `Vec<X>` cannot be built from `std::iter::Iterator<Item=&X>`
|
= help: the trait `FromIterator<&X>` is not implemented for `Vec<X>`
= help: the trait `FromIterator<T>` is implemented for `Vec<T>`
note: the method call chain might not have had the expected associated types
--> $DIR/invalid-iterator-chain.rs:4:26
|
LL | fn iter_to_vec<'b, X>(i: Iter<'b, X>) -> Vec<X> {
| ^^^^^^^^^^^ `Iterator::Item` is `&X` here
LL | let i = i.map(|x| x.clone());
| ------------------ `Iterator::Item` remains `&X` here
note: required by a bound in `collect`
--> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
error[E0277]: a value of type `i32` cannot be made by summing an iterator over elements of type `()`
--> $DIR/invalid-iterator-chain.rs:7:27
--> $DIR/invalid-iterator-chain.rs:15:27
|
LL | println!("{}", scores.sum::<i32>());
| ^^^ value of type `i32` cannot be made by summing a `std::iter::Iterator<Item=()>`
@ -9,7 +27,7 @@ LL | println!("{}", scores.sum::<i32>());
<i32 as Sum<&'a i32>>
<i32 as Sum>
note: the method call chain might not have had the expected associated types
--> $DIR/invalid-iterator-chain.rs:4:10
--> $DIR/invalid-iterator-chain.rs:12:10
|
LL | let scores = vec![(0, 0)]
| ------------ this expression has type `Vec<({integer}, {integer})>`
@ -24,7 +42,7 @@ note: required by a bound in `std::iter::Iterator::sum`
--> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
error[E0277]: a value of type `i32` cannot be made by summing an iterator over elements of type `()`
--> $DIR/invalid-iterator-chain.rs:18:14
--> $DIR/invalid-iterator-chain.rs:26:14
|
LL | .sum::<i32>(),
| ^^^ value of type `i32` cannot be made by summing a `std::iter::Iterator<Item=()>`
@ -34,7 +52,7 @@ LL | .sum::<i32>(),
<i32 as Sum<&'a i32>>
<i32 as Sum>
note: the method call chain might not have had the expected associated types
--> $DIR/invalid-iterator-chain.rs:12:14
--> $DIR/invalid-iterator-chain.rs:20:14
|
LL | vec![0, 1]
| ---------- this expression has type `Vec<{integer}>`
@ -56,7 +74,7 @@ note: required by a bound in `std::iter::Iterator::sum`
--> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
error[E0277]: a value of type `i32` cannot be made by summing an iterator over elements of type `f64`
--> $DIR/invalid-iterator-chain.rs:28:14
--> $DIR/invalid-iterator-chain.rs:36:14
|
LL | .sum::<i32>(),
| ^^^ value of type `i32` cannot be made by summing a `std::iter::Iterator<Item=f64>`
@ -66,7 +84,7 @@ LL | .sum::<i32>(),
<i32 as Sum<&'a i32>>
<i32 as Sum>
note: the method call chain might not have had the expected associated types
--> $DIR/invalid-iterator-chain.rs:24:14
--> $DIR/invalid-iterator-chain.rs:32:14
|
LL | vec![0, 1]
| ---------- this expression has type `Vec<{integer}>`
@ -84,7 +102,7 @@ note: required by a bound in `std::iter::Iterator::sum`
--> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
error[E0277]: a value of type `i32` cannot be made by summing an iterator over elements of type `()`
--> $DIR/invalid-iterator-chain.rs:30:54
--> $DIR/invalid-iterator-chain.rs:38:54
|
LL | println!("{}", vec![0, 1].iter().map(|x| { x; }).sum::<i32>());
| ^^^ value of type `i32` cannot be made by summing a `std::iter::Iterator<Item=()>`
@ -94,7 +112,7 @@ LL | println!("{}", vec![0, 1].iter().map(|x| { x; }).sum::<i32>());
<i32 as Sum<&'a i32>>
<i32 as Sum>
note: the method call chain might not have had the expected associated types
--> $DIR/invalid-iterator-chain.rs:30:38
--> $DIR/invalid-iterator-chain.rs:38:38
|
LL | println!("{}", vec![0, 1].iter().map(|x| { x; }).sum::<i32>());
| ---------- ------ ^^^^^^^^^^^^^^^ `Iterator::Item` changed to `()` here
@ -105,7 +123,7 @@ note: required by a bound in `std::iter::Iterator::sum`
--> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
error[E0277]: a value of type `i32` cannot be made by summing an iterator over elements of type `&()`
--> $DIR/invalid-iterator-chain.rs:31:40
--> $DIR/invalid-iterator-chain.rs:39:40
|
LL | println!("{}", vec![(), ()].iter().sum::<i32>());
| ^^^ value of type `i32` cannot be made by summing a `std::iter::Iterator<Item=&()>`
@ -115,7 +133,7 @@ LL | println!("{}", vec![(), ()].iter().sum::<i32>());
<i32 as Sum<&'a i32>>
<i32 as Sum>
note: the method call chain might not have had the expected associated types
--> $DIR/invalid-iterator-chain.rs:31:33
--> $DIR/invalid-iterator-chain.rs:39:33
|
LL | println!("{}", vec![(), ()].iter().sum::<i32>());
| ------------ ^^^^^^ `Iterator::Item` is `&()` here
@ -125,7 +143,7 @@ note: required by a bound in `std::iter::Iterator::sum`
--> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
error[E0277]: a value of type `Vec<i32>` cannot be built from an iterator over elements of type `()`
--> $DIR/invalid-iterator-chain.rs:40:25
--> $DIR/invalid-iterator-chain.rs:48:25
|
LL | let g: Vec<i32> = f.collect();
| ^^^^^^^ value of type `Vec<i32>` cannot be built from `std::iter::Iterator<Item=()>`
@ -133,7 +151,7 @@ LL | let g: Vec<i32> = f.collect();
= help: the trait `FromIterator<()>` is not implemented for `Vec<i32>`
= help: the trait `FromIterator<T>` is implemented for `Vec<T>`
note: the method call chain might not have had the expected associated types
--> $DIR/invalid-iterator-chain.rs:36:15
--> $DIR/invalid-iterator-chain.rs:44:15
|
LL | let a = vec![0];
| ------- this expression has type `Vec<{integer}>`
@ -153,6 +171,6 @@ LL | let f = e.filter(|_| false);
note: required by a bound in `collect`
--> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
error: aborting due to 6 previous errors
error: aborting due to 7 previous errors
For more information about this error, try `rustc --explain E0277`.