user0/rust
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Suggest impl Iterator when possible for _ return type

Browse source 
Address #106096.
This commit is contained in:
Esteban Küber 2022-12-26 17:44:16 -08:00
parent caa64e5b5e
commit 1b341fe8a1
5 changed files with 96 additions and 3 deletions
Download patch file Download diff file Expand all files Collapse all files

8
src/test/ui/typeck/typeck_type_placeholder_item.rs
View file

@ -220,3 +220,11 @@ fn value() -> Option<&'static _> {
const _: Option<_> = map(value);
//~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
fn evens_squared(n: usize) -> _ {
//~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
(1..n).filter(|x| x % 2 == 0).map(|x| x * x)
}
const _: _ = (1..10).filter(|x| x % 2 == 0).map(|x| x * x);
//~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants

23
src/test/ui/typeck/typeck_type_placeholder_item.stderr
View file

@ -428,6 +428,27 @@ LL | const _: Option<_> = map(value);
| not allowed in type signatures
| help: replace with the correct type: `Option<u8>`
error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
--> $DIR/typeck_type_placeholder_item.rs:224:31
|
LL | fn evens_squared(n: usize) -> _ {
| ^
| |
| not allowed in type signatures
| help: replace with an appropriate return type: `impl Iterator<Item = usize>`
error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
--> $DIR/typeck_type_placeholder_item.rs:229:10
|
LL | const _: _ = (1..10).filter(|x| x % 2 == 0).map(|x| x * x);
| ^ not allowed in type signatures
|
note: however, the inferred type `Map<Filter<std::ops::Range<i32>, [closure@$DIR/typeck_type_placeholder_item.rs:229:29: 229:32]>, [closure@$DIR/typeck_type_placeholder_item.rs:229:49: 229:52]>` cannot be named
--> $DIR/typeck_type_placeholder_item.rs:229:14
|
LL | const _: _ = (1..10).filter(|x| x % 2 == 0).map(|x| x * x);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
--> $DIR/typeck_type_placeholder_item.rs:140:31
|
@ -636,7 +657,7 @@ LL | const D: _ = 42;
| not allowed in type signatures
| help: replace with the correct type: `i32`
error: aborting due to 69 previous errors
error: aborting due to 71 previous errors
Some errors have detailed explanations: E0121, E0282, E0403.
For more information about an error, try `rustc --explain E0121`.