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Add a suggestion when using a type alias instead of trait alias

This commit is contained in:
Yuki Okushi 2021-04-01 08:37:29 +09:00
parent a5029ac0ab
commit 539242a07b
8 changed files with 61 additions and 17 deletions

View file

@ -928,7 +928,14 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
let msg = "you might have meant to use `#![feature(trait_alias)]` instead of a \
`type` alias";
if let Some(span) = self.def_span(def_id) {
if let Ok(snip) = self.r.session.source_map().span_to_snippet(span) {
// The span contains a type alias so we should be able to
// replace `type` with `trait`.
let snip = snip.replacen("type", "trait", 1);
err.span_suggestion(span, msg, snip, Applicability::MaybeIncorrect);
} else {
err.span_help(span, msg);
}
} else {
err.help(msg);
}

View file

@ -5,10 +5,9 @@ LL | impl Bar for Baz { }
| ^^^ type aliases cannot be used as traits
|
help: you might have meant to use `#![feature(trait_alias)]` instead of a `type` alias
--> $DIR/two_files_data.rs:5:1
|
LL | type Bar = dyn Foo;
| ^^^^^^^^^^^^^^^^^^^
LL | trait Bar = dyn Foo;
|
error: aborting due to previous error

View file

@ -5,10 +5,9 @@ LL | impl Foo for S {
| ^^^ type aliases cannot be used as traits
|
help: you might have meant to use `#![feature(trait_alias)]` instead of a `type` alias
--> $DIR/issue-3907.rs:5:1
|
LL | type Foo = dyn issue_3907::Foo;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
LL | trait Foo = dyn issue_3907::Foo;
|
help: consider importing this trait instead
|
LL | use issue_3907::Foo;

View file

@ -11,16 +11,16 @@ LL | trait I {}
| ------- similarly named trait `I` defined here
LL | type K = dyn I;
LL | impl K for isize {}
| ^
| |
| type aliases cannot be used as traits
| help: a trait with a similar name exists: `I`
| ^ type aliases cannot be used as traits
|
help: you might have meant to use `#![feature(trait_alias)]` instead of a `type` alias
--> $DIR/issue-5035.rs:2:1
|
LL | type K = dyn I;
| ^^^^^^^^^^^^^^^
LL | trait K = dyn I;
|
help: a trait with a similar name exists
|
LL | impl I for isize {}
| ^
error: aborting due to 2 previous errors

View file

@ -11,10 +11,9 @@ LL | fn g<F:Typedef(isize) -> isize>(x: F) {}
| ^^^^^^^^^^^^^^^^^^^^^^^ type aliases cannot be used as traits
|
help: you might have meant to use `#![feature(trait_alias)]` instead of a `type` alias
--> $DIR/unboxed-closure-sugar-nonexistent-trait.rs:4:1
|
LL | type Typedef = isize;
| ^^^^^^^^^^^^^^^^^^^^^
LL | trait Typedef = isize;
|
error: aborting due to 2 previous errors

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@ -0,0 +1,13 @@
// Regression test of #43913.
// run-rustfix
#![feature(trait_alias)]
#![allow(bare_trait_objects, dead_code)]
trait Strings = Iterator<Item=String>;
struct Struct<S: Strings>(S);
//~^ ERROR: expected trait, found type alias `Strings`
fn main() {}

View file

@ -0,0 +1,13 @@
// Regression test of #43913.
// run-rustfix
#![feature(trait_alias)]
#![allow(bare_trait_objects, dead_code)]
type Strings = Iterator<Item=String>;
struct Struct<S: Strings>(S);
//~^ ERROR: expected trait, found type alias `Strings`
fn main() {}

View file

@ -0,0 +1,14 @@
error[E0404]: expected trait, found type alias `Strings`
--> $DIR/suggest-trait-alias-instead-of-type.rs:10:18
|
LL | struct Struct<S: Strings>(S);
| ^^^^^^^ type aliases cannot be used as traits
|
help: you might have meant to use `#![feature(trait_alias)]` instead of a `type` alias
|
LL | trait Strings = Iterator<Item=String>;
|
error: aborting due to previous error
For more information about this error, try `rustc --explain E0404`.