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Account for type params with bounds

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This commit is contained in:
Esteban Küber 2020-04-05 12:32:34 -07:00
parent 794b644f0b
commit c85fde126e
3 changed files with 30 additions and 6 deletions
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11
src/librustc_trait_selection/traits/error_reporting/suggestions.rs
View File

@ -203,8 +203,7 @@ fn suggest_restriction(
{
if segment.ident.as_str() == impl_name.as_str() {
// `fn foo(t: impl Trait)`
// ^^^^^^^^^^ get this to suggest
// `T` instead
// ^^^^^^^^^^ get this to suggest `T` instead
// There might be more than one `impl Trait`.
ty_spans.push(input.span);
@ -237,7 +236,10 @@ fn suggest_restriction(
None => (generics.span, format!("<{}>", type_param)),
// `fn foo<A>(t: impl Trait)`
// ^^^ suggest `<A, T: Trait>` here
Some(param) => (param.span.shrink_to_hi(), format!(", {}", type_param)),
Some(param) => (
param.bounds_span().unwrap_or(param.span).shrink_to_hi(),
format!(", {}", type_param),
),
},
// `fn foo(t: impl Trait)`
// ^ suggest `where <T as Trait>::A: Bound`
@ -247,8 +249,7 @@ fn suggest_restriction(
// Suggest `fn foo<T: Trait>(t: T) where <T as Trait>::A: Bound`.
err.multipart_suggestion(
"introduce a type parameter with a trait bound instead of using \
`impl Trait`",
"introduce a type parameter with a trait bound instead of using `impl Trait`",
sugg,
Applicability::MaybeIncorrect,
);

8
src/test/ui/suggestions/impl-trait-with-missing-bounds.rs
View File

@ -24,6 +24,14 @@ fn baz(t: impl std::fmt::Debug, constraints: impl Iterator) {
}
}
fn bat<T: std::fmt::Debug>(t: T, constraints: impl Iterator) {
for constraint in constraints {
qux(t);
qux(constraint);
//~^ ERROR `<impl Iterator as std::iter::Iterator>::Item` doesn't implement `std::fmt::Debug`
}
}
fn qux(_: impl std::fmt::Debug) {}
fn main() {}

17
src/test/ui/suggestions/impl-trait-with-missing-bounds.stderr
View File

@ -43,6 +43,21 @@ help: introduce a type parameter with a trait bound instead of using `impl Trait
LL | fn baz<T: Iterator>(t: impl std::fmt::Debug, constraints: T) where <T as std::iter::Iterator>::Item: std::fmt::Debug {
| ^^^^^^^^^^^^^ ^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: aborting due to 3 previous errors
error[E0277]: `<impl Iterator as std::iter::Iterator>::Item` doesn't implement `std::fmt::Debug`
--> $DIR/impl-trait-with-missing-bounds.rs:30:13
|
LL | qux(constraint);
| ^^^^^^^^^^ `<impl Iterator as std::iter::Iterator>::Item` cannot be formatted using `{:?}` because it doesn't implement `std::fmt::Debug`
...
LL | fn qux(_: impl std::fmt::Debug) {}
| --- --------------- required by this bound in `qux`
|
= help: the trait `std::fmt::Debug` is not implemented for `<impl Iterator as std::iter::Iterator>::Item`
help: introduce a type parameter with a trait bound instead of using `impl Trait`
|
LL | fn bat<T: std::fmt::Debug, T: Iterator>(t: T, constraints: T) where <T as std::iter::Iterator>::Item: std::fmt::Debug {
| ^^^^^^^^^^^^^ ^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: aborting due to 4 previous errors
For more information about this error, try `rustc --explain E0277`.