Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Don't type_of on trait assoc ty without default #72149

Merged
merged 1 commit into from
May 22, 2020
Merged

Don't type_of on trait assoc ty without default #72149

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
13 changes: 6 additions & 7 deletions src/librustc_middle/ty/error.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -817,19 +817,18 @@ fn foo(&self) -> Self::T { String::new() }
for item in &items[..] {
match item.kind {
hir::AssocItemKind::Type | hir::AssocItemKind::OpaqueTy => {
if self.type_of(self.hir().local_def_id(item.id.hir_id)) == found {
if let hir::Defaultness::Default { has_value: true } =
item.defaultness
{
// FIXME: account for returning some type in a trait fn impl that has
// an assoc type as a return type (#72076).
if let hir::Defaultness::Default { has_value: true } = item.defaultness
{
if self.type_of(self.hir().local_def_id(item.id.hir_id)) == found {
db.span_label(
item.span,
"associated type defaults can't be assumed inside the \
trait defining them",
);
} else {
db.span_label(item.span, "expected this associated type");
return true;
}
return true;
}
}
_ => {}
Expand Down
6 changes: 6 additions & 0 deletions src/test/ui/issues/issue-72076.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,6 @@
trait X {
type S;
fn f() -> Self::S {} //~ ERROR mismatched types
}

fn main() {}
14 changes: 14 additions & 0 deletions src/test/ui/issues/issue-72076.stderr
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,14 @@
error[E0308]: mismatched types
--> $DIR/issue-72076.rs:3:23
|
LL | fn f() -> Self::S {}
| ^^ expected associated type, found `()`
|
= note: expected associated type `<Self as X>::S`
found unit type `()`
= help: consider constraining the associated type `<Self as X>::S` to `()` or calling a method that returns `<Self as X>::S`
= note: for more information, visit https://doc.rust-lang.org/book/ch19-03-advanced-traits.html

error: aborting due to previous error

For more information about this error, try `rustc --explain E0308`.
1 change: 1 addition & 0 deletions src/test/ui/suggestions/trait-with-missing-associated-type-restriction.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@ trait Trait<T = Self> {

fn func(&self) -> Self::A;
fn funk(&self, _: Self::A);
fn funq(&self) -> Self::A {} //~ ERROR mismatched types
}

fn foo(_: impl Trait, x: impl Trait) {
Expand Down
37 changes: 27 additions & 10 deletions src/test/ui/suggestions/trait-with-missing-associated-type-restriction.stderr
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,5 +1,19 @@
error[E0308]: mismatched types
--> $DIR/trait-with-missing-associated-type-restriction.rs:13:9
--> $DIR/trait-with-missing-associated-type-restriction.rs:10:31
|
LL | fn funq(&self) -> Self::A {}
| ^^ expected associated type, found `()`
|
= note: expected associated type `<Self as Trait<T>>::A`
found unit type `()`
help: a method is available that returns `<Self as Trait<T>>::A`
--> $DIR/trait-with-missing-associated-type-restriction.rs:8:5
|
LL | fn func(&self) -> Self::A;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ consider calling `Trait::func`

error[E0308]: mismatched types
--> $DIR/trait-with-missing-associated-type-restriction.rs:14:9
|
LL | qux(x.func())
| ^^^^^^^^ expected `usize`, found associated type
Expand All @@ -12,7 +26,7 @@ LL | fn foo(_: impl Trait, x: impl Trait<A = usize>) {
| ^^^^^^^^^^^

error[E0308]: mismatched types
--> $DIR/trait-with-missing-associated-type-restriction.rs:17:9
--> $DIR/trait-with-missing-associated-type-restriction.rs:18:9
|
LL | qux(x.func())
| ^^^^^^^^ expected `usize`, found associated type
Expand All @@ -25,7 +39,7 @@ LL | fn bar<T: Trait<A = usize>>(x: T) {
| ^^^^^^^^^^^

error[E0308]: mismatched types
--> $DIR/trait-with-missing-associated-type-restriction.rs:21:9
--> $DIR/trait-with-missing-associated-type-restriction.rs:22:9
|
LL | qux(x.func())
| ^^^^^^^^ expected `usize`, found associated type
Expand All @@ -38,25 +52,28 @@ LL | fn foo2(x: impl Trait<i32, A = usize>) {
| ^^^^^^^^^^^

error[E0308]: mismatched types
--> $DIR/trait-with-missing-associated-type-restriction.rs:25:12
--> $DIR/trait-with-missing-associated-type-restriction.rs:26:12
|
LL | x.funk(3);
| ^ expected associated type, found integer
|
= note: expected associated type `<T as Trait<i32>>::A`
found type `{integer}`
help: a method is available that returns `<T as Trait<i32>>::A`
help: some methods are available that return `<T as Trait<i32>>::A`
--> $DIR/trait-with-missing-associated-type-restriction.rs:8:5
|
LL | fn func(&self) -> Self::A;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ consider calling `Trait::func`
LL | fn funk(&self, _: Self::A);
LL | fn funq(&self) -> Self::A {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^ consider calling `Trait::funq`
help: consider constraining the associated type `<T as Trait<i32>>::A` to `{integer}`
|
LL | fn bar2<T: Trait<i32, A = {integer}>>(x: T) {
| ^^^^^^^^^^^^^^^

error[E0308]: mismatched types
--> $DIR/trait-with-missing-associated-type-restriction.rs:26:9
--> $DIR/trait-with-missing-associated-type-restriction.rs:27:9
|
LL | qux(x.func())
| ^^^^^^^^ expected `usize`, found associated type
Expand All @@ -69,7 +86,7 @@ LL | fn bar2<T: Trait<i32, A = usize>>(x: T) {
| ^^^^^^^^^^^

error[E0308]: mismatched types
--> $DIR/trait-with-missing-associated-type-restriction.rs:30:9
--> $DIR/trait-with-missing-associated-type-restriction.rs:31:9
|
LL | fn baz<D: std::fmt::Debug, T: Trait<A = D>>(x: T) {
| - this type parameter
Expand All @@ -80,13 +97,13 @@ LL | qux(x.func())
found type parameter `D`

error[E0308]: mismatched types
--> $DIR/trait-with-missing-associated-type-restriction.rs:34:9
--> $DIR/trait-with-missing-associated-type-restriction.rs:35:9
|
LL | qux(x.func())
| ^^^^^^^^ expected `usize`, found `()`

error[E0308]: mismatched types
--> $DIR/trait-with-missing-associated-type-restriction.rs:38:9
--> $DIR/trait-with-missing-associated-type-restriction.rs:39:9
|
LL | qux(x.func())
| ^^^^^^^^ expected `usize`, found associated type
Expand All @@ -98,6 +115,6 @@ help: consider constraining the associated type `<T as Trait>::A` to `usize`
LL | fn ban<T>(x: T) where T: Trait<A = usize> {
| ^^^^^^^^^^^

error: aborting due to 8 previous errors
error: aborting due to 9 previous errors

For more information about this error, try `rustc --explain E0308`.