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Don't type_of on trait assoc ty without default

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Fix #72076.
This commit is contained in:
Esteban Küber 2020-05-12 10:56:26 -07:00
parent d903a9def4
commit a3f30bbc2d
5 changed files with 54 additions and 17 deletions
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13
src/librustc_middle/ty/error.rs
View file

@ -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;
}
}
_ => {}

6
src/test/ui/issues/issue-72076.rs Normal file
View file

@ -0,0 +1,6 @@
trait X {
type S;
fn f() -> Self::S {} //~ ERROR mismatched types
}
fn main() {}

14
src/test/ui/issues/issue-72076.stderr Normal file
View file

@ -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
src/test/ui/suggestions/trait-with-missing-associated-type-restriction.rs
View file

@ -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) {

37
src/test/ui/suggestions/trait-with-missing-associated-type-restriction.stderr
View file

@ -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
@ -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
@ -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
@ -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
@ -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
@ -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
@ -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`.