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tweak suggestion for argument-position impl ?Sized #112614

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merged 2 commits into from
Jun 16, 2023
Merged

tweak suggestion for argument-position impl ?Sized #112614

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ee7e717
tweak suggestion for argument-position `impl ?Sized`
Jun 14, 2023
b6a3f12
change `std::marker::Sized` to just `Sized`
Jun 14, 2023
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48 changes: 31 additions & 17 deletions compiler/rustc_middle/src/ty/diagnostics.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -14,8 +14,8 @@ use rustc_errors::{Applicability, Diagnostic, DiagnosticArgValue, IntoDiagnostic
use rustc_hir as hir;
use rustc_hir::def::DefKind;
use rustc_hir::def_id::DefId;
use rustc_hir::WherePredicate;
use rustc_span::Span;
use rustc_hir::{PredicateOrigin, WherePredicate};
use rustc_span::{BytePos, Span};
use rustc_type_ir::sty::TyKind::*;

impl<'tcx> IntoDiagnosticArg for Ty<'tcx> {
Expand Down Expand Up @@ -156,10 +156,11 @@ enum SuggestChangingConstraintsMessage<'a> {
RestrictBoundFurther,
RestrictType { ty: &'a str },
RestrictTypeFurther { ty: &'a str },
RemovingQSized,
RemoveMaybeUnsized,
ReplaceMaybeUnsizedWithSized,
}

fn suggest_removing_unsized_bound(
fn suggest_changing_unsized_bound(
generics: &hir::Generics<'_>,
suggestions: &mut Vec<(Span, String, SuggestChangingConstraintsMessage<'_>)>,
param: &hir::GenericParam<'_>,
Expand All @@ -183,12 +184,25 @@ fn suggest_removing_unsized_bound(
if poly.trait_ref.trait_def_id() != def_id {
continue;
}
let sp = generics.span_for_bound_removal(where_pos, pos);
suggestions.push((
sp,
String::new(),
SuggestChangingConstraintsMessage::RemovingQSized,
));
if predicate.origin == PredicateOrigin::ImplTrait && predicate.bounds.len() == 1 {
// For `impl ?Sized` with no other bounds, suggest `impl Sized` instead.
let bound_span = bound.span();
if bound_span.can_be_used_for_suggestions() {
let question_span = bound_span.with_hi(bound_span.lo() + BytePos(1));
suggestions.push((
question_span,
String::new(),
SuggestChangingConstraintsMessage::ReplaceMaybeUnsizedWithSized,
));
}
} else {
let sp = generics.span_for_bound_removal(where_pos, pos);
suggestions.push((
sp,
String::new(),
SuggestChangingConstraintsMessage::RemoveMaybeUnsized,
));
}
}
}
}
Expand Down Expand Up @@ -238,14 +252,11 @@ pub fn suggest_constraining_type_params<'a>(
{
let mut sized_constraints =
constraints.extract_if(|(_, def_id)| *def_id == tcx.lang_items().sized_trait());
if let Some((constraint, def_id)) = sized_constraints.next() {
if let Some((_, def_id)) = sized_constraints.next() {
applicability = Applicability::MaybeIncorrect;

err.span_label(
param.span,
format!("this type parameter needs to be `{}`", constraint),
);
suggest_removing_unsized_bound(generics, &mut suggestions, param, def_id);
err.span_label(param.span, "this type parameter needs to be `Sized`");
suggest_changing_unsized_bound(generics, &mut suggestions, param, def_id);
}
}

Expand Down Expand Up @@ -395,9 +406,12 @@ pub fn suggest_constraining_type_params<'a>(
SuggestChangingConstraintsMessage::RestrictTypeFurther { ty } => {
Cow::from(format!("consider further restricting type parameter `{}`", ty))
}
SuggestChangingConstraintsMessage::RemovingQSized => {
SuggestChangingConstraintsMessage::RemoveMaybeUnsized => {
Cow::from("consider removing the `?Sized` bound to make the type parameter `Sized`")
}
SuggestChangingConstraintsMessage::ReplaceMaybeUnsizedWithSized => {
Cow::from("consider replacing `?Sized` with `Sized`")
}
};

err.span_suggestion_verbose(span, msg, suggestion, applicability);
Expand Down
2 changes: 1 addition & 1 deletion tests/ui/const-generics/const-argument-if-length.full.stderr
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Expand Up @@ -2,7 +2,7 @@ error[E0277]: the size for values of type `T` cannot be known at compilation tim
--> $DIR/const-argument-if-length.rs:15:12
|
LL | pub struct AtLeastByte<T: ?Sized> {
| - this type parameter needs to be `std::marker::Sized`
| - this type parameter needs to be `Sized`
LL | value: T,
| ^ doesn't have a size known at compile-time
|
Expand Down
2 changes: 1 addition & 1 deletion tests/ui/const-generics/const-argument-if-length.min.stderr
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Expand Up @@ -11,7 +11,7 @@ error[E0277]: the size for values of type `T` cannot be known at compilation tim
--> $DIR/const-argument-if-length.rs:15:12
|
LL | pub struct AtLeastByte<T: ?Sized> {
| - this type parameter needs to be `std::marker::Sized`
| - this type parameter needs to be `Sized`
LL | value: T,
| ^ doesn't have a size known at compile-time
|
Expand Down
4 changes: 2 additions & 2 deletions tests/ui/dst/dst-object-from-unsized-type.stderr
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Expand Up @@ -2,7 +2,7 @@ error[E0277]: the size for values of type `T` cannot be known at compilation tim
--> $DIR/dst-object-from-unsized-type.rs:8:23
|
LL | fn test1<T: ?Sized + Foo>(t: &T) {
| - this type parameter needs to be `std::marker::Sized`
| - this type parameter needs to be `Sized`
LL | let u: &dyn Foo = t;
| ^ doesn't have a size known at compile-time
|
Expand All @@ -17,7 +17,7 @@ error[E0277]: the size for values of type `T` cannot be known at compilation tim
--> $DIR/dst-object-from-unsized-type.rs:13:23
|
LL | fn test2<T: ?Sized + Foo>(t: &T) {
| - this type parameter needs to be `std::marker::Sized`
| - this type parameter needs to be `Sized`
LL | let v: &dyn Foo = t as &dyn Foo;
| ^ doesn't have a size known at compile-time
|
Expand Down
2 changes: 1 addition & 1 deletion tests/ui/generic-associated-types/issue-88287.stderr
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Expand Up @@ -2,7 +2,7 @@ error[E0277]: the size for values of type `A` cannot be known at compilation tim
--> $DIR/issue-88287.rs:34:9
|
LL | type SearchFutureTy<'f, A, B: 'f>
| - this type parameter needs to be `std::marker::Sized`
| - this type parameter needs to be `Sized`
...
LL | async move { todo!() }
| ^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
Expand Down
2 changes: 1 addition & 1 deletion tests/ui/offset-of/offset-of-dst-field.stderr
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Expand Up @@ -70,7 +70,7 @@ error[E0277]: the size for values of type `T` cannot be known at compilation tim
--> $DIR/offset-of-dst-field.rs:50:5
|
LL | fn generic_with_maybe_sized<T: ?Sized>() -> usize {
| - this type parameter needs to be `std::marker::Sized`
| - this type parameter needs to be `Sized`
LL | offset_of!(Delta<T>, z)
| ^^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
|
Expand Down
2 changes: 1 addition & 1 deletion tests/ui/packed/issue-27060-2.stderr
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Expand Up @@ -2,7 +2,7 @@ error[E0277]: the size for values of type `T` cannot be known at compilation tim
--> $DIR/issue-27060-2.rs:3:11
|
LL | pub struct Bad<T: ?Sized> {
| - this type parameter needs to be `std::marker::Sized`
| - this type parameter needs to be `Sized`
LL | data: T,
| ^ doesn't have a size known at compile-time
|
Expand Down
2 changes: 1 addition & 1 deletion tests/ui/suggestions/adt-param-with-implicit-sized-bound.stderr
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Expand Up @@ -2,7 +2,7 @@ error[E0277]: the size for values of type `T` cannot be known at compilation tim
--> $DIR/adt-param-with-implicit-sized-bound.rs:25:9
|
LL | struct Struct5<T: ?Sized>{
| - this type parameter needs to be `std::marker::Sized`
| - this type parameter needs to be `Sized`
LL | _t: X<T>,
| ^^^^ doesn't have a size known at compile-time
|
Expand Down
6 changes: 3 additions & 3 deletions tests/ui/suggestions/removal-of-multiline-trait-bound-in-where-clause.stderr
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Expand Up @@ -4,7 +4,7 @@ error[E0277]: the size for values of type `T` cannot be known at compilation tim
LL | fn foo<T>(foo: Wrapper<T>)
| - ^^^^^^^^^^ doesn't have a size known at compile-time
| |
| this type parameter needs to be `std::marker::Sized`
| this type parameter needs to be `Sized`
|
note: required by a bound in `Wrapper`
--> $DIR/removal-of-multiline-trait-bound-in-where-clause.rs:1:16
Expand Down Expand Up @@ -33,7 +33,7 @@ error[E0277]: the size for values of type `T` cannot be known at compilation tim
LL | fn bar<T>(foo: Wrapper<T>)
| - ^^^^^^^^^^ doesn't have a size known at compile-time
| |
| this type parameter needs to be `std::marker::Sized`
| this type parameter needs to be `Sized`
|
note: required by a bound in `Wrapper`
--> $DIR/removal-of-multiline-trait-bound-in-where-clause.rs:1:16
Expand All @@ -58,7 +58,7 @@ error[E0277]: the size for values of type `T` cannot be known at compilation tim
LL | fn qux<T>(foo: Wrapper<T>)
| - ^^^^^^^^^^ doesn't have a size known at compile-time
| |
| this type parameter needs to be `std::marker::Sized`
| this type parameter needs to be `Sized`
|
note: required by a bound in `Wrapper`
--> $DIR/removal-of-multiline-trait-bound-in-where-clause.rs:1:16
Expand Down
4 changes: 4 additions & 0 deletions tests/ui/trait-bounds/apit-unsized.rs
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@@ -0,0 +1,4 @@
fn foo(_: impl Iterator<Item = i32> + ?Sized) {} //~ ERROR [E0277]
fn bar(_: impl ?Sized) {} //~ ERROR [E0277]

fn main() {}
41 changes: 41 additions & 0 deletions tests/ui/trait-bounds/apit-unsized.stderr
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@@ -0,0 +1,41 @@
error[E0277]: the size for values of type `impl Iterator<Item = i32> + ?Sized` cannot be known at compilation time
--> $DIR/apit-unsized.rs:1:8
|
LL | fn foo(_: impl Iterator<Item = i32> + ?Sized) {}
| ^ ---------------------------------- this type parameter needs to be `Sized`
| |
| doesn't have a size known at compile-time
|
= help: unsized fn params are gated as an unstable feature
help: consider removing the `?Sized` bound to make the type parameter `Sized`
|
LL - fn foo(_: impl Iterator<Item = i32> + ?Sized) {}
LL + fn foo(_: impl Iterator<Item = i32>) {}
|
help: function arguments must have a statically known size, borrowed types always have a known size
|
LL | fn foo(_: &impl Iterator<Item = i32> + ?Sized) {}
| +

error[E0277]: the size for values of type `impl ?Sized` cannot be known at compilation time
--> $DIR/apit-unsized.rs:2:8
|
LL | fn bar(_: impl ?Sized) {}
| ^ ----------- this type parameter needs to be `Sized`
| |
| doesn't have a size known at compile-time
|
= help: unsized fn params are gated as an unstable feature
help: consider replacing `?Sized` with `Sized`
|
LL - fn bar(_: impl ?Sized) {}
LL + fn bar(_: impl Sized) {}
|
help: function arguments must have a statically known size, borrowed types always have a known size
|
LL | fn bar(_: &impl ?Sized) {}
| +

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0277`.
30 changes: 13 additions & 17 deletions tests/ui/trait-bounds/unsized-bound.stderr
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Expand Up @@ -4,7 +4,7 @@ error[E0277]: the size for values of type `B` cannot be known at compilation tim
LL | impl<A, B> Trait<(A, B)> for (A, B) where A: ?Sized, B: ?Sized, {}
| - ^^^^^^ doesn't have a size known at compile-time
| |
| this type parameter needs to be `std::marker::Sized`
| this type parameter needs to be `Sized`
|
= note: required because it appears within the type `(A, B)`
note: required by a bound in `Trait`
Expand All @@ -28,7 +28,7 @@ error[E0277]: the size for values of type `A` cannot be known at compilation tim
LL | impl<A, B> Trait<(A, B)> for (A, B) where A: ?Sized, B: ?Sized, {}
| - ^^^^^^ doesn't have a size known at compile-time
| |
| this type parameter needs to be `std::marker::Sized`
| this type parameter needs to be `Sized`
|
= note: only the last element of a tuple may have a dynamically sized type
help: consider removing the `?Sized` bound to make the type parameter `Sized`
Expand All @@ -43,7 +43,7 @@ error[E0277]: the size for values of type `C` cannot be known at compilation tim
LL | impl<A, B: ?Sized, C: ?Sized> Trait<(A, B, C)> for (A, B, C) where A: ?Sized, {}
| - ^^^^^^^^^ doesn't have a size known at compile-time
| |
| this type parameter needs to be `std::marker::Sized`
| this type parameter needs to be `Sized`
|
= note: required because it appears within the type `(A, B, C)`
note: required by a bound in `Trait`
Expand All @@ -65,9 +65,7 @@ error[E0277]: the size for values of type `A` cannot be known at compilation tim
--> $DIR/unsized-bound.rs:5:52
|
LL | impl<A, B: ?Sized, C: ?Sized> Trait<(A, B, C)> for (A, B, C) where A: ?Sized, {}
| - ^^^^^^^^^ doesn't have a size known at compile-time
| |
| this type parameter needs to be `std::marker::Sized`
| - this type parameter needs to be `Sized` ^^^^^^^^^ doesn't have a size known at compile-time
|
= note: only the last element of a tuple may have a dynamically sized type
help: consider removing the `?Sized` bound to make the type parameter `Sized`
Expand All @@ -80,9 +78,7 @@ error[E0277]: the size for values of type `B` cannot be known at compilation tim
--> $DIR/unsized-bound.rs:5:52
|
LL | impl<A, B: ?Sized, C: ?Sized> Trait<(A, B, C)> for (A, B, C) where A: ?Sized, {}
| - ^^^^^^^^^ doesn't have a size known at compile-time
| |
| this type parameter needs to be `std::marker::Sized`
| - this type parameter needs to be `Sized` ^^^^^^^^^ doesn't have a size known at compile-time
|
= note: only the last element of a tuple may have a dynamically sized type
help: consider removing the `?Sized` bound to make the type parameter `Sized`
Expand All @@ -97,7 +93,7 @@ error[E0277]: the size for values of type `B` cannot be known at compilation tim
LL | impl<A: ?Sized, B: ?Sized> Trait2<(A, B)> for (A, B) {}
| - ^^^^^^ doesn't have a size known at compile-time
| |
| this type parameter needs to be `std::marker::Sized`
| this type parameter needs to be `Sized`
|
= note: required because it appears within the type `(A, B)`
note: required by a bound in `Trait2`
Expand All @@ -121,7 +117,7 @@ error[E0277]: the size for values of type `A` cannot be known at compilation tim
LL | impl<A: ?Sized, B: ?Sized> Trait2<(A, B)> for (A, B) {}
| - ^^^^^^ doesn't have a size known at compile-time
| |
| this type parameter needs to be `std::marker::Sized`
| this type parameter needs to be `Sized`
|
= note: only the last element of a tuple may have a dynamically sized type
help: consider removing the `?Sized` bound to make the type parameter `Sized`
Expand All @@ -136,7 +132,7 @@ error[E0277]: the size for values of type `A` cannot be known at compilation tim
LL | impl<A> Trait3<A> for A where A: ?Sized {}
| - ^ doesn't have a size known at compile-time
| |
| this type parameter needs to be `std::marker::Sized`
| this type parameter needs to be `Sized`
|
note: required by a bound in `Trait3`
--> $DIR/unsized-bound.rs:13:14
Expand All @@ -159,7 +155,7 @@ error[E0277]: the size for values of type `A` cannot be known at compilation tim
LL | impl<A: ?Sized> Trait4<A> for A {}
| - ^ doesn't have a size known at compile-time
| |
| this type parameter needs to be `std::marker::Sized`
| this type parameter needs to be `Sized`
|
note: required by a bound in `Trait4`
--> $DIR/unsized-bound.rs:16:14
Expand All @@ -182,7 +178,7 @@ error[E0277]: the size for values of type `X` cannot be known at compilation tim
LL | impl<X, Y> Trait5<X, Y> for X where X: ?Sized {}
| - ^ doesn't have a size known at compile-time
| |
| this type parameter needs to be `std::marker::Sized`
| this type parameter needs to be `Sized`
|
note: required by a bound in `Trait5`
--> $DIR/unsized-bound.rs:19:14
Expand All @@ -205,7 +201,7 @@ error[E0277]: the size for values of type `X` cannot be known at compilation tim
LL | impl<X: ?Sized, Y> Trait6<X, Y> for X {}
| - ^ doesn't have a size known at compile-time
| |
| this type parameter needs to be `std::marker::Sized`
| this type parameter needs to be `Sized`
|
note: required by a bound in `Trait6`
--> $DIR/unsized-bound.rs:22:14
Expand All @@ -228,7 +224,7 @@ error[E0277]: the size for values of type `Y` cannot be known at compilation tim
LL | impl<X, Y> Trait7<X, Y> for X where Y: ?Sized {}
| - ^^^^^^^^^^^^ doesn't have a size known at compile-time
| |
| this type parameter needs to be `std::marker::Sized`
| this type parameter needs to be `Sized`
|
note: required by a bound in `Trait7`
--> $DIR/unsized-bound.rs:25:17
Expand All @@ -251,7 +247,7 @@ error[E0277]: the size for values of type `Y` cannot be known at compilation tim
LL | impl<X, Y: ?Sized> Trait8<X, Y> for X {}
| - ^^^^^^^^^^^^ doesn't have a size known at compile-time
| |
| this type parameter needs to be `std::marker::Sized`
| this type parameter needs to be `Sized`
|
note: required by a bound in `Trait8`
--> $DIR/unsized-bound.rs:28:17
Expand Down
4 changes: 2 additions & 2 deletions tests/ui/traits/suggest-where-clause.stderr
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Expand Up @@ -2,7 +2,7 @@ error[E0277]: the size for values of type `U` cannot be known at compilation tim
--> $DIR/suggest-where-clause.rs:7:20
|
LL | fn check<T: Iterator, U: ?Sized>() {
| - this type parameter needs to be `std::marker::Sized`
| - this type parameter needs to be `Sized`
LL | // suggest a where-clause, if needed
LL | mem::size_of::<U>();
| ^ doesn't have a size known at compile-time
Expand All @@ -19,7 +19,7 @@ error[E0277]: the size for values of type `U` cannot be known at compilation tim
--> $DIR/suggest-where-clause.rs:10:20
|
LL | fn check<T: Iterator, U: ?Sized>() {
| - this type parameter needs to be `std::marker::Sized`
| - this type parameter needs to be `Sized`
...
LL | mem::size_of::<Misc<U>>();
| ^^^^^^^ doesn't have a size known at compile-time
Expand Down
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