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Rollup merge of #127717 - gurry:127441-stray-impl-sugg, r=compiler-errors
Fix malformed suggestion for repeated maybe unsized bounds Fixes #127441 Now when we encounter something like `foo(a : impl ?Sized + ?Sized)`, instead of suggesting removal of both bounds and leaving `foo(a: impl )` behind, we suggest changing the first bound to `Sized` and removing the second bound, resulting in `foo(a: impl Sized)`. Although the issue was reported for impl trait types, it also occurred with regular param bounds. So if we encounter `foo<T: ?Sized + ?Sized>(a: T)` we now detect that all the bounds are `?Sized` and therefore emit the suggestion to remove the entire predicate `: ?Sized + ?Sized` resulting in `foo<T>(a: T)`. Lastly, if we encounter a situation where some of the bounds are something other than `?Sized`, then we emit separate removal suggestions for each `?Sized` bound. E.g. if we see `foo(a: impl ?Sized + Bar + ?Sized)` or `foo<T: ?Sized + Bar + ?Sized>(a: T)` we emit suggestions such that the user will be left with `foo(a : impl Bar)` or `foo<T: Bar>(a: T)` respectively.
This commit is contained in:
Matthias Krüger
GitHub
commit
2ff33bb1df
@ -763,7 +763,7 @@ impl<'hir> Generics<'hir> {
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)
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}
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fn span_for_predicate_removal(&self, pos: usize) -> Span {
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pub fn span_for_predicate_removal(&self, pos: usize) -> Span {
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let predicate = &self.predicates[pos];
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let span = predicate.span();
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@ -806,15 +806,21 @@ impl<'hir> Generics<'hir> {
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return self.span_for_predicate_removal(predicate_pos);
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}
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let span = bounds[bound_pos].span();
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if bound_pos == 0 {
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// where T: ?Sized + Bar, Foo: Bar,
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// ^^^^^^^^^
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span.to(bounds[1].span().shrink_to_lo())
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let bound_span = bounds[bound_pos].span();
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if bound_pos < bounds.len() - 1 {
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// If there's another bound after the current bound
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// include the following '+' e.g.:
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//
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// `T: Foo + CurrentBound + Bar`
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// ^^^^^^^^^^^^^^^
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bound_span.to(bounds[bound_pos + 1].span().shrink_to_lo())
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} else {
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// where T: Bar + ?Sized, Foo: Bar,
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// ^^^^^^^^^
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bounds[bound_pos - 1].span().shrink_to_hi().to(span)
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// If the current bound is the last bound
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// include the preceding '+' E.g.:
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//
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// `T: Foo + Bar + CurrentBound`
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// ^^^^^^^^^^^^^^^
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bound_span.with_lo(bounds[bound_pos - 1].span().hi())
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}
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}
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}
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@ -188,31 +188,60 @@ fn suggest_changing_unsized_bound(
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continue;
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};
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for (pos, bound) in predicate.bounds.iter().enumerate() {
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let hir::GenericBound::Trait(poly, hir::TraitBoundModifier::Maybe) = bound else {
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continue;
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};
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if poly.trait_ref.trait_def_id() != def_id {
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continue;
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}
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if predicate.origin == PredicateOrigin::ImplTrait && predicate.bounds.len() == 1 {
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// For `impl ?Sized` with no other bounds, suggest `impl Sized` instead.
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let bound_span = bound.span();
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if bound_span.can_be_used_for_suggestions() {
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let question_span = bound_span.with_hi(bound_span.lo() + BytePos(1));
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suggestions.push((
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let unsized_bounds = predicate
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.bounds
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.iter()
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.enumerate()
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.filter(|(_, bound)| {
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if let hir::GenericBound::Trait(poly, hir::TraitBoundModifier::Maybe) = bound
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&& poly.trait_ref.trait_def_id() == def_id
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{
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true
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} else {
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false
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}
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})
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.collect::<Vec<_>>();
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if unsized_bounds.is_empty() {
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continue;
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}
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let mut push_suggestion = |sp, msg| suggestions.push((sp, String::new(), msg));
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if predicate.bounds.len() == unsized_bounds.len() {
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// All the bounds are unsized bounds, e.g.
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// `T: ?Sized + ?Sized` or `_: impl ?Sized + ?Sized`,
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// so in this case:
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// - if it's an impl trait predicate suggest changing the
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// the first bound to sized and removing the rest
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// - Otherwise simply suggest removing the entire predicate
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if predicate.origin == PredicateOrigin::ImplTrait {
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let first_bound = unsized_bounds[0].1;
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let first_bound_span = first_bound.span();
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if first_bound_span.can_be_used_for_suggestions() {
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let question_span =
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first_bound_span.with_hi(first_bound_span.lo() + BytePos(1));
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push_suggestion(
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question_span,
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String::new(),
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SuggestChangingConstraintsMessage::ReplaceMaybeUnsizedWithSized,
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));
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);
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for (pos, _) in unsized_bounds.iter().skip(1) {
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let sp = generics.span_for_bound_removal(where_pos, *pos);
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push_suggestion(sp, SuggestChangingConstraintsMessage::RemoveMaybeUnsized);
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}
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}
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} else {
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let sp = generics.span_for_predicate_removal(where_pos);
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push_suggestion(sp, SuggestChangingConstraintsMessage::RemoveMaybeUnsized);
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}
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} else {
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// Some of the bounds are other than unsized.
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// So push separate removal suggestion for each unsized bound
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for (pos, _) in unsized_bounds {
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let sp = generics.span_for_bound_removal(where_pos, pos);
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suggestions.push((
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sp,
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String::new(),
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SuggestChangingConstraintsMessage::RemoveMaybeUnsized,
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));
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push_suggestion(sp, SuggestChangingConstraintsMessage::RemoveMaybeUnsized);
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}
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}
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}
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@ -0,0 +1,39 @@
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// Regression test for #127441
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// Tests that we make the correct suggestion
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// in case there are more than one `?Sized`
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// bounds on a function parameter
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use std::fmt::Debug;
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fn foo1<T: ?Sized>(a: T) {}
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//~^ ERROR he size for values of type `T` cannot be known at compilation time
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fn foo2<T: ?Sized + ?Sized>(a: T) {}
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//~^ ERROR type parameter has more than one relaxed default bound, only one is supported
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//~| ERROR the size for values of type `T` cannot be known at compilation time
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fn foo3<T: ?Sized + ?Sized + Debug>(a: T) {}
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//~^ ERROR type parameter has more than one relaxed default bound, only one is supported
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//~| ERROR he size for values of type `T` cannot be known at compilation time
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fn foo4<T: ?Sized + Debug + ?Sized >(a: T) {}
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//~^ ERROR type parameter has more than one relaxed default bound, only one is supported
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//~| ERROR the size for values of type `T` cannot be known at compilation time
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fn foo5(_: impl ?Sized) {}
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//~^ ERROR the size for values of type `impl ?Sized` cannot be known at compilation time
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fn foo6(_: impl ?Sized + ?Sized) {}
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//~^ ERROR type parameter has more than one relaxed default bound, only one is supported
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//~| ERROR the size for values of type `impl ?Sized + ?Sized` cannot be known at compilation tim
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fn foo7(_: impl ?Sized + ?Sized + Debug) {}
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//~^ ERROR type parameter has more than one relaxed default bound, only one is supported
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//~| ERROR the size for values of type `impl ?Sized + ?Sized + Debug` cannot be known at compilation time
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fn foo8(_: impl ?Sized + Debug + ?Sized ) {}
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//~^ ERROR type parameter has more than one relaxed default bound, only one is supported
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//~| ERROR the size for values of type `impl ?Sized + Debug + ?Sized` cannot be known at compilation time
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fn main() {}
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@ -0,0 +1,192 @@
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error[E0203]: type parameter has more than one relaxed default bound, only one is supported
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--> $DIR/bad-suggestionf-for-repeated-unsized-bound-127441.rs:12:12
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LL | fn foo2<T: ?Sized + ?Sized>(a: T) {}
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| ^^^^^^ ^^^^^^
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error[E0203]: type parameter has more than one relaxed default bound, only one is supported
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--> $DIR/bad-suggestionf-for-repeated-unsized-bound-127441.rs:16:12
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LL | fn foo3<T: ?Sized + ?Sized + Debug>(a: T) {}
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| ^^^^^^ ^^^^^^
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error[E0203]: type parameter has more than one relaxed default bound, only one is supported
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--> $DIR/bad-suggestionf-for-repeated-unsized-bound-127441.rs:20:12
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LL | fn foo4<T: ?Sized + Debug + ?Sized >(a: T) {}
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| ^^^^^^ ^^^^^^
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error[E0203]: type parameter has more than one relaxed default bound, only one is supported
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--> $DIR/bad-suggestionf-for-repeated-unsized-bound-127441.rs:27:17
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LL | fn foo6(_: impl ?Sized + ?Sized) {}
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| ^^^^^^ ^^^^^^
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error[E0203]: type parameter has more than one relaxed default bound, only one is supported
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--> $DIR/bad-suggestionf-for-repeated-unsized-bound-127441.rs:31:17
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LL | fn foo7(_: impl ?Sized + ?Sized + Debug) {}
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| ^^^^^^ ^^^^^^
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error[E0203]: type parameter has more than one relaxed default bound, only one is supported
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--> $DIR/bad-suggestionf-for-repeated-unsized-bound-127441.rs:35:17
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LL | fn foo8(_: impl ?Sized + Debug + ?Sized ) {}
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| ^^^^^^ ^^^^^^
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error[E0277]: the size for values of type `T` cannot be known at compilation time
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--> $DIR/bad-suggestionf-for-repeated-unsized-bound-127441.rs:9:20
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LL | fn foo1<T: ?Sized>(a: T) {}
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| - ^ doesn't have a size known at compile-time
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| |
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| this type parameter needs to be `Sized`
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= help: unsized fn params are gated as an unstable feature
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help: consider removing the `?Sized` bound to make the type parameter `Sized`
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LL - fn foo1<T: ?Sized>(a: T) {}
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LL + fn foo1<T>(a: T) {}
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help: function arguments must have a statically known size, borrowed types always have a known size
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LL | fn foo1<T: ?Sized>(a: &T) {}
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| +
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error[E0277]: the size for values of type `T` cannot be known at compilation time
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--> $DIR/bad-suggestionf-for-repeated-unsized-bound-127441.rs:12:29
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LL | fn foo2<T: ?Sized + ?Sized>(a: T) {}
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| - ^ doesn't have a size known at compile-time
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| |
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| this type parameter needs to be `Sized`
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= help: unsized fn params are gated as an unstable feature
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help: consider removing the `?Sized` bound to make the type parameter `Sized`
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LL - fn foo2<T: ?Sized + ?Sized>(a: T) {}
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LL + fn foo2<T>(a: T) {}
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help: function arguments must have a statically known size, borrowed types always have a known size
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LL | fn foo2<T: ?Sized + ?Sized>(a: &T) {}
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| +
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error[E0277]: the size for values of type `T` cannot be known at compilation time
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--> $DIR/bad-suggestionf-for-repeated-unsized-bound-127441.rs:16:37
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LL | fn foo3<T: ?Sized + ?Sized + Debug>(a: T) {}
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| - ^ doesn't have a size known at compile-time
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| |
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| this type parameter needs to be `Sized`
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= help: unsized fn params are gated as an unstable feature
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help: consider restricting type parameters
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LL - fn foo3<T: ?Sized + ?Sized + Debug>(a: T) {}
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LL + fn foo3<T: Debug>(a: T) {}
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help: function arguments must have a statically known size, borrowed types always have a known size
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LL | fn foo3<T: ?Sized + ?Sized + Debug>(a: &T) {}
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| +
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error[E0277]: the size for values of type `T` cannot be known at compilation time
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--> $DIR/bad-suggestionf-for-repeated-unsized-bound-127441.rs:20:38
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LL | fn foo4<T: ?Sized + Debug + ?Sized >(a: T) {}
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| - ^ doesn't have a size known at compile-time
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| |
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| this type parameter needs to be `Sized`
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= help: unsized fn params are gated as an unstable feature
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help: consider restricting type parameters
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LL - fn foo4<T: ?Sized + Debug + ?Sized >(a: T) {}
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LL + fn foo4<T: Debug >(a: T) {}
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help: function arguments must have a statically known size, borrowed types always have a known size
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LL | fn foo4<T: ?Sized + Debug + ?Sized >(a: &T) {}
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| +
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error[E0277]: the size for values of type `impl ?Sized` cannot be known at compilation time
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--> $DIR/bad-suggestionf-for-repeated-unsized-bound-127441.rs:24:9
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LL | fn foo5(_: impl ?Sized) {}
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| ^ ----------- this type parameter needs to be `Sized`
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| |
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| doesn't have a size known at compile-time
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= help: unsized fn params are gated as an unstable feature
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help: consider replacing `?Sized` with `Sized`
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LL - fn foo5(_: impl ?Sized) {}
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LL + fn foo5(_: impl Sized) {}
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help: function arguments must have a statically known size, borrowed types always have a known size
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LL | fn foo5(_: &impl ?Sized) {}
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| +
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error[E0277]: the size for values of type `impl ?Sized + ?Sized` cannot be known at compilation time
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--> $DIR/bad-suggestionf-for-repeated-unsized-bound-127441.rs:27:9
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LL | fn foo6(_: impl ?Sized + ?Sized) {}
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| ^ -------------------- this type parameter needs to be `Sized`
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| |
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| doesn't have a size known at compile-time
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= help: unsized fn params are gated as an unstable feature
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help: consider restricting type parameters
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LL - fn foo6(_: impl ?Sized + ?Sized) {}
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LL + fn foo6(_: impl Sized) {}
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help: function arguments must have a statically known size, borrowed types always have a known size
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LL | fn foo6(_: &impl ?Sized + ?Sized) {}
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| +
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error[E0277]: the size for values of type `impl ?Sized + ?Sized + Debug` cannot be known at compilation time
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--> $DIR/bad-suggestionf-for-repeated-unsized-bound-127441.rs:31:9
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LL | fn foo7(_: impl ?Sized + ?Sized + Debug) {}
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| ^ ---------------------------- this type parameter needs to be `Sized`
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| |
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| doesn't have a size known at compile-time
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= help: unsized fn params are gated as an unstable feature
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help: consider restricting type parameters
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|
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LL - fn foo7(_: impl ?Sized + ?Sized + Debug) {}
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LL + fn foo7(_: impl Debug) {}
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|
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help: function arguments must have a statically known size, borrowed types always have a known size
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LL | fn foo7(_: &impl ?Sized + ?Sized + Debug) {}
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| +
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error[E0277]: the size for values of type `impl ?Sized + Debug + ?Sized` cannot be known at compilation time
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--> $DIR/bad-suggestionf-for-repeated-unsized-bound-127441.rs:35:9
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|
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LL | fn foo8(_: impl ?Sized + Debug + ?Sized ) {}
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| ^ ---------------------------- this type parameter needs to be `Sized`
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| |
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| doesn't have a size known at compile-time
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|
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= help: unsized fn params are gated as an unstable feature
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help: consider restricting type parameters
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|
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LL - fn foo8(_: impl ?Sized + Debug + ?Sized ) {}
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LL + fn foo8(_: impl Debug ) {}
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|
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help: function arguments must have a statically known size, borrowed types always have a known size
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|
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LL | fn foo8(_: &impl ?Sized + Debug + ?Sized ) {}
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| +
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error: aborting due to 14 previous errors
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Some errors have detailed explanations: E0203, E0277.
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For more information about an error, try `rustc --explain E0203`.
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