Unconstrained parameter fix #148788
Unconstrained parameter fix #148788
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This PR modifies |
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r? @davidtwco rustbot has assigned @davidtwco. Use |
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| diag.multipart_suggestions(msg, suggestions, Applicability::MaybeIncorrect); |
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I don't think we should use a multi-part suggestion for this, these should be multiple distinct suggestions
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| // search if the parameter is used in the impl body | ||
| let mut visitor = ParamUsageVisitor { | ||
| tcx, // Pass the TyCtxt |
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| tcx, // Pass the TyCtxt | |
| tcx, |
| LL - unsafe impl<Q: Trait> Send for Inner {} | ||
| LL + unsafe impl Send for Inner {} | ||
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| LL | unsafe impl<Q: Trait> Send for Inner<Q> {} |
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We should only suggest this if it could be correct (maybe by checking if the self type has generic parameters), or we should be very clear that it's just illustrative:
help: if `Inner` takes generic parameters, consider instantiating it with `Q` to constrain `Q`
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LL - unsafe impl<Q: Trait> Send for Inner {}
LL + unsafe impl<Q: Trait> Send for Inner<Q> {}
| ^^^ `Q` could be used here
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Well there would another error if the Inner struct took a generic parameter. I made a similar example here:
struct Foo<N> {x: N}
impl<N> Foo {}which obviously gives the error, that the generic parameter N should be provided for the implementation of Foo:
error[E0107]: missing generics for struct `Foo`
--> src/lib.rs:3:9
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3 | impl<N> Foo {}
| ^^^ expected 1 generic argument
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note: struct defined here, with 1 generic parameter: `N`
--> src/lib.rs:1:8
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1 | struct Foo<N> {x: N}
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help: add missing generic argument
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3 | impl<N> Foo<N> {}
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For more information about this error, try `rustc --explain E0107`.Therefore I would even suggest never suggesting to add the generic argument in general or did I miss some edgecase?
Or we could suggest adding it as a type parameter to the struct and to the impl
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| help: make use of the lifetime parameter `'a` in the `self` type | ||
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| LL | impl<'a> Foo<fn(&()), 'a> { |
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Similarly to above, we should make sure this is correct or clearly indicate that it is purely illustrative.
| self.tcx | ||
| } | ||
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| /// We use `ControlFlow` to stop visiting as soon as we find what we're looking for. |
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Some of the comments in this impl feel redundant
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This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed. Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers. |
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This PR is an attempt to solve the issue described in the issue #107295