Apply stricter orphan rules for traits with defaulted impls #23038
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nikomatsakis
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| self.tcx.sess.span_err( | ||
| item.span, | ||
| "cross-crate traits with a default impl \ | ||
| can only be implemented for a struct/enum type \ |
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nit: can we make these 2 error messages consistent struct/enum vs struct or enum
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☔ The latest upstream changes (presumably #23026) made this pull request unmergeable. Please resolve the merge conflicts. |
now have a simple set of trait def-ids. During coherence, we use a separate table to track the default impls for any given trait so that we can report a nice error. This fixes various bugs in the metadata encoding that led to `ty::trait_has_default_impl` yielding the wrong values in the cross-crate case. (In particular, default impl def-ids were not included in the list of all impl def-ids; I debated fixing just that, but this approach seemed cleaner overall, since we usually treat the "defaulted" bit on traits as being a property of the trait, and now iterating over a list of impls doesn't intermingle default impls with normal impls.)
since there are separate checks that apply to Copy (and Send uses the generic defaulted trait rules). Also prohibit `Sized` from being manually implemented for now.
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@flaper87 I addressed your nits. Can you please r? the final commit, it's got new material. |
| // We only want to permit structs/enums, but not *all* structs/enums. | ||
| // They must be local to the current crate, so that people | ||
| // can't do `unsafe impl Send for Rc<SomethingLocal>` or | ||
| // `unsafe impl !Send for Box<SomethingLocalAndSend>`. |
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nit: negative impls aren't unsafe
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Couple of nits, otherwise, it looks good to me. |
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Fixes #22978.
r? @flaper87