Simplify the HIR ty lowering of trait object lifetime bounds#157591
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Letting `lower_lifetime` check `tcx.named_bound_var` & call `re_infer` just means we now end up passing `lifetime.ident.span` to `re_infer` instead of the `span` of the trait object type. However, 1. in the case of `LifetimeKind::ImplicitObjectLifetimeDefault` `lifetime.ident.span` is actually equal to said span. 2. in the case of `LifetimeKind::Infer` the span now makes more sense; consider `dyn Trait + '_` where the span now just contains the `'_` not the entire type which is just better.
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…nfer` This makes it really obvious that we're computing object region bounds for `Infer`, too, not just for `ImplicitObjectLifetimeDefault` which was really hard to see beforehand. It's unclear to me whether this was intentional or not, needs investigation. Introduce method `lower_trait_object_lifetime` to allow usage of early returns to make the control flow clearer compared to the `unwrap_or_else`.
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| // Curiously, we also use the *object region bound* for `Infer` (`'_`) | ||
| // while we obviously don't use the *object lifetime default* for it... |
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For a tiny bit more background information, see the large paragraph in the PR description of rust-lang/reference#2281 (the one about compute_object_lifetime_bound vs. RBV's named_bound_var).
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Thanks for pointing this out, I'll take a closer look at this reference tomorrow
Kivooeo
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…ivooeo Simplify the HIR ty lowering of trait object lifetime bounds See individual commit messages for details.
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Rollup of 4 pull requests Successful merges: - #157547 (Reorganize `tests/ui/issues` [6/N]) - #157549 (Remove comments already covered by rustdoc) - #157591 (Simplify the HIR ty lowering of trait object lifetime bounds) - #157623 (rustc_resolve: point the label span at the segment that could not be resolved)
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Rollup merge of #157591 - fmease:hirtylo-obj-lt-cleanup, r=Kivooeo Simplify the HIR ty lowering of trait object lifetime bounds See individual commit messages for details.
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