avoid translating roots with predicates that do not hold #42797
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NOTE: I want to talk about this with @nikomatsakis to confirm this is the correct strategy - anyone else should not r+ this. |
alexcrichton
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friendly ping @nikomatsakis, pinging you in IRC too! |
src/librustc_trans/collector.rs
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| @@ -304,6 +304,7 @@ fn collect_roots<'a, 'tcx>(scx: &SharedCrateContext<'a, 'tcx>, | |||
| scx.tcx().hir.krate().visit_all_item_likes(&mut visitor); | |||
| } | |||
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| roots.retain(|root| root.is_instantiable(scx.tcx())); | |||
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Hmm. This seems perfectly reasonable, but perhaps not optimal? (Also, why do we check below for whether something is instantiable, but not other places?)
Put another way, it might be better to have some helper routine for pushing into self.output that checks for "is instantiable" at that point -- perhaps this would also avoid enumerating the things reachable from a non-instantiable thing?
However, I see no obvious reason that this code is wrong.
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Everywhere except for roots and vtables, instantiability is guaranteed by the program type-checking, so we want to produce a clean ICE if the item is not instantiable.
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Aren't the roots just the content of the things pushed to self.output?
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As discussed on IRC, r=me w/ a comment. |
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@bors r=nikomatsakis |
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📌 Commit a6ca302 has been approved by |
avoid translating roots with predicates that do not hold Finally I got around to doing this. Fixes #37725. r? @nikomatsakis
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☀️ Test successful - status-appveyor, status-travis |
Finally I got around to doing this.
Fixes #37725.
r? @nikomatsakis