In lifetime_generate, only select from all_impls(trait_id) on demand #932
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| // (We add each impl for T to this when we process T) | ||
| // (To avoid importing unnecessary impls, we delay processing impl until all t are used) | ||
| // t1 -> impl, ..., tn -> impl | ||
| typ_to_trait_impls: HashMap<DefId, Vec<DefId>>, |
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This took me a bit to parse. Can we rename it to, e.g. typ_used_in_trait_impls or similar?
| for t in &datatypes { | ||
| if !state.typ_to_trait_impls.contains_key(t) { | ||
| state.typ_to_trait_impls.insert(*t, Vec::new()); | ||
| } | ||
| _ => (), | ||
| state.typ_to_trait_impls.get_mut(&t).unwrap().push(impl_id); |
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You should be able to do:
state.typ_to_trait_impls.entry(&t).or_insert(Vec::new()).extend(datatypes.iter());and skip the additional look-up.
| assert!(!state.impl_to_remaining_typs.contains_key(&impl_id)); | ||
| state.impl_to_remaining_typs.insert(impl_id, (name.clone(), datatypes)); |
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I think you can just assert that insert returned None.
| // t1 -> impl, ..., tn -> impl | ||
| typ_to_trait_impls: HashMap<DefId, Vec<DefId>>, | ||
| // impl -> (t1, ..., tn) and process impl when t1...tn is empty | ||
| impl_to_remaining_typs: HashMap<DefId, (Id, Vec<DefId>)>, |
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remaining_typs_to_process_impl?
If some of the type arguments are unreached, then the impl itself will be unreached. External types should be unreachable since they are supposed to be disallowed from the verified code altogether. (There are some places we still need to check this, such as "impl InternalTrait for ExternalType", but that would be a separate well-formedness issue.) |
Previously, the use of
ctxt.tcx.all_impls(trait_id)was pulling in many unrelated definitions from the Rust library, which led to various failures when using a Rust library trait (e.g.IntoIterator). This pull request prunes away the unneeded definitions, omitting trait impls for types that aren't used.