rustc_metadata: track the simplified Self type for every trait impl.#75008
Merged
bors merged 1 commit intorust-lang:masterfrom Aug 6, 2020
Merged
rustc_metadata: track the simplified Self type for every trait impl.#75008bors merged 1 commit intorust-lang:masterfrom
bors merged 1 commit intorust-lang:masterfrom
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For the
traits_impls_ofquery, we index the impls byfast_reject::SimplifiedType(a "shallow type"), which allows some simple cases likeimpl Trait<..> for Foo<..>to be efficiently iterated over, by e.g.for_each_relevant_impl.This PR encodes the
fast_reject::SimplifiedTypecross-crate to avoid needing to deserialize theSelftype of everyimplin order to simplify it - the simplification itself should be cheap, but the deserialization is less so.We could go further from here and make loading the list of impls lazy, for a given simplified
Selftype, but that would have more complicated implications for performance, and this PR doesn't do anything in that regard.r? @nikomatsakis cc @Mark-Simulacrum