Auto merge of #75008 - eddyb:rmeta-indexed-trait-impls, r=nikomatsakis

rustc_metadata: track the simplified Self type for every trait impl.

For the `traits_impls_of` query, we index the impls by `fast_reject::SimplifiedType` (a "shallow type"), which allows some simple cases like `impl Trait<..> for Foo<..>` to be efficiently iterated over, by e.g. `for_each_relevant_impl`.

This PR encodes the `fast_reject::SimplifiedType` cross-crate to avoid needing to deserialize the `Self` type of every `impl` in 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 `Self` type, but that would have more complicated implications for performance, and this PR doesn't do anything in that regard.

r? @nikomatsakis cc @Mark-Simulacrum

1 files changed, 1 insertions, 1 deletions

diff --git a/src/librustdoc/passes/collect_trait_impls.rs b/src/librustdoc/passes/collect_trait_impls.rs
index 0fdeefd79e9..3000afde0c2 100644
--- a/src/librustdoc/passes/collect_trait_impls.rs
+++ b/src/librustdoc/passes/collect_trait_impls.rs
@@ -28,7 +28,7 @@ pub fn collect_trait_impls(krate: Crate, cx: &DocContext<'_>) -> Crate {
     let mut new_items = Vec::new();
 
     for &cnum in cx.tcx.crates().iter() {
-        for &did in cx.tcx.all_trait_implementations(cnum).iter() {
+        for &(did, _) in cx.tcx.all_trait_implementations(cnum).iter() {
             inline::build_impl(cx, did, None, &mut new_items);
         }
     }