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Auto merge of #119192 - michaelwoerister:mcp533-push, r=cjgillot

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Replace a number of FxHashMaps/Sets with stable-iteration-order alternatives

This PR replaces almost all of the remaining `FxHashMap`s in query results with either `FxIndexMap` or `UnordMap`. The only case that is missing is the `EffectiveVisibilities` struct which turned out to not be straightforward to transform. Once that is done too, we can remove the `HashStable` implementation from `HashMap`.

The first commit adds the `StableCompare` trait which is a companion trait to `StableOrd`. Some types like `Symbol` can be compared in a cross-session stable way, but their `Ord` implementation is not stable. In such cases, a `StableCompare` implementation can be provided to offer a lightweight way for stable sorting. The more heavyweight option is to sort via `ToStableHashKey`, but then sorting needs to have access to a stable hashing context and `ToStableHashKey` can also be expensive as in the case of `Symbol` where it has to allocate a `String`.

The rest of the commits are rather mechanical and don't overlap, so they are best reviewed individually.

Part of [MCP 533](https://github.com/rust-lang/compiler-team/issues/533).
This commit is contained in:
bors
2024-01-05 19:38:27 +00:00
parent 11035f9f52 077540cedf
commit b8c207435c
30 changed files with 256 additions and 147 deletions
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6
compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
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@@ -1,6 +1,6 @@
use super::potentially_plural_count;
use crate::errors::LifetimesOrBoundsMismatchOnTrait;
use hir::def_id::{DefId, LocalDefId};
use hir::def_id::{DefId, DefIdMap, LocalDefId};
use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexSet};
use rustc_errors::{pluralize, struct_span_err, Applicability, DiagnosticId, ErrorGuaranteed};
use rustc_hir as hir;
@@ -478,7 +478,7 @@ fn compare_asyncness<'tcx>(
pub(super) fn collect_return_position_impl_trait_in_trait_tys<'tcx>(
tcx: TyCtxt<'tcx>,
impl_m_def_id: LocalDefId,
) -> Result<&'tcx FxHashMap<DefId, ty::EarlyBinder<Ty<'tcx>>>, ErrorGuaranteed> {
) -> Result<&'tcx DefIdMap<ty::EarlyBinder<Ty<'tcx>>>, ErrorGuaranteed> {
let impl_m = tcx.opt_associated_item(impl_m_def_id.to_def_id()).unwrap();
let trait_m = tcx.opt_associated_item(impl_m.trait_item_def_id.unwrap()).unwrap();
let impl_trait_ref =
@@ -706,7 +706,7 @@ pub(super) fn collect_return_position_impl_trait_in_trait_tys<'tcx>(
);
ocx.resolve_regions_and_report_errors(impl_m_def_id, &outlives_env)?;
let mut remapped_types = FxHashMap::default();
let mut remapped_types = DefIdMap::default();
for (def_id, (ty, args)) in collected_types {
match infcx.fully_resolve((ty, args)) {
Ok((ty, args)) => {