Auto merge of #95573 - cjgillot:lower-query, r=michaelwoerister

Make lowering a query

Split from https://github.com/rust-lang/rust/pull/88186.

This PR refactors the relationship between lowering and the resolver outputs in order to make lowering itself a query.
In a first part, lowering is changed to avoid modifying resolver outputs, by maintaining its own data structures for creating new `NodeId`s and so.

Then, the `TyCtxt` is modified to allow creating new `LocalDefId`s from inside it. This is done by:
- enclosing `Definitions` in a lock, so as to allow modification;
- creating a query `register_def` whose purpose is to declare a `LocalDefId` to the query system.

See `TyCtxt::create_def` and `TyCtxt::iter_local_def_id` for more detailed explanations of the design.

compiler/rustc_mir_transform/src/coverage/mod.rs

@@ -15,7 +15,6 @@ use spans::{CoverageSpan, CoverageSpans};
 use crate::MirPass;
 
 use rustc_data_structures::graph::WithNumNodes;
-use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::sync::Lrc;
 use rustc_index::vec::IndexVec;
 use rustc_middle::hir;
@@ -576,12 +575,6 @@ fn get_body_span<'tcx>(
 
 fn hash_mir_source<'tcx>(tcx: TyCtxt<'tcx>, hir_body: &'tcx rustc_hir::Body<'tcx>) -> u64 {
     // FIXME(cjgillot) Stop hashing HIR manually here.
-    let mut hcx = tcx.create_no_span_stable_hashing_context();
-    let mut stable_hasher = StableHasher::new();
     let owner = hir_body.id().hir_id.owner;
-    let bodies = &tcx.hir_owner_nodes(owner).unwrap().bodies;
-    hcx.with_hir_bodies(false, owner, bodies, |hcx| {
-        hir_body.value.hash_stable(hcx, &mut stable_hasher)
-    });
-    stable_hasher.finish()
+    tcx.hir_owner_nodes(owner).unwrap().hash_including_bodies.to_smaller_hash()
 }

compiler/rustc_mir_transform/src/inline.rs

@@ -588,7 +588,7 @@ impl<'tcx> Inliner<'tcx> {
                 );
                 expn_data.def_site = callee_body.span;
                 let expn_data =
-                    LocalExpnId::fresh(expn_data, self.tcx.create_stable_hashing_context());
+                    self.tcx.with_stable_hashing_context(|hcx| LocalExpnId::fresh(expn_data, hcx));
                 let mut integrator = Integrator {
                     args: &args,
                     new_locals: Local::new(caller_body.local_decls.len())..,