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_lint/src/late.rs

@@ -34,7 +34,7 @@ use tracing::debug;
 
 /// Extract the `LintStore` from the query context.
 /// This function exists because we've erased `LintStore` as `dyn Any` in the context.
-pub(crate) fn unerased_lint_store(tcx: TyCtxt<'_>) -> &LintStore {
+pub fn unerased_lint_store(tcx: TyCtxt<'_>) -> &LintStore {
     let store: &dyn Any = &*tcx.lint_store;
     store.downcast_ref().unwrap()
 }

compiler/rustc_lint/src/lib.rs

@@ -99,7 +99,7 @@ pub use builtin::SoftLints;
 pub use context::{CheckLintNameResult, FindLintError, LintStore};
 pub use context::{EarlyContext, LateContext, LintContext};
 pub use early::{check_ast_node, EarlyCheckNode};
-pub use late::check_crate;
+pub use late::{check_crate, unerased_lint_store};
 pub use passes::{EarlyLintPass, LateLintPass};
 pub use rustc_session::lint::Level::{self, *};
 pub use rustc_session::lint::{BufferedEarlyLint, FutureIncompatibleInfo, Lint, LintId};