Auto merge of #109611 - Zoxc:query-engine-rem, r=cjgillot

Remove `QueryEngine` trait

This removes the `QueryEngine` trait and `Queries` from `rustc_query_impl` and replaced them with function pointers and fields in `QuerySystem`. As a side effect `OnDiskCache` is moved back into `rustc_middle` and the `OnDiskCache` trait is also removed.

This has a couple of benefits.
- `TyCtxt` is used in the query system instead of the removed `QueryCtxt` which is larger.
- Function pointers are more flexible to work with. A variant of https://github.com/rust-lang/rust/pull/107802 is included which avoids the double indirection. For https://github.com/rust-lang/rust/pull/108938 we can name entry point `__rust_end_short_backtrace` to avoid some overhead. For https://github.com/rust-lang/rust/pull/108062 it avoids the duplicate `QueryEngine` structs.
- `QueryContext` now implements `DepContext` which avoids many `dep_context()` calls in `rustc_query_system`.
- The `rustc_driver` size is reduced by 0.33%, hopefully that means some bootstrap improvements.
- This avoids the unsafe code around the `QueryEngine` trait.

r? `@cjgillot`

1 files changed, 3 insertions, 2 deletions

diff --git a/compiler/rustc_interface/src/util.rs b/compiler/rustc_interface/src/util.rs
index a27a1e2978a..8d37b1053d8 100644
--- a/compiler/rustc_interface/src/util.rs
+++ b/compiler/rustc_interface/src/util.rs
@@ -170,7 +170,8 @@ pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce() -> R + Send, R: Send>(
 ) -> R {
     use rustc_data_structures::jobserver;
     use rustc_middle::ty::tls;
-    use rustc_query_impl::{deadlock, QueryContext, QueryCtxt};
+    use rustc_query_impl::QueryCtxt;
+    use rustc_query_system::query::{deadlock, QueryContext};
 
     let registry = sync::Registry::new(threads);
     let mut builder = rayon::ThreadPoolBuilder::new()
@@ -182,7 +183,7 @@ pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce() -> R + Send, R: Send>(
             // On deadlock, creates a new thread and forwards information in thread
             // locals to it. The new thread runs the deadlock handler.
             let query_map = tls::with(|tcx| {
-                QueryCtxt::from_tcx(tcx)
+                QueryCtxt::new(tcx)
                     .try_collect_active_jobs()
                     .expect("active jobs shouldn't be locked in deadlock handler")
             });