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, 2 insertions, 1 deletions

diff --git a/compiler/rustc_interface/src/interface.rs b/compiler/rustc_interface/src/interface.rs
index be7fa9378ca..8e9150ba8ad 100644
--- a/compiler/rustc_interface/src/interface.rs
+++ b/compiler/rustc_interface/src/interface.rs
@@ -12,6 +12,7 @@ use rustc_lint::LintStore;
 use rustc_middle::ty;
 use rustc_parse::maybe_new_parser_from_source_str;
 use rustc_query_impl::QueryCtxt;
+use rustc_query_system::query::print_query_stack;
 use rustc_session::config::{self, CheckCfg, ErrorOutputType, Input, OutputFilenames};
 use rustc_session::lint;
 use rustc_session::parse::{CrateConfig, ParseSess};
@@ -317,7 +318,7 @@ pub fn try_print_query_stack(handler: &Handler, num_frames: Option<usize>) {
     // state if it was responsible for triggering the panic.
     let i = ty::tls::with_context_opt(|icx| {
         if let Some(icx) = icx {
-            QueryCtxt::from_tcx(icx.tcx).try_print_query_stack(icx.query, handler, num_frames)
+            print_query_stack(QueryCtxt { tcx: icx.tcx }, icx.query, handler, num_frames)
         } else {
             0
         }