Rollup merge of #152704 - Zalathar:query-ctxt, r=nnethercote

Remove `QueryCtxt` and trait `HasDepContext`

- Follow-up to #152636.
- Potentially waiting on #152703 to reduce conflicts.
---

With the `QueryContext` trait removed, wrapper struct `QueryCtxt` no longer serves a purpose and can be replaced with `TyCtxt` everywhere.

After that, the only obstacle to removing trait `HasDepContext` is `DepGraph::with_task`, which uses the trait to allow passing both a `TyCtxt` and a query vtable through the context argument. But we can achieve the same result by passing the vtable through the other argument instead, in a tuple alongside the query key.

r? nnethercote

Author: jdonszelmann

compiler/rustc_interface/src/interface.rs

@@ -16,7 +16,7 @@ use rustc_parse::lexer::StripTokens;
 use rustc_parse::new_parser_from_source_str;
 use rustc_parse::parser::Recovery;
 use rustc_parse::parser::attr::AllowLeadingUnsafe;
-use rustc_query_impl::{QueryCtxt, print_query_stack};
+use rustc_query_impl::print_query_stack;
 use rustc_session::config::{self, Cfg, CheckCfg, ExpectedValues, Input, OutFileName};
 use rustc_session::parse::ParseSess;
 use rustc_session::{CompilerIO, EarlyDiagCtxt, Session, lint};
@@ -556,7 +556,7 @@ pub fn try_print_query_stack(
     let all_frames = ty::tls::with_context_opt(|icx| {
         if let Some(icx) = icx {
             ty::print::with_no_queries!(print_query_stack(
-                QueryCtxt::new(icx.tcx),
+                icx.tcx,
                 icx.query,
                 dcx,
                 limit_frames,

compiler/rustc_interface/src/util.rs

@@ -18,6 +18,7 @@ use rustc_data_structures::sync;
 use rustc_metadata::{DylibError, EncodedMetadata, load_symbol_from_dylib};
 use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
 use rustc_middle::ty::{CurrentGcx, TyCtxt};
+use rustc_query_impl::collect_active_jobs_from_all_queries;
 use rustc_session::config::{
     Cfg, CrateType, OutFileName, OutputFilenames, OutputTypes, Sysroot, host_tuple,
 };
@@ -184,7 +185,7 @@ pub(crate) fn run_in_thread_pool_with_globals<
     use rustc_data_structures::defer;
     use rustc_data_structures::sync::FromDyn;
     use rustc_middle::ty::tls;
-    use rustc_query_impl::{QueryCtxt, break_query_cycles};
+    use rustc_query_impl::break_query_cycles;
 
     let thread_stack_size = init_stack_size(thread_builder_diag);
 
@@ -253,7 +254,7 @@ internal compiler error: query cycle handler thread panicked, aborting process";
                                     || {
                                         // Ensure there were no errors collecting all active jobs.
                                         // We need the complete map to ensure we find a cycle to break.
-                                        QueryCtxt::new(tcx).collect_active_jobs_from_all_queries(false).expect(
+                                        collect_active_jobs_from_all_queries(tcx, false).expect(
                                             "failed to collect active queries in deadlock handler",
                                         )
                                     },

compiler/rustc_middle/src/dep_graph/graph.rs

@@ -23,7 +23,7 @@ use {super::debug::EdgeFilter, std::env};
 
 use super::query::DepGraphQuery;
 use super::serialized::{GraphEncoder, SerializedDepGraph, SerializedDepNodeIndex};
-use super::{DepKind, DepNode, HasDepContext, WorkProductId, read_deps, with_deps};
+use super::{DepKind, DepNode, WorkProductId, read_deps, with_deps};
 use crate::dep_graph::edges::EdgesVec;
 use crate::ich::StableHashingContext;
 use crate::ty::TyCtxt;
@@ -268,17 +268,17 @@ impl DepGraph {
     }
 
     #[inline(always)]
-    pub fn with_task<'tcx, Ctxt: HasDepContext<'tcx>, A: Debug, R>(
+    pub fn with_task<'tcx, A: Debug, R>(
         &self,
-        key: DepNode,
-        cx: Ctxt,
-        arg: A,
-        task: fn(Ctxt, A) -> R,
+        dep_node: DepNode,
+        tcx: TyCtxt<'tcx>,
+        task_arg: A,
+        task_fn: fn(tcx: TyCtxt<'tcx>, task_arg: A) -> R,
         hash_result: Option<fn(&mut StableHashingContext<'_>, &R) -> Fingerprint>,
     ) -> (R, DepNodeIndex) {
         match self.data() {
-            Some(data) => data.with_task(key, cx, arg, task, hash_result),
-            None => (task(cx, arg), self.next_virtual_depnode_index()),
+            Some(data) => data.with_task(dep_node, tcx, task_arg, task_fn, hash_result),
+            None => (task_fn(tcx, task_arg), self.next_virtual_depnode_index()),
         }
     }
 
@@ -310,66 +310,50 @@ impl DepGraphData {
     /// prevent implicit 'leaks' of tracked state into the task (which
     /// could then be read without generating correct edges in the
     /// dep-graph -- see the [rustc dev guide] for more details on
-    /// the dep-graph). To this end, the task function gets exactly two
-    /// pieces of state: the context `cx` and an argument `arg`. Both
-    /// of these bits of state must be of some type that implements
-    /// `DepGraphSafe` and hence does not leak.
-    ///
-    /// The choice of two arguments is not fundamental. One argument
-    /// would work just as well, since multiple values can be
-    /// collected using tuples. However, using two arguments works out
-    /// to be quite convenient, since it is common to need a context
-    /// (`cx`) and some argument (e.g., a `DefId` identifying what
-    /// item to process).
+    /// the dep-graph).
     ///
-    /// For cases where you need some other number of arguments:
-    ///
-    /// - If you only need one argument, just use `()` for the `arg`
-    ///   parameter.
-    /// - If you need 3+ arguments, use a tuple for the
-    ///   `arg` parameter.
+    /// Therefore, the task function takes a `TyCtxt`, plus exactly one
+    /// additional argument, `task_arg`. The additional argument type can be
+    /// `()` if no argument is needed, or a tuple if multiple arguments are
+    /// needed.
     ///
     /// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/queries/incremental-compilation.html
     #[inline(always)]
-    pub fn with_task<'tcx, Ctxt: HasDepContext<'tcx>, A: Debug, R>(
+    pub fn with_task<'tcx, A: Debug, R>(
         &self,
-        key: DepNode,
-        cx: Ctxt,
-        arg: A,
-        task: fn(Ctxt, A) -> R,
+        dep_node: DepNode,
+        tcx: TyCtxt<'tcx>,
+        task_arg: A,
+        task_fn: fn(tcx: TyCtxt<'tcx>, task_arg: A) -> R,
         hash_result: Option<fn(&mut StableHashingContext<'_>, &R) -> Fingerprint>,
     ) -> (R, DepNodeIndex) {
         // If the following assertion triggers, it can have two reasons:
         // 1. Something is wrong with DepNode creation, either here or
         //    in `DepGraph::try_mark_green()`.
         // 2. Two distinct query keys get mapped to the same `DepNode`
         //    (see for example #48923).
-        self.assert_dep_node_not_yet_allocated_in_current_session(
-            cx.dep_context().sess,
-            &key,
-            || {
-                format!(
-                    "forcing query with already existing `DepNode`\n\
-                 - query-key: {arg:?}\n\
-                 - dep-node: {key:?}"
-                )
-            },
-        );
+        self.assert_dep_node_not_yet_allocated_in_current_session(tcx.sess, &dep_node, || {
+            format!(
+                "forcing query with already existing `DepNode`\n\
+                 - query-key: {task_arg:?}\n\
+                 - dep-node: {dep_node:?}"
+            )
+        });
 
-        let with_deps = |task_deps| with_deps(task_deps, || task(cx, arg));
-        let (result, edges) = if cx.dep_context().is_eval_always(key.kind) {
+        let with_deps = |task_deps| with_deps(task_deps, || task_fn(tcx, task_arg));
+        let (result, edges) = if tcx.is_eval_always(dep_node.kind) {
             (with_deps(TaskDepsRef::EvalAlways), EdgesVec::new())
         } else {
             let task_deps = Lock::new(TaskDeps::new(
                 #[cfg(debug_assertions)]
-                Some(key),
+                Some(dep_node),
                 0,
             ));
             (with_deps(TaskDepsRef::Allow(&task_deps)), task_deps.into_inner().reads)
         };
 
         let dep_node_index =
-            self.hash_result_and_alloc_node(cx.dep_context(), key, edges, &result, hash_result);
+            self.hash_result_and_alloc_node(tcx, dep_node, edges, &result, hash_result);
 
         (result, dep_node_index)
     }
@@ -954,7 +938,7 @@ impl DepGraphData {
 
         // We failed to mark it green, so we try to force the query.
         debug!("trying to force dependency {dep_dep_node:?}");
-        if !tcx.dep_context().try_force_from_dep_node(*dep_dep_node, parent_dep_node_index, frame) {
+        if !tcx.try_force_from_dep_node(*dep_dep_node, parent_dep_node_index, frame) {
             // The DepNode could not be forced.
             debug!("dependency {dep_dep_node:?} could not be forced");
             return None;
@@ -1001,10 +985,7 @@ impl DepGraphData {
         let frame = MarkFrame { index: prev_dep_node_index, parent: frame };
 
         // We never try to mark eval_always nodes as green
-        debug_assert!(
-            !tcx.dep_context()
-                .is_eval_always(self.previous.index_to_node(prev_dep_node_index).kind)
-        );
+        debug_assert!(!tcx.is_eval_always(self.previous.index_to_node(prev_dep_node_index).kind));
 
         let prev_deps = self.previous.edge_targets_from(prev_dep_node_index);
 

compiler/rustc_middle/src/dep_graph/mod.rs

@@ -25,22 +25,6 @@ mod graph;
 mod query;
 mod serialized;
 
-pub trait HasDepContext<'tcx>: Copy {
-    fn dep_context(&self) -> TyCtxt<'tcx>;
-}
-
-impl<'tcx> HasDepContext<'tcx> for TyCtxt<'tcx> {
-    fn dep_context(&self) -> TyCtxt<'tcx> {
-        *self
-    }
-}
-
-impl<'tcx, T: HasDepContext<'tcx>, Q: Copy> HasDepContext<'tcx> for (T, Q) {
-    fn dep_context(&self) -> TyCtxt<'tcx> {
-        self.0.dep_context()
-    }
-}
-
 /// Describes the contents of the fingerprint generated by a given query.
 ///
 /// This is mainly for determining whether and how we can reconstruct a key