From f96e960ccfa92895217562ede43043405194eab0 Mon Sep 17 00:00:00 2001
From: Camille GILLOT <gillot.camille@gmail.com>
Date: Thu, 12 Nov 2020 20:48:37 +0100
Subject: [PATCH 1/6] Access the session directly from DepContext.

---
 Cargo.lock                                        |  1 +
 compiler/rustc_middle/src/dep_graph/mod.rs        | 15 +++++++--------
 compiler/rustc_query_impl/src/plumbing.rs         | 15 ---------------
 compiler/rustc_query_system/Cargo.toml            |  1 +
 .../rustc_query_system/src/dep_graph/dep_node.rs  |  5 ++++-
 .../rustc_query_system/src/dep_graph/graph.rs     |  6 +++---
 compiler/rustc_query_system/src/dep_graph/mod.rs  |  7 ++++---
 compiler/rustc_query_system/src/query/mod.rs      |  9 ---------
 compiler/rustc_query_system/src/query/plumbing.rs |  2 +-
 9 files changed, 21 insertions(+), 40 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 0576a55a4472e..4f16bf6ca3ffa 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4203,6 +4203,7 @@ dependencies = [
  "rustc_index",
  "rustc_macros",
  "rustc_serialize",
+ "rustc_session",
  "rustc_span",
  "smallvec 1.6.1",
  "tracing",
diff --git a/compiler/rustc_middle/src/dep_graph/mod.rs b/compiler/rustc_middle/src/dep_graph/mod.rs
index d862db2674ebd..c688b23be1d02 100644
--- a/compiler/rustc_middle/src/dep_graph/mod.rs
+++ b/compiler/rustc_middle/src/dep_graph/mod.rs
@@ -2,6 +2,7 @@ use crate::ich::StableHashingContext;
 use crate::ty::{self, TyCtxt};
 use rustc_data_structures::profiling::SelfProfilerRef;
 use rustc_data_structures::sync::Lock;
+use rustc_session::Session;
 
 #[macro_use]
 mod dep_node;
@@ -101,20 +102,18 @@ impl<'tcx> DepContext for TyCtxt<'tcx> {
         TyCtxt::create_stable_hashing_context(*self)
     }
 
-    fn debug_dep_tasks(&self) -> bool {
-        self.sess.opts.debugging_opts.dep_tasks
-    }
-    fn debug_dep_node(&self) -> bool {
-        self.sess.opts.debugging_opts.incremental_info
-            || self.sess.opts.debugging_opts.query_dep_graph
-    }
-
     #[inline]
     fn dep_graph(&self) -> &DepGraph {
         &self.dep_graph
     }
 
+    #[inline(always)]
     fn profiler(&self) -> &SelfProfilerRef {
         &self.prof
     }
+
+    #[inline(always)]
+    fn sess(&self) -> &Session {
+        self.sess
+    }
 }
diff --git a/compiler/rustc_query_impl/src/plumbing.rs b/compiler/rustc_query_impl/src/plumbing.rs
index d4093f281ddd3..100e9c5ceb034 100644
--- a/compiler/rustc_query_impl/src/plumbing.rs
+++ b/compiler/rustc_query_impl/src/plumbing.rs
@@ -47,13 +47,6 @@ impl HasDepContext for QueryCtxt<'tcx> {
 impl QueryContext for QueryCtxt<'tcx> {
     type Query = Query<'tcx>;
 
-    fn incremental_verify_ich(&self) -> bool {
-        self.sess.opts.debugging_opts.incremental_verify_ich
-    }
-    fn verbose(&self) -> bool {
-        self.sess.verbose()
-    }
-
     fn def_path_str(&self, def_id: DefId) -> String {
         self.tcx.def_path_str(def_id)
     }
@@ -132,14 +125,6 @@ impl QueryContext for QueryCtxt<'tcx> {
         (cb.force_from_dep_node)(*self, dep_node)
     }
 
-    fn has_errors_or_delayed_span_bugs(&self) -> bool {
-        self.sess.has_errors_or_delayed_span_bugs()
-    }
-
-    fn diagnostic(&self) -> &rustc_errors::Handler {
-        self.sess.diagnostic()
-    }
-
     // Interactions with on_disk_cache
     fn load_diagnostics(&self, prev_dep_node_index: SerializedDepNodeIndex) -> Vec<Diagnostic> {
         self.on_disk_cache
diff --git a/compiler/rustc_query_system/Cargo.toml b/compiler/rustc_query_system/Cargo.toml
index d18a2a6faed6c..7d3357f8fa2ef 100644
--- a/compiler/rustc_query_system/Cargo.toml
+++ b/compiler/rustc_query_system/Cargo.toml
@@ -16,6 +16,7 @@ rustc_errors = { path = "../rustc_errors" }
 rustc_macros = { path = "../rustc_macros" }
 rustc_index = { path = "../rustc_index" }
 rustc_serialize = { path = "../rustc_serialize" }
+rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
 parking_lot = "0.11"
 smallvec = { version = "1.6.1", features = ["union", "may_dangle"] }
diff --git a/compiler/rustc_query_system/src/dep_graph/dep_node.rs b/compiler/rustc_query_system/src/dep_graph/dep_node.rs
index 1319a31b8f54d..f55e2f777a26a 100644
--- a/compiler/rustc_query_system/src/dep_graph/dep_node.rs
+++ b/compiler/rustc_query_system/src/dep_graph/dep_node.rs
@@ -87,7 +87,10 @@ impl<K: DepKind> DepNode<K> {
 
         #[cfg(debug_assertions)]
         {
-            if !kind.can_reconstruct_query_key() && tcx.debug_dep_node() {
+            if !kind.can_reconstruct_query_key()
+                && (tcx.sess().opts.debugging_opts.incremental_info
+                    || tcx.sess().opts.debugging_opts.query_dep_graph)
+            {
                 tcx.dep_graph().register_dep_node_debug_str(dep_node, || arg.to_debug_str(tcx));
             }
         }
diff --git a/compiler/rustc_query_system/src/dep_graph/graph.rs b/compiler/rustc_query_system/src/dep_graph/graph.rs
index f579052c106b6..0f25572170f53 100644
--- a/compiler/rustc_query_system/src/dep_graph/graph.rs
+++ b/compiler/rustc_query_system/src/dep_graph/graph.rs
@@ -280,7 +280,7 @@ impl<K: DepKind> DepGraph<K> {
             let mut hcx = dcx.create_stable_hashing_context();
             let current_fingerprint = hash_result(&mut hcx, &result);
 
-            let print_status = cfg!(debug_assertions) && dcx.debug_dep_tasks();
+            let print_status = cfg!(debug_assertions) && dcx.sess().opts.debugging_opts.dep_tasks;
 
             // Intern the new `DepNode`.
             let dep_node_index = if let Some(prev_index) = data.previous.node_to_index_opt(&key) {
@@ -731,7 +731,7 @@ impl<K: DepKind> DepGraph<K> {
                                 return None;
                             }
                             None => {
-                                if !tcx.has_errors_or_delayed_span_bugs() {
+                                if !tcx.dep_context().sess().has_errors_or_delayed_span_bugs() {
                                     panic!(
                                         "try_mark_previous_green() - Forcing the DepNode \
                                           should have set its color"
@@ -835,7 +835,7 @@ impl<K: DepKind> DepGraph<K> {
             // Promote the previous diagnostics to the current session.
             tcx.store_diagnostics(dep_node_index, diagnostics.clone().into());
 
-            let handle = tcx.diagnostic();
+            let handle = tcx.dep_context().sess().diagnostic();
 
             for diagnostic in diagnostics {
                 handle.emit_diagnostic(&diagnostic);
diff --git a/compiler/rustc_query_system/src/dep_graph/mod.rs b/compiler/rustc_query_system/src/dep_graph/mod.rs
index a647381fb03fa..e8fb71be3e08f 100644
--- a/compiler/rustc_query_system/src/dep_graph/mod.rs
+++ b/compiler/rustc_query_system/src/dep_graph/mod.rs
@@ -13,6 +13,7 @@ pub use serialized::{SerializedDepGraph, SerializedDepNodeIndex};
 
 use rustc_data_structures::profiling::SelfProfilerRef;
 use rustc_data_structures::sync::Lock;
+use rustc_session::Session;
 
 use std::fmt;
 use std::hash::Hash;
@@ -24,9 +25,6 @@ pub trait DepContext: Copy {
     /// Create a hashing context for hashing new results.
     fn create_stable_hashing_context(&self) -> Self::StableHashingContext;
 
-    fn debug_dep_tasks(&self) -> bool;
-    fn debug_dep_node(&self) -> bool;
-
     /// Access the DepGraph.
     fn dep_graph(&self) -> &DepGraph<Self::DepKind>;
 
@@ -34,6 +32,9 @@ pub trait DepContext: Copy {
 
     /// Access the profiler.
     fn profiler(&self) -> &SelfProfilerRef;
+
+    /// Access the compiler session.
+    fn sess(&self) -> &Session;
 }
 
 pub trait HasDepContext: Copy {
diff --git a/compiler/rustc_query_system/src/query/mod.rs b/compiler/rustc_query_system/src/query/mod.rs
index c935e1b9c5cd6..bc5ad2cc38527 100644
--- a/compiler/rustc_query_system/src/query/mod.rs
+++ b/compiler/rustc_query_system/src/query/mod.rs
@@ -26,9 +26,6 @@ use rustc_span::def_id::DefId;
 pub trait QueryContext: HasDepContext {
     type Query: Clone + HashStable<Self::StableHashingContext>;
 
-    fn incremental_verify_ich(&self) -> bool;
-    fn verbose(&self) -> bool;
-
     /// Get string representation from DefPath.
     fn def_path_str(&self, def_id: DefId) -> String;
 
@@ -43,12 +40,6 @@ pub trait QueryContext: HasDepContext {
     /// Try to force a dep node to execute and see if it's green.
     fn try_force_from_dep_node(&self, dep_node: &DepNode<Self::DepKind>) -> bool;
 
-    /// Return whether the current session is tainted by errors.
-    fn has_errors_or_delayed_span_bugs(&self) -> bool;
-
-    /// Return the diagnostic handler.
-    fn diagnostic(&self) -> &rustc_errors::Handler;
-
     /// Load diagnostics associated to the node in the previous session.
     fn load_diagnostics(&self, prev_dep_node_index: SerializedDepNodeIndex) -> Vec<Diagnostic>;
 
diff --git a/compiler/rustc_query_system/src/query/plumbing.rs b/compiler/rustc_query_system/src/query/plumbing.rs
index bd22ee2c18b2b..fdc73dcc5408e 100644
--- a/compiler/rustc_query_system/src/query/plumbing.rs
+++ b/compiler/rustc_query_system/src/query/plumbing.rs
@@ -550,7 +550,7 @@ where
 
     // If `-Zincremental-verify-ich` is specified, re-hash results from
     // the cache and make sure that they have the expected fingerprint.
-    if unlikely!(tcx.incremental_verify_ich()) {
+    if unlikely!(tcx.dep_context().sess().opts.debugging_opts.incremental_verify_ich) {
         incremental_verify_ich(*tcx.dep_context(), &result, dep_node, dep_node_index, query);
     }
 

From 0144d6a3b7e2f2bba4c7cc9adc04c2b6e4e01b93 Mon Sep 17 00:00:00 2001
From: Camille GILLOT <gillot.camille@gmail.com>
Date: Sat, 26 Dec 2020 16:36:55 +0100
Subject: [PATCH 2/6] Do not hold query key in Query.

---
 compiler/rustc_query_impl/src/lib.rs          |   3 +-
 compiler/rustc_query_impl/src/plumbing.rs     | 113 ++++++++++--------
 .../rustc_query_system/src/query/config.rs    |   4 +-
 .../rustc_query_system/src/query/plumbing.rs  |   7 +-
 4 files changed, 69 insertions(+), 58 deletions(-)

diff --git a/compiler/rustc_query_impl/src/lib.rs b/compiler/rustc_query_impl/src/lib.rs
index 43dfe6892b1a9..f58092105c874 100644
--- a/compiler/rustc_query_impl/src/lib.rs
+++ b/compiler/rustc_query_impl/src/lib.rs
@@ -26,10 +26,9 @@ use rustc_middle::dep_graph;
 use rustc_middle::ich::StableHashingContext;
 use rustc_middle::ty::query::{query_keys, query_storage, query_stored, query_values};
 use rustc_middle::ty::query::{Providers, QueryEngine};
-use rustc_middle::ty::TyCtxt;
+use rustc_middle::ty::{self, TyCtxt};
 use rustc_serialize::opaque;
 use rustc_span::{Span, DUMMY_SP};
-use std::mem;
 
 #[macro_use]
 mod plumbing;
diff --git a/compiler/rustc_query_impl/src/plumbing.rs b/compiler/rustc_query_impl/src/plumbing.rs
index 100e9c5ceb034..2bb201945ad48 100644
--- a/compiler/rustc_query_impl/src/plumbing.rs
+++ b/compiler/rustc_query_impl/src/plumbing.rs
@@ -45,7 +45,7 @@ impl HasDepContext for QueryCtxt<'tcx> {
 }
 
 impl QueryContext for QueryCtxt<'tcx> {
-    type Query = Query<'tcx>;
+    type Query = Query;
 
     fn def_path_str(&self, def_id: DefId) -> String {
         self.tcx.def_path_str(def_id)
@@ -59,7 +59,7 @@ impl QueryContext for QueryCtxt<'tcx> {
         &self,
     ) -> Option<FxHashMap<QueryJobId<Self::DepKind>, QueryJobInfo<Self::DepKind, Self::Query>>>
     {
-        self.queries.try_collect_active_jobs()
+        self.queries.try_collect_active_jobs(**self)
     }
 
     fn try_load_from_on_disk_cache(&self, dep_node: &DepNode) {
@@ -185,12 +185,12 @@ impl<'tcx> QueryCtxt<'tcx> {
     #[cold]
     pub(super) fn report_cycle(
         self,
-        CycleError { usage, cycle: stack }: CycleError<Query<'tcx>>,
+        CycleError { usage, cycle: stack }: CycleError<Query>,
     ) -> DiagnosticBuilder<'tcx> {
         assert!(!stack.is_empty());
 
-        let fix_span = |span: Span, query: &Query<'tcx>| {
-            self.sess.source_map().guess_head_span(query.default_span(*self, span))
+        let fix_span = |span: Span, query: &Query| {
+            self.sess.source_map().guess_head_span(query.default_span(span))
         };
 
         // Disable naming impls with types in this path, since that
@@ -204,24 +204,24 @@ impl<'tcx> QueryCtxt<'tcx> {
                 span,
                 E0391,
                 "cycle detected when {}",
-                stack[0].query.describe(self)
+                stack[0].query.description
             );
 
             for i in 1..stack.len() {
                 let query = &stack[i].query;
                 let span = fix_span(stack[(i + 1) % stack.len()].span, query);
-                err.span_note(span, &format!("...which requires {}...", query.describe(self)));
+                err.span_note(span, &format!("...which requires {}...", query.description));
             }
 
             err.note(&format!(
                 "...which again requires {}, completing the cycle",
-                stack[0].query.describe(self)
+                stack[0].query.description
             ));
 
             if let Some((span, query)) = usage {
                 err.span_note(
                     fix_span(span, &query),
-                    &format!("cycle used when {}", query.describe(self)),
+                    &format!("cycle used when {}", query.description),
                 );
             }
 
@@ -371,54 +371,58 @@ macro_rules! define_queries {
             input: ($(([$($modifiers)*] [$($attr)*] [$name]))*)
         }
 
-        #[allow(nonstandard_style)]
         #[derive(Clone, Debug)]
-        pub enum Query<$tcx> {
-            $($(#[$attr])* $name(query_keys::$name<$tcx>)),*
+        pub struct Query {
+            pub name: &'static str,
+            hash: Fingerprint,
+            description: String,
+            span: Option<Span>,
         }
 
-        impl<$tcx> Query<$tcx> {
-            pub fn name(&self) -> &'static str {
-                match *self {
-                    $(Query::$name(_) => stringify!($name),)*
-                }
-            }
-
-            pub(crate) fn describe(&self, tcx: QueryCtxt<$tcx>) -> String {
-                let (r, name) = match *self {
-                    $(Query::$name(key) => {
-                        (queries::$name::describe(tcx, key), stringify!($name))
-                    })*
+        impl Query {
+            $(#[allow(nonstandard_style)] $(#[$attr])*
+            pub fn $name<$tcx>(tcx: QueryCtxt<$tcx>, key: query_keys::$name<$tcx>) -> Self {
+                let kind = dep_graph::DepKind::$name;
+                let name = stringify!($name);
+                let description = ty::print::with_forced_impl_filename_line(
+                    // Force filename-line mode to avoid invoking `type_of` query.
+                    || queries::$name::describe(tcx, key)
+                );
+                let description = if tcx.sess.verbose() {
+                    format!("{} [{}]", description, name)
+                } else {
+                    description
                 };
-                if tcx.sess.verbose() {
-                    format!("{} [{}]", r, name)
+                let span = if kind == dep_graph::DepKind::def_span {
+                    // The `def_span` query is used to calculate `default_span`,
+                    // so exit to avoid infinite recursion.
+                    None
                 } else {
-                    r
-                }
-            }
+                    Some(key.default_span(*tcx))
+                };
+                let hash = {
+                    let mut hcx = tcx.create_stable_hashing_context();
+                    let mut hasher = StableHasher::new();
+                    std::mem::discriminant(&kind).hash_stable(&mut hcx, &mut hasher);
+                    key.hash_stable(&mut hcx, &mut hasher);
+                    hasher.finish()
+                };
+
+                Self { name, description, span, hash }
+            })*
 
             // FIXME(eddyb) Get more valid `Span`s on queries.
-            pub fn default_span(&self, tcx: TyCtxt<$tcx>, span: Span) -> Span {
+            pub fn default_span(&self, span: Span) -> Span {
                 if !span.is_dummy() {
                     return span;
                 }
-                // The `def_span` query is used to calculate `default_span`,
-                // so exit to avoid infinite recursion.
-                if let Query::def_span(..) = *self {
-                    return span
-                }
-                match *self {
-                    $(Query::$name(key) => key.default_span(tcx),)*
-                }
+                self.span.unwrap_or(span)
             }
         }
 
-        impl<'a, $tcx> HashStable<StableHashingContext<'a>> for Query<$tcx> {
+        impl<'a> HashStable<StableHashingContext<'a>> for Query {
             fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
-                mem::discriminant(self).hash_stable(hcx, hasher);
-                match *self {
-                    $(Query::$name(key) => key.hash_stable(hcx, hasher),)*
-                }
+                self.hash.hash_stable(hcx, hasher)
             }
         }
 
@@ -446,7 +450,9 @@ macro_rules! define_queries {
             type Cache = query_storage::$name<$tcx>;
 
             #[inline(always)]
-            fn query_state<'a>(tcx: QueryCtxt<$tcx>) -> &'a QueryState<crate::dep_graph::DepKind, Query<$tcx>, Self::Key> {
+            fn query_state<'a>(tcx: QueryCtxt<$tcx>) -> &'a QueryState<crate::dep_graph::DepKind, Query, Self::Key>
+                where QueryCtxt<$tcx>: 'a
+            {
                 &tcx.queries.$name
             }
 
@@ -478,7 +484,7 @@ macro_rules! define_queries {
 
             fn handle_cycle_error(
                 tcx: QueryCtxt<'tcx>,
-                error: CycleError<Query<'tcx>>
+                error: CycleError<Query>
             ) -> Self::Value {
                 handle_cycle_error!([$($modifiers)*][tcx, error])
             }
@@ -581,7 +587,7 @@ macro_rules! define_queries_struct {
 
             $($(#[$attr])*  $name: QueryState<
                 crate::dep_graph::DepKind,
-                Query<$tcx>,
+                Query,
                 query_keys::$name<$tcx>,
             >,)*
         }
@@ -599,13 +605,16 @@ macro_rules! define_queries_struct {
             }
 
             pub(crate) fn try_collect_active_jobs(
-                &self
-            ) -> Option<FxHashMap<QueryJobId<crate::dep_graph::DepKind>, QueryJobInfo<crate::dep_graph::DepKind, Query<$tcx>>>> {
+                &$tcx self,
+                tcx: TyCtxt<$tcx>,
+            ) -> Option<FxHashMap<QueryJobId<crate::dep_graph::DepKind>, QueryJobInfo<crate::dep_graph::DepKind, Query>>> {
+                let tcx = QueryCtxt { tcx, queries: self };
                 let mut jobs = FxHashMap::default();
 
                 $(
                     self.$name.try_collect_active_jobs(
-                        <queries::$name<'tcx> as QueryAccessors<QueryCtxt<'tcx>>>::DEP_KIND,
+                        tcx,
+                        dep_graph::DepKind::$name,
                         Query::$name,
                         &mut jobs,
                     )?;
@@ -651,7 +660,7 @@ macro_rules! define_queries_struct {
                 handler: &Handler,
                 num_frames: Option<usize>,
             ) -> usize {
-                let query_map = self.try_collect_active_jobs();
+                let query_map = self.try_collect_active_jobs(tcx);
 
                 let mut current_query = query;
                 let mut i = 0;
@@ -671,8 +680,8 @@ macro_rules! define_queries_struct {
                         &format!(
                             "#{} [{}] {}",
                             i,
-                            query_info.info.query.name(),
-                            query_info.info.query.describe(QueryCtxt { tcx, queries: self })
+                            query_info.info.query.name,
+                            query_info.info.query.description,
                         ),
                     );
                     diag.span = tcx.sess.source_map().guess_head_span(query_info.info.span).into();
diff --git a/compiler/rustc_query_system/src/query/config.rs b/compiler/rustc_query_system/src/query/config.rs
index 3873b47d4d40b..8239f34792336 100644
--- a/compiler/rustc_query_system/src/query/config.rs
+++ b/compiler/rustc_query_system/src/query/config.rs
@@ -73,7 +73,9 @@ pub trait QueryAccessors<CTX: QueryContext>: QueryConfig {
     type Cache: QueryCache<Key = Self::Key, Stored = Self::Stored, Value = Self::Value>;
 
     // Don't use this method to access query results, instead use the methods on TyCtxt
-    fn query_state<'a>(tcx: CTX) -> &'a QueryState<CTX::DepKind, CTX::Query, Self::Key>;
+    fn query_state<'a>(tcx: CTX) -> &'a QueryState<CTX::DepKind, CTX::Query, Self::Key>
+    where
+        CTX: 'a;
 
     // Don't use this method to access query results, instead use the methods on TyCtxt
     fn query_cache<'a>(tcx: CTX) -> &'a QueryCacheStore<Self::Cache>
diff --git a/compiler/rustc_query_system/src/query/plumbing.rs b/compiler/rustc_query_system/src/query/plumbing.rs
index fdc73dcc5408e..dbe7c4c2320cc 100644
--- a/compiler/rustc_query_system/src/query/plumbing.rs
+++ b/compiler/rustc_query_system/src/query/plumbing.rs
@@ -119,10 +119,11 @@ where
         shards.iter().all(|shard| shard.active.is_empty())
     }
 
-    pub fn try_collect_active_jobs(
+    pub fn try_collect_active_jobs<CTX: Copy>(
         &self,
+        tcx: CTX,
         kind: D,
-        make_query: fn(K) -> Q,
+        make_query: fn(CTX, K) -> Q,
         jobs: &mut QueryMap<D, Q>,
     ) -> Option<()> {
         // We use try_lock_shards here since we are called from the
@@ -133,7 +134,7 @@ where
             shard.active.iter().filter_map(move |(k, v)| {
                 if let QueryResult::Started(ref job) = *v {
                     let id = QueryJobId::new(job.id, shard_id, kind);
-                    let info = QueryInfo { span: job.span, query: make_query(k.clone()) };
+                    let info = QueryInfo { span: job.span, query: make_query(tcx, k.clone()) };
                     Some((id, QueryJobInfo { info, job: job.clone() }))
                 } else {
                     None

From 3897395787866281e98e3f0e41cf26dab5d94d7b Mon Sep 17 00:00:00 2001
From: Camille GILLOT <gillot.camille@gmail.com>
Date: Sat, 28 Nov 2020 22:48:05 +0100
Subject: [PATCH 3/6] Move Query to rustc_query_system.

Rename it to QueryStackFrame and document a bit.
---
 compiler/rustc_query_impl/src/lib.rs          |  1 -
 compiler/rustc_query_impl/src/plumbing.rs     | 58 ++++--------
 .../rustc_query_system/src/query/config.rs    |  8 +-
 compiler/rustc_query_system/src/query/job.rs  | 91 +++++++++----------
 compiler/rustc_query_system/src/query/mod.rs  | 51 +++++++++--
 .../rustc_query_system/src/query/plumbing.rs  | 69 +++++++-------
 6 files changed, 140 insertions(+), 138 deletions(-)

diff --git a/compiler/rustc_query_impl/src/lib.rs b/compiler/rustc_query_impl/src/lib.rs
index f58092105c874..bfba7c7410ede 100644
--- a/compiler/rustc_query_impl/src/lib.rs
+++ b/compiler/rustc_query_impl/src/lib.rs
@@ -17,7 +17,6 @@ extern crate rustc_middle;
 extern crate tracing;
 
 use rustc_data_structures::fingerprint::Fingerprint;
-use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_errors::{Diagnostic, Handler, Level};
 use rustc_hir::def_id::CrateNum;
diff --git a/compiler/rustc_query_impl/src/plumbing.rs b/compiler/rustc_query_impl/src/plumbing.rs
index 2bb201945ad48..01fb5a7ba2029 100644
--- a/compiler/rustc_query_impl/src/plumbing.rs
+++ b/compiler/rustc_query_impl/src/plumbing.rs
@@ -2,16 +2,15 @@
 //! generate the actual methods on tcx which find and execute the provider,
 //! manage the caches, and so forth.
 
-use super::{queries, Query};
+use super::queries;
 use rustc_middle::dep_graph::{DepKind, DepNode, DepNodeExt, DepNodeIndex, SerializedDepNodeIndex};
 use rustc_middle::ty::query::on_disk_cache;
 use rustc_middle::ty::tls::{self, ImplicitCtxt};
 use rustc_middle::ty::{self, TyCtxt};
 use rustc_query_system::dep_graph::HasDepContext;
-use rustc_query_system::query::{CycleError, QueryJobId, QueryJobInfo};
-use rustc_query_system::query::{QueryContext, QueryDescription};
+use rustc_query_system::query::{CycleError, QueryJobId};
+use rustc_query_system::query::{QueryContext, QueryDescription, QueryMap, QueryStackFrame};
 
-use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::sync::Lock;
 use rustc_data_structures::thin_vec::ThinVec;
 use rustc_errors::{struct_span_err, Diagnostic, DiagnosticBuilder};
@@ -45,8 +44,6 @@ impl HasDepContext for QueryCtxt<'tcx> {
 }
 
 impl QueryContext for QueryCtxt<'tcx> {
-    type Query = Query;
-
     fn def_path_str(&self, def_id: DefId) -> String {
         self.tcx.def_path_str(def_id)
     }
@@ -55,10 +52,7 @@ impl QueryContext for QueryCtxt<'tcx> {
         tls::with_related_context(**self, |icx| icx.query)
     }
 
-    fn try_collect_active_jobs(
-        &self,
-    ) -> Option<FxHashMap<QueryJobId<Self::DepKind>, QueryJobInfo<Self::DepKind, Self::Query>>>
-    {
+    fn try_collect_active_jobs(&self) -> Option<QueryMap<Self::DepKind>> {
         self.queries.try_collect_active_jobs(**self)
     }
 
@@ -185,11 +179,11 @@ impl<'tcx> QueryCtxt<'tcx> {
     #[cold]
     pub(super) fn report_cycle(
         self,
-        CycleError { usage, cycle: stack }: CycleError<Query>,
+        CycleError { usage, cycle: stack }: CycleError,
     ) -> DiagnosticBuilder<'tcx> {
         assert!(!stack.is_empty());
 
-        let fix_span = |span: Span, query: &Query| {
+        let fix_span = |span: Span, query: &QueryStackFrame| {
             self.sess.source_map().guess_head_span(query.default_span(span))
         };
 
@@ -371,17 +365,12 @@ macro_rules! define_queries {
             input: ($(([$($modifiers)*] [$($attr)*] [$name]))*)
         }
 
-        #[derive(Clone, Debug)]
-        pub struct Query {
-            pub name: &'static str,
-            hash: Fingerprint,
-            description: String,
-            span: Option<Span>,
-        }
+        mod make_query {
+            use super::*;
 
-        impl Query {
+            // Create an eponymous constructor for each query.
             $(#[allow(nonstandard_style)] $(#[$attr])*
-            pub fn $name<$tcx>(tcx: QueryCtxt<$tcx>, key: query_keys::$name<$tcx>) -> Self {
+            pub fn $name<$tcx>(tcx: QueryCtxt<$tcx>, key: query_keys::$name<$tcx>) -> QueryStackFrame {
                 let kind = dep_graph::DepKind::$name;
                 let name = stringify!($name);
                 let description = ty::print::with_forced_impl_filename_line(
@@ -408,22 +397,8 @@ macro_rules! define_queries {
                     hasher.finish()
                 };
 
-                Self { name, description, span, hash }
+                QueryStackFrame::new(name, description, span, hash)
             })*
-
-            // FIXME(eddyb) Get more valid `Span`s on queries.
-            pub fn default_span(&self, span: Span) -> Span {
-                if !span.is_dummy() {
-                    return span;
-                }
-                self.span.unwrap_or(span)
-            }
-        }
-
-        impl<'a> HashStable<StableHashingContext<'a>> for Query {
-            fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
-                self.hash.hash_stable(hcx, hasher)
-            }
         }
 
         #[allow(nonstandard_style)]
@@ -450,7 +425,7 @@ macro_rules! define_queries {
             type Cache = query_storage::$name<$tcx>;
 
             #[inline(always)]
-            fn query_state<'a>(tcx: QueryCtxt<$tcx>) -> &'a QueryState<crate::dep_graph::DepKind, Query, Self::Key>
+            fn query_state<'a>(tcx: QueryCtxt<$tcx>) -> &'a QueryState<crate::dep_graph::DepKind, Self::Key>
                 where QueryCtxt<$tcx>: 'a
             {
                 &tcx.queries.$name
@@ -484,7 +459,7 @@ macro_rules! define_queries {
 
             fn handle_cycle_error(
                 tcx: QueryCtxt<'tcx>,
-                error: CycleError<Query>
+                error: CycleError,
             ) -> Self::Value {
                 handle_cycle_error!([$($modifiers)*][tcx, error])
             }
@@ -587,7 +562,6 @@ macro_rules! define_queries_struct {
 
             $($(#[$attr])*  $name: QueryState<
                 crate::dep_graph::DepKind,
-                Query,
                 query_keys::$name<$tcx>,
             >,)*
         }
@@ -607,15 +581,15 @@ macro_rules! define_queries_struct {
             pub(crate) fn try_collect_active_jobs(
                 &$tcx self,
                 tcx: TyCtxt<$tcx>,
-            ) -> Option<FxHashMap<QueryJobId<crate::dep_graph::DepKind>, QueryJobInfo<crate::dep_graph::DepKind, Query>>> {
+            ) -> Option<QueryMap<crate::dep_graph::DepKind>> {
                 let tcx = QueryCtxt { tcx, queries: self };
-                let mut jobs = FxHashMap::default();
+                let mut jobs = QueryMap::default();
 
                 $(
                     self.$name.try_collect_active_jobs(
                         tcx,
                         dep_graph::DepKind::$name,
-                        Query::$name,
+                        make_query::$name,
                         &mut jobs,
                     )?;
                 )*
diff --git a/compiler/rustc_query_system/src/query/config.rs b/compiler/rustc_query_system/src/query/config.rs
index 8239f34792336..d01b0de3b4803 100644
--- a/compiler/rustc_query_system/src/query/config.rs
+++ b/compiler/rustc_query_system/src/query/config.rs
@@ -27,7 +27,7 @@ pub(crate) struct QueryVtable<CTX: QueryContext, K, V> {
     pub compute: fn(CTX, K) -> V,
 
     pub hash_result: fn(&mut CTX::StableHashingContext, &V) -> Option<Fingerprint>,
-    pub handle_cycle_error: fn(CTX, CycleError<CTX::Query>) -> V,
+    pub handle_cycle_error: fn(CTX, CycleError) -> V,
     pub cache_on_disk: fn(CTX, &K, Option<&V>) -> bool,
     pub try_load_from_disk: fn(CTX, SerializedDepNodeIndex) -> Option<V>,
 }
@@ -52,7 +52,7 @@ impl<CTX: QueryContext, K, V> QueryVtable<CTX, K, V> {
         (self.hash_result)(hcx, value)
     }
 
-    pub(crate) fn handle_cycle_error(&self, tcx: CTX, error: CycleError<CTX::Query>) -> V {
+    pub(crate) fn handle_cycle_error(&self, tcx: CTX, error: CycleError) -> V {
         (self.handle_cycle_error)(tcx, error)
     }
 
@@ -73,7 +73,7 @@ pub trait QueryAccessors<CTX: QueryContext>: QueryConfig {
     type Cache: QueryCache<Key = Self::Key, Stored = Self::Stored, Value = Self::Value>;
 
     // Don't use this method to access query results, instead use the methods on TyCtxt
-    fn query_state<'a>(tcx: CTX) -> &'a QueryState<CTX::DepKind, CTX::Query, Self::Key>
+    fn query_state<'a>(tcx: CTX) -> &'a QueryState<CTX::DepKind, Self::Key>
     where
         CTX: 'a;
 
@@ -90,7 +90,7 @@ pub trait QueryAccessors<CTX: QueryContext>: QueryConfig {
         result: &Self::Value,
     ) -> Option<Fingerprint>;
 
-    fn handle_cycle_error(tcx: CTX, error: CycleError<CTX::Query>) -> Self::Value;
+    fn handle_cycle_error(tcx: CTX, error: CycleError) -> Self::Value;
 }
 
 pub trait QueryDescription<CTX: QueryContext>: QueryAccessors<CTX> {
diff --git a/compiler/rustc_query_system/src/query/job.rs b/compiler/rustc_query_system/src/query/job.rs
index 0ecc2694a7906..cc3cefe46bef2 100644
--- a/compiler/rustc_query_system/src/query/job.rs
+++ b/compiler/rustc_query_system/src/query/job.rs
@@ -1,4 +1,5 @@
 use crate::query::plumbing::CycleError;
+use crate::query::QueryStackFrame;
 
 use rustc_data_structures::fx::FxHashMap;
 use rustc_span::Span;
@@ -26,13 +27,13 @@ use {
 
 /// Represents a span and a query key.
 #[derive(Clone, Debug)]
-pub struct QueryInfo<Q> {
+pub struct QueryInfo {
     /// The span corresponding to the reason for which this query was required.
     pub span: Span,
-    pub query: Q,
+    pub query: QueryStackFrame,
 }
 
-pub(crate) type QueryMap<D, Q> = FxHashMap<QueryJobId<D>, QueryJobInfo<D, Q>>;
+pub type QueryMap<D> = FxHashMap<QueryJobId<D>, QueryJobInfo<D>>;
 
 /// A value uniquely identifying an active query job within a shard in the query cache.
 #[derive(Copy, Clone, Eq, PartialEq, Hash)]
@@ -59,34 +60,34 @@ where
         QueryJobId { job, shard: u16::try_from(shard).unwrap(), kind }
     }
 
-    fn query<Q: Clone>(self, map: &QueryMap<D, Q>) -> Q {
+    fn query(self, map: &QueryMap<D>) -> QueryStackFrame {
         map.get(&self).unwrap().info.query.clone()
     }
 
     #[cfg(parallel_compiler)]
-    fn span<Q: Clone>(self, map: &QueryMap<D, Q>) -> Span {
+    fn span(self, map: &QueryMap<D>) -> Span {
         map.get(&self).unwrap().job.span
     }
 
     #[cfg(parallel_compiler)]
-    fn parent<Q: Clone>(self, map: &QueryMap<D, Q>) -> Option<QueryJobId<D>> {
+    fn parent(self, map: &QueryMap<D>) -> Option<QueryJobId<D>> {
         map.get(&self).unwrap().job.parent
     }
 
     #[cfg(parallel_compiler)]
-    fn latch<'a, Q: Clone>(self, map: &'a QueryMap<D, Q>) -> Option<&'a QueryLatch<D, Q>> {
+    fn latch<'a>(self, map: &'a QueryMap<D>) -> Option<&'a QueryLatch<D>> {
         map.get(&self).unwrap().job.latch.as_ref()
     }
 }
 
-pub struct QueryJobInfo<D, Q> {
-    pub info: QueryInfo<Q>,
-    pub job: QueryJob<D, Q>,
+pub struct QueryJobInfo<D> {
+    pub info: QueryInfo,
+    pub job: QueryJob<D>,
 }
 
 /// Represents an active query job.
 #[derive(Clone)]
-pub struct QueryJob<D, Q> {
+pub struct QueryJob<D> {
     pub id: QueryShardJobId,
 
     /// The span corresponding to the reason for which this query was required.
@@ -97,15 +98,14 @@ pub struct QueryJob<D, Q> {
 
     /// The latch that is used to wait on this job.
     #[cfg(parallel_compiler)]
-    latch: Option<QueryLatch<D, Q>>,
+    latch: Option<QueryLatch<D>>,
 
-    dummy: PhantomData<QueryLatch<D, Q>>,
+    dummy: PhantomData<QueryLatch<D>>,
 }
 
-impl<D, Q> QueryJob<D, Q>
+impl<D> QueryJob<D>
 where
     D: Copy + Clone + Eq + Hash,
-    Q: Clone,
 {
     /// Creates a new query job.
     pub fn new(id: QueryShardJobId, span: Span, parent: Option<QueryJobId<D>>) -> Self {
@@ -120,7 +120,7 @@ where
     }
 
     #[cfg(parallel_compiler)]
-    pub(super) fn latch(&mut self, _id: QueryJobId<D>) -> QueryLatch<D, Q> {
+    pub(super) fn latch(&mut self, _id: QueryJobId<D>) -> QueryLatch<D> {
         if self.latch.is_none() {
             self.latch = Some(QueryLatch::new());
         }
@@ -128,8 +128,8 @@ where
     }
 
     #[cfg(not(parallel_compiler))]
-    pub(super) fn latch(&mut self, id: QueryJobId<D>) -> QueryLatch<D, Q> {
-        QueryLatch { id, dummy: PhantomData }
+    pub(super) fn latch(&mut self, id: QueryJobId<D>) -> QueryLatch<D> {
+        QueryLatch { id }
     }
 
     /// Signals to waiters that the query is complete.
@@ -148,23 +148,21 @@ where
 
 #[cfg(not(parallel_compiler))]
 #[derive(Clone)]
-pub(super) struct QueryLatch<D, Q> {
+pub(super) struct QueryLatch<D> {
     id: QueryJobId<D>,
-    dummy: PhantomData<Q>,
 }
 
 #[cfg(not(parallel_compiler))]
-impl<D, Q> QueryLatch<D, Q>
+impl<D> QueryLatch<D>
 where
     D: Copy + Clone + Eq + Hash,
-    Q: Clone,
 {
     pub(super) fn find_cycle_in_stack(
         &self,
-        query_map: QueryMap<D, Q>,
+        query_map: QueryMap<D>,
         current_job: &Option<QueryJobId<D>>,
         span: Span,
-    ) -> CycleError<Q> {
+    ) -> CycleError {
         // Find the waitee amongst `current_job` parents
         let mut cycle = Vec::new();
         let mut current_job = Option::clone(current_job);
@@ -198,15 +196,15 @@ where
 }
 
 #[cfg(parallel_compiler)]
-struct QueryWaiter<D, Q> {
+struct QueryWaiter<D> {
     query: Option<QueryJobId<D>>,
     condvar: Condvar,
     span: Span,
-    cycle: Lock<Option<CycleError<Q>>>,
+    cycle: Lock<Option<CycleError>>,
 }
 
 #[cfg(parallel_compiler)]
-impl<D, Q> QueryWaiter<D, Q> {
+impl<D> QueryWaiter<D> {
     fn notify(&self, registry: &rayon_core::Registry) {
         rayon_core::mark_unblocked(registry);
         self.condvar.notify_one();
@@ -214,19 +212,19 @@ impl<D, Q> QueryWaiter<D, Q> {
 }
 
 #[cfg(parallel_compiler)]
-struct QueryLatchInfo<D, Q> {
+struct QueryLatchInfo<D> {
     complete: bool,
-    waiters: Vec<Lrc<QueryWaiter<D, Q>>>,
+    waiters: Vec<Lrc<QueryWaiter<D>>>,
 }
 
 #[cfg(parallel_compiler)]
 #[derive(Clone)]
-pub(super) struct QueryLatch<D, Q> {
-    info: Lrc<Mutex<QueryLatchInfo<D, Q>>>,
+pub(super) struct QueryLatch<D> {
+    info: Lrc<Mutex<QueryLatchInfo<D>>>,
 }
 
 #[cfg(parallel_compiler)]
-impl<D: Eq + Hash, Q: Clone> QueryLatch<D, Q> {
+impl<D: Eq + Hash> QueryLatch<D> {
     fn new() -> Self {
         QueryLatch {
             info: Lrc::new(Mutex::new(QueryLatchInfo { complete: false, waiters: Vec::new() })),
@@ -235,13 +233,13 @@ impl<D: Eq + Hash, Q: Clone> QueryLatch<D, Q> {
 }
 
 #[cfg(parallel_compiler)]
-impl<D, Q> QueryLatch<D, Q> {
+impl<D> QueryLatch<D> {
     /// Awaits for the query job to complete.
     pub(super) fn wait_on(
         &self,
         query: Option<QueryJobId<D>>,
         span: Span,
-    ) -> Result<(), CycleError<Q>> {
+    ) -> Result<(), CycleError> {
         let waiter =
             Lrc::new(QueryWaiter { query, span, cycle: Lock::new(None), condvar: Condvar::new() });
         self.wait_on_inner(&waiter);
@@ -256,7 +254,7 @@ impl<D, Q> QueryLatch<D, Q> {
     }
 
     /// Awaits the caller on this latch by blocking the current thread.
-    fn wait_on_inner(&self, waiter: &Lrc<QueryWaiter<D, Q>>) {
+    fn wait_on_inner(&self, waiter: &Lrc<QueryWaiter<D>>) {
         let mut info = self.info.lock();
         if !info.complete {
             // We push the waiter on to the `waiters` list. It can be accessed inside
@@ -290,7 +288,7 @@ impl<D, Q> QueryLatch<D, Q> {
 
     /// Removes a single waiter from the list of waiters.
     /// This is used to break query cycles.
-    fn extract_waiter(&self, waiter: usize) -> Lrc<QueryWaiter<D, Q>> {
+    fn extract_waiter(&self, waiter: usize) -> Lrc<QueryWaiter<D>> {
         let mut info = self.info.lock();
         debug_assert!(!info.complete);
         // Remove the waiter from the list of waiters
@@ -312,14 +310,13 @@ type Waiter<D> = (QueryJobId<D>, usize);
 /// required information to resume the waiter.
 /// If all `visit` calls returns None, this function also returns None.
 #[cfg(parallel_compiler)]
-fn visit_waiters<D, Q, F>(
-    query_map: &QueryMap<D, Q>,
+fn visit_waiters<D, F>(
+    query_map: &QueryMap<D>,
     query: QueryJobId<D>,
     mut visit: F,
 ) -> Option<Option<Waiter<D>>>
 where
     D: Copy + Clone + Eq + Hash,
-    Q: Clone,
     F: FnMut(Span, QueryJobId<D>) -> Option<Option<Waiter<D>>>,
 {
     // Visit the parent query which is a non-resumable waiter since it's on the same stack
@@ -349,8 +346,8 @@ where
 /// If a cycle is detected, this initial value is replaced with the span causing
 /// the cycle.
 #[cfg(parallel_compiler)]
-fn cycle_check<D, Q>(
-    query_map: &QueryMap<D, Q>,
+fn cycle_check<D>(
+    query_map: &QueryMap<D>,
     query: QueryJobId<D>,
     span: Span,
     stack: &mut Vec<(Span, QueryJobId<D>)>,
@@ -358,7 +355,6 @@ fn cycle_check<D, Q>(
 ) -> Option<Option<Waiter<D>>>
 where
     D: Copy + Clone + Eq + Hash,
-    Q: Clone,
 {
     if !visited.insert(query) {
         return if let Some(p) = stack.iter().position(|q| q.1 == query) {
@@ -394,14 +390,13 @@ where
 /// from `query` without going through any of the queries in `visited`.
 /// This is achieved with a depth first search.
 #[cfg(parallel_compiler)]
-fn connected_to_root<D, Q>(
-    query_map: &QueryMap<D, Q>,
+fn connected_to_root<D>(
+    query_map: &QueryMap<D>,
     query: QueryJobId<D>,
     visited: &mut FxHashSet<QueryJobId<D>>,
 ) -> bool
 where
     D: Copy + Clone + Eq + Hash,
-    Q: Clone,
 {
     // We already visited this or we're deliberately ignoring it
     if !visited.insert(query) {
@@ -422,7 +417,7 @@ where
 // Deterministically pick an query from a list
 #[cfg(parallel_compiler)]
 fn pick_query<'a, CTX, T, F>(
-    query_map: &QueryMap<CTX::DepKind, CTX::Query>,
+    query_map: &QueryMap<CTX::DepKind>,
     tcx: CTX,
     queries: &'a [T],
     f: F,
@@ -456,9 +451,9 @@ where
 /// the function returns false.
 #[cfg(parallel_compiler)]
 fn remove_cycle<CTX: QueryContext>(
-    query_map: &QueryMap<CTX::DepKind, CTX::Query>,
+    query_map: &QueryMap<CTX::DepKind>,
     jobs: &mut Vec<QueryJobId<CTX::DepKind>>,
-    wakelist: &mut Vec<Lrc<QueryWaiter<CTX::DepKind, CTX::Query>>>,
+    wakelist: &mut Vec<Lrc<QueryWaiter<CTX::DepKind>>>,
     tcx: CTX,
 ) -> bool {
     let mut visited = FxHashSet::default();
diff --git a/compiler/rustc_query_system/src/query/mod.rs b/compiler/rustc_query_system/src/query/mod.rs
index bc5ad2cc38527..7b46674c74338 100644
--- a/compiler/rustc_query_system/src/query/mod.rs
+++ b/compiler/rustc_query_system/src/query/mod.rs
@@ -4,7 +4,7 @@ pub use self::plumbing::*;
 mod job;
 #[cfg(parallel_compiler)]
 pub use self::job::deadlock;
-pub use self::job::{QueryInfo, QueryJob, QueryJobId, QueryJobInfo};
+pub use self::job::{QueryInfo, QueryJob, QueryJobId, QueryJobInfo, QueryMap};
 
 mod caches;
 pub use self::caches::{
@@ -15,24 +15,63 @@ mod config;
 pub use self::config::{QueryAccessors, QueryConfig, QueryDescription};
 
 use crate::dep_graph::{DepNode, DepNodeIndex, HasDepContext, SerializedDepNodeIndex};
-use crate::query::job::QueryMap;
 
-use rustc_data_structures::stable_hasher::HashStable;
+use rustc_data_structures::fingerprint::Fingerprint;
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::sync::Lock;
 use rustc_data_structures::thin_vec::ThinVec;
 use rustc_errors::Diagnostic;
 use rustc_span::def_id::DefId;
+use rustc_span::Span;
 
-pub trait QueryContext: HasDepContext {
-    type Query: Clone + HashStable<Self::StableHashingContext>;
+/// Description of a frame in the query stack.
+///
+/// This is mostly used in case of cycles for error reporting.
+#[derive(Clone, Debug)]
+pub struct QueryStackFrame {
+    pub name: &'static str,
+    pub description: String,
+    span: Option<Span>,
+    /// This hash is used to deterministically pick
+    /// a query to remove cycles in the parallel compiler.
+    hash: Fingerprint,
+}
+
+impl QueryStackFrame {
+    #[inline]
+    pub fn new(
+        name: &'static str,
+        description: String,
+        span: Option<Span>,
+        hash: Fingerprint,
+    ) -> Self {
+        Self { name, hash, description, span }
+    }
+
+    // FIXME(eddyb) Get more valid `Span`s on queries.
+    #[inline]
+    pub fn default_span(&self, span: Span) -> Span {
+        if !span.is_dummy() {
+            return span;
+        }
+        self.span.unwrap_or(span)
+    }
+}
+
+impl<CTX> HashStable<CTX> for QueryStackFrame {
+    fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
+        self.hash.hash_stable(hcx, hasher)
+    }
+}
 
+pub trait QueryContext: HasDepContext {
     /// Get string representation from DefPath.
     fn def_path_str(&self, def_id: DefId) -> String;
 
     /// Get the query information from the TLS context.
     fn current_query_job(&self) -> Option<QueryJobId<Self::DepKind>>;
 
-    fn try_collect_active_jobs(&self) -> Option<QueryMap<Self::DepKind, Self::Query>>;
+    fn try_collect_active_jobs(&self) -> Option<QueryMap<Self::DepKind>>;
 
     /// Load data from the on-disk cache.
     fn try_load_from_on_disk_cache(&self, dep_node: &DepNode<Self::DepKind>);
diff --git a/compiler/rustc_query_system/src/query/plumbing.rs b/compiler/rustc_query_system/src/query/plumbing.rs
index dbe7c4c2320cc..28ee1a179942c 100644
--- a/compiler/rustc_query_system/src/query/plumbing.rs
+++ b/compiler/rustc_query_system/src/query/plumbing.rs
@@ -7,7 +7,7 @@ use crate::dep_graph::{DepNodeIndex, SerializedDepNodeIndex};
 use crate::query::caches::QueryCache;
 use crate::query::config::{QueryDescription, QueryVtable, QueryVtableExt};
 use crate::query::job::{QueryInfo, QueryJob, QueryJobId, QueryJobInfo, QueryShardJobId};
-use crate::query::{QueryContext, QueryMap};
+use crate::query::{QueryContext, QueryMap, QueryStackFrame};
 
 #[cfg(not(parallel_compiler))]
 use rustc_data_structures::cold_path;
@@ -81,37 +81,36 @@ impl<C: QueryCache> QueryCacheStore<C> {
     }
 }
 
-struct QueryStateShard<D, Q, K> {
-    active: FxHashMap<K, QueryResult<D, Q>>,
+struct QueryStateShard<D, K> {
+    active: FxHashMap<K, QueryResult<D>>,
 
     /// Used to generate unique ids for active jobs.
     jobs: u32,
 }
 
-impl<D, Q, K> Default for QueryStateShard<D, Q, K> {
-    fn default() -> QueryStateShard<D, Q, K> {
+impl<D, K> Default for QueryStateShard<D, K> {
+    fn default() -> QueryStateShard<D, K> {
         QueryStateShard { active: Default::default(), jobs: 0 }
     }
 }
 
-pub struct QueryState<D, Q, K> {
-    shards: Sharded<QueryStateShard<D, Q, K>>,
+pub struct QueryState<D, K> {
+    shards: Sharded<QueryStateShard<D, K>>,
 }
 
 /// Indicates the state of a query for a given key in a query map.
-enum QueryResult<D, Q> {
+enum QueryResult<D> {
     /// An already executing query. The query job can be used to await for its completion.
-    Started(QueryJob<D, Q>),
+    Started(QueryJob<D>),
 
     /// The query panicked. Queries trying to wait on this will raise a fatal error which will
     /// silently panic.
     Poisoned,
 }
 
-impl<D, Q, K> QueryState<D, Q, K>
+impl<D, K> QueryState<D, K>
 where
     D: Copy + Clone + Eq + Hash,
-    Q: Clone,
     K: Eq + Hash + Clone + Debug,
 {
     pub fn all_inactive(&self) -> bool {
@@ -123,8 +122,8 @@ where
         &self,
         tcx: CTX,
         kind: D,
-        make_query: fn(CTX, K) -> Q,
-        jobs: &mut QueryMap<D, Q>,
+        make_query: fn(CTX, K) -> QueryStackFrame,
+        jobs: &mut QueryMap<D>,
     ) -> Option<()> {
         // We use try_lock_shards here since we are called from the
         // deadlock handler, and this shouldn't be locked.
@@ -146,30 +145,28 @@ where
     }
 }
 
-impl<D, Q, K> Default for QueryState<D, Q, K> {
-    fn default() -> QueryState<D, Q, K> {
+impl<D, K> Default for QueryState<D, K> {
+    fn default() -> QueryState<D, K> {
         QueryState { shards: Default::default() }
     }
 }
 
 /// A type representing the responsibility to execute the job in the `job` field.
 /// This will poison the relevant query if dropped.
-struct JobOwner<'tcx, D, Q, C>
+struct JobOwner<'tcx, D, C>
 where
     D: Copy + Clone + Eq + Hash,
-    Q: Clone,
     C: QueryCache,
 {
-    state: &'tcx QueryState<D, Q, C::Key>,
+    state: &'tcx QueryState<D, C::Key>,
     cache: &'tcx QueryCacheStore<C>,
     key: C::Key,
     id: QueryJobId<D>,
 }
 
-impl<'tcx, D, Q, C> JobOwner<'tcx, D, Q, C>
+impl<'tcx, D, C> JobOwner<'tcx, D, C>
 where
     D: Copy + Clone + Eq + Hash,
-    Q: Clone,
     C: QueryCache,
 {
     /// Either gets a `JobOwner` corresponding the query, allowing us to
@@ -183,13 +180,13 @@ where
     #[inline(always)]
     fn try_start<'b, CTX>(
         tcx: CTX,
-        state: &'b QueryState<CTX::DepKind, CTX::Query, C::Key>,
+        state: &'b QueryState<CTX::DepKind, C::Key>,
         cache: &'b QueryCacheStore<C>,
         span: Span,
         key: &C::Key,
         lookup: QueryLookup,
         query: &QueryVtable<CTX, C::Key, C::Value>,
-    ) -> TryGetJob<'b, CTX::DepKind, CTX::Query, C>
+    ) -> TryGetJob<'b, CTX::DepKind, C>
     where
         CTX: QueryContext,
     {
@@ -243,7 +240,7 @@ where
         // so we just return the error.
         #[cfg(not(parallel_compiler))]
         return TryGetJob::Cycle(cold_path(|| {
-            let error: CycleError<CTX::Query> = latch.find_cycle_in_stack(
+            let error: CycleError = latch.find_cycle_in_stack(
                 tcx.try_collect_active_jobs().unwrap(),
                 &tcx.current_query_job(),
                 span,
@@ -328,10 +325,9 @@ where
     (result, diagnostics.into_inner())
 }
 
-impl<'tcx, D, Q, C> Drop for JobOwner<'tcx, D, Q, C>
+impl<'tcx, D, C> Drop for JobOwner<'tcx, D, C>
 where
     D: Copy + Clone + Eq + Hash,
-    Q: Clone,
     C: QueryCache,
 {
     #[inline(never)]
@@ -356,21 +352,20 @@ where
 }
 
 #[derive(Clone)]
-pub struct CycleError<Q> {
+pub struct CycleError {
     /// The query and related span that uses the cycle.
-    pub usage: Option<(Span, Q)>,
-    pub cycle: Vec<QueryInfo<Q>>,
+    pub usage: Option<(Span, QueryStackFrame)>,
+    pub cycle: Vec<QueryInfo>,
 }
 
 /// The result of `try_start`.
-enum TryGetJob<'tcx, D, Q, C>
+enum TryGetJob<'tcx, D, C>
 where
     D: Copy + Clone + Eq + Hash,
-    Q: Clone,
     C: QueryCache,
 {
     /// The query is not yet started. Contains a guard to the cache eventually used to start it.
-    NotYetStarted(JobOwner<'tcx, D, Q, C>),
+    NotYetStarted(JobOwner<'tcx, D, C>),
 
     /// The query was already completed.
     /// Returns the result of the query and its dep-node index
@@ -414,7 +409,7 @@ where
 
 fn try_execute_query<CTX, C>(
     tcx: CTX,
-    state: &QueryState<CTX::DepKind, CTX::Query, C::Key>,
+    state: &QueryState<CTX::DepKind, C::Key>,
     cache: &QueryCacheStore<C>,
     span: Span,
     key: C::Key,
@@ -426,7 +421,7 @@ where
     C::Key: crate::dep_graph::DepNodeParams<CTX::DepContext>,
     CTX: QueryContext,
 {
-    let job = match JobOwner::<'_, CTX::DepKind, CTX::Query, C>::try_start(
+    let job = match JobOwner::<'_, CTX::DepKind, C>::try_start(
         tcx, state, cache, span, &key, lookup, query,
     ) {
         TryGetJob::NotYetStarted(job) => job,
@@ -590,7 +585,7 @@ fn incremental_verify_ich<CTX, K, V: Debug>(
 fn force_query_with_job<C, CTX>(
     tcx: CTX,
     key: C::Key,
-    job: JobOwner<'_, CTX::DepKind, CTX::Query, C>,
+    job: JobOwner<'_, CTX::DepKind, C>,
     dep_node: DepNode<CTX::DepKind>,
     query: &QueryVtable<CTX, C::Key, C::Value>,
 ) -> (C::Stored, DepNodeIndex)
@@ -650,7 +645,7 @@ where
 #[inline(never)]
 fn get_query_impl<CTX, C>(
     tcx: CTX,
-    state: &QueryState<CTX::DepKind, CTX::Query, C::Key>,
+    state: &QueryState<CTX::DepKind, C::Key>,
     cache: &QueryCacheStore<C>,
     span: Span,
     key: C::Key,
@@ -708,7 +703,7 @@ where
 #[inline(never)]
 fn force_query_impl<CTX, C>(
     tcx: CTX,
-    state: &QueryState<CTX::DepKind, CTX::Query, C::Key>,
+    state: &QueryState<CTX::DepKind, C::Key>,
     cache: &QueryCacheStore<C>,
     key: C::Key,
     span: Span,
@@ -736,7 +731,7 @@ fn force_query_impl<CTX, C>(
         Err(lookup) => lookup,
     };
 
-    let job = match JobOwner::<'_, CTX::DepKind, CTX::Query, C>::try_start(
+    let job = match JobOwner::<'_, CTX::DepKind, C>::try_start(
         tcx, state, cache, span, &key, lookup, query,
     ) {
         TryGetJob::NotYetStarted(job) => job,

From c26d965714e38d62b1610780f67bec14dafe25c3 Mon Sep 17 00:00:00 2001
From: Camille GILLOT <gillot.camille@gmail.com>
Date: Sun, 29 Nov 2020 00:21:56 +0100
Subject: [PATCH 4/6] Move report_cycle to rustc_query_system.

The call to `ty::print::with_forced_impl_filename_line`
is done when constructing the description,
at the construction of the QueryStackFrame.
---
 compiler/rustc_query_impl/src/lib.rs          |  2 +-
 compiler/rustc_query_impl/src/plumbing.rs     | 62 ++-----------------
 .../rustc_query_system/src/query/config.rs    | 10 +--
 compiler/rustc_query_system/src/query/job.rs  | 36 +++++++++++
 .../rustc_query_system/src/query/plumbing.rs  |  8 ++-
 5 files changed, 54 insertions(+), 64 deletions(-)

diff --git a/compiler/rustc_query_impl/src/lib.rs b/compiler/rustc_query_impl/src/lib.rs
index bfba7c7410ede..176c68cf0fc12 100644
--- a/compiler/rustc_query_impl/src/lib.rs
+++ b/compiler/rustc_query_impl/src/lib.rs
@@ -18,7 +18,7 @@ extern crate tracing;
 
 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
-use rustc_errors::{Diagnostic, Handler, Level};
+use rustc_errors::{Diagnostic, DiagnosticBuilder, Handler, Level};
 use rustc_hir::def_id::CrateNum;
 use rustc_index::vec::IndexVec;
 use rustc_middle::dep_graph;
diff --git a/compiler/rustc_query_impl/src/plumbing.rs b/compiler/rustc_query_impl/src/plumbing.rs
index 01fb5a7ba2029..00392fbcf5606 100644
--- a/compiler/rustc_query_impl/src/plumbing.rs
+++ b/compiler/rustc_query_impl/src/plumbing.rs
@@ -8,15 +8,13 @@ use rustc_middle::ty::query::on_disk_cache;
 use rustc_middle::ty::tls::{self, ImplicitCtxt};
 use rustc_middle::ty::{self, TyCtxt};
 use rustc_query_system::dep_graph::HasDepContext;
-use rustc_query_system::query::{CycleError, QueryJobId};
-use rustc_query_system::query::{QueryContext, QueryDescription, QueryMap, QueryStackFrame};
+use rustc_query_system::query::{QueryContext, QueryDescription, QueryJobId, QueryMap};
 
 use rustc_data_structures::sync::Lock;
 use rustc_data_structures::thin_vec::ThinVec;
-use rustc_errors::{struct_span_err, Diagnostic, DiagnosticBuilder};
+use rustc_errors::Diagnostic;
 use rustc_serialize::opaque;
 use rustc_span::def_id::{DefId, LocalDefId};
-use rustc_span::Span;
 
 #[derive(Copy, Clone)]
 pub struct QueryCtxt<'tcx> {
@@ -175,54 +173,6 @@ impl QueryContext for QueryCtxt<'tcx> {
 }
 
 impl<'tcx> QueryCtxt<'tcx> {
-    #[inline(never)]
-    #[cold]
-    pub(super) fn report_cycle(
-        self,
-        CycleError { usage, cycle: stack }: CycleError,
-    ) -> DiagnosticBuilder<'tcx> {
-        assert!(!stack.is_empty());
-
-        let fix_span = |span: Span, query: &QueryStackFrame| {
-            self.sess.source_map().guess_head_span(query.default_span(span))
-        };
-
-        // Disable naming impls with types in this path, since that
-        // sometimes cycles itself, leading to extra cycle errors.
-        // (And cycle errors around impls tend to occur during the
-        // collect/coherence phases anyhow.)
-        ty::print::with_forced_impl_filename_line(|| {
-            let span = fix_span(stack[1 % stack.len()].span, &stack[0].query);
-            let mut err = struct_span_err!(
-                self.sess,
-                span,
-                E0391,
-                "cycle detected when {}",
-                stack[0].query.description
-            );
-
-            for i in 1..stack.len() {
-                let query = &stack[i].query;
-                let span = fix_span(stack[(i + 1) % stack.len()].span, query);
-                err.span_note(span, &format!("...which requires {}...", query.description));
-            }
-
-            err.note(&format!(
-                "...which again requires {}, completing the cycle",
-                stack[0].query.description
-            ));
-
-            if let Some((span, query)) = usage {
-                err.span_note(
-                    fix_span(span, &query),
-                    &format!("cycle used when {}", query.description),
-                );
-            }
-
-            err
-        })
-    }
-
     pub(super) fn encode_query_results(
         self,
         encoder: &mut on_disk_cache::CacheEncoder<'a, 'tcx, opaque::FileEncoder>,
@@ -302,16 +252,16 @@ pub struct QueryStruct {
 
 macro_rules! handle_cycle_error {
     ([][$tcx: expr, $error:expr]) => {{
-        $tcx.report_cycle($error).emit();
+        $error.emit();
         Value::from_cycle_error($tcx)
     }};
     ([fatal_cycle $($rest:tt)*][$tcx:expr, $error:expr]) => {{
-        $tcx.report_cycle($error).emit();
+        $error.emit();
         $tcx.sess.abort_if_errors();
         unreachable!()
     }};
     ([cycle_delay_bug $($rest:tt)*][$tcx:expr, $error:expr]) => {{
-        $tcx.report_cycle($error).delay_as_bug();
+        $error.delay_as_bug();
         Value::from_cycle_error($tcx)
     }};
     ([$other:ident $(($($other_args:tt)*))* $(, $($modifiers:tt)*)*][$($args:tt)*]) => {
@@ -459,7 +409,7 @@ macro_rules! define_queries {
 
             fn handle_cycle_error(
                 tcx: QueryCtxt<'tcx>,
-                error: CycleError,
+                mut error: DiagnosticBuilder<'_>,
             ) -> Self::Value {
                 handle_cycle_error!([$($modifiers)*][tcx, error])
             }
diff --git a/compiler/rustc_query_system/src/query/config.rs b/compiler/rustc_query_system/src/query/config.rs
index d01b0de3b4803..4e2515c3ac3fa 100644
--- a/compiler/rustc_query_system/src/query/config.rs
+++ b/compiler/rustc_query_system/src/query/config.rs
@@ -3,10 +3,10 @@
 use crate::dep_graph::DepNode;
 use crate::dep_graph::SerializedDepNodeIndex;
 use crate::query::caches::QueryCache;
-use crate::query::plumbing::CycleError;
 use crate::query::{QueryCacheStore, QueryContext, QueryState};
 
 use rustc_data_structures::fingerprint::Fingerprint;
+use rustc_errors::DiagnosticBuilder;
 use std::fmt::Debug;
 use std::hash::Hash;
 
@@ -27,7 +27,7 @@ pub(crate) struct QueryVtable<CTX: QueryContext, K, V> {
     pub compute: fn(CTX, K) -> V,
 
     pub hash_result: fn(&mut CTX::StableHashingContext, &V) -> Option<Fingerprint>,
-    pub handle_cycle_error: fn(CTX, CycleError) -> V,
+    pub handle_cycle_error: fn(CTX, DiagnosticBuilder<'_>) -> V,
     pub cache_on_disk: fn(CTX, &K, Option<&V>) -> bool,
     pub try_load_from_disk: fn(CTX, SerializedDepNodeIndex) -> Option<V>,
 }
@@ -52,8 +52,8 @@ impl<CTX: QueryContext, K, V> QueryVtable<CTX, K, V> {
         (self.hash_result)(hcx, value)
     }
 
-    pub(crate) fn handle_cycle_error(&self, tcx: CTX, error: CycleError) -> V {
-        (self.handle_cycle_error)(tcx, error)
+    pub(crate) fn handle_cycle_error(&self, tcx: CTX, diag: DiagnosticBuilder<'_>) -> V {
+        (self.handle_cycle_error)(tcx, diag)
     }
 
     pub(crate) fn cache_on_disk(&self, tcx: CTX, key: &K, value: Option<&V>) -> bool {
@@ -90,7 +90,7 @@ pub trait QueryAccessors<CTX: QueryContext>: QueryConfig {
         result: &Self::Value,
     ) -> Option<Fingerprint>;
 
-    fn handle_cycle_error(tcx: CTX, error: CycleError) -> Self::Value;
+    fn handle_cycle_error(tcx: CTX, diag: DiagnosticBuilder<'_>) -> Self::Value;
 }
 
 pub trait QueryDescription<CTX: QueryContext>: QueryAccessors<CTX> {
diff --git a/compiler/rustc_query_system/src/query/job.rs b/compiler/rustc_query_system/src/query/job.rs
index cc3cefe46bef2..a30cd078d6c0c 100644
--- a/compiler/rustc_query_system/src/query/job.rs
+++ b/compiler/rustc_query_system/src/query/job.rs
@@ -2,6 +2,8 @@ use crate::query::plumbing::CycleError;
 use crate::query::QueryStackFrame;
 
 use rustc_data_structures::fx::FxHashMap;
+use rustc_errors::{struct_span_err, DiagnosticBuilder};
+use rustc_session::Session;
 use rustc_span::Span;
 
 use std::convert::TryFrom;
@@ -590,3 +592,37 @@ pub fn deadlock<CTX: QueryContext>(tcx: CTX, registry: &rayon_core::Registry) {
 
     on_panic.disable();
 }
+
+#[inline(never)]
+#[cold]
+pub(crate) fn report_cycle<'a>(
+    sess: &'a Session,
+    CycleError { usage, cycle: stack }: CycleError,
+) -> DiagnosticBuilder<'a> {
+    assert!(!stack.is_empty());
+
+    let fix_span = |span: Span, query: &QueryStackFrame| {
+        sess.source_map().guess_head_span(query.default_span(span))
+    };
+
+    let span = fix_span(stack[1 % stack.len()].span, &stack[0].query);
+    let mut err =
+        struct_span_err!(sess, span, E0391, "cycle detected when {}", stack[0].query.description);
+
+    for i in 1..stack.len() {
+        let query = &stack[i].query;
+        let span = fix_span(stack[(i + 1) % stack.len()].span, query);
+        err.span_note(span, &format!("...which requires {}...", query.description));
+    }
+
+    err.note(&format!(
+        "...which again requires {}, completing the cycle",
+        stack[0].query.description
+    ));
+
+    if let Some((span, query)) = usage {
+        err.span_note(fix_span(span, &query), &format!("cycle used when {}", query.description));
+    }
+
+    err
+}
diff --git a/compiler/rustc_query_system/src/query/plumbing.rs b/compiler/rustc_query_system/src/query/plumbing.rs
index 28ee1a179942c..0050670b338ea 100644
--- a/compiler/rustc_query_system/src/query/plumbing.rs
+++ b/compiler/rustc_query_system/src/query/plumbing.rs
@@ -6,7 +6,9 @@ use crate::dep_graph::{DepContext, DepKind, DepNode};
 use crate::dep_graph::{DepNodeIndex, SerializedDepNodeIndex};
 use crate::query::caches::QueryCache;
 use crate::query::config::{QueryDescription, QueryVtable, QueryVtableExt};
-use crate::query::job::{QueryInfo, QueryJob, QueryJobId, QueryJobInfo, QueryShardJobId};
+use crate::query::job::{
+    report_cycle, QueryInfo, QueryJob, QueryJobId, QueryJobInfo, QueryShardJobId,
+};
 use crate::query::{QueryContext, QueryMap, QueryStackFrame};
 
 #[cfg(not(parallel_compiler))]
@@ -245,6 +247,7 @@ where
                 &tcx.current_query_job(),
                 span,
             );
+            let error = report_cycle(tcx.dep_context().sess(), error);
             let value = query.handle_cycle_error(tcx, error);
             cache.cache.store_nocache(value)
         }));
@@ -256,6 +259,7 @@ where
             let result = latch.wait_on(tcx.current_query_job(), span);
 
             if let Err(cycle) = result {
+                let cycle = report_cycle(tcx.dep_context().sess(), cycle);
                 let value = query.handle_cycle_error(tcx, cycle);
                 let value = cache.cache.store_nocache(value);
                 return TryGetJob::Cycle(value);
@@ -352,7 +356,7 @@ where
 }
 
 #[derive(Clone)]
-pub struct CycleError {
+pub(crate) struct CycleError {
     /// The query and related span that uses the cycle.
     pub usage: Option<(Span, QueryStackFrame)>,
     pub cycle: Vec<QueryInfo>,

From a87de890fd1a797952ab49459aeca4ce598d8f15 Mon Sep 17 00:00:00 2001
From: Camille GILLOT <gillot.camille@gmail.com>
Date: Sun, 29 Nov 2020 00:39:34 +0100
Subject: [PATCH 5/6] Move print_query_stack to rustc_query_system.

---
 compiler/rustc_query_impl/src/lib.rs         |  2 +-
 compiler/rustc_query_impl/src/plumbing.rs    | 34 +--------------
 compiler/rustc_query_system/src/query/job.rs | 46 ++++++++++++++++++--
 compiler/rustc_query_system/src/query/mod.rs |  2 +-
 4 files changed, 46 insertions(+), 38 deletions(-)

diff --git a/compiler/rustc_query_impl/src/lib.rs b/compiler/rustc_query_impl/src/lib.rs
index 176c68cf0fc12..e9314797fbdc5 100644
--- a/compiler/rustc_query_impl/src/lib.rs
+++ b/compiler/rustc_query_impl/src/lib.rs
@@ -18,7 +18,7 @@ extern crate tracing;
 
 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
-use rustc_errors::{Diagnostic, DiagnosticBuilder, Handler, Level};
+use rustc_errors::{DiagnosticBuilder, Handler};
 use rustc_hir::def_id::CrateNum;
 use rustc_index::vec::IndexVec;
 use rustc_middle::dep_graph;
diff --git a/compiler/rustc_query_impl/src/plumbing.rs b/compiler/rustc_query_impl/src/plumbing.rs
index 00392fbcf5606..4618671ddf076 100644
--- a/compiler/rustc_query_impl/src/plumbing.rs
+++ b/compiler/rustc_query_impl/src/plumbing.rs
@@ -584,38 +584,8 @@ macro_rules! define_queries_struct {
                 handler: &Handler,
                 num_frames: Option<usize>,
             ) -> usize {
-                let query_map = self.try_collect_active_jobs(tcx);
-
-                let mut current_query = query;
-                let mut i = 0;
-
-                while let Some(query) = current_query {
-                    if Some(i) == num_frames {
-                        break;
-                    }
-                    let query_info = if let Some(info) = query_map.as_ref().and_then(|map| map.get(&query))
-                    {
-                        info
-                    } else {
-                        break;
-                    };
-                    let mut diag = Diagnostic::new(
-                        Level::FailureNote,
-                        &format!(
-                            "#{} [{}] {}",
-                            i,
-                            query_info.info.query.name,
-                            query_info.info.query.description,
-                        ),
-                    );
-                    diag.span = tcx.sess.source_map().guess_head_span(query_info.info.span).into();
-                    handler.force_print_diagnostic(diag);
-
-                    current_query = query_info.job.parent;
-                    i += 1;
-                }
-
-                i
+                let qcx = QueryCtxt { tcx, queries: self };
+                rustc_query_system::query::print_query_stack(qcx, query, handler, num_frames)
             }
 
             $($(#[$attr])*
diff --git a/compiler/rustc_query_system/src/query/job.rs b/compiler/rustc_query_system/src/query/job.rs
index a30cd078d6c0c..30dce1e501893 100644
--- a/compiler/rustc_query_system/src/query/job.rs
+++ b/compiler/rustc_query_system/src/query/job.rs
@@ -1,8 +1,9 @@
+use crate::dep_graph::DepContext;
 use crate::query::plumbing::CycleError;
-use crate::query::QueryStackFrame;
+use crate::query::{QueryContext, QueryStackFrame};
 
 use rustc_data_structures::fx::FxHashMap;
-use rustc_errors::{struct_span_err, DiagnosticBuilder};
+use rustc_errors::{struct_span_err, Diagnostic, DiagnosticBuilder, Handler, Level};
 use rustc_session::Session;
 use rustc_span::Span;
 
@@ -13,8 +14,6 @@ use std::num::NonZeroU32;
 
 #[cfg(parallel_compiler)]
 use {
-    crate::dep_graph::DepContext,
-    crate::query::QueryContext,
     parking_lot::{Condvar, Mutex},
     rustc_data_structures::fx::FxHashSet,
     rustc_data_structures::stable_hasher::{HashStable, StableHasher},
@@ -626,3 +625,42 @@ pub(crate) fn report_cycle<'a>(
 
     err
 }
+
+pub fn print_query_stack<CTX: QueryContext>(
+    tcx: CTX,
+    mut current_query: Option<QueryJobId<CTX::DepKind>>,
+    handler: &Handler,
+    num_frames: Option<usize>,
+) -> usize {
+    // Be careful relying on global state here: this code is called from
+    // a panic hook, which means that the global `Handler` may be in a weird
+    // state if it was responsible for triggering the panic.
+    let mut i = 0;
+    let query_map = tcx.try_collect_active_jobs();
+
+    while let Some(query) = current_query {
+        if Some(i) == num_frames {
+            break;
+        }
+        let query_info = if let Some(info) = query_map.as_ref().and_then(|map| map.get(&query)) {
+            info
+        } else {
+            break;
+        };
+        let mut diag = Diagnostic::new(
+            Level::FailureNote,
+            &format!(
+                "#{} [{}] {}",
+                i, query_info.info.query.name, query_info.info.query.description
+            ),
+        );
+        diag.span =
+            tcx.dep_context().sess().source_map().guess_head_span(query_info.info.span).into();
+        handler.force_print_diagnostic(diag);
+
+        current_query = query_info.job.parent;
+        i += 1;
+    }
+
+    i
+}
diff --git a/compiler/rustc_query_system/src/query/mod.rs b/compiler/rustc_query_system/src/query/mod.rs
index 7b46674c74338..81e2b4877fd60 100644
--- a/compiler/rustc_query_system/src/query/mod.rs
+++ b/compiler/rustc_query_system/src/query/mod.rs
@@ -4,7 +4,7 @@ pub use self::plumbing::*;
 mod job;
 #[cfg(parallel_compiler)]
 pub use self::job::deadlock;
-pub use self::job::{QueryInfo, QueryJob, QueryJobId, QueryJobInfo, QueryMap};
+pub use self::job::{print_query_stack, QueryInfo, QueryJob, QueryJobId, QueryJobInfo, QueryMap};
 
 mod caches;
 pub use self::caches::{

From 903f65f215812ca4d40e1efc6a5f234e0ab5728c Mon Sep 17 00:00:00 2001
From: Camille GILLOT <gillot.camille@gmail.com>
Date: Tue, 9 Feb 2021 18:53:38 +0100
Subject: [PATCH 6/6] Simplify hashing.

---
 compiler/rustc_query_impl/src/plumbing.rs    |  4 +--
 compiler/rustc_query_system/src/query/job.rs | 36 ++++++++------------
 compiler/rustc_query_system/src/query/mod.rs | 21 ++++++------
 3 files changed, 26 insertions(+), 35 deletions(-)

diff --git a/compiler/rustc_query_impl/src/plumbing.rs b/compiler/rustc_query_impl/src/plumbing.rs
index 4618671ddf076..37a176de94196 100644
--- a/compiler/rustc_query_impl/src/plumbing.rs
+++ b/compiler/rustc_query_impl/src/plumbing.rs
@@ -339,12 +339,12 @@ macro_rules! define_queries {
                 } else {
                     Some(key.default_span(*tcx))
                 };
-                let hash = {
+                let hash = || {
                     let mut hcx = tcx.create_stable_hashing_context();
                     let mut hasher = StableHasher::new();
                     std::mem::discriminant(&kind).hash_stable(&mut hcx, &mut hasher);
                     key.hash_stable(&mut hcx, &mut hasher);
-                    hasher.finish()
+                    hasher.finish::<u64>()
                 };
 
                 QueryStackFrame::new(name, description, span, hash)
diff --git a/compiler/rustc_query_system/src/query/job.rs b/compiler/rustc_query_system/src/query/job.rs
index 30dce1e501893..35a2ac865f259 100644
--- a/compiler/rustc_query_system/src/query/job.rs
+++ b/compiler/rustc_query_system/src/query/job.rs
@@ -14,9 +14,9 @@ use std::num::NonZeroU32;
 
 #[cfg(parallel_compiler)]
 use {
+    crate::dep_graph::DepKind,
     parking_lot::{Condvar, Mutex},
     rustc_data_structures::fx::FxHashSet,
-    rustc_data_structures::stable_hasher::{HashStable, StableHasher},
     rustc_data_structures::sync::Lock,
     rustc_data_structures::sync::Lrc,
     rustc_data_structures::{jobserver, OnDrop},
@@ -417,30 +417,23 @@ where
 
 // Deterministically pick an query from a list
 #[cfg(parallel_compiler)]
-fn pick_query<'a, CTX, T, F>(
-    query_map: &QueryMap<CTX::DepKind>,
-    tcx: CTX,
-    queries: &'a [T],
-    f: F,
-) -> &'a T
+fn pick_query<'a, D, T, F>(query_map: &QueryMap<D>, queries: &'a [T], f: F) -> &'a T
 where
-    CTX: QueryContext,
-    F: Fn(&T) -> (Span, QueryJobId<CTX::DepKind>),
+    D: Copy + Clone + Eq + Hash,
+    F: Fn(&T) -> (Span, QueryJobId<D>),
 {
     // Deterministically pick an entry point
     // FIXME: Sort this instead
-    let mut hcx = tcx.dep_context().create_stable_hashing_context();
     queries
         .iter()
         .min_by_key(|v| {
             let (span, query) = f(v);
-            let mut stable_hasher = StableHasher::new();
-            query.query(query_map).hash_stable(&mut hcx, &mut stable_hasher);
+            let hash = query.query(query_map).hash;
             // Prefer entry points which have valid spans for nicer error messages
             // We add an integer to the tuple ensuring that entry points
             // with valid spans are picked first
             let span_cmp = if span == DUMMY_SP { 1 } else { 0 };
-            (span_cmp, stable_hasher.finish::<u64>())
+            (span_cmp, hash)
         })
         .unwrap()
 }
@@ -451,11 +444,10 @@ where
 /// If a cycle was not found, the starting query is removed from `jobs` and
 /// the function returns false.
 #[cfg(parallel_compiler)]
-fn remove_cycle<CTX: QueryContext>(
-    query_map: &QueryMap<CTX::DepKind>,
-    jobs: &mut Vec<QueryJobId<CTX::DepKind>>,
-    wakelist: &mut Vec<Lrc<QueryWaiter<CTX::DepKind>>>,
-    tcx: CTX,
+fn remove_cycle<D: DepKind>(
+    query_map: &QueryMap<D>,
+    jobs: &mut Vec<QueryJobId<D>>,
+    wakelist: &mut Vec<Lrc<QueryWaiter<D>>>,
 ) -> bool {
     let mut visited = FxHashSet::default();
     let mut stack = Vec::new();
@@ -505,15 +497,15 @@ fn remove_cycle<CTX: QueryContext>(
                         None
                     } else {
                         // Deterministically pick one of the waiters to show to the user
-                        let waiter = *pick_query(query_map, tcx, &waiters, |s| *s);
+                        let waiter = *pick_query(query_map, &waiters, |s| *s);
                         Some((span, query, Some(waiter)))
                     }
                 }
             })
-            .collect::<Vec<(Span, QueryJobId<CTX::DepKind>, Option<(Span, QueryJobId<CTX::DepKind>)>)>>();
+            .collect::<Vec<(Span, QueryJobId<D>, Option<(Span, QueryJobId<D>)>)>>();
 
         // Deterministically pick an entry point
-        let (_, entry_point, usage) = pick_query(query_map, tcx, &entry_points, |e| (e.0, e.1));
+        let (_, entry_point, usage) = pick_query(query_map, &entry_points, |e| (e.0, e.1));
 
         // Shift the stack so that our entry point is first
         let entry_point_pos = stack.iter().position(|(_, query)| query == entry_point);
@@ -570,7 +562,7 @@ pub fn deadlock<CTX: QueryContext>(tcx: CTX, registry: &rayon_core::Registry) {
     let mut found_cycle = false;
 
     while jobs.len() > 0 {
-        if remove_cycle(&query_map, &mut jobs, &mut wakelist, tcx) {
+        if remove_cycle(&query_map, &mut jobs, &mut wakelist) {
             found_cycle = true;
         }
     }
diff --git a/compiler/rustc_query_system/src/query/mod.rs b/compiler/rustc_query_system/src/query/mod.rs
index 81e2b4877fd60..aef8a13ccef32 100644
--- a/compiler/rustc_query_system/src/query/mod.rs
+++ b/compiler/rustc_query_system/src/query/mod.rs
@@ -16,8 +16,6 @@ pub use self::config::{QueryAccessors, QueryConfig, QueryDescription};
 
 use crate::dep_graph::{DepNode, DepNodeIndex, HasDepContext, SerializedDepNodeIndex};
 
-use rustc_data_structures::fingerprint::Fingerprint;
-use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::sync::Lock;
 use rustc_data_structures::thin_vec::ThinVec;
 use rustc_errors::Diagnostic;
@@ -34,7 +32,8 @@ pub struct QueryStackFrame {
     span: Option<Span>,
     /// This hash is used to deterministically pick
     /// a query to remove cycles in the parallel compiler.
-    hash: Fingerprint,
+    #[cfg(parallel_compiler)]
+    hash: u64,
 }
 
 impl QueryStackFrame {
@@ -43,9 +42,15 @@ impl QueryStackFrame {
         name: &'static str,
         description: String,
         span: Option<Span>,
-        hash: Fingerprint,
+        _hash: impl FnOnce() -> u64,
     ) -> Self {
-        Self { name, hash, description, span }
+        Self {
+            name,
+            description,
+            span,
+            #[cfg(parallel_compiler)]
+            hash: _hash(),
+        }
     }
 
     // FIXME(eddyb) Get more valid `Span`s on queries.
@@ -58,12 +63,6 @@ impl QueryStackFrame {
     }
 }
 
-impl<CTX> HashStable<CTX> for QueryStackFrame {
-    fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
-        self.hash.hash_stable(hcx, hasher)
-    }
-}
-
 pub trait QueryContext: HasDepContext {
     /// Get string representation from DefPath.
     fn def_path_str(&self, def_id: DefId) -> String;