From 988f28d442d2e959897e43a239f67d42e0297990 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Tue, 3 Dec 2024 22:47:08 +0000
Subject: [PATCH] Make sure to record deps from cached task in new solver on
 first run

---
 .../rustc_query_system/src/dep_graph/graph.rs   | 17 +++++++++++++++--
 .../rustc_query_system/src/query/plumbing.rs    |  8 +++++---
 .../src/traits/select/mod.rs                    |  5 +----
 compiler/rustc_type_ir/src/search_graph/mod.rs  |  2 +-
 4 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/compiler/rustc_query_system/src/dep_graph/graph.rs b/compiler/rustc_query_system/src/dep_graph/graph.rs
index 9b26a5bbcc6..4b47ce8389c 100644
--- a/compiler/rustc_query_system/src/dep_graph/graph.rs
+++ b/compiler/rustc_query_system/src/dep_graph/graph.rs
@@ -302,7 +302,11 @@ impl<D: Deps> DepGraph<D> {
         OP: FnOnce() -> R,
     {
         match self.data() {
-            Some(data) => data.with_anon_task(cx, dep_kind, op),
+            Some(data) => {
+                let (result, index) = data.with_anon_task_inner(cx, dep_kind, op);
+                self.read_index(index);
+                (result, index)
+            }
             None => (op(), self.next_virtual_depnode_index()),
         }
     }
@@ -397,7 +401,16 @@ impl<D: Deps> DepGraphData<D> {
 
     /// Executes something within an "anonymous" task, that is, a task the
     /// `DepNode` of which is determined by the list of inputs it read from.
-    pub(crate) fn with_anon_task<Tcx: DepContext<Deps = D>, OP, R>(
+    ///
+    /// NOTE: this does not actually count as a read of the DepNode here.
+    /// Using the result of this task without reading the DepNode will result
+    /// in untracked dependencies which may lead to ICEs as nodes are
+    /// incorrectly marked green.
+    ///
+    /// FIXME: This could perhaps return a `WithDepNode` to ensure that the
+    /// user of this function actually performs the read; we'll have to see
+    /// how to make that work with `anon` in `execute_job_incr`, though.
+    pub(crate) fn with_anon_task_inner<Tcx: DepContext<Deps = D>, OP, R>(
         &self,
         cx: Tcx,
         dep_kind: DepKind,
diff --git a/compiler/rustc_query_system/src/query/plumbing.rs b/compiler/rustc_query_system/src/query/plumbing.rs
index aac8ab87c64..6fb5e37d2d0 100644
--- a/compiler/rustc_query_system/src/query/plumbing.rs
+++ b/compiler/rustc_query_system/src/query/plumbing.rs
@@ -520,9 +520,11 @@ where
     let (result, dep_node_index) =
         qcx.start_query(job_id, query.depth_limit(), Some(&diagnostics), || {
             if query.anon() {
-                return dep_graph_data.with_anon_task(*qcx.dep_context(), query.dep_kind(), || {
-                    query.compute(qcx, key)
-                });
+                return dep_graph_data.with_anon_task_inner(
+                    *qcx.dep_context(),
+                    query.dep_kind(),
+                    || query.compute(qcx, key),
+                );
             }
 
             // `to_dep_node` is expensive for some `DepKind`s.
diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs
index 41a35c31fe4..d362866cbc3 100644
--- a/compiler/rustc_trait_selection/src/traits/select/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs
@@ -1400,10 +1400,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     where
         OP: FnOnce(&mut Self) -> R,
     {
-        let (result, dep_node) =
-            self.tcx().dep_graph.with_anon_task(self.tcx(), dep_kinds::TraitSelect, || op(self));
-        self.tcx().dep_graph.read_index(dep_node);
-        (result, dep_node)
+        self.tcx().dep_graph.with_anon_task(self.tcx(), dep_kinds::TraitSelect, || op(self))
     }
 
     /// filter_impls filters candidates that have a positive impl for a negative
diff --git a/compiler/rustc_type_ir/src/search_graph/mod.rs b/compiler/rustc_type_ir/src/search_graph/mod.rs
index 5010fc09adc..3cc2dcbaca6 100644
--- a/compiler/rustc_type_ir/src/search_graph/mod.rs
+++ b/compiler/rustc_type_ir/src/search_graph/mod.rs
@@ -511,7 +511,7 @@ impl<D: Delegate<Cx = X>, X: Cx> SearchGraph<D> {
 
         // This is for global caching, so we properly track query dependencies.
         // Everything that affects the `result` should be performed within this
-        // `with_anon_task` closure. If computing this goal depends on something
+        // `with_cached_task` closure. If computing this goal depends on something
         // not tracked by the cache key and from outside of this anon task, it
         // must not be added to the global cache. Notably, this is the case for
         // trait solver cycles participants.