3 files changed, 15 insertions, 5 deletions
diff --git a/compiler/rustc_interface/src/callbacks.rs b/compiler/rustc_interface/src/callbacks.rs
index 786e2bb511f..f66b9eb3a28 100644
--- a/compiler/rustc_interface/src/callbacks.rs
+++ b/compiler/rustc_interface/src/callbacks.rs
@@ -18,11 +18,19 @@ use rustc_query_system::dep_graph::dep_node::default_dep_kind_debug;
 use rustc_query_system::dep_graph::{DepContext, DepKind, DepNode};
 
 fn track_span_parent(def_id: rustc_span::def_id::LocalDefId) {
-    tls::with_opt(|tcx| {
-        if let Some(tcx) = tcx {
-            let _span = tcx.source_span(def_id);
-            // Sanity check: relative span's parent must be an absolute span.
-            debug_assert_eq!(_span.data_untracked().parent, None);
+    tls::with_context_opt(|icx| {
+        if let Some(icx) = icx {
+            // `track_span_parent` gets called a lot from HIR lowering code.
+            // Skip doing anything if we aren't tracking dependencies.
+            let tracks_deps = match icx.task_deps {
+                TaskDepsRef::Allow(..) => true,
+                TaskDepsRef::EvalAlways | TaskDepsRef::Ignore | TaskDepsRef::Forbid => false,
+            };
+            if tracks_deps {
+                let _span = icx.tcx.source_span(def_id);
+                // Sanity check: relative span's parent must be an absolute span.
+                debug_assert_eq!(_span.data_untracked().parent, None);
+            }
         }
     })
 }
diff --git a/compiler/rustc_interface/src/lib.rs b/compiler/rustc_interface/src/lib.rs
index 3492df69b8d..3b6c2acaf30 100644
--- a/compiler/rustc_interface/src/lib.rs
+++ b/compiler/rustc_interface/src/lib.rs
@@ -2,6 +2,7 @@
 #![feature(decl_macro)]
 #![feature(let_chains)]
 #![feature(try_blocks)]
+#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 mod callbacks;
diff --git a/compiler/rustc_interface/src/tests.rs b/compiler/rustc_interface/src/tests.rs
index 34f2dca7c42..486136a2bcc 100644
--- a/compiler/rustc_interface/src/tests.rs
+++ b/compiler/rustc_interface/src/tests.rs
@@ -774,6 +774,7 @@ fn test_unstable_options_tracking_hash() {
     tracked!(direct_access_external_data, Some(true));
     tracked!(dual_proc_macros, true);
     tracked!(dwarf_version, Some(5));
+    tracked!(embed_source, true);
     tracked!(emit_thin_lto, false);
     tracked!(export_executable_symbols, true);
     tracked!(fewer_names, Some(true));