2 files changed, 5 insertions, 4 deletions
diff --git a/compiler/rustc_driver_impl/src/lib.rs b/compiler/rustc_driver_impl/src/lib.rs
index 7b1070f309b..c4488354135 100644
--- a/compiler/rustc_driver_impl/src/lib.rs
+++ b/compiler/rustc_driver_impl/src/lib.rs
@@ -1327,6 +1327,9 @@ pub fn install_ice_hook(
     panic::update_hook(Box::new(
         move |default_hook: &(dyn Fn(&PanicInfo<'_>) + Send + Sync + 'static),
               info: &PanicInfo<'_>| {
+            // Lock stderr to prevent interleaving of concurrent panics.
+            let _guard = io::stderr().lock();
+
             // If the error was caused by a broken pipe then this is not a bug.
             // Write the error and return immediately. See #98700.
             #[cfg(windows)]
diff --git a/compiler/rustc_driver_impl/src/pretty.rs b/compiler/rustc_driver_impl/src/pretty.rs
index c0c6201f73d..c9bbe45b212 100644
--- a/compiler/rustc_driver_impl/src/pretty.rs
+++ b/compiler/rustc_driver_impl/src/pretty.rs
@@ -336,8 +336,7 @@ pub fn print<'tcx>(sess: &Session, ppm: PpMode, ex: PrintExtra<'tcx>) {
         ThirTree => {
             let tcx = ex.tcx();
             let mut out = String::new();
-            rustc_hir_analysis::check_crate(tcx);
-            if tcx.dcx().has_errors().is_some() {
+            if rustc_hir_analysis::check_crate(tcx).is_err() {
                 FatalError.raise();
             }
             debug!("pretty printing THIR tree");
@@ -349,8 +348,7 @@ pub fn print<'tcx>(sess: &Session, ppm: PpMode, ex: PrintExtra<'tcx>) {
         ThirFlat => {
             let tcx = ex.tcx();
             let mut out = String::new();
-            rustc_hir_analysis::check_crate(tcx);
-            if tcx.dcx().has_errors().is_some() {
+            if rustc_hir_analysis::check_crate(tcx).is_err() {
                 FatalError.raise();
             }
             debug!("pretty printing THIR flat");