From b63b83922c84dba84455199ccca19e2e844d37b1 Mon Sep 17 00:00:00 2001
From: qaijuang <237468078+qaijuang@users.noreply.github.com>
Date: Wed, 27 May 2026 04:37:36 -0400
Subject: [PATCH 1/2] add red test

---
 tests/ui/uninhabited/unreachable.rs | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/tests/ui/uninhabited/unreachable.rs b/tests/ui/uninhabited/unreachable.rs
index e4a5ba406a72e..10e77d27370ef 100644
--- a/tests/ui/uninhabited/unreachable.rs
+++ b/tests/ui/uninhabited/unreachable.rs
@@ -4,6 +4,8 @@
 //@ check-pass
 #![deny(unreachable_code)]
 
+use std::process::ExitCode;
+
 enum Never {}
 
 fn make_never() -> Never {
@@ -28,6 +30,14 @@ fn branchy() {
     }
 }
 
+// Regression test for https://github.com/rust-lang/rust/issues/152559.
+// The final expression is unreachable at runtime, but it cannot be removed
+// because it supplies the function's required return type.
+fn required_return_value() -> ExitCode {
+    make_never();
+    ExitCode::FAILURE
+}
+
 fn main() {
     func();
     block();

From 7451f1da2e6380e013264914f38375b9ee226836 Mon Sep 17 00:00:00 2001
From: qaijuang <237468078+qaijuang@users.noreply.github.com>
Date: Wed, 27 May 2026 04:51:08 -0400
Subject: [PATCH 2/2] avoid `unreachable_code` on required return values

---
 compiler/rustc_mir_build/src/builder/mod.rs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/compiler/rustc_mir_build/src/builder/mod.rs b/compiler/rustc_mir_build/src/builder/mod.rs
index e9f9da9c8cd91..d158f55a3111c 100644
--- a/compiler/rustc_mir_build/src/builder/mod.rs
+++ b/compiler/rustc_mir_build/src/builder/mod.rs
@@ -890,6 +890,12 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     {
                         continue;
                     }
+                    // Ignore return value plumbing. After a call returning a non-`!`
+                    // uninhabited type, a tail expression can be unreachable while
+                    // still being needed to satisfy the surrounding return type.
+                    StatementKind::Assign((place, _)) if place.as_local() == Some(RETURN_PLACE) => {
+                        continue;
+                    }
                     StatementKind::StorageLive(_) | StatementKind::StorageDead(_) => {
                         continue;
                     }