[clang] Fix MSVC "not all control paths return a value" warning. NFC. (PR #182482)

[Simon Pilgrim via cfe-commits]

https://github.com/RKSimon created https://github.com/llvm/llvm-project/pull/182482

None

>From 01de6c2125edc897b08d9faec10b3f43e183fc2d Mon Sep 17 00:00:00 2001
From: Simon Pilgrim <llvm-dev at redking.me.uk>
Date: Fri, 20 Feb 2026 11:47:23 +0000
Subject: [PATCH] Fix MSVC "not all control paths return a value" warning. NFC.

---
 clang/lib/CodeGen/CGExprScalar.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/clang/lib/CodeGen/CGExprScalar.cpp b/clang/lib/CodeGen/CGExprScalar.cpp
index 3ef9da7806606..75a18c9f60b96 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -224,6 +224,7 @@ getOverflowBehaviorConsideringType(const CodeGenFunction &CGF,
   case LangOptions::SignedOverflowBehaviorTy::SOB_Trapping:
     return LangOptions::OverflowBehaviorKind::OB_Trap;
   }
+  llvm_unreachable("Unknown SignedOverflowBehaviorTy");
 }
 
 /// Check if we can skip the overflow check for \p Op.