[clang] [WinEH] Fix crash, object unwinding in the except block (PR #172287)

[via cfe-commits]

https://github.com/GkvJwa updated https://github.com/llvm/llvm-project/pull/172287

>From f16a7e15a2e54d2bb0090a06d99181176abb65e5 Mon Sep 17 00:00:00 2001
From: GkvJwa <gkvjwa at gmail.com>
Date: Tue, 20 Jan 2026 22:50:18 +0800
Subject: [PATCH] Test

---
 clang/lib/CodeGen/CGDecl.cpp             |  8 ++++++-
 clang/test/CodeGenCXX/exceptions-seh.cpp | 29 ++++++++++++++++++++++++
 2 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/clang/lib/CodeGen/CGDecl.cpp b/clang/lib/CodeGen/CGDecl.cpp
index 8b1cd83af2396..182570d9586a7 100644
--- a/clang/lib/CodeGen/CGDecl.cpp
+++ b/clang/lib/CodeGen/CGDecl.cpp
@@ -2212,8 +2212,14 @@ void CodeGenFunction::EmitAutoVarCleanups(const AutoVarEmission &emission) {
   const VarDecl &D = *emission.Variable;
 
   // Check the type for a cleanup.
-  if (QualType::DestructionKind dtorKind = D.needsDestruction(getContext()))
+  if (QualType::DestructionKind dtorKind = D.needsDestruction(getContext())) {
+    // Check if we're in a SEH block and this is a C++ destructor
+    if (dtorKind == QualType::DK_cxx_destructor)
+      if (currentFunctionUsesSEHTry())
+        getContext().getDiagnostics().Report(D.getLocation(),
+                                             diag::err_seh_expected_handler);
     emitAutoVarTypeCleanup(emission, dtorKind);
+  }
 
   // In GC mode, honor objc_precise_lifetime.
   if (getLangOpts().getGC() != LangOptions::NonGC &&
diff --git a/clang/test/CodeGenCXX/exceptions-seh.cpp b/clang/test/CodeGenCXX/exceptions-seh.cpp
index bb374dd1f5bd5..6a48e8384bb34 100644
--- a/clang/test/CodeGenCXX/exceptions-seh.cpp
+++ b/clang/test/CodeGenCXX/exceptions-seh.cpp
@@ -4,6 +4,12 @@
 // RUN: %clang_cc1 -std=c++11 -fblocks -fms-extensions %s -triple=x86_64-windows-msvc -emit-llvm \
 // RUN:         -o - -mconstructor-aliases -O1 -disable-llvm-passes | \
 // RUN:         FileCheck %s --check-prefix=CHECK --check-prefix=NOCXX
+// RUN: %clang_cc1 -triple x86_64-windows -fasync-exceptions -fcxx-exceptions -fexceptions \
+// RUN:         -fms-extensions -x c++ -emit-llvm -verify %s -DERR1
+// RUN: %clang_cc1 -triple x86_64-windows -fasync-exceptions -fcxx-exceptions -fexceptions \
+// RUN:         -fms-extensions -x c++ -emit-llvm -verify %s -DERR2
+// RUN: %clang_cc1 -triple x86_64-windows -fasync-exceptions -fcxx-exceptions -fexceptions \
+// RUN:         -fms-extensions -x c++ -emit-llvm -verify %s -DERR3
 
 extern "C" unsigned long _exception_code();
 extern "C" void might_throw();
@@ -175,3 +181,26 @@ void use_inline() {
 // CHECK: attributes #[[NOINLINE]] = { {{.*noinline.*}} }
 
 void seh_in_noexcept() noexcept { __try {} __finally {} }
+
+#if defined(ERR1)
+void seh_unwinding() {
+  __try {
+    HasCleanup x; // expected-error{{expected '__except' or '__finally' block}}
+  } __except (1) {
+  }
+}
+#elif defined(ERR2)
+void seh_unwinding() {
+  __try {
+  } __except (1) {
+    HasCleanup x; // expected-error{{expected '__except' or '__finally' block}}
+  }
+}
+#elif defined(ERR3)
+void seh_unwinding() {
+  HasCleanup x; // expected-error{{expected '__except' or '__finally' block}}
+  __try {
+  } __except (1) {
+  }
+}
+#endif