[clang] Add test for CWG593 (#87752)

[CWG593](https://cplusplus.github.io/CWG/issues/593.html) "Falling off
the end of a destructor's function-try-block handler". As usual with CWG
issues resolved as NAD, we test for status-quo confirmed by CWG.

clang/test/CXX/drs/dr593.cpp

@@ -0,0 +1,35 @@
+// RUN: %clang_cc1 -std=c++98 %s -triple x86_64-linux-gnu -emit-llvm -o - -fexceptions -fcxx-exceptions -pedantic-errors | llvm-cxxfilt -n | FileCheck %s --check-prefixes CHECK
+// RUN: %clang_cc1 -std=c++11 %s -triple x86_64-linux-gnu -emit-llvm -o - -fexceptions -fcxx-exceptions -pedantic-errors | llvm-cxxfilt -n | FileCheck %s --check-prefixes CHECK
+// RUN: %clang_cc1 -std=c++14 %s -triple x86_64-linux-gnu -emit-llvm -o - -fexceptions -fcxx-exceptions -pedantic-errors | llvm-cxxfilt -n | FileCheck %s --check-prefixes CHECK
+// RUN: %clang_cc1 -std=c++17 %s -triple x86_64-linux-gnu -emit-llvm -o - -fexceptions -fcxx-exceptions -pedantic-errors | llvm-cxxfilt -n | FileCheck %s --check-prefixes CHECK
+// RUN: %clang_cc1 -std=c++20 %s -triple x86_64-linux-gnu -emit-llvm -o - -fexceptions -fcxx-exceptions -pedantic-errors | llvm-cxxfilt -n | FileCheck %s --check-prefixes CHECK
+// RUN: %clang_cc1 -std=c++23 %s -triple x86_64-linux-gnu -emit-llvm -o - -fexceptions -fcxx-exceptions -pedantic-errors | llvm-cxxfilt -n | FileCheck %s --check-prefixes CHECK
+// RUN: %clang_cc1 -std=c++2c %s -triple x86_64-linux-gnu -emit-llvm -o - -fexceptions -fcxx-exceptions -pedantic-errors | llvm-cxxfilt -n | FileCheck %s --check-prefixes CHECK
+
+#if __cplusplus == 199711L
+#define NOTHROW throw()
+#else
+#define NOTHROW noexcept(true)
+#endif
+
+namespace dr593 { // dr593: 2.8
+
+void f();
+void fence() NOTHROW;
+
+struct A {
+  ~A() try {
+    f();
+  } catch (...) {
+    fence();
+  }
+};
+
+void g() {
+  A();
+}
+
+} // namespace dr593
+
+// CHECK:      call void @dr593::fence()()
+// CHECK-NEXT: invoke void @__cxa_rethrow()

clang/test/CXX/drs/dr5xx.cpp

@@ -1098,7 +1098,7 @@ namespace dr591 { // dr591: no
 }
 
 // dr592: na
-// dr593 needs an IRGen test.
+// dr593 is in dr593.cpp
 // dr594: na
 
 namespace dr595 { // dr595: dup 1330

clang/www/cxx_dr_status.html

@@ -3600,7 +3600,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2>
     <td><a href="https://cplusplus.github.io/CWG/issues/593.html">593</a></td>
     <td>NAD</td>
     <td>Falling off the end of a destructor's <I>function-try-block</I> handler</td>
-    <td class="unknown" align="center">Unknown</td>
+    <td class="full" align="center">Clang 2.8</td>
   </tr>
   <tr id="594">
     <td><a href="https://cplusplus.github.io/CWG/issues/594.html">594</a></td>