[asan] Add use-after-scope test which fails because of bug in clang

compiler-rt/trunk/test/asan/TestCases/use-after-scope-conversion.cc

+// RUN: %clangxx_asan -O0 -fsanitize-address-use-after-scope %s -o %t
+
+// RUN: not %run %t 'A' 2>&1 | FileCheck %s
+// RUN: not %run %t 'B' 2>&1 | FileCheck %s
+
+// Missing lifetime markers in test_a
+// https://bugs.llvm.org/show_bug.cgi?id=34353
+// XFAIL: *
+
+struct B {
+  B() : p('B') {}
+  char p;
+};
+
+struct C {
+  const char *p;
+  explicit C(const char *c) : p(c) {}
+  C(const B &b) : p(&b.p) {} // NOLINT
+};
+
+struct A {
+  char p;
+  explicit A() : p('C') {}
+  const operator C() const { return C(&p); }
+};
+
+volatile char r;
+void test_a() {
+  C s = A();
+  r = *s.p;
+}
+
+void test_b() {
+  C s = B();
+  r = *s.p;
+}
+
+int main(int argc, char **argv) {
+  switch (argv[1][0]) {
+  case 'A':
+    test_a();
+    return 0;
+  case 'B':
+    test_b();
+    return 0;
+  }
+  return 1;
+}
+
+// CHECK: ERROR: AddressSanitizer: stack-use-after-scope