[libcxxabi] When catching an exception of type nullptr_t with a handler of

pointer-to-member type, produce a null value of the right type.

This fixes a bug where throwing an exception of type nullptr_t and catching it
as a pointer-to-member would not guarantee to produce a null value in the catch
handler. The fix is pretty simple: we statically allocate a constant null
pointer-to-data-member representation and a constant null
pointer-to-member-function representation, and produce the address of the
relevant value as the adjusted pointer for the exception.


git-svn-id: https://llvm.org/svn/llvm-project/libcxxabi/trunk@276016 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 49 insertions, 0 deletions

diff --git a/test/catch_reference_nullptr.pass.cpp b/test/catch_reference_nullptr.pass.cpp
new file mode 100644
index 0000000..0e7955f
--- /dev/null
+++ b/test/catch_reference_nullptr.pass.cpp
@@ -0,0 +1,49 @@
+//===--------------------- catch_pointer_nullptr.cpp ----------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03, libcxxabi-no-exceptions
+
+#include <cassert>
+#include <cstdlib>
+
+struct A {};
+
+template<typename T, bool CanCatchNullptr>
+static void catch_nullptr_test() {
+  try {
+    throw nullptr;
+  } catch (T &p) {
+    assert(CanCatchNullptr && !p);
+  } catch (...) {
+    assert(!CanCatchNullptr);
+  }
+}
+
+int main()
+{
+  using nullptr_t = decltype(nullptr);
+
+  // A reference to nullptr_t can catch nullptr.
+  catch_nullptr_test<nullptr_t, true>();
+  catch_nullptr_test<const nullptr_t, true>();
+  catch_nullptr_test<volatile nullptr_t, true>();
+  catch_nullptr_test<const volatile nullptr_t, true>();
+
+  // No other reference type can.
+#if 0
+  // FIXME: These tests fail, because the ABI provides no way for us to
+  // distinguish this from catching by value.
+  catch_nullptr_test<void *, false>();
+  catch_nullptr_test<void * const, false>();
+  catch_nullptr_test<int *, false>();
+  catch_nullptr_test<A *, false>();
+  catch_nullptr_test<int A::*, false>();
+  catch_nullptr_test<int (A::*)(), false>();
+#endif
+}