[cfe-commits] [libcxx] r133656 - in /libcxx/trunk/include: __config memory

[Douglas Gregor]

Author: dgregor
Date: Wed Jun 22 17:17:44 2011
New Revision: 133656

URL: http://llvm.org/viewvc/llvm-project?rev=133656&view=rev
Log:
Teach libc++ about the addressof() overloads it needs to work with
Objective-C Automatic Reference Counting, where Objective-C object
pointers can have several different qualifiers (__strong, __weak,
__autoreleasing, __unsafe_unretained). These addressof() overloads are
only provided in ARC mode, and the __weak variant is conditionalized
on having weak-reference support in the ARC runtime.

For historical reasons, Clang provides these definitions itself, and
defines the macro _LIBCPP_PREDEFINED_OBJC_ARC_ADDRESSOF to note when
it as done so. The code belongs here, and this redundancy will be
eliminated in the future.

Addresses <rdar://problem/9658274>.

Modified:
    libcxx/trunk/include/__config
    libcxx/trunk/include/memory

Modified: libcxx/trunk/include/__config
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/__config?rev=133656&r1=133655&r2=133656&view=diff
==============================================================================
--- libcxx/trunk/include/__config (original)
+++ libcxx/trunk/include/__config Wed Jun 22 17:17:44 2011
@@ -157,6 +157,15 @@
 #define _LIBCPP_HAS_NO_TRAILING_RETURN
 #endif
 
+// Objective-C++ features (opt-in)
+#if __has_feature(objc_arc)
+#define _LIBCPP_HAS_OBJC_ARC
+#endif
+
+#if __has_feature(objc_arc_weak)
+#define _LIBCPP_HAS_OBJC_ARC_WEAK
+#endif
+
 // Inline namespaces are available in Clang regardless of C++ dialect.
 #define _LIBCPP_BEGIN_NAMESPACE_STD namespace std {inline namespace _LIBCPP_NAMESPACE {
 #define _LIBCPP_END_NAMESPACE_STD  } }

Modified: libcxx/trunk/include/memory
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/memory?rev=133656&r1=133655&r2=133656&view=diff
==============================================================================
--- libcxx/trunk/include/memory (original)
+++ libcxx/trunk/include/memory Wed Jun 22 17:17:44 2011
@@ -619,6 +619,46 @@
     return (_Tp*)&(char&)__x;
 }
 
+#if defined(_LIBCPP_HAS_OBJC_ARC) && !defined(_LIBCPP_PREDEFINED_OBJC_ARC_ADDRESSOF)
+// Objective-C++ Automatic Reference Counting uses qualified pointers
+// that require special addressof() signatures. When
+// _LIBCPP_PREDEFINED_OBJC_ARC_ADDRESSOF is defined, the compiler
+// itself is providing these definitions. Otherwise, we provide them.
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+__strong _Tp*
+addressof(__strong _Tp& __x) _NOEXCEPT
+{
+  return &__x;
+}
+
+#ifdef _LIBCPP_HAS_OBJC_ARC_WEAK
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+__weak _Tp*
+addressof(__weak _Tp& __x) _NOEXCEPT
+{
+  return &__x;
+}
+#endif
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+__autoreleasing _Tp*
+addressof(__autoreleasing _Tp& __x) _NOEXCEPT
+{
+  return &__x;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+__unsafe_unretained _Tp*
+addressof(__unsafe_unretained _Tp& __x) _NOEXCEPT
+{
+  return &__x;
+}
+#endif
+
 template <class _Tp> class allocator;
 
 template <>