Implement a new 'availability' attribute, that allows one to specify

which versions of an OS provide a certain facility. For example,

  void foo()
  __attribute__((availability(macosx,introduced=10.2,deprecated=10.4,obsoleted=10.6)));

says that the function "foo" was introduced in 10.2, deprecated in
10.4, and completely obsoleted in 10.6. This attribute ties in with
the deployment targets (e.g., -mmacosx-version-min=10.1 specifies that
we want to deploy back to Mac OS X 10.1). There are several concrete
behaviors that this attribute enables, as illustrated with the
function foo() above:

  - If we choose a deployment target >= Mac OS X 10.4, uses of "foo"
    will result in a deprecation warning, as if we had placed
    attribute((deprecated)) on it (but with a better diagnostic)
  - If we choose a deployment target >= Mac OS X 10.6, uses of "foo"
    will result in an "unavailable" warning (in C)/error (in C++), as
    if we had placed attribute((unavailable)) on it
  - If we choose a deployment target prior to 10.2, foo() is
    weak-imported (if it is a kind of entity that can be weak
    imported), as if we had placed the weak_import attribute on it.

Naturally, there can be multiple availability attributes on a
declaration, for different platforms; only the current platform
matters when checking availability attributes.

The only platforms this attribute currently works for are "ios" and
"macosx", since we already have -mxxxx-version-min flags for them and we
have experience there with macro tricks translating down to the
deprecated/unavailable/weak_import attributes. The end goal is to open
this up to other platforms, and even extension to other "platforms"
that are really libraries (say, through a #pragma clang
define_system), but that hasn't yet been designed and we may want to
shake out more issues with this narrower problem first.

Addresses <rdar://problem/6690412>.

As a drive-by bug-fix, if an entity is both deprecated and
unavailable, we only emit the "unavailable" diagnostic.

llvm-svn: 128127

1 files changed, 8 insertions, 4 deletions

diff --git a/clang/lib/Sema/SemaObjCProperty.cpp b/clang/lib/Sema/SemaObjCProperty.cpp
index 91de095ac7e..f607d658951 100644
--- a/clang/lib/Sema/SemaObjCProperty.cpp
+++ b/clang/lib/Sema/SemaObjCProperty.cpp
@@ -1138,10 +1138,14 @@ Sema::AtomicPropertySetterGetterRules (ObjCImplDecl* IMPDecl,
 static void AddPropertyAttrs(Sema &S, ObjCMethodDecl *PropertyMethod,
                              ObjCPropertyDecl *Property) {
   // Should we just clone all attributes over?
-  if (DeprecatedAttr *A = Property->getAttr<DeprecatedAttr>())
-    PropertyMethod->addAttr(A->clone(S.Context));
-  if (UnavailableAttr *A = Property->getAttr<UnavailableAttr>())
-    PropertyMethod->addAttr(A->clone(S.Context));
+  for (Decl::attr_iterator A = Property->attr_begin(), 
+                        AEnd = Property->attr_end(); 
+       A != AEnd; ++A) {
+    if (isa<DeprecatedAttr>(*A) || 
+        isa<UnavailableAttr>(*A) || 
+        isa<AvailabilityAttr>(*A))
+      PropertyMethod->addAttr((*A)->clone(S.Context));
+  }
 }
 
 /// ProcessPropertyDecl - Make sure that any user-defined setter/getter methods