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.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@128127 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 13 insertions, 4 deletions

diff --git a/lib/Sema/CodeCompleteConsumer.cpp b/lib/Sema/CodeCompleteConsumer.cpp
index b7037ce83e..2334ab5128 100644
--- a/lib/Sema/CodeCompleteConsumer.cpp
+++ b/lib/Sema/CodeCompleteConsumer.cpp
@@ -375,12 +375,21 @@ void CodeCompletionResult::computeCursorKindAndAvailability() {
   switch (Kind) {
   case RK_Declaration:
     // Set the availability based on attributes.
-    Availability = CXAvailability_Available;      
-    if (Declaration->getAttr<UnavailableAttr>())
-      Availability = CXAvailability_NotAvailable;
-    else if (Declaration->getAttr<DeprecatedAttr>())
+    switch (Declaration->getAvailability()) {
+    case AR_Available:
+    case AR_NotYetIntroduced:
+      Availability = CXAvailability_Available;      
+      break;
+      
+    case AR_Deprecated:
       Availability = CXAvailability_Deprecated;
+      break;
       
+    case AR_Unavailable:
+      Availability = CXAvailability_NotAvailable;
+      break;
+    }
+
     if (FunctionDecl *Function = dyn_cast<FunctionDecl>(Declaration))
       if (Function->isDeleted())
         Availability = CXAvailability_NotAvailable;