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, 24 insertions, 0 deletions

diff --git a/clang/test/CodeGenObjC/attr-availability.m b/clang/test/CodeGenObjC/attr-availability.m
new file mode 100644
index 0000000..4f1fad8
--- /dev/null
+++ b/clang/test/CodeGenObjC/attr-availability.m
@@ -0,0 +1,24 @@
+// RUN: %clang_cc1 -fobjc-nonfragile-abi "-triple" "x86_64-apple-darwin8.0.0" -emit-llvm -o - %s | FileCheck -check-prefix=CHECK-10_4 %s
+// RUN: %clang_cc1 -fobjc-nonfragile-abi "-triple" "x86_64-apple-darwin9.0.0" -emit-llvm -o - %s | FileCheck -check-prefix=CHECK-10_5 %s
+// RUN: %clang_cc1 -fobjc-nonfragile-abi "-triple" "x86_64-apple-darwin10.0.0" -emit-llvm -o - %s | FileCheck -check-prefix=CHECK-10_6 %s
+
+// CHECK-10_4: @"OBJC_CLASS_$_WeakClass1" = extern_weak global
+// CHECK-10_5: @"OBJC_CLASS_$_WeakClass1" = external global
+// CHECK-10_6: @"OBJC_CLASS_$_WeakClass1" = external global
+__attribute__((availability(macosx,introduced=10.5)))
+@interface WeakClass1 @end
+
+@implementation WeakClass1(MyCategory) @end
+
+@implementation WeakClass1(YourCategory) @end
+
+// CHECK-10_4: @"OBJC_CLASS_$_WeakClass2" = extern_weak global 
+// CHECK-10_5: @"OBJC_CLASS_$_WeakClass2" = extern_weak global 
+// CHECK-10_6: @"OBJC_CLASS_$_WeakClass2" = external global 
+__attribute__((availability(macosx,introduced=10.6)))
+@interface WeakClass2 @end
+
+@implementation WeakClass2(MyCategory) @end
+
+@implementation WeakClass2(YourCategory) @end
+