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, 126 insertions, 0 deletions

diff --git a/include/clang/Basic/VersionTuple.h b/include/clang/Basic/VersionTuple.h
new file mode 100644
index 0000000000..91eb68eaad
--- /dev/null
+++ b/include/clang/Basic/VersionTuple.h
@@ -0,0 +1,126 @@
+//===- VersionTuple.h - Version Number Handling -----------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This header defines the VersionTuple class, which represents a version in
+// the form major[.minor[.subminor]].
+//
+//===----------------------------------------------------------------------===//
+#ifndef LLVM_CLANG_BASIC_VERSIONTUPLE_H
+#define LLVM_CLANG_BASIC_VERSIONTUPLE_H
+
+#include "llvm/ADT/Optional.h"
+#include <string>
+
+namespace llvm {
+  class raw_ostream;
+}
+
+namespace clang {
+
+/// \brief Represents a version number in the form major[.minor[.subminor]].
+class VersionTuple {
+  unsigned Major;
+  unsigned Minor : 31;
+  unsigned Subminor : 31;
+  unsigned HasMinor : 1;
+  unsigned HasSubminor : 1;
+
+public:
+  VersionTuple() 
+    : Major(0), Minor(0), Subminor(0), HasMinor(false), HasSubminor(false) { }
+
+  explicit VersionTuple(unsigned Major)
+    : Major(Major), Minor(0), Subminor(0), HasMinor(false), HasSubminor(false)
+  { }
+
+  explicit VersionTuple(unsigned Major, unsigned Minor)
+    : Major(Major), Minor(Minor), Subminor(0), HasMinor(true), 
+      HasSubminor(false)
+  { }
+
+  explicit VersionTuple(unsigned Major, unsigned Minor, unsigned Subminor)
+    : Major(Major), Minor(Minor), Subminor(Subminor), HasMinor(true), 
+      HasSubminor(true)
+  { }
+
+  /// \brief Determine whether this version information is empty
+  /// (e.g., all version components are zero).
+  bool empty() const { return Major == 0 && Minor == 0 && Subminor == 0; }
+
+  /// \brief Retrieve the major version number.
+  unsigned getMajor() const { return Major; }
+
+  /// \brief Retrieve the minor version number, if provided.
+  llvm::Optional<unsigned> getMinor() const { 
+    if (!HasMinor)
+      return llvm::Optional<unsigned>();
+    return Minor;
+  }
+
+  /// \brief Retrieve the subminor version number, if provided.
+  llvm::Optional<unsigned> getSubminor() const { 
+    if (!HasSubminor)
+      return llvm::Optional<unsigned>();
+    return Subminor;
+  }
+
+  /// \brief Determine if two version numbers are equivalent. If not
+  /// provided, minor and subminor version numbers are considered to be zero.
+  friend bool operator==(const VersionTuple& X, const VersionTuple &Y) {
+    return X.Major == Y.Major && X.Minor == Y.Minor && X.Subminor == Y.Subminor;
+  }
+
+  /// \brief Determine if two version numbers are not equivalent. If
+  /// not provided, minor and subminor version numbers are considered to be 
+  /// zero.
+  friend bool operator!=(const VersionTuple &X, const VersionTuple &Y) {
+    return !(X == Y);
+  }
+
+  /// \brief Determine whether one version number precedes another. If not
+  /// provided, minor and subminor version numbers are considered to be zero.
+  friend bool operator<(const VersionTuple &X, const VersionTuple &Y) {
+    if (X.Major != Y.Major)
+      return X.Major < Y.Major;
+
+    if (X.Minor != Y.Minor)
+      return X.Minor < Y.Minor;
+
+    return X.Subminor < Y.Subminor;
+  }
+
+  /// \brief Determine whether one version number follows another. If not
+  /// provided, minor and subminor version numbers are considered to be zero.
+  friend bool operator>(const VersionTuple &X, const VersionTuple &Y) {
+    return Y < X;
+  }
+
+  /// \brief Determine whether one version number precedes or is
+  /// equivalent to another. If not provided, minor and subminor
+  /// version numbers are considered to be zero.
+  friend bool operator<=(const VersionTuple &X, const VersionTuple &Y) {
+    return !(Y < X);
+  }
+
+  /// \brief Determine whether one version number follows or is
+  /// equivalent to another. If not provided, minor and subminor
+  /// version numbers are considered to be zero.
+  friend bool operator>=(const VersionTuple &X, const VersionTuple &Y) {
+    return !(X < Y);
+  }
+
+  /// \brief Retrieve a string representation of the version number/
+  std::string getAsString() const;
+};
+
+/// \brief Print a version number.
+llvm::raw_ostream& operator<<(llvm::raw_ostream &Out, const VersionTuple &V);
+
+} // end namespace clang
+#endif // LLVM_CLANG_BASIC_VERSIONTUPLE_H