[ObjC Availability] Implement parser support for Objective-C's @available

[erik.pilkington]

Summary

This patch is the first of the feature I proposed on Monday here: http://lists.llvm.org/pipermail/cfe-dev/2016-July/049851.html

This patch adds a new AST node, ObjCAvailabilityCheckExpr, and teaches the parser and Sema to build it. Currently, if compiled without -fsyntax-only, Clang errors out in CodeGen. Up next is a patch that implements the availability violation warning itself, then CodeGen support.

ObjCAvailabilityCheckExpr is an predicate expression that will end up compiling into a runtime check of the host's OS version. It can be spelled in two ways:

@available(macos 10.10, *); // Objective-C only
__builtin_available(macos 10.10, *); // C, C++, and Objective-C

It's main purpose in life is to guard calls to API calls that are marked with an __attribute__((availability())) greater than the current deployment target, so users can safely use new APIs while still supporting old OS versions.

Thanks!

[manmanren]

Thanks for working on this, Erik.

Manman

include/clang/AST/Availability.h

32 ↗

(On Diff #63310)

Can you put a description for "Version"? i.e if it represents a range, specify the range here.

42 ↗

(On Diff #63310)

Can you make this comment a full sentence?

51 ↗

(On Diff #63310)

Same here.

include/clang/Basic/VersionTuple.h

29 ↗

(On Diff #63310)

If this changes in this file are not related to @available, please commit it separately.

lib/AST/StmtPrinter.cpp

502 ↗

(On Diff #63310)

Why not print other information of Node?

lib/Parse/ParseDecl.cpp

723 ↗

(On Diff #63310)

I don't quite get what motivates this change. Are we not setting the range correctly before, for version tuples?

lib/Parse/ParseExpr.cpp

2875 ↗

(On Diff #63310)

Please comment on the return value, i.e return true if invalid.

2957 ↗

(On Diff #63310)

Why use "for (;;)" instead of "while(true)"?

2964 ↗

(On Diff #63310)

Can you verify that when having error parsing a single spec, the compiler can still reasonably continue? Should we skip until the next comma, or the next right paren?

lib/Parse/ParseObjc.cpp

2863 ↗

(On Diff #63310)

Should we move ConsumeToken to inside ParseAvailabilityCheckExpr, or at least provide a comment on skipping "@available", to be consistent with other parsing functions?

2865 ↗

(On Diff #63310)

Is this a format change for "default:"? If yes, can you commit it before this @available change?

[erik.pilkington]

This patch addresses most of Manman's comments.

lib/AST/StmtPrinter.cpp

502 ↗

(On Diff #63310)

Because by the time that we have the ObjCAvailabilityCheckExpr, we no longer keep track of the AvailabilitySpecs that are no longer relevant (ie, watchos if the platform we are targeting is macos), therefore we cannot replicate the text that lead to this particular @available. Is it worth it to carry these specs around? I can't think of any other time they are useful. (FWIW, many other AST nodes are also not fully supported, for example ObjCAtCatchStmt just above this.)

lib/Parse/ParseDecl.cpp

723 ↗

(On Diff #63310)

Yes, Range = Tok.getLocation() sets both the Begin & End locations in Range to the same location, which makes us place the cursor at the wrong place in some diagnostics. I've fixed this a bit in the new patch.

[erik.pilkington]

Ping!

[manmanren]

LGTM.

Manman

cfe/trunk/include/clang-c/Index.h

enum CXCursorKind {
   /** \brief Represents the "self" expression in an Objective-C method.
    */
   CXCursor_ObjCSelfExpr                  = 146,
 
   /** \brief OpenMP 4.0 [2.4, Array Section].
    */
   CXCursor_OMPArraySectionExpr           = 147,
 
-  CXCursor_LastExpr                      = CXCursor_OMPArraySectionExpr,
+  /** \brief Represents an @available(...) check.
+   */
+  CXCursor_ObjCAvailabilityCheckExpr     = 148,
+
+  CXCursor_LastExpr                      = CXCursor_ObjCAvailabilityCheckExpr,
 
   /* Statements */
   CXCursor_FirstStmt                     = 200,
   /**
    * \brief A statement whose specific kind is not exposed via this
    * interface.
    *
    * Unexposed statements have the same operations as any other kind of

cfe/trunk/include/clang/AST/Availability.h

+//===--- Availability.h - Classes for availability --------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This files defines some classes that implement availability checking.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_AST_AVAILABILITY_H
+#define LLVM_CLANG_AST_AVAILABILITY_H
+
+#include "clang/Basic/SourceLocation.h"
+#include "clang/Basic/VersionTuple.h"
+#include "llvm/ADT/StringRef.h"
+
+namespace clang {
+
+/// \brief One specifier in an @available expression.
+///
+/// \code
+///   @available(macos 10.10, *)
+/// \endcode
+///
+/// Here, 'macos 10.10' and '*' both map to an instance of this type.
+///
+class AvailabilitySpec {
+  /// Represents the version that this specifier requires. If the host OS
+  /// version is greater than or equal to Version, the @available will evaluate
+  /// to true.
+  VersionTuple Version;
+
+  /// Name of the platform that Version corresponds to.
+  StringRef Platform;
+
+  SourceLocation BeginLoc, EndLoc;
+
+public:
+  AvailabilitySpec(VersionTuple Version, StringRef Platform,
+                   SourceLocation BeginLoc, SourceLocation EndLoc)
+      : Version(Version), Platform(Platform), BeginLoc(BeginLoc),
+        EndLoc(EndLoc) {}
+
+  /// This constructor is used when representing the '*' case.
+  AvailabilitySpec(SourceLocation StarLoc)
+      : BeginLoc(StarLoc), EndLoc(StarLoc) {}
+
+  VersionTuple getVersion() const { return Version; }
+  StringRef getPlatform() const { return Platform; }
+  SourceLocation getBeginLoc() const { return BeginLoc; }
+  SourceLocation getEndLoc() const { return EndLoc; }
+
+  /// Returns true when this represents the '*' case.
+  bool isOtherPlatformSpec() const { return Version.empty(); }
+};
+
+} // end namespace clang
+
+#endif

cfe/trunk/include/clang/AST/ExprObjC.h

public:
   SourceLocation getLocEnd() const LLVM_READONLY {
     return getSubExpr()->getLocEnd();
   }
   
   static bool classof(const Stmt *T) {
     return T->getStmtClass() == ObjCBridgedCastExprClass;
   }
 };
-  
+/// \brief A runtime availability query.
+///
+/// There are 2 ways to spell this node:
+/// \code
+///   @available(macos 10.10, ios 8, *); // Objective-C
+///   __builtin_available(macos 10.10, ios 8, *); // C, C++, and Objective-C
+/// \endcode
+///
+/// Note that we only need to keep track of one \c VersionTuple here, which is
+/// the one that corresponds to the current deployment target. This is meant to
+/// be used in the condition of an \c if, but it is also usable as top level
+/// expressions.
+///
+class ObjCAvailabilityCheckExpr : public Expr {
+  VersionTuple VersionToCheck;
+  SourceLocation AtLoc, RParen;
+
+  friend class ASTStmtReader;
+public:
+  ObjCAvailabilityCheckExpr(VersionTuple VersionToCheck, SourceLocation AtLoc,
+                            SourceLocation RParen, QualType Ty)
+      : Expr(ObjCAvailabilityCheckExprClass, Ty, VK_RValue, OK_Ordinary, false,
+             false, false, false),
+        VersionToCheck(VersionToCheck), AtLoc(AtLoc), RParen(RParen) {}
+
+  explicit ObjCAvailabilityCheckExpr(EmptyShell Shell)
+      : Expr(ObjCAvailabilityCheckExprClass, Shell) {}
+
+  SourceLocation getLocStart() const { return AtLoc; }
+  SourceLocation getLocEnd() const { return RParen; }
+  SourceRange getSourceRange() const { return {AtLoc, RParen}; }
+
+  /// \brief This may be '*', in which case this should fold to true.
+  bool hasVersion() const { return !VersionToCheck.empty(); }
+  VersionTuple getVersion() { return VersionToCheck; }
+
+  child_range children() {
+    return child_range(child_iterator(), child_iterator());
+  }
+
+  static bool classof(const Stmt *T) {
+    return T->getStmtClass() == ObjCAvailabilityCheckExprClass;
+  }
+};
+
 }  // end namespace clang
 
 #endif

cfe/trunk/include/clang/AST/RecursiveASTVisitor.h

 DEF_TRAVERSE_STMT(ObjCPropertyRefExpr, {})
 DEF_TRAVERSE_STMT(ObjCSubscriptRefExpr, {})
 DEF_TRAVERSE_STMT(ObjCProtocolExpr, {})
 DEF_TRAVERSE_STMT(ObjCSelectorExpr, {})
 DEF_TRAVERSE_STMT(ObjCIndirectCopyRestoreExpr, {})
 DEF_TRAVERSE_STMT(ObjCBridgedCastExpr, {
   TRY_TO(TraverseTypeLoc(S->getTypeInfoAsWritten()->getTypeLoc()));
 })
+DEF_TRAVERSE_STMT(ObjCAvailabilityCheckExpr, {})
 DEF_TRAVERSE_STMT(ParenExpr, {})
 DEF_TRAVERSE_STMT(ParenListExpr, {})
 DEF_TRAVERSE_STMT(PredefinedExpr, {})
 DEF_TRAVERSE_STMT(ShuffleVectorExpr, {})
 DEF_TRAVERSE_STMT(ConvertVectorExpr, {})
 DEF_TRAVERSE_STMT(StmtExpr, {})
 DEF_TRAVERSE_STMT(UnresolvedLookupExpr, {
   TRY_TO(TraverseNestedNameSpecifierLoc(S->getQualifierLoc()));

cfe/trunk/include/clang/Basic/DiagnosticGroups.td

 
 def CXX11CompatDeprecatedWritableStr :
   DiagGroup<"c++11-compat-deprecated-writable-strings">;
 
 def DeprecatedAttributes : DiagGroup<"deprecated-attributes">;
 def DeprecatedDeclarations : DiagGroup<"deprecated-declarations">;
 def UnavailableDeclarations : DiagGroup<"unavailable-declarations">;
 def PartialAvailability : DiagGroup<"partial-availability">;
+def UnguardedAvailability : DiagGroup<"unguarded-availability">;
 def DeprecatedImplementations :DiagGroup<"deprecated-implementations">;
 def DeprecatedIncrementBool : DiagGroup<"deprecated-increment-bool">;
 def DeprecatedRegister : DiagGroup<"deprecated-register">;
 def DeprecatedWritableStr : DiagGroup<"deprecated-writable-strings",
                                       [CXX11CompatDeprecatedWritableStr]>;
 // FIXME: Why is DeprecatedImplementations not in this group?
 def Deprecated : DiagGroup<"deprecated", [DeprecatedAttributes,
                                           DeprecatedDeclarations,

cfe/trunk/include/clang/Basic/DiagnosticParseKinds.td

def err_availability_unknown_change : Error<
   "'obsoleted'">;
 def err_availability_redundant : Error<
   "redundant %0 availability change; only the last specified change will "
   "be used">;
 def warn_availability_and_unavailable : Warning<
   "'unavailable' availability overrides all other availability information">,
   InGroup<Availability>;
 
+// @available(...)
+def err_avail_query_expected_condition : Error<
+  "expected an availability condition here">;
+def err_avail_query_expected_platform_name : Error<
+  "expected a platform name here">;
+
+def err_avail_query_unrecognized_platform_name : Error<
+  "unrecognized platform name %0">;
+def err_availability_query_wildcard_required: Error<
+  "must handle potential future platforms with '*'">;
+def err_availability_query_repeated_platform: Error<
+  "version for '%0' already specified">;
+def err_availability_query_repeated_star : Error<
+  "'*' query has already been specified">;
+
 // Type safety attributes
 def err_type_safety_unknown_flag : Error<
   "invalid comparison flag %0; use 'layout_compatible' or 'must_be_null'">;
 
 // Type traits
 def err_type_trait_arity : Error<
   "type trait requires %0%select{| or more}1 argument%select{|s}2; have "
   "%3 argument%s3">;

cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td

def warn_mismatched_availability_override_unavail : Warning<
   "%select{the protocol method it implements|its overridden method}1 is "
   "available">,
   InGroup<Availability>;
 def note_overridden_method : Note<
   "overridden method is here">;
 def note_protocol_method : Note<
   "protocol method is here">;
 
+def warn_available_using_star_case : Warning<
+  "using '*' case here, platform %0 is not accounted for">, InGroup<UnguardedAvailability>;
+
 // Thread Safety Attributes
 def warn_invalid_capability_name : Warning<
   "invalid capability name '%0'; capability name must be 'mutex' or 'role'">,
   InGroup<ThreadSafetyAttributes>, DefaultIgnore;
 def warn_thread_attribute_ignored : Warning<
   "ignoring %0 attribute because its argument is invalid">,
   InGroup<ThreadSafetyAttributes>, DefaultIgnore;
 def warn_thread_attribute_argument_not_lockable : Warning<

cfe/trunk/include/clang/Basic/StmtNodes.td

 def ObjCSelectorExpr : DStmt<Expr>;
 def ObjCProtocolExpr : DStmt<Expr>;
 def ObjCIvarRefExpr : DStmt<Expr>;
 def ObjCPropertyRefExpr : DStmt<Expr>;
 def ObjCIsaExpr : DStmt<Expr>;
 def ObjCIndirectCopyRestoreExpr : DStmt<Expr>;
 def ObjCBoolLiteralExpr : DStmt<Expr>;
 def ObjCSubscriptRefExpr : DStmt<Expr>;
+def ObjCAvailabilityCheckExpr : DStmt<Expr>;
 
 // Obj-C ARC Expressions.
 def ObjCBridgedCastExpr : DStmt<ExplicitCastExpr>;
 
 // CUDA Expressions.
 def CUDAKernelCallExpr : DStmt<CallExpr>;
 
 // Clang Extensions.

cfe/trunk/include/clang/Basic/TokenKinds.def

 // Borland Extensions which should be disabled in strict conformance mode.
 ALIAS("_pascal"      , __pascal   , KEYBORLAND)
 
 // Clang Extensions.
 KEYWORD(__builtin_convertvector   , KEYALL)
 ALIAS("__char16_t"   , char16_t   , KEYCXX)
 ALIAS("__char32_t"   , char32_t   , KEYCXX)
 
+KEYWORD(__builtin_available       , KEYALL)
+
 // Clang-specific keywords enabled only in testing.
 TESTING_KEYWORD(__unknown_anytype , KEYALL)
 
 
 //===----------------------------------------------------------------------===//
 // Objective-C @-preceded keywords.
 //===----------------------------------------------------------------------===//
 

 
 OBJC2_AT_KEYWORD(property)
 OBJC2_AT_KEYWORD(package)
 OBJC2_AT_KEYWORD(required)
 OBJC2_AT_KEYWORD(optional)
 OBJC2_AT_KEYWORD(synthesize)
 OBJC2_AT_KEYWORD(dynamic)
 OBJC2_AT_KEYWORD(import)
+OBJC2_AT_KEYWORD(available)
 
 // TODO: What to do about context-sensitive keywords like:
 //       bycopy/byref/in/inout/oneway/out?
 
 ANNOTATION(cxxscope)     // annotation for a C++ scope spec, e.g. "::foo::bar::"
 ANNOTATION(typename)     // annotation for a C typedef name, a C++ (possibly
                          // qualified) typename, e.g. "foo::MyClass", or
                          // template-id that names a type ("std::vector<int>")

cfe/trunk/include/clang/Parse/Parser.h

 //===--- Parser.h - C Language Parser ---------------------------*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 //  This file defines the Parser interface.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CLANG_PARSE_PARSER_H
 #define LLVM_CLANG_PARSE_PARSER_H
 
+#include "clang/AST/Availability.h"
 #include "clang/Basic/OpenMPKinds.h"
 #include "clang/Basic/OperatorPrecedence.h"
 #include "clang/Basic/Specifiers.h"
 #include "clang/Lex/CodeCompletionHandler.h"
 #include "clang/Lex/Preprocessor.h"
 #include "clang/Sema/DeclSpec.h"
 #include "clang/Sema/LoopHint.h"
 #include "clang/Sema/Sema.h"
private:
   void ParseAvailabilityAttribute(IdentifierInfo &Availability,
                                   SourceLocation AvailabilityLoc,
                                   ParsedAttributes &attrs,
                                   SourceLocation *endLoc,
                                   IdentifierInfo *ScopeName,
                                   SourceLocation ScopeLoc,
                                   AttributeList::Syntax Syntax);
 
+  Optional<AvailabilitySpec> ParseAvailabilitySpec();
+  ExprResult ParseAvailabilityCheckExpr(SourceLocation StartLoc);
+
   void ParseObjCBridgeRelatedAttribute(IdentifierInfo &ObjCBridgeRelated,
                                        SourceLocation ObjCBridgeRelatedLoc,
                                        ParsedAttributes &attrs,
                                        SourceLocation *endLoc,
                                        IdentifierInfo *ScopeName,
                                        SourceLocation ScopeLoc,
                                        AttributeList::Syntax Syntax);
 

cfe/trunk/include/clang/Sema/Sema.h

 // builds ASTs.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CLANG_SEMA_SEMA_H
 #define LLVM_CLANG_SEMA_SEMA_H
 
 #include "clang/AST/Attr.h"
+#include "clang/AST/Availability.h"
 #include "clang/AST/DeclarationName.h"
 #include "clang/AST/Expr.h"
 #include "clang/AST/ExprObjC.h"
 #include "clang/AST/ExternalASTSource.h"
 #include "clang/AST/LocInfoType.h"
 #include "clang/AST/MangleNumberingContext.h"
 #include "clang/AST/NSAPI.h"
 #include "clang/AST/PrettyPrinter.h"
public:
 
   /// ActOnCXXBoolLiteral - Parse {true,false} literals.
   ExprResult ActOnCXXBoolLiteral(SourceLocation OpLoc, tok::TokenKind Kind);
 
 
   /// ActOnObjCBoolLiteral - Parse {__objc_yes,__objc_no} literals.
   ExprResult ActOnObjCBoolLiteral(SourceLocation OpLoc, tok::TokenKind Kind);
 
+  ExprResult
+  ActOnObjCAvailabilityCheckExpr(llvm::ArrayRef<AvailabilitySpec> AvailSpecs,
+                                 SourceLocation AtLoc, SourceLocation RParen);
+
   /// ActOnCXXNullPtrLiteral - Parse 'nullptr'.
   ExprResult ActOnCXXNullPtrLiteral(SourceLocation Loc);
 
   //// ActOnCXXThrow -  Parse throw expressions.
   ExprResult ActOnCXXThrow(Scope *S, SourceLocation OpLoc, Expr *expr);
   ExprResult BuildCXXThrow(SourceLocation OpLoc, Expr *Ex,
                            bool IsThrownVarInScope);
   bool CheckCXXThrowOperand(SourceLocation ThrowLoc, QualType ThrowTy, Expr *E);

cfe/trunk/include/clang/Serialization/ASTBitCodes.h

enum StmtCode {
       /// \brief An ObjCAtTryStmt record.
       STMT_OBJC_AT_TRY,
       /// \brief An ObjCAtSynchronizedStmt record.
       STMT_OBJC_AT_SYNCHRONIZED,
       /// \brief An ObjCAtThrowStmt record.
       STMT_OBJC_AT_THROW,
       /// \brief An ObjCAutoreleasePoolStmt record.
       STMT_OBJC_AUTORELEASE_POOL,
-      /// \brief A ObjCBoolLiteralExpr record.
+      /// \brief An ObjCBoolLiteralExpr record.
       EXPR_OBJC_BOOL_LITERAL,
+      /// \brief An ObjCAvailabilityCheckExpr record.
+      EXPR_OBJC_AVAILABILITY_CHECK,
 
       // C++
       
       /// \brief A CXXCatchStmt record.
       STMT_CXX_CATCH,
       /// \brief A CXXTryStmt record.
       STMT_CXX_TRY,
       /// \brief A CXXForRangeStmt record.

cfe/trunk/lib/AST/Expr.cpp

bool Expr::HasSideEffects(const ASTContext &Ctx,
   case TypeTraitExprClass:
   case ArrayTypeTraitExprClass:
   case ExpressionTraitExprClass:
   case CXXNoexceptExprClass:
   case SizeOfPackExprClass:
   case ObjCStringLiteralClass:
   case ObjCEncodeExprClass:
   case ObjCBoolLiteralExprClass:
+  case ObjCAvailabilityCheckExprClass:
   case CXXUuidofExprClass:
   case OpaqueValueExprClass:
     // These never have a side-effect.
     return false;
 
   case CallExprClass:
   case CXXOperatorCallExprClass:
   case CXXMemberCallExprClass:

cfe/trunk/lib/AST/ExprClassification.cpp

#include "clang/AST/StmtNodes.inc"
   case Expr::ExpressionTraitExprClass:
   case Expr::ObjCSelectorExprClass:
   case Expr::ObjCProtocolExprClass:
   case Expr::ObjCStringLiteralClass:
   case Expr::ObjCBoxedExprClass:
   case Expr::ObjCArrayLiteralClass:
   case Expr::ObjCDictionaryLiteralClass:
   case Expr::ObjCBoolLiteralExprClass:
+  case Expr::ObjCAvailabilityCheckExprClass:
   case Expr::ParenListExprClass:
   case Expr::SizeOfPackExprClass:
   case Expr::SubstNonTypeTemplateParmPackExprClass:
   case Expr::AsTypeExprClass:
   case Expr::ObjCIndirectCopyRestoreExprClass:
   case Expr::AtomicExprClass:
   case Expr::CXXFoldExprClass:
   case Expr::NoInitExprClass:

cfe/trunk/lib/AST/ExprConstant.cpp

#include "clang/AST/StmtNodes.inc"
   case Expr::ObjCEncodeExprClass:
   case Expr::ObjCMessageExprClass:
   case Expr::ObjCSelectorExprClass:
   case Expr::ObjCProtocolExprClass:
   case Expr::ObjCIvarRefExprClass:
   case Expr::ObjCPropertyRefExprClass:
   case Expr::ObjCSubscriptRefExprClass:
   case Expr::ObjCIsaExprClass:
+  case Expr::ObjCAvailabilityCheckExprClass:
   case Expr::ShuffleVectorExprClass:
   case Expr::ConvertVectorExprClass:
   case Expr::BlockExprClass:
   case Expr::NoStmtClass:
   case Expr::OpaqueValueExprClass:
   case Expr::PackExpansionExprClass:
   case Expr::SubstNonTypeTemplateParmPackExprClass:
   case Expr::FunctionParmPackExprClass:

cfe/trunk/lib/AST/ItaniumMangle.cpp

#include "clang/AST/StmtNodes.inc"
   case Expr::ObjCProtocolExprClass:
   case Expr::ObjCSelectorExprClass:
   case Expr::ObjCStringLiteralClass:
   case Expr::ObjCBoxedExprClass:
   case Expr::ObjCArrayLiteralClass:
   case Expr::ObjCDictionaryLiteralClass:
   case Expr::ObjCSubscriptRefExprClass:
   case Expr::ObjCIndirectCopyRestoreExprClass:
+  case Expr::ObjCAvailabilityCheckExprClass:
   case Expr::OffsetOfExprClass:
   case Expr::PredefinedExprClass:
   case Expr::ShuffleVectorExprClass:
   case Expr::ConvertVectorExprClass:
   case Expr::StmtExprClass:
   case Expr::TypeTraitExprClass:
   case Expr::ArrayTypeTraitExprClass:
   case Expr::ExpressionTraitExprClass:

cfe/trunk/lib/AST/StmtPrinter.cpp

void StmtPrinter::VisitObjCAtThrowStmt(ObjCAtThrowStmt *Node) {
   Indent() << "@throw";
   if (Node->getThrowExpr()) {
     OS << " ";
     PrintExpr(Node->getThrowExpr());
   }
   OS << ";\n";
 }
 
+void StmtPrinter::VisitObjCAvailabilityCheckExpr(
+    ObjCAvailabilityCheckExpr *Node) {
+  OS << "@available(...)";
+}
+
 void StmtPrinter::VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt *Node) {
   Indent() << "@synchronized (";
   PrintExpr(Node->getSynchExpr());
   OS << ")";
   PrintRawCompoundStmt(Node->getSynchBody());
   OS << "\n";
 }
 

cfe/trunk/lib/AST/StmtProfile.cpp

void StmtProfiler::VisitObjCIndirectCopyRestoreExpr(
   ID.AddBoolean(S->shouldCopy());
 }
 
 void StmtProfiler::VisitObjCBridgedCastExpr(const ObjCBridgedCastExpr *S) {
   VisitExplicitCastExpr(S);
   ID.AddBoolean(S->getBridgeKind());
 }
 
+void StmtProfiler::VisitObjCAvailabilityCheckExpr(
+    const ObjCAvailabilityCheckExpr *S) {
+  VisitExpr(S);
+}
+
 void StmtProfiler::VisitDecl(const Decl *D) {
   ID.AddInteger(D? D->getKind() : 0);
 
   if (Canonical && D) {
     if (const NonTypeTemplateParmDecl *NTTP =
           dyn_cast<NonTypeTemplateParmDecl>(D)) {
       ID.AddInteger(NTTP->getDepth());
       ID.AddInteger(NTTP->getIndex());

cfe/trunk/lib/Parse/ParseDecl.cpp

 
 /// \brief Parse a version number.
 ///
 /// version:
 ///   simple-integer
 ///   simple-integer ',' simple-integer
 ///   simple-integer ',' simple-integer ',' simple-integer
 VersionTuple Parser::ParseVersionTuple(SourceRange &Range) {
-  Range = Tok.getLocation();
+  Range = SourceRange(Tok.getLocation(), Tok.getEndLoc());
 
   if (!Tok.is(tok::numeric_constant)) {
     Diag(Tok, diag::err_expected_version);
     SkipUntil(tok::comma, tok::r_paren,
               StopAtSemi | StopBeforeMatch | StopAtCodeCompletion);
     return VersionTuple();
   }
 

cfe/trunk/lib/Parse/ParseExpr.cpp

#undef RTT_JOIN
   case tok::utf8_string_literal:
   case tok::utf16_string_literal:
   case tok::utf32_string_literal:
     Res = ParseStringLiteralExpression(true);
     break;
   case tok::kw__Generic:   // primary-expression: generic-selection [C11 6.5.1]
     Res = ParseGenericSelectionExpression();
     break;
+  case tok::kw___builtin_available:
+    return ParseAvailabilityCheckExpr(Tok.getLocation());
   case tok::kw___builtin_va_arg:
   case tok::kw___builtin_offsetof:
   case tok::kw___builtin_choose_expr:
   case tok::kw___builtin_astype: // primary-expression: [OCL] as_type()
   case tok::kw___builtin_convertvector:
     return ParseBuiltinPrimaryExpression();
   case tok::kw___null:
     return Actions.ActOnGNUNullExpr(ConsumeToken());

 /// ParseObjCBoolLiteral - This handles the objective-c Boolean literals.
 ///
 ///         '__objc_yes'
 ///         '__objc_no'
 ExprResult Parser::ParseObjCBoolLiteral() {
   tok::TokenKind Kind = Tok.getKind();
   return Actions.ActOnObjCBoolLiteral(ConsumeToken(), Kind);
 }
+
+/// Validate availability spec list, emitting diagnostics if necessary. Returns
+/// true if invalid.
+static bool CheckAvailabilitySpecList(Parser &P,
+                                      ArrayRef<AvailabilitySpec> AvailSpecs) {
+  llvm::SmallSet<StringRef, 4> Platforms;
+  bool HasOtherPlatformSpec = false;
+  bool Valid = true;
+  for (const auto &Spec : AvailSpecs) {
+    if (Spec.isOtherPlatformSpec()) {
+      if (HasOtherPlatformSpec) {
+        P.Diag(Spec.getBeginLoc(), diag::err_availability_query_repeated_star);
+        Valid = false;
+      }
+
+      HasOtherPlatformSpec = true;
+      continue;
+    }
+
+    bool Inserted = Platforms.insert(Spec.getPlatform()).second;
+    if (!Inserted) {
+      // Rule out multiple version specs referring to the same platform.
+      // For example, we emit an error for:
+      // @available(macos 10.10, macos 10.11, *)
+      StringRef Platform = Spec.getPlatform();
+      P.Diag(Spec.getBeginLoc(), diag::err_availability_query_repeated_platform)
+          << Spec.getEndLoc() << Platform;
+      Valid = false;
+    }
+  }
+
+  if (!HasOtherPlatformSpec) {
+    SourceLocation InsertWildcardLoc = AvailSpecs.back().getEndLoc();
+    P.Diag(InsertWildcardLoc, diag::err_availability_query_wildcard_required)
+        << FixItHint::CreateInsertion(InsertWildcardLoc, ", *");
+    return true;
+  }
+
+  return !Valid;
+}
+
+/// Parse availability query specification.
+///
+///  availability-spec:
+///     '*'
+///     identifier version-tuple
+Optional<AvailabilitySpec> Parser::ParseAvailabilitySpec() {
+  if (Tok.is(tok::star)) {
+    return AvailabilitySpec(ConsumeToken());
+  } else {
+    // Parse the platform name.
+    if (Tok.isNot(tok::identifier)) {
+      Diag(Tok, diag::err_avail_query_expected_platform_name);
+      return None;
+    }
+
+    IdentifierLoc *PlatformIdentifier = ParseIdentifierLoc();
+    SourceRange VersionRange;
+    VersionTuple Version = ParseVersionTuple(VersionRange);
+
+    if (Version.empty())
+      return None;
+
+    StringRef Platform = PlatformIdentifier->Ident->getName();
+
+    if (AvailabilityAttr::getPrettyPlatformName(Platform).empty()) {
+      Diag(PlatformIdentifier->Loc,
+           diag::err_avail_query_unrecognized_platform_name)
+          << Platform;
+      return None;
+    }
+
+    return AvailabilitySpec(Version, Platform, PlatformIdentifier->Loc,
+                            VersionRange.getEnd());
+  }
+}
+
+ExprResult Parser::ParseAvailabilityCheckExpr(SourceLocation BeginLoc) {
+  assert(Tok.is(tok::kw___builtin_available) ||
+         Tok.isObjCAtKeyword(tok::objc_available));
+
+  // Eat the available or __builtin_available.
+  ConsumeToken();
+
+  BalancedDelimiterTracker Parens(*this, tok::l_paren);
+  if (Parens.expectAndConsume())
+    return ExprError();
+
+  SmallVector<AvailabilitySpec, 4> AvailSpecs;
+  bool HasError = false;
+  while (true) {
+    Optional<AvailabilitySpec> Spec = ParseAvailabilitySpec();
+    if (!Spec)
+      HasError = true;
+    else
+      AvailSpecs.push_back(*Spec);
+
+    if (!TryConsumeToken(tok::comma))
+      break;
+  }
+
+  if (HasError) {
+    SkipUntil(tok::r_paren, StopAtSemi);
+    return ExprError();
+  }
+
+  CheckAvailabilitySpecList(*this, AvailSpecs);
+
+  if (Parens.consumeClose())
+    return ExprError();
+
+  return Actions.ActOnObjCAvailabilityCheckExpr(AvailSpecs, BeginLoc,
+                                                Parens.getCloseLocation());
+}

cfe/trunk/lib/Parse/ParseObjc.cpp

default:
 
     switch (Tok.getIdentifierInfo()->getObjCKeywordID()) {
     case tok::objc_encode:
       return ParsePostfixExpressionSuffix(ParseObjCEncodeExpression(AtLoc));
     case tok::objc_protocol:
       return ParsePostfixExpressionSuffix(ParseObjCProtocolExpression(AtLoc));
     case tok::objc_selector:
       return ParsePostfixExpressionSuffix(ParseObjCSelectorExpression(AtLoc));
+    case tok::objc_available:
+      return ParseAvailabilityCheckExpr(AtLoc);
       default: {
         const char *str = nullptr;
         if (GetLookAheadToken(1).is(tok::l_brace)) {
           char ch = Tok.getIdentifierInfo()->getNameStart()[0];
           str =  
             ch == 't' ? "try" 
                       : (ch == 'f' ? "finally" 
                                    : (ch == 'a' ? "autoreleasepool" : nullptr));

cfe/trunk/lib/Sema/SemaExceptionSpec.cpp

CanThrowResult Sema::canThrow(const Expr *E) {
   case Expr::BinaryConditionalOperatorClass:
   case Expr::BlockExprClass:
   case Expr::CUDAKernelCallExprClass:
   case Expr::DeclRefExprClass:
   case Expr::ObjCBridgedCastExprClass:
   case Expr::ObjCIndirectCopyRestoreExprClass:
   case Expr::ObjCProtocolExprClass:
   case Expr::ObjCSelectorExprClass:
+  case Expr::ObjCAvailabilityCheckExprClass:
   case Expr::OffsetOfExprClass:
   case Expr::PackExpansionExprClass:
   case Expr::PseudoObjectExprClass:
   case Expr::SubstNonTypeTemplateParmExprClass:
   case Expr::SubstNonTypeTemplateParmPackExprClass:
   case Expr::FunctionParmPackExprClass:
   case Expr::UnaryExprOrTypeTraitExprClass:
   case Expr::UnresolvedLookupExprClass:

cfe/trunk/lib/Sema/SemaExpr.cpp

if (LookupName(Result, getCurScope()) && Result.isSingleResult()) {
         Context.setBOOLDecl(TD);
     }
   }
   if (Context.getBOOLDecl())
     BoolT = Context.getBOOLType();
   return new (Context)
       ObjCBoolLiteralExpr(Kind == tok::kw___objc_yes, BoolT, OpLoc);
 }
+
+ExprResult Sema::ActOnObjCAvailabilityCheckExpr(
+    llvm::ArrayRef<AvailabilitySpec> AvailSpecs, SourceLocation AtLoc,
+    SourceLocation RParen) {
+
+  StringRef Platform = getASTContext().getTargetInfo().getPlatformName();
+
+  auto Spec = std::find_if(AvailSpecs.begin(), AvailSpecs.end(),
+                           [&](const AvailabilitySpec &Spec) {
+                             return Spec.getPlatform() == Platform;
+                           });
+
+  VersionTuple Version;
+  if (Spec != AvailSpecs.end())
+    Version = Spec->getVersion();
+  else
+    // This is the '*' case in @available. We should diagnose this; the
+    // programmer should explicitly account for this case if they target this
+    // platform.
+    Diag(AtLoc, diag::warn_available_using_star_case) << RParen << Platform;
+
+  return new (Context)
+      ObjCAvailabilityCheckExpr(Version, AtLoc, RParen, Context.BoolTy);
+}

cfe/trunk/lib/Sema/TreeTransform.h

if (!getDerived().AlwaysRebuild() &&
       Result.get() == E->getSubExpr())
     return E;
 
   return SemaRef.BuildObjCBridgedCast(E->getLParenLoc(), E->getBridgeKind(),
                                       E->getBridgeKeywordLoc(), TSInfo,
                                       Result.get());
 }
 
-template<typename Derived>
+template <typename Derived>
+ExprResult TreeTransform<Derived>::TransformObjCAvailabilityCheckExpr(
+    ObjCAvailabilityCheckExpr *E) {
+  return E;
+}
+
+template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformObjCMessageExpr(ObjCMessageExpr *E) {
   // Transform arguments.
   bool ArgChanged = false;
   SmallVector<Expr*, 8> Args;
   Args.reserve(E->getNumArgs());
   if (getDerived().TransformExprs(E->getArgs(), E->getNumArgs(), false, Args,
                                   &ArgChanged))

cfe/trunk/lib/Serialization/ASTReaderStmt.cpp

 }
 
 void ASTStmtReader::VisitObjCBoolLiteralExpr(ObjCBoolLiteralExpr *E) {
   VisitExpr(E);
   E->setValue(Record[Idx++]);
   E->setLocation(ReadSourceLocation(Record, Idx));
 }
 
+void ASTStmtReader::VisitObjCAvailabilityCheckExpr(ObjCAvailabilityCheckExpr *E) {
+  VisitExpr(E);
+  SourceRange R = Reader.ReadSourceRange(F, Record, Idx);
+  E->AtLoc = R.getBegin();
+  E->RParen = R.getEnd();
+  E->VersionToCheck = Reader.ReadVersionTuple(Record, Idx);
+}
+
 //===----------------------------------------------------------------------===//
 // C++ Expressions and Statements
 //===----------------------------------------------------------------------===//
 
 void ASTStmtReader::VisitCXXCatchStmt(CXXCatchStmt *S) {
   VisitStmt(S);
   S->CatchLoc = ReadSourceLocation(Record, Idx);
   S->ExceptionDecl = ReadDeclAs<VarDecl>(Record, Idx);
case STMT_OBJC_AT_THROW:
       S = new (Context) ObjCAtThrowStmt(Empty);
       break;
     case STMT_OBJC_AUTORELEASE_POOL:
       S = new (Context) ObjCAutoreleasePoolStmt(Empty);
       break;
     case EXPR_OBJC_BOOL_LITERAL:
       S = new (Context) ObjCBoolLiteralExpr(Empty);
       break;
+    case EXPR_OBJC_AVAILABILITY_CHECK:
+      S = new (Context) ObjCAvailabilityCheckExpr(Empty);
+      break;
     case STMT_SEH_LEAVE:
       S = new (Context) SEHLeaveStmt(Empty);
       break;
     case STMT_SEH_EXCEPT:
       S = new (Context) SEHExceptStmt(Empty);
       break;
     case STMT_SEH_FINALLY:
       S = new (Context) SEHFinallyStmt(Empty);

cfe/trunk/lib/Serialization/ASTWriterStmt.cpp

 
 void ASTStmtWriter::VisitObjCBoolLiteralExpr(ObjCBoolLiteralExpr *E) {
   VisitExpr(E);
   Record.push_back(E->getValue());
   Record.AddSourceLocation(E->getLocation());
   Code = serialization::EXPR_OBJC_BOOL_LITERAL;
 }
 
+void ASTStmtWriter::VisitObjCAvailabilityCheckExpr(ObjCAvailabilityCheckExpr *E) {
+  VisitExpr(E);
+  Record.AddSourceRange(E->getSourceRange());
+  Record.AddVersionTuple(E->getVersion());
+  Code = serialization::EXPR_OBJC_AVAILABILITY_CHECK;
+}
+
 //===----------------------------------------------------------------------===//
 // C++ Expressions and Statements.
 //===----------------------------------------------------------------------===//
 
 void ASTStmtWriter::VisitCXXCatchStmt(CXXCatchStmt *S) {
   VisitStmt(S);
   Record.AddSourceLocation(S->getCatchLoc());
   Record.AddDeclRef(S->getExceptionDecl());

cfe/trunk/lib/StaticAnalyzer/Core/ExprEngine.cpp

switch (S->getStmtClass()) {
     case Stmt::AddrLabelExprClass:
     case Stmt::AttributedStmtClass:
     case Stmt::IntegerLiteralClass:
     case Stmt::CharacterLiteralClass:
     case Stmt::ImplicitValueInitExprClass:
     case Stmt::CXXScalarValueInitExprClass:
     case Stmt::CXXBoolLiteralExprClass:
     case Stmt::ObjCBoolLiteralExprClass:
+    case Stmt::ObjCAvailabilityCheckExprClass:
     case Stmt::FloatingLiteralClass:
     case Stmt::NoInitExprClass:
     case Stmt::SizeOfPackExprClass:
     case Stmt::StringLiteralClass:
     case Stmt::ObjCStringLiteralClass:
     case Stmt::CXXPseudoDestructorExprClass:
     case Stmt::SubstNonTypeTemplateParmExprClass:
     case Stmt::CXXNullPtrLiteralExprClass:

cfe/trunk/test/Parser/objc-available.m

+// RUN: %clang_cc1 -fsyntax-only -Wunguarded-availability -triple x86_64-apple-macosx10.10.0 -verify %s
+
+void f() {
+
+  if (@available(macos 10.12, *)) {}
+  else if (@available(macos 10.11, *)) {}
+  else {}
+
+  (void)__builtin_available(ios 8, macos 10.10, *);
+
+  (void)@available(macos 10.11); // expected-error{{must handle potential future platforms with '*'}}
+  (void)@available(macos 10.11, macos 10.11, *); // expected-error{{version for 'macos' already specified}}
+
+  (void)@available(erik_os 10.11, *); // expected-error{{unrecognized platform name erik_os}}
+
+  (void)@available(erik_os 10.10, hat_os 1.0, *); // expected-error 2 {{unrecognized platform name}}
+
+  (void)@available(ios 8, *); // expected-warning{{using '*' case here, platform macos is not accounted for}}
+
+  (void)@available(); // expected-error{{expected a platform name here}}
+  (void)@available(macos 10.10,); // expected-error{{expected a platform name here}}
+  (void)@available(macos); // expected-error{{expected a version}}
+  (void)@available; // expected-error{{expected '('}}
+}

cfe/trunk/tools/libclang/CIndex.cpp

CXString clang_getCursorKindSpelling(enum CXCursorKind Kind) {
   case CXCursor_CXXDeleteExpr:
       return cxstring::createRef("CXXDeleteExpr");
   case CXCursor_UnaryExpr:
       return cxstring::createRef("UnaryExpr");
   case CXCursor_ObjCStringLiteral:
       return cxstring::createRef("ObjCStringLiteral");
   case CXCursor_ObjCBoolLiteralExpr:
       return cxstring::createRef("ObjCBoolLiteralExpr");
+  case CXCursor_ObjCAvailabilityCheckExpr:
+      return cxstring::createRef("ObjCAvailabilityCheckExpr");
   case CXCursor_ObjCSelfExpr:
       return cxstring::createRef("ObjCSelfExpr");
   case CXCursor_ObjCEncodeExpr:
       return cxstring::createRef("ObjCEncodeExpr");
   case CXCursor_ObjCSelectorExpr:
       return cxstring::createRef("ObjCSelectorExpr");
   case CXCursor_ObjCProtocolExpr:
       return cxstring::createRef("ObjCProtocolExpr");

cfe/trunk/tools/libclang/CXCursor.cpp

CXCursor cxcursor::MakeCXCursor(const Stmt *S, const Decl *Parent,
 
   case Stmt::ObjCProtocolExprClass:
     K = CXCursor_ObjCProtocolExpr;
     break;
       
   case Stmt::ObjCBoolLiteralExprClass:
     K = CXCursor_ObjCBoolLiteralExpr;
     break;
-      
+  case Stmt::ObjCAvailabilityCheckExprClass:
+    K = CXCursor_ObjCAvailabilityCheckExpr;
+    break;
+
   case Stmt::ObjCBridgedCastExprClass:
     K = CXCursor_ObjCBridgedCastExpr;
     break;
 
   case Stmt::BlockExprClass:
     K = CXCursor_BlockExpr;
     break;