[API Notes] Add Swift versioning to API notes files

Extend the API notes format with support for specifying API notes at a
particular Swift version. A single API notes file has "unversioned"
information, followed optionally by more information about the various
classes/functions/etc. at a specific Swift version. The intent is to
allow API notes to provide backward-compatibility information

Parse Swift-versioned API notes, store version API notes in the binary
format, and ensure that it round-trips. For now, Clang still only adds
attributes based on the unversioned information. This is the first
step of rdar://problem/28455809.

Author: DougGregor

include/clang/APINotes/APINotesReader.h

@@ -17,6 +17,7 @@
 #define LLVM_CLANG_API_NOTES_READER_H
 
 #include "clang/APINotes/Types.h"
+#include "clang/Basic/VersionTuple.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include <memory>
@@ -65,21 +66,33 @@ class APINotesReader {
   /// Retrieve the module options
   ModuleOptions getModuleOptions() const;
 
+  /// Look for the context ID of the given Objective-C class.
+  ///
+  /// \param name The name of the class we're looking for.
+  ///
+  /// \returns The ID, if known.
+  Optional<ContextID> lookupObjCClassID(StringRef name);
+
   /// Look for information regarding the given Objective-C class.
   ///
   /// \param name The name of the class we're looking for.
   ///
-  /// \returns The ID and information about the class, if known.
-  Optional<std::pair<ContextID, ObjCContextInfo>>
-  lookupObjCClass(StringRef name);
+  /// \returns The information about the class, if known.
+  Optional<ObjCContextInfo> lookupObjCClassInfo(StringRef name);
+
+  /// Look for the context ID of the given Objective-C protocol.
+  ///
+  /// \param name The name of the protocol we're looking for.
+  ///
+  /// \returns The ID of the protocol, if known.
+  Optional<ContextID> lookupObjCProtocolID(StringRef name);
 
   /// Look for information regarding the given Objective-C protocol.
   ///
   /// \param name The name of the protocol we're looking for.
   ///
-  /// \returns The ID and information about the protocol, if known.
-  Optional<std::pair<ContextID, ObjCContextInfo>>
-  lookupObjCProtocol(StringRef name);
+  /// \returns The information about the protocol, if known.
+  Optional<ObjCContextInfo> lookupObjCProtocolInfo(StringRef name);
 
   /// Look for information regarding the given Objective-C property in
   /// the given context.
@@ -88,6 +101,7 @@ class APINotesReader {
   /// \param name The name of the property we're looking for.
   /// \param isInstance Whether we are looking for an instance property (vs.
   /// a class property).
+  /// \param swiftVersion The Swift version to filter for, if any.
   ///
   /// \returns Information about the property, if known.
   Optional<ObjCPropertyInfo> lookupObjCProperty(ContextID contextID,
@@ -149,39 +163,48 @@ class APINotesReader {
 
     /// Visit an Objective-C class.
     virtual void visitObjCClass(ContextID contextID, StringRef name,
-                                const ObjCContextInfo &info);
+                                const ObjCContextInfo &info,
+                                VersionTuple swiftVersion);
 
     /// Visit an Objective-C protocol.
     virtual void visitObjCProtocol(ContextID contextID, StringRef name,
-                                   const ObjCContextInfo &info);
+                                   const ObjCContextInfo &info,
+                                   VersionTuple swiftVersion);
 
     /// Visit an Objective-C method.
     virtual void visitObjCMethod(ContextID contextID, StringRef selector,
                                  bool isInstanceMethod,
-                                 const ObjCMethodInfo &info);
+                                 const ObjCMethodInfo &info,
+                                 VersionTuple swiftVersion);
 
     /// Visit an Objective-C property.
     virtual void visitObjCProperty(ContextID contextID, StringRef name,
                                    bool isInstance,
-                                   const ObjCPropertyInfo &info);
+                                   const ObjCPropertyInfo &info,
+                                   VersionTuple swiftVersion);
 
     /// Visit a global variable.
     virtual void visitGlobalVariable(StringRef name,
-                                     const GlobalVariableInfo &info);
+                                     const GlobalVariableInfo &info,
+                                     VersionTuple swiftVersion);
 
     /// Visit a global function.
     virtual void visitGlobalFunction(StringRef name,
-                                     const GlobalFunctionInfo &info);
+                                     const GlobalFunctionInfo &info,
+                                     VersionTuple swiftVersion);
 
     /// Visit an enumerator.
     virtual void visitEnumConstant(StringRef name,
-                                   const EnumConstantInfo &info);
+                                   const EnumConstantInfo &info,
+                                   VersionTuple swiftVersion);
 
     /// Visit a tag.
-    virtual void visitTag(StringRef name, const TagInfo &info);
+    virtual void visitTag(StringRef name, const TagInfo &info,
+                          VersionTuple swiftVersion);
 
     /// Visit a typedef.
-    virtual void visitTypedef(StringRef name, const TypedefInfo &info);
+    virtual void visitTypedef(StringRef name, const TypedefInfo &info,
+                              VersionTuple swiftVersion);
   };
 
   /// Visit the contents of the API notes file, passing each entity to the

include/clang/APINotes/APINotesWriter.h

@@ -16,6 +16,7 @@
 #ifndef LLVM_CLANG_API_NOTES_WRITER_H
 #define LLVM_CLANG_API_NOTES_WRITER_H
 
+#include "clang/Basic/VersionTuple.h"
 #include "clang/APINotes/Types.h"
 
 namespace llvm {
@@ -46,23 +47,17 @@ class APINotesWriter {
   /// Write the API notes data to the given stream.
   void writeToStream(llvm::raw_ostream &os);
 
-  /// Add information about a specific Objective-C class.
+  /// Add information about a specific Objective-C class or protocol.
   ///
-  /// \param name The name of this class.
-  /// \param info Information about this class.
+  /// \param name The name of this class/protocol.
+  /// \param isClass Whether this is a class (vs. a protocol).
+  /// \param info Information about this class/protocol.
   ///
-  /// \returns the ID of the class, which can be used to add properties and
-  /// methods to the class.
-  ContextID addObjCClass(StringRef name, const ObjCContextInfo &info);
-
-  /// Add information about a specific Objective-C protocol.
-  ///
-  /// \param name The name of this protocol.
-  /// \param info Information about this protocol.
-  ///
-  /// \returns the ID of the protocol, which can be used to add properties and
-  /// methods to the protocol.
-  ContextID addObjCProtocol(StringRef name, const ObjCContextInfo &info);
+  /// \returns the ID of the class or protocol, which can be used to add
+  /// properties and methods to the class/protocol.
+  ContextID addObjCContext(StringRef name, bool isClass,
+                           const ObjCContextInfo &info,
+                           VersionTuple swiftVersion);
 
   /// Add information about a specific Objective-C property.
   ///
@@ -71,7 +66,8 @@ class APINotesWriter {
   /// \param info Information about this property.
   void addObjCProperty(ContextID contextID, StringRef name,
                        bool isInstanceProperty,
-                       const ObjCPropertyInfo &info);
+                       const ObjCPropertyInfo &info,
+                       VersionTuple swiftVersion);
 
   /// Add information about a specific Objective-C method.
   ///
@@ -81,37 +77,43 @@ class APINotesWriter {
   /// (vs. a class method).
   /// \param info Information about this method.
   void addObjCMethod(ContextID contextID, ObjCSelectorRef selector,
-                     bool isInstanceMethod, const ObjCMethodInfo &info);
+                     bool isInstanceMethod, const ObjCMethodInfo &info,
+                     VersionTuple swiftVersion);
 
   /// Add information about a global variable.
   ///
   /// \param name The name of this global variable.
   /// \param info Information about this global variable.
-  void addGlobalVariable(StringRef name, const GlobalVariableInfo &info);
+  void addGlobalVariable(StringRef name, const GlobalVariableInfo &info,
+                         VersionTuple swiftVersion);
 
   /// Add information about a global function.
   ///
   /// \param name The name of this global function.
   /// \param info Information about this global function.
-  void addGlobalFunction(StringRef name, const GlobalFunctionInfo &info);
+  void addGlobalFunction(StringRef name, const GlobalFunctionInfo &info,
+                         VersionTuple swiftVersion);
 
   /// Add information about an enumerator.
   ///
   /// \param name The name of this enumerator.
   /// \param info Information about this enumerator.
-  void addEnumConstant(StringRef name, const EnumConstantInfo &info);
+  void addEnumConstant(StringRef name, const EnumConstantInfo &info,
+                       VersionTuple swiftVersion);
 
   /// Add information about a tag (struct/union/enum/C++ class).
   ///
   /// \param name The name of this tag.
   /// \param info Information about this tag.
-  void addTag(StringRef name, const TagInfo &info);
+  void addTag(StringRef name, const TagInfo &info,
+              VersionTuple swiftVersion);
 
   /// Add information about a typedef.
   ///
   /// \param name The name of this typedef.
   /// \param info Information about this typedef.
-  void addTypedef(StringRef name, const TypedefInfo &info);
+  void addTypedef(StringRef name, const TypedefInfo &info,
+                  VersionTuple swiftVersion);
 
   /// Add module options
   void addModuleOptions(ModuleOptions opts);

include/clang/Basic/VersionTuple.h

@@ -17,6 +17,7 @@
 
 #include "clang/Basic/LLVM.h"
 #include "llvm/ADT/Optional.h"
+#include "llvm/ADT/DenseMapInfo.h"
 #include <string>
 #include <tuple>
 
@@ -70,6 +71,9 @@ class VersionTuple {
     return Major == 0 && Minor == 0 && Subminor == 0 && Build == 0;
   }
 
+  /// Whether this is a non-empty version tuple.
+  explicit operator bool () const { return !empty(); }
+
   /// \brief Retrieve the major version number.
   unsigned getMajor() const { return Major; }
 
@@ -165,4 +169,35 @@ class VersionTuple {
 raw_ostream& operator<<(raw_ostream &Out, const VersionTuple &V);
 
 } // end namespace clang
+
+namespace llvm {
+  // Provide DenseMapInfo for version tuples.
+  template<>
+  struct DenseMapInfo<clang::VersionTuple> {
+    static inline clang::VersionTuple getEmptyKey() {
+      return clang::VersionTuple(0x7FFFFFFF);
+    }
+    static inline clang::VersionTuple getTombstoneKey() {
+      return clang::VersionTuple(0x7FFFFFFE);
+    }
+    static unsigned getHashValue(const clang::VersionTuple& value) {
+      unsigned result = value.getMajor();
+      if (auto minor = value.getMinor())
+        result = combineHashValue(result, *minor);
+      if (auto subminor = value.getSubminor())
+        result = combineHashValue(result, *subminor);
+      if (auto build = value.getBuild())
+        result = combineHashValue(result, *build);
+
+      return result;
+    }
+
+    static bool isEqual(const clang::VersionTuple &lhs,
+                        const clang::VersionTuple &rhs) {
+      return lhs == rhs;
+    }
+  };
+
+} // end namespace llvm
+
 #endif // LLVM_CLANG_BASIC_VERSIONTUPLE_H

lib/APINotes/APINotesFormat.h

@@ -36,7 +36,7 @@ const uint16_t VERSION_MAJOR = 0;
 /// API notes file minor version number.
 ///
 /// When the format changes IN ANY WAY, this number should be incremented.
-const uint16_t VERSION_MINOR = 15;  // source file info
+const uint16_t VERSION_MINOR = 16;  // versioned API notes.
 
 using IdentifierID = PointerEmbeddedInt<unsigned, 31>;
 using IdentifierIDField = BCVBR<16>;
@@ -60,8 +60,8 @@ enum BlockID {
   /// The identifier data block, which maps identifier strings to IDs.
   IDENTIFIER_BLOCK_ID,
 
-  /// The Objective-C class data block, which maps Objective-C class
-  /// names to information about the class.
+  /// The Objective-C context data block, which contains information about
+  /// Objective-C classes and protocols.
   OBJC_CONTEXT_BLOCK_ID,
 
   /// The Objective-C property data block, which maps Objective-C
@@ -147,13 +147,20 @@ namespace identifier_block {
 
 namespace objc_context_block {
   enum {
-    OBJC_CONTEXT_DATA = 1,
+    OBJC_CONTEXT_ID_DATA = 1,
+    OBJC_CONTEXT_INFO_DATA = 2,
   };
 
-  using ObjCContextDataLayout = BCRecordLayout<
-    OBJC_CONTEXT_DATA,  // record ID
+  using ObjCContextIDLayout = BCRecordLayout<
+    OBJC_CONTEXT_ID_DATA,  // record ID
     BCVBR<16>,  // table offset within the blob (see below)
-    BCBlob  // map from ObjC class names (as IDs) to ObjC class information
+    BCBlob  // map from ObjC class names/protocol (as IDs) to context IDs
+  >;
+
+  using ObjCContextInfoLayout = BCRecordLayout<
+    OBJC_CONTEXT_INFO_DATA,  // record ID
+    BCVBR<16>,  // table offset within the blob (see below)
+    BCBlob      // map from ObjC context IDs to context information.
   >;
 }