Introduce CGFloat as a distinct struct type.

CGFloat is 32-bit on 32-bit architectures and 64-bit on 64-bit
architectures for historical reasons. Rather than having it alias
either Float (32-bit) or Double (64-bit), introduce a distinct struct
type for CGFloat. CGFloat provides a complete set of comparisons and
arithmetic operators (including tgmath functions), initializers allows
explicit conversion between it an Int, UInt, Float, and Double, as
well as conforming to all of the protocols that Float/Double do.

This formulation of CGFloat makes use of CGFloat
architecture-independent, although it still requires a number of casts.
Fixes <rdar://problem/17224725>

Swift SVN r19689

lib/ClangImporter/ImportDecl.cpp

@@ -279,6 +279,11 @@ getSwiftStdlibType(const clang::TypedefNameDecl *D,
                               ClangCtx.getObjCClassRedefinitionType()))
       return std::make_pair(Type(), "");
     break;
+
+  case MappedCTypeKind::CGFloat:
+    if (!ClangType->isFloatingType())
+      return std::make_pair(Type(), "");
+    break;
   }
 
   Module *M;

lib/ClangImporter/ImportType.cpp

@@ -1113,12 +1113,15 @@ Type ClangImporter::Implementation::getNamedSwiftType(Module *module,
     return Type();
 
   // Look for the type.
-  UnqualifiedLookup lookup(SwiftContext.getIdentifier(name), module,
-                           getTypeResolver());
-  if (auto type = lookup.getSingleTypeResult()) {
-    if (typeResolver)
-      typeResolver->resolveDeclSignature(type);
-    return type->getDeclaredType();
+  SmallVector<ValueDecl *, 2> results;
+  module->lookupValue({ }, SwiftContext.getIdentifier(name),
+                      NLKind::UnqualifiedLookup, results);
+  if (results.size() == 1) {
+    if (auto type = dyn_cast<TypeDecl>(results.front())) {
+      if (typeResolver)
+        typeResolver->resolveDeclSignature(type);
+      return type->getDeclaredType();
+    }
   }
 
   return Type();

lib/ClangImporter/ImporterImpl.h

@@ -158,6 +158,7 @@ enum class MappedCTypeKind {
   ObjCSel,
   ObjCId,
   ObjCClass,
+  CGFloat,
 };
 
 /// \brief Describes what to do with the C name of a type that can be mapped to

lib/ClangImporter/MappedTypes.def

@@ -103,6 +103,9 @@ MAP_STDLIB_TYPE("NSInteger", SignedWord, 0, "Int",  ObjC1, false, DefineOnly)
 // confusing.
 MAP_STDLIB_TYPE("NSUInteger", UnsignedWord, 0, "Int", ObjC1, false, DoNothing)
 
+// CoreGraphics types.
+MAP_TYPE("CGFloat", CGFloat, 0, "CoreGraphics", "CGFloat", All, false, 
+         DoNothing)
 
 // CoreFoundation types.
 // Note that we're preserving the typealias for CFIndex.

lib/IRGen/GenClangType.cpp

@@ -157,6 +157,18 @@ class GenClangType : public CanTypeVisitor<GenClangType, clang::CanQualType> {
 }
 
 clang::CanQualType GenClangType::visitStructType(CanStructType type) {
+  auto swiftDecl = type->getDecl();
+  auto &swiftCtx = type->getASTContext();
+  if (swiftDecl->getName().str() == "CGFloat") {
+    // Dig out the underlying type.
+    auto underlyingTypeDecl
+      = cast<TypeDecl>(
+          swiftDecl->lookupDirect(swiftCtx.getIdentifier("NativeType"))[0]);
+    return Converter.convert(IGM,
+                             underlyingTypeDecl->getDeclaredType()
+                               ->getCanonicalType());
+  }
+
   // Everything else should have been handled as an imported type
   // or an importer-primitive type.
   llvm_unreachable("Unhandled struct type in Clang type generation");

lib/Sema/TypeCheckType.cpp

@@ -2446,6 +2446,15 @@ void TypeChecker::fillObjCRepresentableTypeCache(const DeclContext *DC) {
     lookupLibraryTypes(*this, ObjCModule, StdlibTypeNames, ObjCMappedTypes);
   }
 
+  Identifier ID_CoreGraphics = Context.getIdentifier("CoreGraphics");
+  if (auto CoreGraphicsModule = Context.getLoadedModule(ID_CoreGraphics)) {
+    StdlibTypeNames.clear();
+    StdlibTypeNames.push_back(Context.getIdentifier("CGFloat"));
+    lookupLibraryTypes(*this, CoreGraphicsModule, StdlibTypeNames,
+                       ObjCMappedTypes);
+  }
+
+
   Identifier ID_Foundation = Context.getIdentifier(FOUNDATION_MODULE_NAME);
   if (auto FoundationModule = Context.getLoadedModule(ID_Foundation)) {
     StdlibTypeNames.clear();