Add a function to detect whether an Xcode SDK supports Swift

Differential Revision: https://reviews.llvm.org/D79535

(cherry picked from commit dec1c94)

lldb/include/lldb/Utility/XcodeSDK.h

@@ -70,7 +70,10 @@ class XcodeSDK {
   llvm::VersionTuple GetVersion() const;
   Type GetType() const;
   llvm::StringRef GetString() const;
+  /// Whether this Xcode SDK supports Swift.
+  bool SupportsSwift() const;
 
+  /// Whether LLDB feels confident importing Clang modules from this SDK.
   static bool SDKSupportsModules(Type type, llvm::VersionTuple version);
   static bool SDKSupportsModules(Type desired_type, const FileSpec &sdk_path);
   /// Return the canonical SDK name, such as "macosx" for the macOS SDK.

lldb/source/Utility/XcodeSDK.cpp

@@ -181,6 +181,27 @@ bool XcodeSDK::SDKSupportsModules(XcodeSDK::Type sdk_type,
   return false;
 }
 
+bool XcodeSDK::SupportsSwift() const {
+  XcodeSDK::Info info = Parse();
+  switch (info.type) {
+  case Type::MacOSX:
+    return info.version.empty() || info.version >= llvm::VersionTuple(10, 10);
+  case Type::iPhoneOS:
+  case Type::iPhoneSimulator:
+    return info.version.empty() || info.version >= llvm::VersionTuple(8);
+  case Type::AppleTVSimulator:
+  case Type::AppleTVOS:
+    return info.version.empty() || info.version >= llvm::VersionTuple(9);
+  case Type::WatchSimulator:
+  case Type::watchOS:
+    return info.version.empty() || info.version >= llvm::VersionTuple(2);
+  case Type::Linux:
+    return true;
+  default:
+    return false;
+  }
+}
+
 bool XcodeSDK::SDKSupportsModules(XcodeSDK::Type desired_type,
                                   const FileSpec &sdk_path) {
   ConstString last_path_component = sdk_path.GetLastPathComponent();

lldb/unittests/Utility/XcodeSDKTest.cpp

@@ -84,6 +84,17 @@ TEST(XcodeSDKTest, SDKSupportsModules) {
       FileSpec(base + "MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk")));
 }
 
+TEST(XcodeSDKTest, SDKSupportsSwift) {
+  EXPECT_TRUE(XcodeSDK("iPhoneSimulator12.0.sdk").SupportsSwift());
+  EXPECT_TRUE(XcodeSDK("iPhoneSimulator12.0.Internal.sdk").SupportsSwift());
+  EXPECT_FALSE(XcodeSDK("iPhoneSimulator7.2.sdk").SupportsSwift());
+  EXPECT_TRUE(XcodeSDK("MacOSX10.10.sdk").SupportsSwift());
+  EXPECT_FALSE(XcodeSDK("MacOSX10.9.sdk").SupportsSwift());
+  EXPECT_TRUE(XcodeSDK("Linux.sdk").SupportsSwift());
+  EXPECT_TRUE(XcodeSDK("MacOSX.sdk").SupportsSwift());
+  EXPECT_FALSE(XcodeSDK("EverythingElse.sdk").SupportsSwift());
+}
+
 TEST(XcodeSDKTest, GetCanonicalName) {
   XcodeSDK::Info info;
   info.type = XcodeSDK::Type::MacOSX;