Cherry-pick from main for x2

clang/lib/Driver/ToolChains/Darwin.cpp

@@ -1690,6 +1690,15 @@ getDeploymentTargetFromEnvironmentVariables(const Driver &TheDriver,
   return None;
 }
 
+/// Returns the SDK name without the optional prefix that ends with a '.' or an
+/// empty string otherwise.
+static StringRef dropSDKNamePrefix(StringRef SDKName) {
+  size_t PrefixPos = SDKName.find('.');
+  if (PrefixPos == StringRef::npos)
+    return "";
+  return SDKName.substr(PrefixPos + 1);
+}
+
 /// Tries to infer the deployment target from the SDK specified by -isysroot
 /// (or SDKROOT). Uses the version specified in the SDKSettings.json file if
 /// it's available.
@@ -1719,22 +1728,29 @@ inferDeploymentTargetFromSDK(DerivedArgList &Args,
   if (Version.empty())
     return None;
 
-  if (SDK.startswith("iPhoneOS") || SDK.startswith("iPhoneSimulator"))
-    return DarwinPlatform::createFromSDK(
-        Darwin::IPhoneOS, Version,
-        /*IsSimulator=*/SDK.startswith("iPhoneSimulator"));
-  else if (SDK.startswith("MacOSX"))
-    return DarwinPlatform::createFromSDK(Darwin::MacOS,
-                                         getSystemOrSDKMacOSVersion(Version));
-  else if (SDK.startswith("WatchOS") || SDK.startswith("WatchSimulator"))
-    return DarwinPlatform::createFromSDK(
-        Darwin::WatchOS, Version,
-        /*IsSimulator=*/SDK.startswith("WatchSimulator"));
-  else if (SDK.startswith("AppleTVOS") || SDK.startswith("AppleTVSimulator"))
-    return DarwinPlatform::createFromSDK(
-        Darwin::TvOS, Version,
-        /*IsSimulator=*/SDK.startswith("AppleTVSimulator"));
-  return None;
+  auto CreatePlatformFromSDKName =
+      [&](StringRef SDK) -> Optional<DarwinPlatform> {
+    if (SDK.startswith("iPhoneOS") || SDK.startswith("iPhoneSimulator"))
+      return DarwinPlatform::createFromSDK(
+          Darwin::IPhoneOS, Version,
+          /*IsSimulator=*/SDK.startswith("iPhoneSimulator"));
+    else if (SDK.startswith("MacOSX"))
+      return DarwinPlatform::createFromSDK(Darwin::MacOS,
+                                           getSystemOrSDKMacOSVersion(Version));
+    else if (SDK.startswith("WatchOS") || SDK.startswith("WatchSimulator"))
+      return DarwinPlatform::createFromSDK(
+          Darwin::WatchOS, Version,
+          /*IsSimulator=*/SDK.startswith("WatchSimulator"));
+    else if (SDK.startswith("AppleTVOS") || SDK.startswith("AppleTVSimulator"))
+      return DarwinPlatform::createFromSDK(
+          Darwin::TvOS, Version,
+          /*IsSimulator=*/SDK.startswith("AppleTVSimulator"));
+    return None;
+  };
+  if (auto Result = CreatePlatformFromSDKName(SDK))
+    return Result;
+  // The SDK can be an SDK variant with a name like `<prefix>.<platform>`.
+  return CreatePlatformFromSDKName(dropSDKNamePrefix(SDK));
 }
 
 std::string getOSVersion(llvm::Triple::OSType OS, const llvm::Triple &Triple,
@@ -2000,7 +2016,9 @@ void Darwin::AddDeploymentTarget(DerivedArgList &Args) const {
       StringRef SDKName = SDK.slice(0, StartVer);
       // Don't warn about the macabi SDK.
       // FIXME: Can we warn here?
-      if (!SDKName.startswith(getPlatformFamily()) && Environment != MacABI)
+      if (!SDKName.startswith(getPlatformFamily()) &&
+          !dropSDKNamePrefix(SDKName).startswith(getPlatformFamily())
+          && Environment != MacABI)
         getDriver().Diag(diag::warn_incompatible_sysroot)
             << SDKName << getPlatformFamily();
     }

clang/lib/Sema/SemaDeclAttr.cpp

@@ -153,7 +153,8 @@ static bool isInstanceMethod(const Decl *D) {
   return false;
 }
 
-static inline bool isNSStringType(QualType T, ASTContext &Ctx) {
+static inline bool isNSStringType(QualType T, ASTContext &Ctx,
+                                  bool AllowNSAttributedString = false) {
   const auto *PT = T->getAs<ObjCObjectPointerType>();
   if (!PT)
     return false;
@@ -164,6 +165,9 @@ static inline bool isNSStringType(QualType T, ASTContext &Ctx) {
 
   IdentifierInfo* ClsName = Cls->getIdentifier();
 
+  if (AllowNSAttributedString &&
+      ClsName == &Ctx.Idents.get("NSAttributedString"))
+    return true;
   // FIXME: Should we walk the chain of classes?
   return ClsName == &Ctx.Idents.get("NSString") ||
          ClsName == &Ctx.Idents.get("NSMutableString");
@@ -3328,7 +3332,7 @@ static void handleFormatArgAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
     return;
   }
   Ty = getFunctionOrMethodResultType(D);
-  if (!isNSStringType(Ty, S.Context) &&
+  if (!isNSStringType(Ty, S.Context, /*AllowNSAttributedString=*/true) &&
       !isCFStringType(Ty, S.Context) &&
       (!Ty->isPointerType() ||
        !Ty->castAs<PointerType>()->getPointeeType()->isCharType())) {

clang/test/Driver/darwin-sdk-with-prefix.c

@@ -0,0 +1,10 @@
+// RUN: rm -rf %t.dir
+// RUN: mkdir -p %t.dir
+
+// RUN: rm -rf %t.dir/prefix.iPhoneOS12.0.0.sdk
+// RUN: mkdir -p %t.dir/prefix.iPhoneOS12.0.0.sdk
+// RUN: %clang -c -isysroot %t.dir/prefix.iPhoneOS12.0.0.sdk -target arm64-apple-darwin %s -### 2>&1 | FileCheck %s
+// RUN: env SDKROOT=%t.dir/prefix.iPhoneOS12.0.0.sdk %clang -c -target arm64-apple-darwin %s -### 2>&1 | FileCheck %s
+//
+// CHECK-NOT: warning: using sysroot for
+// CHECK: "-triple" "arm64-apple-ios12.0.0"

clang/test/SemaObjC/format-arg-attribute.m

@@ -1,6 +1,7 @@
 // RUN: %clang_cc1 -verify -fsyntax-only %s
 
 @class NSString;
+@class NSAttributedString;
 
 extern NSString *fa2 (const NSString *) __attribute__((format_arg(1)));
 extern NSString *fa3 (NSString *) __attribute__((format_arg(1)));
@@ -25,3 +26,5 @@
 extern int fi3 (const NSString *) __attribute__((format_arg(1)));  // expected-error {{function does not return NSString}}
 extern NSString *fi4 (const NSString *) __attribute__((format_arg(1))); 
 extern NSString *fi5 (const NSString *) __attribute__((format_arg(1))); 
+
+extern NSAttributedString *fattrs (const NSString *) __attribute__((format_arg(1)));