LLVM/Clang does not process visionOS (xros) availability correctly

[stuartcarnie]

The following snippet of Objective-C code, which declares the typedef as available on watchOS, and unavailable on iOS, macOS and tvOS platforms:

#import <Foundation/Foundation.h>

API_UNAVAILABLE(visionos) @interface Foo
@end

typedef void(^Bar)(Foo *foo) API_AVAILABLE(watchos(5.0)) API_UNAVAILABLE(ios,macos,tvos);

Given iOS is unavailable, it also includes derivatives, which means visionOS.

Compiling this snippet with Apple's clang compiler works as expected:

echo "#import <Foundation/Foundation.h>\nAPI_UNAVAILABLE(visionos) @interface Foo\n@end\n typedef void(^Bar)(Foo *foo) API_AVAILABLE(watchos(5.0)) API_UNAVAILABLE(ios,macos,tvos);" | xcrun -sdk xros clang -mtargetos=xros2.5 -O2 -x objective-c -c -o test.o -

However, compiling with clang from here fails:

echo -e "#import <Foundation/Foundation.h>\nAPI_UNAVAILABLE(visionos) @interface Foo\n@end\ntypedef void(^Bar)(Foo *foo) API_AVAILABLE(watchos(5.0)) API_UNAVAILABLE(ios,macos,tvos);" | arm-apple-darwin11-clang -isysroot /root/SDKs/XROS2.5.sdk/ -mtargetos=xros2.5 -O2 -x objective-c -c -o test.o -

Output:

<stdin>:4:20: error: 'Foo' is unavailable: not available on visionOS
    4 | typedef void(^Bar)(Foo *foo) API_AVAILABLE(watchos(5.0)) API_UNAVAILABLE(ios,macos,tvos);
      |                    ^                                                                                                                                          <stdin>:2:38: note: 'Foo' has been explicitly marked unavailable here                                                                                                     2 | API_UNAVAILABLE(visionos) @interface Foo
      |                                      ^
1 error generated.

If I explicitly add visionos to the typedef declaration, it passes.

Unfortunately, this problem occurs when compiling Apple's SDKs, such as CoreMotion with llvm / clang, that has declarations such as:

/*!
 * @typedef CMDyskineticSymptomResultHandler
 * @brief Completion handler for CMDyskineticSymptomResult values.
 */
typedef void(^CMDyskineticSymptomResultHandler)(NSArray<CMDyskineticSymptomResult *> * _Nonnull dyskineticSymptomResult, NSError * _Nullable error) API_AVAILABLE(watchos(5.0)) API_UNAVAILABLE(ios, macos, tvos);

[llvmbot]

@llvm/issue-subscribers-clang-driver

Author: Stuart Carnie (stuartcarnie)

The following snippet of Objective-C code, which declares the `typedef` as available on watchOS, and unavailable on iOS, macOS and tvOS platforms:

#import <Foundation/Foundation.h>

API_UNAVAILABLE(visionos) @<!-- -->interface Foo
@<!-- -->end

typedef void(^Bar)(Foo *foo) API_AVAILABLE(watchos(5.0)) API_UNAVAILABLE(ios,macos,tvos);

Given iOS is unavailable, it also includes derivatives, which means visionOS.

Compiling this snippet with Apple's clang compiler works as expected:

echo "#import &lt;Foundation/Foundation.h&gt;\nAPI_UNAVAILABLE(visionos) @<!-- -->interface Foo\n@<!-- -->end\n typedef void(^Bar)(Foo *foo) API_AVAILABLE(watchos(5.0)) API_UNAVAILABLE(ios,macos,tvos);" | xcrun -sdk xros clang -mtargetos=xros2.5 -O2 -x objective-c -c -o test.o -

However, compiling with clang from here fails:

echo -e "#import &lt;Foundation/Foundation.h&gt;\nAPI_UNAVAILABLE(visionos) @<!-- -->interface Foo\n@<!-- -->end\ntypedef void(^Bar)(Foo *foo) API_AVAILABLE(watchos(5.0)) API_UNAVAILABLE(ios,macos,tvos);" | arm-apple-darwin11-clang -isysroot /root/SDKs/XROS2.5.sdk/ -mtargetos=xros2.5 -O2 -x objective-c -c -o test.o -

Output:

<stdin>:4:20: error: 'Foo' is unavailable: not available on visionOS
    4 | typedef void(^Bar)(Foo *foo) API_AVAILABLE(watchos(5.0)) API_UNAVAILABLE(ios,macos,tvos);
      |                    ^                                                                                                                                          &lt;stdin&gt;:2:38: note: 'Foo' has been explicitly marked unavailable here                                                                                                     2 | API_UNAVAILABLE(visionos) @<!-- -->interface Foo
      |                                      ^
1 error generated.

If I explicitly add visionos to the typedef declaration, it passes.

Unfortunately, this problem occurs when compiling Apple's SDKs, such as CoreMotion with llvm / clang, that has declarations such as:

/*!
 * @<!-- -->typedef CMDyskineticSymptomResultHandler
 * @<!-- -->brief Completion handler for CMDyskineticSymptomResult values.
 */
typedef void(^CMDyskineticSymptomResultHandler)(NSArray&lt;CMDyskineticSymptomResult *&gt; * _Nonnull dyskineticSymptomResult, NSError * _Nullable error) API_AVAILABLE(watchos(5.0)) API_UNAVAILABLE(ios, macos, tvos);

[shafik]

CC @Bigcheese @rjmccall

[stuartcarnie]

diff --git a/clang/include/clang/Basic/DarwinSDKInfo.h b/clang/include/clang/Basic/DarwinSDKInfo.h
index db20b968a..33b36f53c 100644
--- a/clang/include/clang/Basic/DarwinSDKInfo.h
+++ b/clang/include/clang/Basic/DarwinSDKInfo.h
@@ -72,6 +72,13 @@ public:
                        llvm::Triple::TvOS, llvm::Triple::UnknownEnvironment);
     }
 
+    /// Returns the os-environment mapping pair that's used to represent the
+    /// iOS -> visionOS version mapping.
+    static inline constexpr OSEnvPair iOStoXROSPair() {
+      return OSEnvPair(llvm::Triple::IOS, llvm::Triple::UnknownEnvironment,
+                       llvm::Triple::XROS, llvm::Triple::UnknownEnvironment);
+    }
+
   private:
     StorageType Value;
 
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index e2eada24f..26290b3ba 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -2415,6 +2415,48 @@ static void handleAvailabilityAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
       auto NewDeprecated = AdjustTvOSVersion(Deprecated.Version);
       auto NewObsoleted = AdjustTvOSVersion(Obsoleted.Version);
 
+      AvailabilityAttr *NewAttr = S.mergeAvailabilityAttr(
+          ND, AL, NewII, true /*Implicit*/, NewIntroduced, NewDeprecated,
+          NewObsoleted, IsUnavailable, Str, IsStrict, Replacement,
+          Sema::AMK_None, PriorityModifier + Sema::AP_InferredFromOtherPlatform,
+          IIEnvironment);
+      if (NewAttr)
+        D->addAttr(NewAttr);
+    }
+  } else if (S.Context.getTargetInfo().getTriple().isXROS()) {
+    // Transcribe "ios" to "visionos" (and add a new attribute) if the versioning
+    // matches before the start of the visionOS platform.
+    IdentifierInfo *NewII = nullptr;
+    if (II->getName() == "ios")
+      NewII = &S.Context.Idents.get("xros");
+    else if (II->getName() == "ios_app_extension")
+      NewII = &S.Context.Idents.get("xros_app_extension");
+
+    if (NewII) {
+      const auto *SDKInfo = S.getDarwinSDKInfoForAvailabilityChecking();
+      const auto *IOSToXROSMapping =
+          SDKInfo ? SDKInfo->getVersionMapping(
+                        DarwinSDKInfo::OSEnvPair::iOStoXROSPair())
+                  : nullptr;
+
+      auto AdjustTvOSVersion =
+          [IOSToXROSMapping](VersionTuple Version) -> VersionTuple {
+        if (Version.empty())
+          return Version;
+
+        if (IOSToXROSMapping) {
+          if (auto MappedVersion = IOSToXROSMapping->map(
+                  Version, VersionTuple(1, 0), std::nullopt)) {
+            return *MappedVersion;
+          }
+        }
+        return Version;
+      };
+
+      auto NewIntroduced = AdjustTvOSVersion(Introduced.Version);
+      auto NewDeprecated = AdjustTvOSVersion(Deprecated.Version);
+      auto NewObsoleted = AdjustTvOSVersion(Obsoleted.Version);
+
       AvailabilityAttr *NewAttr = S.mergeAvailabilityAttr(
           ND, AL, NewII, true /*Implicit*/, NewIntroduced, NewDeprecated,
           NewObsoleted, IsUnavailable, Str, IsStrict, Replacement,

I created this patch which fixes the issue for me. I replicated the tvOS implementation, which ensures that visionOS is treated as a derivative of ios.

[stuartcarnie]

An alternative without imports:

echo -e "__attribute__((availability(visionos, unavailable))) @interface Foo\n@end\ntypedef void(^Bar)(Foo *foo) __attribute__((availability(watchos, introduced=5.0))) __attribute__((availability(ios, unavailable)));" | clang -isysroot /root/SDKs/XROS2.5.sdk/ -mtargetos=xros2.5 -fsyntax-only -x objective-c -

[stuartcarnie]

Note

With my patch, I was able to successfully cross-compile a static library for visionOS.