[cDAC] Add Apple to RuntimeInfoOperatingSystem

docs/design/datacontracts/RuntimeInfo.md

@@ -21,6 +21,8 @@ public enum RuntimeInfoOperatingSystem : uint
     Unknown = 0,
     Win,
     Unix,
+    Browser,
+    Apple,
 }
 ```
 
@@ -50,6 +52,12 @@ Global variables used:
 The contract implementation returns the architecture and operating system global values parsed as the
 respective enum case-insensitively. If these globals are not available, the contract returns Unknown.
 
+`Apple` covers all Apple platforms (macOS, iOS, tvOS, MacCatalyst) — i.e. any target where the
+runtime is compiled with `TARGET_APPLE` defined. It is distinct from `Unix` so that consumers which
+need to apply Apple-specific ABI or platform rules (for example, the Apple ARM64 stack-argument
+alignment) can detect the target reliably. Apple platforms are still POSIX and will behave like
+`Unix` for the purposes of any `GetTargetOperatingSystem() != Windows` check.
+
 ### Reader versioning scheme
 
 When the .NET runtime team wants to signal that an update is recommended we update both the

src/coreclr/vm/datadescriptor/datadescriptor.inc

@@ -1311,6 +1311,11 @@ CDAC_GLOBALS_BEGIN()
 #error Handle 'Browser' define
 #endif // Browser
 CDAC_GLOBAL_STRING(OperatingSystem, Browser)
+#elif defined(TARGET_APPLE)
+#ifdef Apple
+#error Handle 'Apple' define
+#endif // Apple
+CDAC_GLOBAL_STRING(OperatingSystem, Apple)
 #elif defined(TARGET_UNIX)
 #ifdef Unix
 #error Handle 'Unix' define

src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeInfo.cs

@@ -27,6 +27,7 @@ public enum RuntimeInfoOperatingSystem : uint
     Windows,
     Unix,
     Browser,
+    Apple,
 }
 
 public interface IRuntimeInfo : IContract

src/native/managed/cdac/tests/DumpTests/RuntimeInfoDumpTests.cs

@@ -52,7 +52,8 @@ public void RuntimeInfo_OperatingSystemMatchesDumpMetadata(TestConfiguration con
         RuntimeInfoOperatingSystem expected = DumpMetadata.Os switch
         {
             "windows" => RuntimeInfoOperatingSystem.Windows,
-            "linux" or "osx" or "freebsd" => RuntimeInfoOperatingSystem.Unix,
+            "osx" => RuntimeInfoOperatingSystem.Apple,
+            "linux" or "freebsd" => RuntimeInfoOperatingSystem.Unix,
             _ => RuntimeInfoOperatingSystem.Unknown,
         };