Normalize macOS version

Project.toml

@@ -1,6 +1,6 @@
 name = "ObjectiveC"
 uuid = "e86c9b32-1129-44ac-8ea0-90d5bb39ded9"
-version = "3.4.1"
+version = "3.4.2"
 
 [deps]
 CEnum = "fa961155-64e5-5f13-b03f-caf6b980ea82"

src/version.jl

@@ -23,7 +23,7 @@ end
     const darwin_version = OncePerProcess{VersionNumber}() do
         _syscall_version("kern.osrelease")
     end
-    const macos_version = OncePerProcess{VersionNumber}() do
+    const _macos_version = OncePerProcess{VersionNumber}() do
         _syscall_version("kern.osproductversion")
     end
 else
@@ -35,15 +35,24 @@ else
         _darwin_version[]
     end
 
-    const _macos_version = Ref{VersionNumber}()
-    function macos_version()
-        if !isassigned(_macos_version)
-            _macos_version[] = _syscall_version("kern.osproductversion")
+    const __macos_version = Ref{VersionNumber}()
+    function _macos_version()
+        if !isassigned(__macos_version)
+            __macos_version[] = _syscall_version("kern.osproductversion")
         end
-        _macos_version[]
+        __macos_version[]
     end
 end
 
+function macos_version(normalize=true)
+    ver = _macos_version()
+    if normalize && ver.major == 16
+        # on older SDKs, macOS Tahoe (26) is reported as v16.
+        # normalize this to v26 regardless of the SDK to simplify use.
+        return VersionNumber(26, ver.minor, ver.patch)
+    end    
+    return ver
+end
 @doc """
     ObjectiveC.darwin_version()::VersionNumber