[clang] Add support for anyAppleOS availability (PR #181953)

[Akira Hatanaka via cfe-commits]

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@@ -2697,6 +2698,74 @@ static void handleAvailabilityAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
     }
   }
 
+  // Handle anyAppleOS specially: create implicit platform-specific attributes
+  // instead of the original anyAppleOS attribute.
+  if (II->getName() == "anyappleos") {
+    // Validate and correct anyAppleOS versions.
+    auto ValidateAndCorrectVersion =
+        [&](const llvm::VersionTuple &Version,
+            SourceLocation Loc) -> llvm::VersionTuple {
+      if (Version.empty())
+        return Version;
+      auto [IsValid, CorrectedVersion] =
+          AvailabilitySpec::validateAnyAppleOSVersion(Version);
+      if (!IsValid) {
+        S.Diag(Loc, diag::warn_availability_invalid_os_version)
+            << Version.getAsString() << "anyAppleOS";
+        S.Diag(Loc, diag::note_availability_invalid_os_version_adjusted)
+            << CorrectedVersion.getAsString();
+      }
+      return CorrectedVersion;
+    };
+
+    // Correct the versions.
+    auto CorrectedIntroduced =
+        ValidateAndCorrectVersion(Introduced.Version, Introduced.KeywordLoc);
+    auto CorrectedDeprecated =
+        ValidateAndCorrectVersion(Deprecated.Version, Deprecated.KeywordLoc);
+    auto CorrectedObsoleted =
+        ValidateAndCorrectVersion(Obsoleted.Version, Obsoleted.KeywordLoc);
+
+    auto GetPlatformName = [](const llvm::Triple &T) -> StringRef {
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ahatanak wrote:

I used lambda CreateImplicitAvailabilityAttr because it was called from multiple places in our internal branch, but it's not needed for open source. I removed both lambdas.

https://github.com/llvm/llvm-project/pull/181953