Try to avoid the deserialized swiftmodule contains un-supported platform visionOS

This is the quick fix for non-visionOS build (like iOS) when seeing the @available decl

Author: dreampiggy

lib/Serialization/Deserialization.cpp

@@ -2762,6 +2762,17 @@ ModuleDecl *ModuleFile::getModule(ImportPath::Module name,
   return getContext().getLoadedModule(name);
 }
 
+static void filterUnsupportedPlatformKinds(SmallVectorImpl<AvailableAttr *> &availabilityAttrs) {
+  auto it = availabilityAttrs.begin();
+  while(it != availabilityAttrs.end()) {
+    unsigned platform = (unsigned)(*it)->Platform;
+    if (platform >= /*PlatformKind::visionOS*/13) {
+      it = availabilityAttrs.erase(it);
+    } else {
+      ++it;
+    }
+  }
+}
 
 /// Translate from the Serialization associativity enum values to the AST
 /// strongly-typed enum.
@@ -5280,6 +5291,11 @@ DeclDeserializer::readAvailable_DECL_ATTR(SmallVectorImpl<uint64_t> &scratch,
       isPackageDescriptionVersionSpecific, isSPI, LIST_VER_TUPLE_PIECES(Introduced),
       LIST_VER_TUPLE_PIECES(Deprecated), LIST_VER_TUPLE_PIECES(Obsoleted),
       platform, renameDeclID, messageSize, renameSize);
+  
+  // Hack: Filter the un-supported platforms from swiftmodule
+  if (platform >= /*PlatformKind::visionOS*/13) {
+    return nullptr;
+  }
 
   ValueDecl *renameDecl = nullptr;
   if (renameDeclID) {
@@ -5513,6 +5529,7 @@ llvm::Error DeclDeserializer::deserializeDeclCommon() {
 
       case decls_block::Available_DECL_ATTR: {
         Attr = readAvailable_DECL_ATTR(scratch, blobData);
+        if (!Attr) skipAttr = true;
         break;
       }
 
@@ -5629,6 +5646,15 @@ llvm::Error DeclDeserializer::deserializeDeclCommon() {
           restoreOffset2.cancel();
           --numAvailabilityAttrs;
         }
+        
+        // Hack: When deserialized from some un-supported @available attr decl, we should remove it
+        // @available (iOS, macOS, visionOS) -> @available (iOS, macOS)
+        filterUnsupportedPlatformKinds(availabilityAttrs);
+        if (availabilityAttrs.empty()) {
+          // If attr list is empty, then remove this attr
+          skipAttr = true;
+          break;
+        }
 
         auto specializedSig = MF.getGenericSignature(specializedSigID);
         Attr = SpecializeAttr::create(ctx, exported != 0, specializationKind,