Serialization: Remove serialization support for @_allowFeatureSuppression.

It isn't used since the attribute doesn't get serialized.

Author: tshortli

lib/Serialization/Deserialization.cpp

@@ -6034,22 +6034,6 @@ llvm::Error DeclDeserializer::deserializeDeclCommon() {
         break;
       }
 
-      case decls_block::AllowFeatureSuppression_DECL_ATTR: {
-        bool isImplicit;
-        ArrayRef<uint64_t> featureIds;
-        serialization::decls_block::AllowFeatureSuppressionDeclAttrLayout
-                     ::readRecord(scratch, isImplicit, featureIds);
-
-        SmallVector<Identifier, 4> features;
-        for (auto id : featureIds)
-          features.push_back(MF.getIdentifier(id));
-
-        Attr = AllowFeatureSuppressionAttr::create(ctx, SourceLoc(),
-                                                   SourceRange(), isImplicit,
-                                                   features);
-        break;
-      }
-
       case decls_block::UnavailableFromAsync_DECL_ATTR: {
         bool isImplicit;
         serialization::decls_block::UnavailableFromAsyncDeclAttrLayout::

lib/Serialization/ModuleFormat.h

@@ -2138,12 +2138,6 @@ namespace decls_block {
     BCArray<IdentifierIDField> // name components
   >;
 
-  using AllowFeatureSuppressionDeclAttrLayout = BCRecordLayout<
-    AllowFeatureSuppression_DECL_ATTR,
-    BCFixed<1>,   // implicit flag
-    BCArray<IdentifierIDField>  // feature names
-  >;
-
   using SPIAccessControlDeclAttrLayout = BCRecordLayout<
     SPIAccessControl_DECL_ATTR,
     BCArray<IdentifierIDField>  // SPI names
@@ -2254,6 +2248,8 @@ namespace decls_block {
   using ClangImporterSynthesizedTypeDeclAttrLayout
     = BCRecordLayout<ClangImporterSynthesizedType_DECL_ATTR>;
   using PrivateImportDeclAttrLayout = BCRecordLayout<PrivateImport_DECL_ATTR>;
+  using AllowFeatureSuppressionDeclAttrLayout =
+      BCRecordLayout<AllowFeatureSuppression_DECL_ATTR>;
   using ProjectedValuePropertyDeclAttrLayout = BCRecordLayout<
       ProjectedValueProperty_DECL_ATTR,
       BCFixed<1>,        // isImplicit

lib/Serialization/Serialization.cpp

@@ -2717,6 +2717,7 @@ class Serializer::DeclSerializer : public DeclVisitor<DeclSerializer> {
     case DeclAttrKind::RestatedObjCConformance:
     case DeclAttrKind::ClangImporterSynthesizedType:
     case DeclAttrKind::PrivateImport:
+    case DeclAttrKind::AllowFeatureSuppression:
       llvm_unreachable("cannot serialize attribute");
 
 #define SIMPLE_DECL_ATTR(_, CLASS, ...)                                        \
@@ -2769,20 +2770,6 @@ class Serializer::DeclSerializer : public DeclVisitor<DeclSerializer> {
       return;
     }
 
-    case DeclAttrKind::AllowFeatureSuppression: {
-      auto *theAttr = cast<AllowFeatureSuppressionAttr>(DA);
-      auto abbrCode =
-        S.DeclTypeAbbrCodes[AllowFeatureSuppressionDeclAttrLayout::Code];
-
-      SmallVector<IdentifierID> ids;
-      for (auto id : theAttr->getSuppressedFeatures())
-        ids.push_back(S.addUniquedStringRef(id.str()));
-
-      AllowFeatureSuppressionDeclAttrLayout::emitRecord(
-          S.Out, S.ScratchRecord, abbrCode, theAttr->isImplicit(), ids);
-      return;
-    }
-
     case DeclAttrKind::SPIAccessControl: {
       auto theAttr = cast<SPIAccessControlAttr>(DA);
       auto abbrCode = S.DeclTypeAbbrCodes[SPIAccessControlDeclAttrLayout::Code];