Serialization: Remove Swift3Inferred field from @objc attr.

Author: tshortli

lib/Serialization/Deserialization.cpp

@@ -5540,12 +5540,10 @@ llvm::Error DeclDeserializer::deserializeDeclCommon() {
       case decls_block::ObjC_DECL_ATTR: {
         bool isImplicit;
         bool isImplicitName;
-        bool isSwift3Inferred; // FIXME: Remove, unused
         uint64_t numArgs;
         ArrayRef<uint64_t> rawPieceIDs;
         serialization::decls_block::ObjCDeclAttrLayout::readRecord(
-          scratch, isImplicit, isSwift3Inferred, isImplicitName, numArgs,
-          rawPieceIDs);
+            scratch, isImplicit, isImplicitName, numArgs, rawPieceIDs);
 
         SmallVector<Identifier, 4> pieces;
         for (auto pieceID : rawPieceIDs)

lib/Serialization/ModuleFormat.h

@@ -58,7 +58,7 @@ const uint16_t SWIFTMODULE_VERSION_MAJOR = 0;
 /// describe what change you made. The content of this comment isn't important;
 /// it just ensures a conflict if two people change the module format.
 /// Don't worry about adhering to the 80-column limit for this line.
-const uint16_t SWIFTMODULE_VERSION_MINOR = 834; // relative paths to module-defining .swiftinterface files
+const uint16_t SWIFTMODULE_VERSION_MINOR = 835; // remove Swift3Inferred
 
 /// A standard hash seed used for all string hashes in a serialized module.
 ///
@@ -2243,7 +2243,6 @@ namespace decls_block {
   using ObjCDeclAttrLayout = BCRecordLayout<
     ObjC_DECL_ATTR,
     BCFixed<1>, // implicit flag
-    BCFixed<1>, // Swift 3 inferred
     BCFixed<1>, // implicit name flag
     BCVBR<4>,   // # of arguments (+1) or zero if no name
     BCArray<IdentifierIDField>

lib/Serialization/Serialization.cpp

@@ -2898,7 +2898,7 @@ class Serializer::DeclSerializer : public DeclVisitor<DeclSerializer> {
       }
       auto abbrCode = S.DeclTypeAbbrCodes[ObjCDeclAttrLayout::Code];
       ObjCDeclAttrLayout::emitRecord(
-          S.Out, S.ScratchRecord, abbrCode, theAttr->isImplicit(), false,
+          S.Out, S.ScratchRecord, abbrCode, theAttr->isImplicit(),
           theAttr->isNameImplicit(), numArgs, pieces);
       return;
     }