Introduce special name for destructors

This name is not used yet

include/swift/AST/Identifier.h

@@ -214,7 +214,8 @@ class DeclBaseName {
 public:
   enum class Kind: uint8_t {
     Normal,
-    Subscript
+    Subscript,
+    Destructor
   };
   
 private:
@@ -223,6 +224,8 @@ private:
   /// This is an implementation detail that should never leak outside of
   /// DeclName.
   static void *SubscriptIdentifierData;
+  /// As above, for special destructor DeclNames.
+  static void *DestructorIdentifierData;
 
   Identifier Ident;
 
@@ -235,9 +238,15 @@ public:
     return DeclBaseName(Identifier((const char *)SubscriptIdentifierData));
   }
 
+  static DeclBaseName createDestructor() {
+    return DeclBaseName(Identifier((const char *)DestructorIdentifierData));
+  }
+
   Kind getKind() const {
     if (Ident.get() == SubscriptIdentifierData) {
       return Kind::Subscript;
+    } else if (Ident.get() == DestructorIdentifierData) {
+        return Kind::Destructor;
     } else {
       return Kind::Normal;
     }
@@ -273,6 +282,8 @@ public:
       return getIdentifier().str();
     case Kind::Subscript:
       return "subscript";
+    case Kind::Destructor:
+      return "deinit";
     }
   }
 

include/swift/Serialization/ModuleFormat.h

@@ -54,7 +54,7 @@ const uint16_t VERSION_MAJOR = 0;
 /// in source control, you should also update the comment to briefly
 /// 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.
-const uint16_t VERSION_MINOR = 353; // Last change: count inherited conformances
+const uint16_t VERSION_MINOR = 354; // Last change: special destructor names
 
 using DeclID = PointerEmbeddedInt<unsigned, 31>;
 using DeclIDField = BCFixed<31>;
@@ -345,7 +345,8 @@ using OptionalTypeKindField = BCFixed<2>;
 // VERSION_MAJOR.
 enum class DeclNameKind: uint8_t {
   Normal,
-  Subscript
+  Subscript,
+  Destructor
 };
 
 // These IDs must \em not be renumbered or reordered without incrementing
@@ -359,6 +360,8 @@ enum SpecialIdentifierID : uint8_t {
   OBJC_HEADER_MODULE_ID,
   /// Special value for the special subscript name
   SUBSCRIPT_ID,
+  /// Special value for the special destructor name
+  DESTRUCTOR_ID,
 
   /// The number of special Identifier IDs. This value should never be encoded;
   /// it should only be used to count the number of names above. As such, it

lib/AST/ASTMangler.cpp

@@ -548,6 +548,8 @@ void ASTMangler::appendDeclName(const ValueDecl *decl) {
     case DeclBaseName::Kind::Subscript:
       appendIdentifier("subscript");
       break;
+    case DeclBaseName::Kind::Destructor:
+      llvm_unreachable("Destructors are not mangled using appendDeclName");
     }
   } else {
     assert(AllowNamelessEntities && "attempt to mangle unnamed decl");

lib/AST/Identifier.cpp

@@ -22,6 +22,8 @@ using namespace swift;
 
 void *DeclBaseName::SubscriptIdentifierData =
     &DeclBaseName::SubscriptIdentifierData;
+void *DeclBaseName::DestructorIdentifierData =
+    &DeclBaseName::DestructorIdentifierData;
 
 raw_ostream &llvm::operator<<(raw_ostream &OS, Identifier I) {
   if (I.get() == nullptr)

lib/ClangImporter/SwiftLookupTable.cpp

@@ -211,6 +211,8 @@ DeclBaseName SerializedSwiftName::toDeclBaseName(ASTContext &Context) const {
     return Context.getIdentifier(Name);
   case DeclBaseName::Kind::Subscript:
     return DeclBaseName::createSubscript();
+  case DeclBaseName::Kind::Destructor:
+    return DeclBaseName::createDestructor();
   }
 }
 
@@ -829,6 +831,9 @@ void SwiftLookupTable::dump() const {
     case DeclBaseName::Kind::Subscript:
       llvm::errs() << "  subscript:\n";
       break;
+    case DeclBaseName::Kind::Destructor:
+      llvm::errs() << "  deinit:\n";
+      break;
     }
     const auto &entries = LookupTable.find(baseName)->second;
     for (const auto &entry : entries) {

lib/ClangImporter/SwiftLookupTable.h

@@ -82,6 +82,8 @@ struct SerializedSwiftName {
       return Name;
     case DeclBaseName::Kind::Subscript:
       return "subscript";
+    case DeclBaseName::Kind::Destructor:
+      return "deinit";
     }
   }
 

lib/SIL/SILFunctionType.cpp

@@ -1621,6 +1621,8 @@ static SelectorFamily getSelectorFamily(SILDeclRef c) {
           return getSelectorFamily(declName.getIdentifier());
         case DeclBaseName::Kind::Subscript:
           return SelectorFamily::None;
+        case DeclBaseName::Kind::Destructor:
+          return SelectorFamily::None;
         }
       }
       return SelectorFamily::None;

lib/Serialization/Deserialization.cpp

@@ -1623,6 +1623,8 @@ DeclBaseName ModuleFile::getDeclBaseName(IdentifierID IID) {
         llvm_unreachable("Cannot get DeclBaseName of special module id");
     case SUBSCRIPT_ID:
       return DeclBaseName::createSubscript();
+    case serialization::DESTRUCTOR_ID:
+      return DeclBaseName::createDestructor();
     case NUM_SPECIAL_IDS:
       llvm_unreachable("implementation detail only");
     }
@@ -1805,6 +1807,7 @@ ModuleDecl *ModuleFile::getModule(ModuleID MID) {
       return clangImporter->getImportedHeaderModule();
     }
     case SUBSCRIPT_ID:
+    case DESTRUCTOR_ID:
       llvm_unreachable("Modules cannot be named with special names");
     case NUM_SPECIAL_IDS:
       llvm_unreachable("implementation detail only");

lib/Serialization/ModuleFile.cpp

@@ -341,6 +341,8 @@ public:
     }
     case static_cast<uint8_t>(DeclNameKind::Subscript):
       return {DeclBaseName::Kind::Subscript, StringRef()};
+    case static_cast<uint8_t>(DeclNameKind::Destructor):
+      return {DeclBaseName::Kind::Destructor, StringRef()};
     default:
       llvm_unreachable("Unknown DeclNameKind");
     }

lib/Serialization/Serialization.cpp

@@ -91,6 +91,8 @@ namespace {
           return llvm::HashString(key.getIdentifier().str());
         case DeclBaseName::Kind::Subscript:
           return static_cast<uint8_t>(DeclNameKind::Subscript);
+        case DeclBaseName::Kind::Destructor:
+          return static_cast<uint8_t>(DeclNameKind::Destructor);
       }
     }
 
@@ -119,6 +121,9 @@ namespace {
       case DeclBaseName::Kind::Subscript:
         writer.write<uint8_t>(static_cast<uint8_t>(DeclNameKind::Subscript));
         break;
+      case DeclBaseName::Kind::Destructor:
+        writer.write<uint8_t>(static_cast<uint8_t>(DeclNameKind::Destructor));
+        break;
       }
     }
 
@@ -509,6 +514,8 @@ IdentifierID Serializer::addDeclBaseNameRef(DeclBaseName ident) {
   }
   case DeclBaseName::Kind::Subscript:
     return SUBSCRIPT_ID;
+  case DeclBaseName::Kind::Destructor:
+    return DESTRUCTOR_ID;
   }
 }