[NFC] Upgrade EnumElementDecl to a DeclContext

Pure plumbing for the sake of default arguments.

Author: CodaFi

include/swift/AST/Decl.h

@@ -5885,7 +5885,7 @@ class EnumCaseDecl final : public Decl,
 /// enum. EnumElementDecls are represented in the AST as members of their
 /// parent EnumDecl, although syntactically they are subordinate to the
 /// EnumCaseDecl.
-class EnumElementDecl : public ValueDecl {
+class EnumElementDecl : public DeclContext, public ValueDecl {
   /// This is the type specified with the enum element, for
   /// example 'Int' in 'case Y(Int)'.  This is null if there is no type
   /// associated with this element, as in 'case Z' or in all elements of enum
@@ -5905,7 +5905,8 @@ class EnumElementDecl : public ValueDecl {
                   SourceLoc EqualsLoc,
                   LiteralExpr *RawValueExpr,
                   DeclContext *DC)
-  : ValueDecl(DeclKind::EnumElement, DC, Name, IdentifierLoc),
+  : DeclContext(DeclContextKind::EnumElementDecl, DC),
+    ValueDecl(DeclKind::EnumElement, DC, Name, IdentifierLoc),
     Params(Params),
     EqualsLoc(EqualsLoc),
     RawValueExpr(RawValueExpr)
@@ -5973,14 +5974,23 @@ class EnumElementDecl : public ValueDecl {
     return getParameterList() != nullptr;
   }
 
+  /// True if the case is marked 'indirect'.
+  bool isIndirect() const {
+    return getAttrs().hasAttribute<IndirectAttr>();
+  }
+
   static bool classof(const Decl *D) {
     return D->getKind() == DeclKind::EnumElement;
   }
 
-  /// True if the case is marked 'indirect'.
-  bool isIndirect() const {
-    return getAttrs().hasAttribute<IndirectAttr>();
+  static bool classof(const DeclContext *DC) {
+    if (auto D = DC->getAsDecl())
+      return classof(D);
+    return false;
   }
+
+  using DeclContext::operator new;
+  using Decl::getASTContext;
 };
 
 inline SourceRange EnumCaseDecl::getSourceRange() const {

include/swift/AST/DeclContext.h

@@ -78,6 +78,7 @@ enum class DeclContextKind : unsigned {
   Initializer,
   TopLevelCodeDecl,
   SubscriptDecl,
+  EnumElementDecl,
   AbstractFunctionDecl,
   SerializedLocal,
   Last_LocalDeclContextKind = SerializedLocal,
@@ -230,6 +231,7 @@ class alignas(1 << DeclContextAlignInBits) DeclContext {
     case DeclContextKind::TopLevelCodeDecl:
     case DeclContextKind::AbstractFunctionDecl:
     case DeclContextKind::SubscriptDecl:
+    case DeclContextKind::EnumElementDecl:
     case DeclContextKind::GenericTypeDecl:
     case DeclContextKind::ExtensionDecl:
       return ASTHierarchy::Decl;

include/swift/AST/DeclNodes.def

@@ -171,7 +171,7 @@ ABSTRACT_DECL(Value, Decl)
     ABSTRACT_FUNCTION_DECL(Func, AbstractFunctionDecl)
       ABSTRACT_FUNCTION_DECL(Accessor, FuncDecl)
     DECL_RANGE(AbstractFunction, Constructor, Accessor)
-  VALUE_DECL(EnumElement, ValueDecl)
+  CONTEXT_VALUE_DECL(EnumElement, ValueDecl)
   DECL_RANGE(Value, Enum, EnumElement)
 
 ITERABLE_GENERIC_DECL(Extension, Decl)

lib/AST/ASTDumper.cpp

@@ -1331,6 +1331,10 @@ void swift::printContext(raw_ostream &os, DeclContext *dc) {
   case DeclContextKind::SubscriptDecl:
     printName(os, cast<SubscriptDecl>(dc)->getFullName());
     break;
+
+  case DeclContextKind::EnumElementDecl:
+    printName(os, cast<EnumElementDecl>(dc)->getFullName());
+    break;
   }
 }
 

lib/AST/ASTMangler.cpp

@@ -1508,6 +1508,11 @@ void ASTMangler::appendContext(const DeclContext *ctx) {
     return appendEntity(fn);
   }
 
+  case DeclContextKind::EnumElementDecl: {
+    auto eed = cast<EnumElementDecl>(ctx);
+    return appendEntity(eed);
+  }
+
   case DeclContextKind::SubscriptDecl:
     // FIXME: We may need to do something here if subscripts contain any symbols
     // exposed with linkage names, or if/when they get generic parameters.

lib/AST/ASTVerifier.cpp

@@ -750,6 +750,7 @@ class Verifier : public ASTWalker {
     FUNCTION_LIKE(ConstructorDecl)
     FUNCTION_LIKE(DestructorDecl)
     FUNCTION_LIKE(FuncDecl)
+    FUNCTION_LIKE(EnumElementDecl)
     SCOPE_LIKE(NominalTypeDecl)
     SCOPE_LIKE(ExtensionDecl)
 

lib/AST/AccessRequests.cpp

@@ -105,6 +105,7 @@ AccessLevelRequest::evaluate(Evaluator &evaluator, ValueDecl *D) const {
   case DeclContextKind::Initializer:
   case DeclContextKind::AbstractFunctionDecl:
   case DeclContextKind::SubscriptDecl:
+  case DeclContextKind::EnumElementDecl:
     return AccessLevel::Private;
   case DeclContextKind::Module:
   case DeclContextKind::FileUnit:

lib/AST/DeclContext.cpp

@@ -405,6 +405,9 @@ DeclContext::isCascadingContextForLookup(bool functionsAreNonCascading) const {
   case DeclContextKind::SubscriptDecl:
     break;
 
+  case DeclContextKind::EnumElementDecl:
+    break;
+
   case DeclContextKind::Module:
   case DeclContextKind::FileUnit:
     return true;
@@ -461,6 +464,8 @@ bool DeclContext::walkContext(ASTWalker &Walker) {
     return cast<AbstractFunctionDecl>(this)->walk(Walker);
   case DeclContextKind::SubscriptDecl:
     return cast<SubscriptDecl>(this)->walk(Walker);
+  case DeclContextKind::EnumElementDecl:
+    return cast<EnumElementDecl>(this)->walk(Walker);
   case DeclContextKind::SerializedLocal:
     llvm_unreachable("walk is unimplemented for deserialized contexts");
   case DeclContextKind::Initializer:
@@ -547,6 +552,7 @@ unsigned DeclContext::printContext(raw_ostream &OS, unsigned indent) const {
     Kind = "AbstractFunctionDecl";
     break;
   case DeclContextKind::SubscriptDecl:    Kind = "SubscriptDecl"; break;
+  case DeclContextKind::EnumElementDecl:  Kind = "EnumElementDecl"; break;
   }
   OS.indent(Depth*2 + indent) << (void*)this << " " << Kind;
 
@@ -601,6 +607,15 @@ unsigned DeclContext::printContext(raw_ostream &OS, unsigned indent) const {
       OS << " : (no type set)";
     break;
   }
+  case DeclContextKind::EnumElementDecl: {
+    auto *EED = cast<EnumElementDecl>(this);
+    OS << " name=" << EED->getBaseName();
+    if (EED->hasInterfaceType())
+      OS << " : " << EED->getInterfaceType();
+    else
+      OS << " : (no type set)";
+    break;
+  }
   case DeclContextKind::Initializer:
     switch (cast<Initializer>(this)->getInitializerKind()) {
     case InitializerKind::PatternBinding: {
@@ -920,6 +935,8 @@ DeclContextKind DeclContext::getContextKind() const {
       return DeclContextKind::TopLevelCodeDecl;
     case DeclKind::Subscript:
       return DeclContextKind::SubscriptDecl;
+    case DeclKind::EnumElement:
+      return DeclContextKind::EnumElementDecl;
     case DeclKind::Extension:
       return DeclContextKind::ExtensionDecl;
     default:

lib/AST/DiagnosticEngine.cpp

@@ -767,6 +767,7 @@ void DiagnosticEngine::emitDiagnostic(const Diagnostic &diagnostic) {
             case DeclContextKind::AbstractClosureExpr:
             case DeclContextKind::AbstractFunctionDecl:
             case DeclContextKind::SubscriptDecl:
+            case DeclContextKind::EnumElementDecl:
               break;
             }
 

lib/IDE/CodeCompletion.cpp

@@ -1437,6 +1437,7 @@ static bool isTopLevelContext(const DeclContext *DC) {
       return true;
     case DeclContextKind::AbstractFunctionDecl:
     case DeclContextKind::SubscriptDecl:
+    case DeclContextKind::EnumElementDecl:
       return false;
     default:
       continue;