[typechecker] check for nominal types as well when comparing enum elements

Author: Suyash Srijan

include/swift/AST/Decl.h

@@ -216,6 +216,9 @@ struct OverloadSignature {
   /// Whether this is a enum element.
   unsigned IsEnumElement : 1;
 
+  /// Whether this is a nominal type.
+  unsigned IsNominal : 1;
+
   /// Whether this signature is part of a protocol extension.
   unsigned InProtocolExtension : 1;
 

lib/AST/Decl.cpp

@@ -2098,6 +2098,12 @@ bool swift::conflicting(ASTContext &ctx,
     return false;
   }
 
+  // Nominal types and enum elements always conflict with each other.
+  if ((sig1.IsNominal && sig2.IsEnumElement) ||
+      (sig1.IsEnumElement && sig2.IsNominal)) {
+    return true;
+  }
+
   // Enum elements always conflict with each other. At this point, they
   // have the same base name but different types.
   if (sig1.IsEnumElement && sig2.IsEnumElement) {
@@ -2263,6 +2269,7 @@ OverloadSignature ValueDecl::getOverloadSignature() const {
   signature.IsVariable = isa<VarDecl>(this);
   signature.IsFunction = isa<AbstractFunctionDecl>(this);
   signature.IsEnumElement = isa<EnumElementDecl>(this);
+  signature.IsNominal = isa<NominalTypeDecl>(this);
 
   // Unary operators also include prefix/postfix.
   if (auto func = dyn_cast<FuncDecl>(this)) {