Sema: Remove duplicate enum case check

This is already handled by the common redeclaration check.

Author: slavapestov

include/swift/AST/DiagnosticsSema.def

@@ -2163,10 +2163,6 @@ ERROR(self_in_nominal,none,
       "'Self' is only available in a protocol or as the result of a "
       "method in a class; did you mean '%0'?", (StringRef))
 
-// Duplicate declarations
-ERROR(duplicate_enum_element,none,
-      "duplicate definition of enum element",())
-
 // Property behaviors
 ERROR(property_behavior_not_protocol,none,
       "property behavior name must refer to a protocol", ())

lib/Sema/TypeCheckDecl.cpp

@@ -4366,28 +4366,6 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
         checkCircularity(TC, ED, diag::circular_enum_inheritance,
                          diag::enum_here, path);
       }
-      {
-        // Check for duplicate enum members.
-        llvm::DenseMap<Identifier, EnumElementDecl *> Elements;
-        bool hasErrors = false;
-        for (auto *EED : ED->getAllElements()) {
-          auto Res = Elements.insert({ EED->getName(), EED });
-          if (!Res.second) {
-            EED->setInvalid();
-
-            auto PreviousEED = Res.first->second;
-            TC.diagnose(EED->getLoc(), diag::duplicate_enum_element);
-            TC.diagnose(PreviousEED->getLoc(),
-                        diag::previous_decldef, true, EED->getName());
-            hasErrors = true;
-          }
-        }
-
-        // If one of the cases is invalid, let's mark
-        // whole enum as invalid as well.
-        if (hasErrors)
-          ED->setInvalid();
-      }
     }
 
     if (!IsFirstPass) {
@@ -4401,7 +4379,7 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
 
       TC.checkConformancesInContext(ED, ED);
     }
-    
+
     for (Decl *member : ED->getMembers())
       visit(member);
 

test/Parse/enum.swift

@@ -324,40 +324,40 @@ enum RawTypeMismatch : Int { // expected-error {{'RawTypeMismatch' declares raw
 }
 
 enum DuplicateMembers1 {
-  case Foo // expected-note {{previous definition of 'Foo' is here}}
-  case Foo // expected-error {{duplicate definition of enum element}}
+  case Foo // expected-note {{'Foo' previously declared here}}
+  case Foo // expected-error {{invalid redeclaration of 'Foo'}}
 }
 
 enum DuplicateMembers2 {
-  case Foo, Bar // expected-note {{previous definition of 'Foo' is here}} expected-note {{previous definition of 'Bar' is here}}
-  case Foo // expected-error {{duplicate definition of enum element}}
-  case Bar // expected-error {{duplicate definition of enum element}}
+  case Foo, Bar // expected-note {{'Foo' previously declared here}} expected-note {{'Bar' previously declared here}}
+  case Foo // expected-error {{invalid redeclaration of 'Foo'}}
+  case Bar // expected-error {{invalid redeclaration of 'Bar'}}
 }
 
 enum DuplicateMembers3 {
-  case Foo // expected-note {{previous definition of 'Foo' is here}}
-  case Foo(Int) // expected-error {{duplicate definition of enum element}}
+  case Foo // expected-note {{'Foo' previously declared here}}
+  case Foo(Int) // expected-error {{invalid redeclaration of 'Foo'}}
 }
 
 enum DuplicateMembers4 : Int { // expected-error {{'DuplicateMembers4' declares raw type 'Int', but does not conform to RawRepresentable and conformance could not be synthesized}}
-  case Foo = 1 // expected-note {{previous definition of 'Foo' is here}}
-  case Foo = 2 // expected-error {{duplicate definition of enum element}}
+  case Foo = 1 // expected-note {{'Foo' previously declared here}}
+  case Foo = 2 // expected-error {{invalid redeclaration of 'Foo'}}
 }
 
 enum DuplicateMembers5 : Int { // expected-error {{'DuplicateMembers5' declares raw type 'Int', but does not conform to RawRepresentable and conformance could not be synthesized}}
-  case Foo = 1 // expected-note {{previous definition of 'Foo' is here}}
-  case Foo = 1 + 1 // expected-error {{duplicate definition of enum element}} expected-error {{raw value for enum case must be a literal}}
+  case Foo = 1 // expected-note {{'Foo' previously declared here}}
+  case Foo = 1 + 1 // expected-error {{invalid redeclaration of 'Foo'}} expected-error {{raw value for enum case must be a literal}}
 }
 
 enum DuplicateMembers6 {
-  case Foo // expected-note 2{{previous definition of 'Foo' is here}}
-  case Foo // expected-error {{duplicate definition of enum element}}
-  case Foo // expected-error {{duplicate definition of enum element}}
+  case Foo // expected-note 2{{'Foo' previously declared here}}
+  case Foo // expected-error {{invalid redeclaration of 'Foo'}}
+  case Foo // expected-error {{invalid redeclaration of 'Foo'}}
 }
 
 enum DuplicateMembers7 : String { // expected-error {{'DuplicateMembers7' declares raw type 'String', but does not conform to RawRepresentable and conformance could not be synthesized}}
-  case Foo // expected-note {{previous definition of 'Foo' is here}}
-  case Foo = "Bar" // expected-error {{duplicate definition of enum element}}
+  case Foo // expected-note {{'Foo' previously declared here}}
+  case Foo = "Bar" // expected-error {{invalid redeclaration of 'Foo'}}
 }
 
 // Refs to duplicated enum cases shouldn't crash the compiler.