Update C++11 scoped enumeration support to match the final proposal:
 - reject definitions of enums within friend declarations
 - require 'enum', not 'enum class', for non-declaring references to scoped
   enumerations


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@147824 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Parse/ParseDecl.cpp b/lib/Parse/ParseDecl.cpp
index 5c4e898..be5d5ae 100644
--- a/lib/Parse/ParseDecl.cpp
+++ b/lib/Parse/ParseDecl.cpp
@@ -2865,15 +2865,14 @@
     return cutOffParsing();
   }
 
-  bool IsScopedEnum = false;
+  SourceLocation ScopedEnumKWLoc;
   bool IsScopedUsingClassTag = false;
 
   if (getLang().CPlusPlus0x &&
       (Tok.is(tok::kw_class) || Tok.is(tok::kw_struct))) {
     Diag(Tok, diag::warn_cxx98_compat_scoped_enum);
-    IsScopedEnum = true;
     IsScopedUsingClassTag = Tok.is(tok::kw_class);
-    ConsumeToken();
+    ScopedEnumKWLoc = ConsumeToken();
   }
   
   // If attributes exist after tag, parse them.
@@ -2922,11 +2921,11 @@
     NameLoc = ConsumeToken();
   }
 
-  if (!Name && IsScopedEnum) {
+  if (!Name && ScopedEnumKWLoc.isValid()) {
     // C++0x 7.2p2: The optional identifier shall not be omitted in the
     // declaration of a scoped enumeration.
     Diag(Tok, diag::err_scoped_enum_missing_identifier);
-    IsScopedEnum = false;
+    ScopedEnumKWLoc = SourceLocation();
     IsScopedUsingClassTag = false;
   }
 
@@ -2993,16 +2992,20 @@
     }
   }
 
-  // There are three options here.  If we have 'enum foo;', then this is a
-  // forward declaration.  If we have 'enum foo {...' then this is a
-  // definition. Otherwise we have something like 'enum foo xyz', a reference.
+  // There are four options here.  If we have 'friend enum foo;' then this is a
+  // friend declaration, and cannot have an accompanying definition. If we have
+  // 'enum foo;', then this is a forward declaration.  If we have
+  // 'enum foo {...' then this is a definition. Otherwise we have something
+  // like 'enum foo xyz', a reference.
   //
   // This is needed to handle stuff like this right (C99 6.7.2.3p11):
   // enum foo {..};  void bar() { enum foo; }    <- new foo in bar.
   // enum foo {..};  void bar() { enum foo x; }  <- use of old foo.
   //
   Sema::TagUseKind TUK;
-  if (Tok.is(tok::l_brace))
+  if (DS.isFriendSpecified())
+    TUK = Sema::TUK_Friend;
+  else if (Tok.is(tok::l_brace))
     TUK = Sema::TUK_Definition;
   else if (Tok.is(tok::semi))
     TUK = Sema::TUK_Declaration;
@@ -3036,7 +3039,7 @@
                                    StartLoc, SS, Name, NameLoc, attrs.getList(),
                                    AS, DS.getModulePrivateSpecLoc(),
                                    MultiTemplateParamsArg(Actions),
-                                   Owned, IsDependent, IsScopedEnum,
+                                   Owned, IsDependent, ScopedEnumKWLoc,
                                    IsScopedUsingClassTag, BaseType);
 
   if (IsDependent) {
@@ -3075,9 +3078,13 @@
     DS.SetTypeSpecError();
     return;
   }
-  
-  if (Tok.is(tok::l_brace))
+
+  if (Tok.is(tok::l_brace)) {
+    if (TUK == Sema::TUK_Friend)
+      Diag(Tok, diag::err_friend_decl_defines_type)
+        << SourceRange(DS.getFriendSpecLoc());
     ParseEnumBody(StartLoc, TagDecl);
+  }
 
   if (DS.SetTypeSpecType(DeclSpec::TST_enum, StartLoc,
                          NameLoc.isValid() ? NameLoc : StartLoc,
diff --git a/lib/Parse/ParseDeclCXX.cpp b/lib/Parse/ParseDeclCXX.cpp
index 05a3463..285dbbb 100644
--- a/lib/Parse/ParseDeclCXX.cpp
+++ b/lib/Parse/ParseDeclCXX.cpp
@@ -1115,7 +1115,7 @@
     if (DS.isFriendSpecified()) {
       // C++ [class.friend]p2:
       //   A class shall not be defined in a friend declaration.
-      Diag(Tok.getLocation(), diag::err_friend_decl_defines_class)
+      Diag(Tok.getLocation(), diag::err_friend_decl_defines_type)
         << SourceRange(DS.getFriendSpecLoc());
 
       // Skip everything up to the semicolon, so that this looks like a proper
@@ -1277,8 +1277,9 @@
     TagOrTempResult = Actions.ActOnTag(getCurScope(), TagType, TUK, StartLoc,
                                        SS, Name, NameLoc, attrs.getList(), AS,
                                        DS.getModulePrivateSpecLoc(),
-                                       TParams, Owned, IsDependent, false,
-                                       false, clang::TypeResult());
+                                       TParams, Owned, IsDependent,
+                                       SourceLocation(), false,
+                                       clang::TypeResult());
 
     // If ActOnTag said the type was dependent, try again with the
     // less common call.
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 4a804bf..a2bf48e 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -7580,7 +7580,8 @@
                      SourceLocation ModulePrivateLoc,
                      MultiTemplateParamsArg TemplateParameterLists,
                      bool &OwnedDecl, bool &IsDependent,
-                     bool ScopedEnum, bool ScopedEnumUsesClassTag,
+                     SourceLocation ScopedEnumKWLoc,
+                     bool ScopedEnumUsesClassTag,
                      TypeResult UnderlyingType) {
   // If this is not a definition, it must have a name.
   assert((Name != 0 || TUK == TUK_Definition) &&
@@ -7589,6 +7590,7 @@
 
   OwnedDecl = false;
   TagTypeKind Kind = TypeWithKeyword::getTagTypeKindForTypeSpec(TagSpec);
+  bool ScopedEnum = ScopedEnumKWLoc.isValid();
 
   // FIXME: Check explicit specializations more carefully.
   bool isExplicitSpecialization = false;
@@ -7919,6 +7921,16 @@
         if (Kind == TTK_Enum && PrevTagDecl->getTagKind() == TTK_Enum) {
           const EnumDecl *PrevEnum = cast<EnumDecl>(PrevTagDecl);
 
+          // If this is an elaborated-type-specifier for a scoped enumeration,
+          // the 'class' keyword is not necessary and not permitted.
+          if (TUK == TUK_Reference || TUK == TUK_Friend) {
+            if (ScopedEnum)
+              Diag(ScopedEnumKWLoc, diag::err_enum_class_reference)
+                << PrevEnum->isScoped()
+                << FixItHint::CreateRemoval(ScopedEnumKWLoc);
+            return PrevTagDecl;
+          }
+
           // All conflicts with previous declarations are recovered by
           // returning the previous declaration.
           if (ScopedEnum != PrevEnum->isScoped()) {
diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index 44c84f3..0ca75df 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -9851,7 +9851,7 @@
                       Attr, AS_public, 
                       /*ModulePrivateLoc=*/SourceLocation(),
                       MultiTemplateParamsArg(), Owned, IsDependent, 
-                      /*ScopedEnum=*/false,
+                      /*ScopedEnumKWLoc=*/SourceLocation(),
                       /*ScopedEnumUsesClassTag=*/false,
                       /*UnderlyingType=*/TypeResult());          
     }
diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
index b6babb6..bcdf32b 100644
--- a/lib/Sema/SemaTemplate.cpp
+++ b/lib/Sema/SemaTemplate.cpp
@@ -6070,7 +6070,7 @@
                         KWLoc, SS, Name, NameLoc, Attr, AS_none,
                         /*ModulePrivateLoc=*/SourceLocation(),
                         MultiTemplateParamsArg(*this, 0, 0),
-                        Owned, IsDependent, false, false,
+                        Owned, IsDependent, SourceLocation(), false,
                         TypeResult());
   assert(!IsDependent && "explicit instantiation of dependent name not yet handled");