Implement DR1460: fix handling of default initializers in unions; don't allow

more than one such initializer in a union, make mem-initializers override
default initializers for other union members, handle anonymous unions with
anonymous struct members better. Fix a couple of semi-related bugs exposed by
the tests for same.

llvm-svn: 196892

2 files changed, 20 insertions, 4 deletions

diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
index 4292d358164..cb967b3fb23 100644
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -1947,6 +1947,7 @@ bool ASTNodeImporter::ImportDefinition(RecordDecl *From, RecordDecl *To,
     ToData.HasProtectedFields = FromData.HasProtectedFields;
     ToData.HasPublicFields = FromData.HasPublicFields;
     ToData.HasMutableFields = FromData.HasMutableFields;
+    ToData.HasVariantMembers = FromData.HasVariantMembers;
     ToData.HasOnlyCMembers = FromData.HasOnlyCMembers;
     ToData.HasInClassInitializer = FromData.HasInClassInitializer;
     ToData.HasUninitializedReferenceMember
diff --git a/clang/lib/AST/DeclCXX.cpp b/clang/lib/AST/DeclCXX.cpp
index 5fd52c4243a..5f7dcd5d46a 100644
--- a/clang/lib/AST/DeclCXX.cpp
+++ b/clang/lib/AST/DeclCXX.cpp
@@ -50,7 +50,7 @@ CXXRecordDecl::DefinitionData::DefinitionData(CXXRecordDecl *D)
     Aggregate(true), PlainOldData(true), Empty(true), Polymorphic(false),
     Abstract(false), IsStandardLayout(true), HasNoNonEmptyBases(true),
     HasPrivateFields(false), HasProtectedFields(false), HasPublicFields(false),
-    HasMutableFields(false), HasOnlyCMembers(true),
+    HasMutableFields(false), HasVariantMembers(false), HasOnlyCMembers(true),
     HasInClassInitializer(false), HasUninitializedReferenceMember(false),
     NeedOverloadResolutionForMoveConstructor(false),
     NeedOverloadResolutionForMoveAssignment(false),
@@ -653,7 +653,13 @@ void CXXRecordDecl::addedMember(Decl *D) {
     // Keep track of the presence of mutable fields.
     if (Field->isMutable())
       data().HasMutableFields = true;
-    
+
+    // C++11 [class.union]p8, DR1460:
+    //   If X is a union, a non-static data member of X that is not an anonymous
+    //   union is a variant member of X.
+    if (isUnion() && !Field->isAnonymousStructOrUnion())
+      data().HasVariantMembers = true;
+
     // C++0x [class]p9:
     //   A POD struct is a class that is both a trivial class and a 
     //   standard-layout class, and has no non-static data members of type 
@@ -689,7 +695,9 @@ void CXXRecordDecl::addedMember(Decl *D) {
     if (!T->isLiteralType(Context) || T.isVolatileQualified())
       data().HasNonLiteralTypeFieldsOrBases = true;
 
-    if (Field->hasInClassInitializer()) {
+    if (Field->hasInClassInitializer() ||
+        (Field->isAnonymousStructOrUnion() &&
+         Field->getType()->getAsCXXRecordDecl()->hasInClassInitializer())) {
       data().HasInClassInitializer = true;
 
       // C++11 [class]p5:
@@ -806,7 +814,7 @@ void CXXRecordDecl::addedMember(Decl *D) {
         // Virtual bases and virtual methods make a class non-empty, but they
         // also make it non-standard-layout so we needn't check here.
         // A non-empty base class may leave the class standard-layout, but not
-        // if we have arrived here, and have at least on non-static data
+        // if we have arrived here, and have at least one non-static data
         // member. If IsStandardLayout remains true, then the first non-static
         // data member must come through here with Empty still true, and Empty
         // will subsequently be set to false below.
@@ -859,6 +867,13 @@ void CXXRecordDecl::addedMember(Decl *D) {
         if (FieldRec->hasUninitializedReferenceMember() &&
             !Field->hasInClassInitializer())
           data().HasUninitializedReferenceMember = true;
+
+        // C++11 [class.union]p8, DR1460:
+        //   a non-static data member of an anonymous union that is a member of
+        //   X is also a variant member of X.
+        if (FieldRec->hasVariantMembers() &&
+            Field->isAnonymousStructOrUnion())
+          data().HasVariantMembers = true;
       }
     } else {
       // Base element type of field is a non-class type.