1 files changed, 36 insertions, 7 deletions

diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 25dbd07b410..9b85c10d594 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -3346,7 +3346,7 @@ bool Sema::SetCtorInitializers(CXXConstructorDecl *Constructor, bool AnyErrors,
 
   for (unsigned i = 0; i < Initializers.size(); i++) {
     CXXCtorInitializer *Member = Initializers[i];
-    
+
     if (Member->isBaseInitializer())
       Info.AllBaseFields[Member->getBaseClass()->getAs<RecordType>()] = Member;
     else
@@ -3367,12 +3367,28 @@ bool Sema::SetCtorInitializers(CXXConstructorDecl *Constructor, bool AnyErrors,
 
     if (CXXCtorInitializer *Value
         = Info.AllBaseFields.lookup(VBase->getType()->getAs<RecordType>())) {
+      // [class.base.init]p7, per DR257:
+      //   A mem-initializer where the mem-initializer-id names a virtual base
+      //   class is ignored during execution of a constructor of any class that
+      //   is not the most derived class.
+      if (ClassDecl->isAbstract()) {
+        // FIXME: Provide a fixit to remove the base specifier. This requires
+        // tracking the location of the associated comma for a base specifier.
+        Diag(Value->getSourceLocation(), diag::warn_abstract_vbase_init_ignored)
+          << VBase->getType() << ClassDecl;
+        DiagnoseAbstractType(ClassDecl);
+      }
+
       Info.AllToInit.push_back(Value);
-    } else if (!AnyErrors) {
+    } else if (!AnyErrors && !ClassDecl->isAbstract()) {
+      // [class.base.init]p8, per DR257:
+      //   If a given [...] base class is not named by a mem-initializer-id
+      //   [...] and the entity is not a virtual base class of an abstract
+      //   class, then [...] the entity is default-initialized.
       bool IsInheritedVirtualBase = !DirectVBases.count(VBase);
       CXXCtorInitializer *CXXBaseInit;
       if (BuildImplicitBaseInitializer(*this, Constructor, Info.IIK,
-                                       VBase, IsInheritedVirtualBase, 
+                                       VBase, IsInheritedVirtualBase,
                                        CXXBaseInit)) {
         HadError = true;
         continue;
@@ -3913,6 +3929,12 @@ void Sema::DiagnoseAbstractType(const CXXRecordDecl *RD) {
   if (PureVirtualClassDiagSet && PureVirtualClassDiagSet->count(RD))
     return;
 
+  // If the diagnostic is suppressed, don't emit the notes. We're only
+  // going to emit them once, so try to attach them to a diagnostic we're
+  // actually going to show.
+  if (Diags.isLastDiagnosticIgnored())
+    return;
+
   CXXFinalOverriderMap FinalOverriders;
   RD->getFinalOverriders(FinalOverriders);
 
@@ -5055,10 +5077,17 @@ bool Sema::ShouldDeleteSpecialMember(CXXMethodDecl *MD, CXXSpecialMember CSM,
         SMI.shouldDeleteForBase(BI))
       return true;
 
-  for (CXXRecordDecl::base_class_iterator BI = RD->vbases_begin(),
-                                          BE = RD->vbases_end(); BI != BE; ++BI)
-    if (SMI.shouldDeleteForBase(BI))
-      return true;
+  // Defect report (no number yet): do not consider virtual bases of
+  // constructors of abstract classes, since we are not going to construct
+  // them. This is an extension of DR257 into the C++11 behavior for special
+  // members.
+  if (!RD->isAbstract() || !SMI.IsConstructor) {
+    for (CXXRecordDecl::base_class_iterator BI = RD->vbases_begin(),
+                                            BE = RD->vbases_end();
+         BI != BE; ++BI)
+      if (SMI.shouldDeleteForBase(BI))
+        return true;
+  }
 
   for (CXXRecordDecl::field_iterator FI = RD->field_begin(),
                                      FE = RD->field_end(); FI != FE; ++FI)