Implement DR257 / fix PR16659:
A constructor for an abstract class does not call constructors for virtual
base classes, so it is not an error if no initializer is present for the
virtual base and the virtual base cannot be default initialized.
Also provide a (disabled by default, for now) warning for the case where a
virtual base class's initializer is ignored in an abstract class's constructor,
and address a defect in DR257 where it was not carried through to C++11's rules
for implicit deletion of special member functions.
Based on a patch by Maurice Bos.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@186803 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index 25dbd07..9b85c10 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -3346,7 +3346,7 @@
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 @@
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 @@
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 @@
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)