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
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 499b23f..834c189 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -880,7 +880,8 @@
diag::err_constexpr_local_var_non_literal_type,
isa<CXXConstructorDecl>(Dcl)))
return false;
- if (!VD->hasInit() && !VD->isCXXForRangeDecl()) {
+ if (!VD->getType()->isDependentType() &&
+ !VD->hasInit() && !VD->isCXXForRangeDecl()) {
SemaRef.Diag(VD->getLocation(),
diag::err_constexpr_local_var_no_init)
<< isa<CXXConstructorDecl>(Dcl);
@@ -932,8 +933,13 @@
if (Field->isUnnamedBitfield())
return;
+ // Anonymous unions with no variant members and empty anonymous structs do not
+ // need to be explicitly initialized. FIXME: Anonymous structs that contain no
+ // indirect fields don't need initializing.
if (Field->isAnonymousStructOrUnion() &&
- Field->getType()->getAsCXXRecordDecl()->isEmpty())
+ (Field->getType()->isUnionType()
+ ? !Field->getType()->getAsCXXRecordDecl()->hasVariantMembers()
+ : Field->getType()->getAsCXXRecordDecl()->isEmpty()))
return;
if (!Inits.count(Field)) {
@@ -1116,11 +1122,12 @@
// DR1359:
// - every non-variant non-static data member and base class sub-object
// shall be initialized;
- // - if the class is a non-empty union, or for each non-empty anonymous
- // union member of a non-union class, exactly one non-static data member
+ // DR1460:
+ // - if the class is a union having variant members, exactly one of them
// shall be initialized;
if (RD->isUnion()) {
- if (Constructor->getNumCtorInitializers() == 0 && !RD->isEmpty()) {
+ if (Constructor->getNumCtorInitializers() == 0 &&
+ RD->hasVariantMembers()) {
Diag(Dcl->getLocation(), diag::err_constexpr_union_ctor_no_init);
return false;
}
@@ -1139,6 +1146,10 @@
break;
}
}
+ // DR1460:
+ // - if the class is a union-like class, but is not a union, for each of
+ // its anonymous union members having variant members, exactly one of
+ // them shall be initialized;
if (AnyAnonStructUnionMembers ||
Constructor->getNumCtorInitializers() != RD->getNumBases() + Fields) {
// Check initialization of non-static data members. Base classes are
@@ -3320,6 +3331,7 @@
ImplicitInitializerKind IIK;
llvm::DenseMap<const void *, CXXCtorInitializer*> AllBaseFields;
SmallVector<CXXCtorInitializer*, 8> AllToInit;
+ llvm::DenseMap<TagDecl*, FieldDecl*> ActiveUnionMember;
BaseAndFieldInfo(Sema &S, CXXConstructorDecl *Ctor, bool ErrorsInInits)
: S(S), Ctor(Ctor), AnyErrorsInInits(ErrorsInInits) {
@@ -3357,20 +3369,50 @@
return false;
}
-};
-}
-/// \brief Determine whether the given indirect field declaration is somewhere
-/// within an anonymous union.
-static bool isWithinAnonymousUnion(IndirectFieldDecl *F) {
- for (IndirectFieldDecl::chain_iterator C = F->chain_begin(),
- CEnd = F->chain_end();
- C != CEnd; ++C)
- if (CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>((*C)->getDeclContext()))
- if (Record->isUnion())
+ bool isInactiveUnionMember(FieldDecl *Field) {
+ RecordDecl *Record = Field->getParent();
+ if (!Record->isUnion())
+ return false;
+
+ FieldDecl *Active = ActiveUnionMember.lookup(Record->getCanonicalDecl());
+ if (Active)
+ return Active != Field->getCanonicalDecl();
+
+ // In an implicit copy or move constructor, ignore any in-class initializer.
+ if (isImplicitCopyOrMove())
+ return true;
+
+ // If there's no explicit initialization, the field is active only if it
+ // has an in-class initializer...
+ if (Field->hasInClassInitializer())
+ return false;
+ // ... or it's an anonymous struct or union whose class has an in-class
+ // initializer.
+ if (!Field->isAnonymousStructOrUnion())
+ return true;
+ CXXRecordDecl *FieldRD = Field->getType()->getAsCXXRecordDecl();
+ return !FieldRD->hasInClassInitializer();
+ }
+
+ /// \brief Determine whether the given field is, or is within, a union member
+ /// that is inactive (because there was an initializer given for a different
+ /// member of the union, or because the union was not initialized at all).
+ bool isWithinInactiveUnionMember(FieldDecl *Field,
+ IndirectFieldDecl *Indirect) {
+ if (!Indirect)
+ return isInactiveUnionMember(Field);
+
+ for (IndirectFieldDecl::chain_iterator C = Indirect->chain_begin(),
+ CEnd = Indirect->chain_end();
+ C != CEnd; ++C) {
+ FieldDecl *Field = dyn_cast<FieldDecl>(*C);
+ if (Field && isInactiveUnionMember(Field))
return true;
-
- return false;
+ }
+ return false;
+ }
+};
}
/// \brief Determine whether the given type is an incomplete or zero-lenfgth
@@ -3399,9 +3441,21 @@
if (CXXCtorInitializer *Init = Info.AllBaseFields.lookup(Field))
return Info.addFieldInitializer(Init);
- // C++11 [class.base.init]p8: if the entity is a non-static data member that
- // has a brace-or-equal-initializer, the entity is initialized as specified
- // in [dcl.init].
+ // C++11 [class.base.init]p8:
+ // if the entity is a non-static data member that has a
+ // brace-or-equal-initializer and either
+ // -- the constructor's class is a union and no other variant member of that
+ // union is designated by a mem-initializer-id or
+ // -- the constructor's class is not a union, and, if the entity is a member
+ // of an anonymous union, no other member of that union is designated by
+ // a mem-initializer-id,
+ // the entity is initialized as specified in [dcl.init].
+ //
+ // We also apply the same rules to handle anonymous structs within anonymous
+ // unions.
+ if (Info.isWithinInactiveUnionMember(Field, Indirect))
+ return false;
+
if (Field->hasInClassInitializer() && !Info.isImplicitCopyOrMove()) {
Expr *DIE = CXXDefaultInitExpr::Create(SemaRef.Context,
Info.Ctor->getLocation(), Field);
@@ -3419,12 +3473,6 @@
return Info.addFieldInitializer(Init);
}
- // Don't build an implicit initializer for union members if none was
- // explicitly specified.
- if (Field->getParent()->isUnion() ||
- (Indirect && isWithinAnonymousUnion(Indirect)))
- return false;
-
// Don't initialize incomplete or zero-length arrays.
if (isIncompleteOrZeroLengthArrayType(SemaRef.Context, Field->getType()))
return false;
@@ -3502,8 +3550,24 @@
if (Member->isBaseInitializer())
Info.AllBaseFields[Member->getBaseClass()->getAs<RecordType>()] = Member;
- else
+ else {
Info.AllBaseFields[Member->getAnyMember()] = Member;
+
+ if (IndirectFieldDecl *F = Member->getIndirectMember()) {
+ for (IndirectFieldDecl::chain_iterator C = F->chain_begin(),
+ CEnd = F->chain_end();
+ C != CEnd; ++C) {
+ FieldDecl *FD = dyn_cast<FieldDecl>(*C);
+ if (FD && FD->getParent()->isUnion())
+ Info.ActiveUnionMember.insert(std::make_pair(
+ FD->getParent()->getCanonicalDecl(), FD->getCanonicalDecl()));
+ }
+ } else if (FieldDecl *FD = Member->getMember()) {
+ if (FD->getParent()->isUnion())
+ Info.ActiveUnionMember.insert(std::make_pair(
+ FD->getParent()->getCanonicalDecl(), FD->getCanonicalDecl()));
+ }
+ }
}
// Keep track of the direct virtual bases.