r227022 - First steps in implementing DR1467: List-initialization of aggregate from same-type object.
Larisse Voufo
lvoufo at google.com
Tue Jan 27 10:56:36 PST 2015
These should all be addressed by r227224.
On Mon, Jan 26, 2015 at 6:50 PM, Larisse Voufo <lvoufo at google.com> wrote:
>
>
> On Mon, Jan 26, 2015 at 11:31 AM, Richard Smith <richard at metafoo.co.uk>
> wrote:
>
>> On Sat, Jan 24, 2015 at 3:09 PM, Larisse Voufo <lvoufo at google.com> wrote:
>> > Author: lvoufo
>> > Date: Sat Jan 24 17:09:54 2015
>> > New Revision: 227022
>> >
>> > URL: http://llvm.org/viewvc/llvm-project?rev=227022&view=rev
>> > Log:
>> > First steps in implementing DR1467: List-initialization of aggregate
>> from same-type object.
>> > Only the first two items for now, changing Sections 8.5.4
>> [dcl.init.list] paragraph 3 and 13.3.1.7 [over.match.list] paragraph 1,
>> > so that defining class objects and character arrays using uniform
>> initialization syntax is actually treated as list initialization
>> > and before it is treated aggregate initialization.
>> >
>> > Modified:
>> > cfe/trunk/lib/Sema/SemaInit.cpp
>> > cfe/trunk/test/CXX/drs/dr14xx.cpp
>> >
>> > Modified: cfe/trunk/lib/Sema/SemaInit.cpp
>> > URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaInit.cpp?rev=227022&r1=227021&r2=227022&view=diff
>> >
>> ==============================================================================
>> > --- cfe/trunk/lib/Sema/SemaInit.cpp (original)
>> > +++ cfe/trunk/lib/Sema/SemaInit.cpp Sat Jan 24 17:09:54 2015
>> > @@ -3222,9 +3222,16 @@ static void TryConstructorInitialization
>> > OverloadCandidateSet::iterator Best;
>> > bool AsInitializerList = false;
>> >
>> > + // C++14 DR 1467 [over.match.list]p1:
>> > + // When objects of non-aggregate type T are list-initialized, such
>> that
>> > + // 8.5.4 [dcl.init.list] specifies that overload resolution is
>> performed
>> > + // according to the rules in this section, overload resolution
>> selects
>> > + // the constructor in two phases:
>> > + //
>> > // C++11 [over.match.list]p1:
>> > // When objects of non-aggregate type T are list-initialized,
>> overload
>> > // resolution selects the constructor in two phases:
>> > + //
>> > // - Initially, the candidate functions are the initializer-list
>> > // constructors of the class T and the argument list consists of
>> the
>> > // initializer list as a single argument.
>> > @@ -3425,42 +3432,88 @@ static void TryListInitialization(Sema &
>> > TryReferenceListInitialization(S, Entity, Kind, InitList,
>> Sequence);
>> > return;
>> > }
>> > - if (DestType->isRecordType()) {
>> > - if (S.RequireCompleteType(InitList->getLocStart(), DestType, 0)) {
>> > - Sequence.setIncompleteTypeFailure(DestType);
>> > - return;
>> > - }
>> >
>> > - // C++11 [dcl.init.list]p3:
>> > - // - If T is an aggregate, aggregate initialization is performed.
>> > - if (!DestType->isAggregateType()) {
>> > - if (S.getLangOpts().CPlusPlus11) {
>> > - // - Otherwise, if the initializer list has no elements and
>> T is a
>> > - // class type with a default constructor, the object is
>> > - // value-initialized.
>> > - if (InitList->getNumInits() == 0) {
>> > - CXXRecordDecl *RD = DestType->getAsCXXRecordDecl();
>> > - if (RD->hasDefaultConstructor()) {
>> > - TryValueInitialization(S, Entity, Kind, Sequence,
>> InitList);
>> > - return;
>> > - }
>> > - }
>> > -
>> > - // - Otherwise, if T is a specialization of
>> std::initializer_list<E>,
>> > - // an initializer_list object constructed [...]
>> > - if (TryInitializerListConstruction(S, InitList, DestType,
>> Sequence))
>> > - return;
>> > + if (DestType->isRecordType() &&
>> > + S.RequireCompleteType(InitList->getLocStart(), DestType, 0)) {
>> > + Sequence.setIncompleteTypeFailure(DestType);
>> > + return;
>> > + }
>> >
>> > - // - Otherwise, if T is a class type, constructors are
>> considered.
>> > + // C++14 DR1467 [dcl.init.list]p3:
>> > + // - If T is a class type and the initializer list has a single
>> element of
>> > + // type cv U, where U is T or a class derived from T, the object is
>> > + // initialized from that element (by copy-initialization for
>> > + // copy-list-initialization, or by direct-initialization for
>> > + // direct-list-initialization).
>> > + // - Otherwise, if T is a character array and the initializer list
>> has a
>> > + // single element that is an appropriately-typed string literal
>> > + // (8.5.2 [dcl.init.string]), initialization is performed as
>> described
>> > + // in that section.
>> > + // - Otherwise, If T is an aggregate, [...] (continue below).
>> > + if (S.getLangOpts().CPlusPlus14 && InitList->getNumInits() == 1) {
>>
>> This issue is in DR status, so should be applied retroactively to all
>> standard revisions where it makes sense. In this case, that means it
>> should apply to C++11 mode as well as C++14 mode.
>>
>
> Ok.
>
>>
>> > + if (DestType->isRecordType()) {
>> > + QualType InitType = InitList->getInit(0)->getType();
>> > + if (S.Context.hasSameUnqualifiedType(InitType, DestType) ||
>> > + S.IsDerivedFrom(InitType, DestType)) {
>> > Expr *InitListAsExpr = InitList;
>> > TryConstructorInitialization(S, Entity, Kind, InitListAsExpr,
>> DestType,
>> > Sequence, /*InitListSyntax*/true);
>> > - } else
>> > - Sequence.SetFailed(
>> > - InitializationSequence::FK_InitListBadDestinationType);
>> > - return;
>> > + return;
>> > + }
>> > + }
>> > + if (const ArrayType *DestAT = S.Context.getAsArrayType(DestType)) {
>> > + Expr *SubInit[1] = {InitList->getInit(0)};
>> > + if (!isa<VariableArrayType>(DestAT) &&
>> > + IsStringInit(SubInit[0], DestAT, S.Context) == SIF_None) {
>> > + InitializationKind SubKind =
>> > + Kind.getKind() == InitializationKind::IK_DirectList
>> > + ? InitializationKind::CreateDirect(Kind.getLocation(),
>> > +
>> InitList->getLBraceLoc(),
>> > +
>> InitList->getRBraceLoc())
>> > + : Kind;
>> > + Sequence.InitializeFrom(S, Entity, SubKind, SubInit,
>> > + /*TopLevelOfInitList*/ true);
>> > +
>> > + // TryStringLiteralInitialization() (in InitializeFrom()) will
>> fail if
>> > + // the element is not an appropriately-typed string literal,
>> in which
>> > + // case we should proceed as in C++11 (below).
>> > + if (Sequence) {
>> > + Sequence.RewrapReferenceInitList(Entity.getType(), InitList);
>> > + return;
>> > + }
>> > + }
>> > }
>> > }
>> > +
>> > + // C++11 [dcl.init.list]p3:
>> > + // - If T is an aggregate, aggregate initialization is performed.
>> > + if (DestType->isRecordType() && !DestType->isAggregateType()) {
>> > + if (S.getLangOpts().CPlusPlus11) {
>> > + // - Otherwise, if the initializer list has no elements and T
>> is a
>> > + // class type with a default constructor, the object is
>> > + // value-initialized.
>> > + if (InitList->getNumInits() == 0) {
>> > + CXXRecordDecl *RD = DestType->getAsCXXRecordDecl();
>> > + if (RD->hasDefaultConstructor()) {
>> > + TryValueInitialization(S, Entity, Kind, Sequence, InitList);
>> > + return;
>> > + }
>> > + }
>> > +
>> > + // - Otherwise, if T is a specialization of
>> std::initializer_list<E>,
>> > + // an initializer_list object constructed [...]
>> > + if (TryInitializerListConstruction(S, InitList, DestType,
>> Sequence))
>> > + return;
>> > +
>> > + // - Otherwise, if T is a class type, constructors are
>> considered.
>> > + Expr *InitListAsExpr = InitList;
>> > + TryConstructorInitialization(S, Entity, Kind, InitListAsExpr,
>> DestType,
>> > + Sequence, /*InitListSyntax*/ true);
>> > + } else
>> > +
>> Sequence.SetFailed(InitializationSequence::FK_InitListBadDestinationType);
>> > + return;
>> > + }
>> > +
>> > if (S.getLangOpts().CPlusPlus && !DestType->isAggregateType() &&
>> > InitList->getNumInits() == 1 &&
>> > InitList->getInit(0)->getType()->isRecordType()) {
>> > @@ -3469,6 +3522,14 @@ static void TryListInitialization(Sema &
>> > // initialized from that element; if a narrowing conversion is
>> required
>> > // to convert the element to T, the program is ill-formed.
>> > //
>> > + // C++14 DR1467:
>> > + // - Otherwise, if the initializer list has a single element of
>> type E
>> > + // [...references are handled above...], the object or
>> reference is
>> > + // initialized from that element (by copy-initialization for
>> > + // copy-list-initialization, or by direct-initialization for
>> > + // direct-list-initialization); if a narrowing conversion is
>> required
>> > + // to convert the element to T, the program is ill-formed.
>> > + //
>> > // Per core-24034, this is direct-initialization if we were
>> performing
>> > // direct-list-initialization and copy-initialization otherwise.
>> > // We can't use InitListChecker for this, because it always
>> performs
>> > @@ -4408,8 +4469,7 @@ static void checkIndirectCopyRestoreSour
>> >
>> > /// \brief Determine whether we have compatible array types for the
>> > /// purposes of GNU by-copy array initialization.
>> > -static bool hasCompatibleArrayTypes(ASTContext &Context,
>> > - const ArrayType *Dest,
>> > +static bool hasCompatibleArrayTypes(ASTContext &Context, const
>> ArrayType *Dest,
>> > const ArrayType *Source) {
>> > // If the source and destination array types are equivalent, we're
>> > // done.
>> > @@ -4668,7 +4728,7 @@ void InitializationSequence::InitializeF
>> > return;
>> > }
>> >
>> > - // Determine whether we should consider writeback conversions for
>> > + // Determine whether we should consider writeback conversions for
>> > // Objective-C ARC.
>> > bool allowObjCWritebackConversion = S.getLangOpts().ObjCAutoRefCount
>> &&
>> > Entity.isParameterKind();
>> >
>> > Modified: cfe/trunk/test/CXX/drs/dr14xx.cpp
>> > URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CXX/drs/dr14xx.cpp?rev=227022&r1=227021&r2=227022&view=diff
>> >
>> ==============================================================================
>> > --- cfe/trunk/test/CXX/drs/dr14xx.cpp (original)
>> > +++ cfe/trunk/test/CXX/drs/dr14xx.cpp Sat Jan 24 17:09:54 2015
>> > @@ -195,3 +195,126 @@ namespace dr1460 { // dr1460: 3.5
>> > }
>> > #endif
>> > }
>> > +
>> > +#if __cplusplus >= 201103L
>> > +namespace std {
>> > + typedef decltype(sizeof(int)) size_t;
>> > +
>> > + // libc++'s implementation
>> > + template <class _E>
>> > + class initializer_list
>> > + {
>> > + const _E* __begin_;
>> > + size_t __size_;
>> > +
>> > + initializer_list(const _E* __b, size_t __s)
>> > + : __begin_(__b),
>> > + __size_(__s)
>> > + {}
>> > +
>> > + public:
>> > + typedef _E value_type;
>> > + typedef const _E& reference;
>> > + typedef const _E& const_reference;
>> > + typedef size_t size_type;
>> > +
>> > + typedef const _E* iterator;
>> > + typedef const _E* const_iterator;
>> > +
>> > + initializer_list() : __begin_(nullptr), __size_(0) {}
>> > +
>> > + size_t size() const {return __size_;}
>> > + const _E* begin() const {return __begin_;}
>> > + const _E* end() const {return __begin_ + __size_;}
>> > + };
>> > +} // std
>>
>> Please put this at the top of the file.
>>
>> > +
>> > +namespace dr1467 {
>>
>> This should be marked as " // dr1467: partial c++11" to indicate that
>> we have partial support for this in trunk, for C++11 onwards. We have
>> a script (www/make_cxx_dr_status) that automatically generates the
>> cxx_dr_status page from these comments.
>>
>
> Ok.
>
>>
>> > + // List-initialization of aggregate from same-type object
>> > +
>> > + namespace basic0 {
>> > +
>> > + struct S {
>> > + int i = 42;
>> > + };
>> > +
>> > + S a;
>> > + S b(a);
>> > + S c{a};
>> > +
>> > + struct SS : public S { } x;
>> > + S y(x);
>> > + S z{x};
>> > +
>> > + } // basic0
>> > +
>> > + namespace basic1 {
>> > +
>> > + struct S {
>> > + int i{42};
>> > + };
>> > +
>> > + S a;
>> > + S b(a);
>> > + S c{a};
>> > +
>> > + struct SS : public S { } x;
>> > + S y(x);
>> > + S z{x};
>> > +
>> > + } // basic1
>> > +
>> > + namespace basic2 {
>> > +
>> > + struct S {
>> > + int i = {42};
>> > + };
>> > +
>> > + S a;
>> > + S b(a);
>> > + S c{a};
>> > +
>> > + struct SS : public S { } x;
>> > + S y(x);
>> > + S z{x};
>> > +
>> > + } // basic2
>> > +
>> > + namespace dr_example {
>> > + struct OK {
>> > + OK() = default;
>> > + OK(const OK&) = default;
>> > + OK(int) { }
>> > + };
>> > +
>> > + OK ok;
>> > + OK ok2{ok};
>> > +
>> > +
>> > + struct X {
>> > + X() = default;
>> > + X(const X&) = default;
>> > + };
>> > +
>> > + X x;
>> > + X x2{x};
>> > +#if __cplusplus == 201103L
>> > + // expected-error at -2 {{excess elements in struct initializer}}
>> > +#endif
>> > +
>> > + // TODO: Only Items 1 and 2 from DR1467 are covered for now.
>> > + // Implement remaining items, and expand here as necessary.
>> > +
>> > + } // dr_example
>> > +
>> > +} // dr1467
>> > +
>> > +
>> > +namespace dr1490 {
>>
>> This should be marked "// dr1490: dup 1467".
>>
>> > + // List-initialization from a string literal
>> > +
>> > + char s[4]{"abc"}; // Ok
>> > + std::initializer_list<char>{"abc"}; // expected-error {{expected
>> unqualified-id}}}
>> > +
>> > +} // dr1490
>> > +#endif
>>
>> Can you add tests for dr1756, 1758, 1631 and 1589 (all resolved by
>> 1467) too, please?
>>
>
> I am still working on these cases. This patch does not handle those yet.
>
>
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