r328680 - [ObjC] Make C++ triviality type traits available to non-trivial C
John McCall via cfe-commits
cfe-commits at lists.llvm.org
Thu Apr 5 12:39:08 PDT 2018
> On Apr 4, 2018, at 7:37 PM, Akira Hatanaka <ahatanaka at apple.com> wrote:
>
>
>
>> On Apr 4, 2018, at 4:24 PM, Akira Hatanaka via cfe-commits <cfe-commits at lists.llvm.org <mailto:cfe-commits at lists.llvm.org>> wrote:
>>
>>>
>>> On Apr 4, 2018, at 3:38 PM, Richard Smith <richard at metafoo.co.uk <mailto:richard at metafoo.co.uk>> wrote:
>>>
>>> Hi Akira,
>>>
>>> This change has broken the C++ versions of these type traits for classes with volatile members. Such classes are required to claim to be trivial per C++ DR 2094 (http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#2094 <http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#2094>) but return false from isNonTrivialToPrimitiveCopy().
>>>
>>
>> Oh that’s right. The function returns false when isNonTrivialToPrimitiveCopy() returns PCK_VolatileTrivial. That is wrong.
>>
>>> Also, exposing these __has_* traits more widely seems like a backwards step to me: these traits are deprecated, near-useless, and we're trying to remove them. No code should be using them under any circumstances; the __is_* traits should be used instead.
>>>
>>
>> The __is_* traits (is_trivially_copy_constructible, etc.) are templates defined in libcxx, so it seems that we can’t use them when compiling in C mode. Is it OK to add their definitions to TokenKinds.def as non-C++ keywords?
>>
>
> Or perhaps redefine the six __has_* traits used here as non-C++ (KEYNOCXX or ‘KEYC99 | KEYC11') keywords?
I think Richard is talking about e.g. the __is_trivially_destructible intrinsic type trait function rather than std::is_trivially_destructible.
Do we have a concrete need to expose these type traits to C?
John.
>
>>> On 27 March 2018 at 17:12, Akira Hatanaka via cfe-commits <cfe-commits at lists.llvm.org <mailto:cfe-commits at lists.llvm.org>> wrote:
>>> Author: ahatanak
>>> Date: Tue Mar 27 17:12:08 2018
>>> New Revision: 328680
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=328680&view=rev <http://llvm.org/viewvc/llvm-project?rev=328680&view=rev>
>>> Log:
>>> [ObjC] Make C++ triviality type traits available to non-trivial C
>>> structs.
>>>
>>> r326307 and r327870 made changes that allowed using non-trivial C
>>> structs with fields qualified with __strong or __weak. This commit makes
>>> the following C++ triviality type traits available to non-trivial C
>>> structs:
>>>
>>> __has_trivial_assign
>>> __has_trivial_move_assign
>>> __has_trivial_copy
>>> __has_trivial_move_constructor
>>> __has_trivial_constructor
>>> __has_trivial_destructor
>>>
>>> rdar://problem/33599681 <rdar://problem/33599681>
>>>
>>> Differential Revision: https://reviews.llvm.org/D44913 <https://reviews.llvm.org/D44913>
>>>
>>> Added:
>>> cfe/trunk/test/SemaObjC/non-trivial-struct-traits.m
>>> Modified:
>>> cfe/trunk/include/clang/Basic/TokenKinds.def
>>> cfe/trunk/lib/Sema/SemaExprCXX.cpp
>>>
>>> Modified: cfe/trunk/include/clang/Basic/TokenKinds.def
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/TokenKinds.def?rev=328680&r1=328679&r2=328680&view=diff <http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/TokenKinds.def?rev=328680&r1=328679&r2=328680&view=diff>
>>> ==============================================================================
>>> --- cfe/trunk/include/clang/Basic/TokenKinds.def (original)
>>> +++ cfe/trunk/include/clang/Basic/TokenKinds.def Tue Mar 27 17:12:08 2018
>>> @@ -433,12 +433,12 @@ TYPE_TRAIT_1(__has_nothrow_assign, HasNo
>>> TYPE_TRAIT_1(__has_nothrow_move_assign, HasNothrowMoveAssign, KEYCXX)
>>> TYPE_TRAIT_1(__has_nothrow_copy, HasNothrowCopy, KEYCXX)
>>> TYPE_TRAIT_1(__has_nothrow_constructor, HasNothrowConstructor, KEYCXX)
>>> -TYPE_TRAIT_1(__has_trivial_assign, HasTrivialAssign, KEYCXX)
>>> -TYPE_TRAIT_1(__has_trivial_move_assign, HasTrivialMoveAssign, KEYCXX)
>>> -TYPE_TRAIT_1(__has_trivial_copy, HasTrivialCopy, KEYCXX)
>>> -TYPE_TRAIT_1(__has_trivial_constructor, HasTrivialDefaultConstructor, KEYCXX)
>>> -TYPE_TRAIT_1(__has_trivial_move_constructor, HasTrivialMoveConstructor, KEYCXX)
>>> -TYPE_TRAIT_1(__has_trivial_destructor, HasTrivialDestructor, KEYCXX)
>>> +TYPE_TRAIT_1(__has_trivial_assign, HasTrivialAssign, KEYALL)
>>> +TYPE_TRAIT_1(__has_trivial_move_assign, HasTrivialMoveAssign, KEYALL)
>>> +TYPE_TRAIT_1(__has_trivial_copy, HasTrivialCopy, KEYALL)
>>> +TYPE_TRAIT_1(__has_trivial_constructor, HasTrivialDefaultConstructor, KEYALL)
>>> +TYPE_TRAIT_1(__has_trivial_move_constructor, HasTrivialMoveConstructor, KEYALL)
>>> +TYPE_TRAIT_1(__has_trivial_destructor, HasTrivialDestructor, KEYALL)
>>> TYPE_TRAIT_1(__has_virtual_destructor, HasVirtualDestructor, KEYCXX)
>>> TYPE_TRAIT_1(__is_abstract, IsAbstract, KEYCXX)
>>> TYPE_TRAIT_1(__is_aggregate, IsAggregate, KEYCXX)
>>>
>>> Modified: cfe/trunk/lib/Sema/SemaExprCXX.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExprCXX.cpp?rev=328680&r1=328679&r2=328680&view=diff <http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExprCXX.cpp?rev=328680&r1=328679&r2=328680&view=diff>
>>> ==============================================================================
>>> --- cfe/trunk/lib/Sema/SemaExprCXX.cpp (original)
>>> +++ cfe/trunk/lib/Sema/SemaExprCXX.cpp Tue Mar 27 17:12:08 2018
>>> @@ -4513,6 +4513,8 @@ static bool EvaluateUnaryTypeTrait(Sema
>>> // does not correctly compute triviality in the presence of multiple special
>>> // members of the same kind. Revisit this once the g++ bug is fixed.
>>> case UTT_HasTrivialDefaultConstructor:
>>> + if (T.isNonTrivialToPrimitiveDefaultInitialize())
>>> + return false;
>>> // http://gcc.gnu.org/onlinedocs/gcc/Type-Traits.html <http://gcc.gnu.org/onlinedocs/gcc/Type-Traits.html>:
>>> // If __is_pod (type) is true then the trait is true, else if type is
>>> // a cv class or union type (or array thereof) with a trivial default
>>> @@ -4524,6 +4526,8 @@ static bool EvaluateUnaryTypeTrait(Sema
>>> !RD->hasNonTrivialDefaultConstructor();
>>> return false;
>>> case UTT_HasTrivialMoveConstructor:
>>> + if (T.isNonTrivialToPrimitiveDestructiveMove())
>>> + return false;
>>> // This trait is implemented by MSVC 2012 and needed to parse the
>>> // standard library headers. Specifically this is used as the logic
>>> // behind std::is_trivially_move_constructible (20.9.4.3).
>>> @@ -4533,6 +4537,8 @@ static bool EvaluateUnaryTypeTrait(Sema
>>> return RD->hasTrivialMoveConstructor() && !RD->hasNonTrivialMoveConstructor();
>>> return false;
>>> case UTT_HasTrivialCopy:
>>> + if (T.isNonTrivialToPrimitiveCopy())
>>> + return false;
>>> // http://gcc.gnu.org/onlinedocs/gcc/Type-Traits.html <http://gcc.gnu.org/onlinedocs/gcc/Type-Traits.html>:
>>> // If __is_pod (type) is true or type is a reference type then
>>> // the trait is true, else if type is a cv class or union type
>>> @@ -4545,6 +4551,8 @@ static bool EvaluateUnaryTypeTrait(Sema
>>> !RD->hasNonTrivialCopyConstructor();
>>> return false;
>>> case UTT_HasTrivialMoveAssign:
>>> + if (T.isNonTrivialToPrimitiveDestructiveMove())
>>> + return false;
>>> // This trait is implemented by MSVC 2012 and needed to parse the
>>> // standard library headers. Specifically it is used as the logic
>>> // behind std::is_trivially_move_assignable (20.9.4.3)
>>> @@ -4554,6 +4562,8 @@ static bool EvaluateUnaryTypeTrait(Sema
>>> return RD->hasTrivialMoveAssignment() && !RD->hasNonTrivialMoveAssignment();
>>> return false;
>>> case UTT_HasTrivialAssign:
>>> + if (T.isNonTrivialToPrimitiveCopy())
>>> + return false;
>>> // http://gcc.gnu.org/onlinedocs/gcc/Type-Traits.html <http://gcc.gnu.org/onlinedocs/gcc/Type-Traits.html>:
>>> // If type is const qualified or is a reference type then the
>>> // trait is false. Otherwise if __is_pod (type) is true then the
>>> @@ -4624,6 +4634,8 @@ static bool EvaluateUnaryTypeTrait(Sema
>>> return true;
>>>
>>> case UTT_HasTrivialDestructor:
>>> + if (T.isDestructedType() == QualType::DK_nontrivial_c_struct)
>>> + return false;
>>> // http://gcc.gnu.org/onlinedocs/gcc/Type-Traits.html <http://gcc.gnu.org/onlinedocs/gcc/Type-Traits.html>
>>> // If __is_pod (type) is true or type is a reference type
>>> // then the trait is true, else if type is a cv class or union
>>>
>>> Added: cfe/trunk/test/SemaObjC/non-trivial-struct-traits.m
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaObjC/non-trivial-struct-traits.m?rev=328680&view=auto <http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaObjC/non-trivial-struct-traits.m?rev=328680&view=auto>
>>> ==============================================================================
>>> --- cfe/trunk/test/SemaObjC/non-trivial-struct-traits.m (added)
>>> +++ cfe/trunk/test/SemaObjC/non-trivial-struct-traits.m Tue Mar 27 17:12:08 2018
>>> @@ -0,0 +1,25 @@
>>> +// RUN: %clang_cc1 -fsyntax-only -fobjc-arc -verify %s
>>> +
>>> +// expected-no-diagnostics
>>> +
>>> +struct Trivial {
>>> + int x;
>>> +};
>>> +
>>> +struct NonTrivial {
>>> + id x;
>>> +};
>>> +
>>> +int trivial_assign[__has_trivial_assign(struct Trivial) ? 1 : -1];
>>> +int trivial_move_assign[__has_trivial_move_assign(struct Trivial) ? 1 : -1];
>>> +int trivial_copy_constructor[__has_trivial_copy(struct Trivial) ? 1 : -1];
>>> +int trivial_move_constructor[__has_trivial_move_constructor(struct Trivial) ? 1 : -1];
>>> +int trivial_constructor[__has_trivial_constructor(struct Trivial) ? 1 : -1];
>>> +int trivial_destructor[__has_trivial_destructor(struct Trivial) ? 1 : -1];
>>> +
>>> +int non_trivial_assign[__has_trivial_assign(struct NonTrivial) ? -1 : 1];
>>> +int non_trivial_move_assign[__has_trivial_move_assign(struct NonTrivial) ? -1 : 1];
>>> +int non_trivial_copy_constructor[__has_trivial_copy(struct NonTrivial) ? -1 : 1];
>>> +int non_trivial_move_constructor[__has_trivial_move_constructor(struct NonTrivial) ? -1 : 1];
>>> +int non_trivial_constructor[__has_trivial_constructor(struct NonTrivial) ? -1 : 1];
>>> +int non_trivial_destructor[__has_trivial_destructor(struct NonTrivial) ? -1 : 1];
>>>
>>>
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>>>
>>
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