Re: [patch] add __is_final trait to fix libstdc++/51365

[Jonathan Wakely <jwakely dot gcc at gmail dot com>]

ping

On 3 December 2011 12:04, Jonathan Wakely wrote:
> On 3 December 2011 12:00, Jonathan Wakely wrote:
>> This implements a new C++ trait, __is_final, to query the 'final'
>> specifier that 4.7 supports. The trait is needed for the library so we
>> can detect when it's not possible to derive from a type in order to
>> exploit the empty base-class optimisation. ?This affects all
>> containers, std::shared_ptr, std::future, std::tuple and anywhere else
>> that tries to use the EBO. ?It's not a C++11-only problem because we
>> support __final in c++98 mode. ?See PR libstdc++/51365 for examples of
>> programs using final classes that cause problems in libstdc++ and for
>> patches to the library that use this trait to solve the problems.
>>
>> I originally thought about naming this __is_final_class, which would
>> allow a possible __is_final_function in future, but I think
>> __is_final(type) is pretty clear. ?There is a proposal to add
>> __is_final to Clang with the same spelling and semantics.
>>
>> Tested x86_64-linux, ok for trunk?
>>
>> c-family/ChangeLog:
>>
>> ? ? ? ?* c-common.c (RID_IS_FINAL): Add.
>> ? ? ? ?* c-common.h (RID_IS_FINAL): Add.
>>
>> cp/ChangeLog:
>>
>> ? ? ? ?* cp-tree.h (CPTK_IS_FINAL): Add.
>> ? ? ? ?* parser.c (cp_parser_translation_unit): Handle RID_IS_FINAL.
>> ? ? ? ?(cp_parser_primary_expression, cp_parser_trait_expr): Likewise.
>> ? ? ? ?* semantics.c (trait_expr_value, finish_trait_expr): Handle
>> ? ? ? ?CPTK_IS_FINAL.
>> ? ? ? ?* cxx-pretty-print.c (pp_cxx_trait_expression): Likewise.
>>
>> ChangeLog:
>>
>> ? ? ? ?* doc/extend.texi (Type Traits): Add __is_final.
>>
>> testsuite/ChangeLog:
>>
>> ? ? ? ?* g++.dg/ext/is_final.C: New.
>

Attachment: 51365-fe.txt
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