Re: [boost] Boost and auto_ptr (was Boost 1.60.0 beta 1...)

On 11 November 2015 at 22:42, Nevin Liber wrote:

On 11 November 2015 at 15:08, Jonathan Wakely wrote:

...

That doesn't mean implementors have to stop providing it, it only means it is no longer defined by the standard.

I'm not convinced they can.

Quoting [namespace.std]: "The behavior of a C++ program is undefined if it adds declarations or definitions to namespace std or to a namespace within namespace std unless otherwise specified."

And there is no wording in diff.cpp14.depr] which otherwise specifies it.

Or does this fall under it being UB, so vendors can define the behavior however they like? (Seems kind of wrong because we have a UB detector [aka constexpr] with defined semantics and are looking to define more of what happens with UB [contracts], but I digress...)

P005R2 proposes a new clause that allows implementations to keep using names that used to be in the standard: 17.6.4.3.x Zombie names [zombie.names] In namespace std, the following names are reserved for previous standardization: auto_ptr, bind1st, bind2nd, binder1st, binder2nd, mem_fun, mem_fun_ref, mem_fun_t,mem_fun1_t, mem_fun_ref_t, mem_fun1_ref_t, const_mem_fun_t, const_mem_fun1_t, const_mem_fun_ref_t, const_mem_fun1_ref_t, not1, not2, unary_negate,binary_negate, ptr_fun, pointer_to_unary_function, pointer_to_binary_function, random_shuffle, unary_function, and binary_function. It is unspecified whether function objects in the C++ standard library additionally provide the following typedefs: result_type, argument_type, first_argument_type, andsecond_argument_type.