[PATCH] PR77990 refactor unique_ptr to encapsulate tuple

[Jonathan Wakely]

On 17/10/16 14:37 +0100, Jonathan Wakely wrote:
>We are incorrectly requiring unique_ptr deleters to be copyable here:
>
>     explicit
>     unique_ptr(pointer __p) noexcept
>     : _M_t(__p, deleter_type())
>     { }
>
>We could just do:
>
>     explicit
>     unique_ptr(pointer __p) noexcept
>     : _M_t()
>     { std::get<0>(_M_t) = __p; }
>
>But having to deal directly with the std::tuple inside unique_ptr has
>been bothering me for some time. The tuple is used so we get the empty
>base-class optimisation for the deleter, but that implementation
>detail
>
>This patch refactors unique_ptr to put the std::tuple member into a
>new type which provides named accessors for the tuple elements, so we
>can stop using get<0> and get<1>. That new type can also provide a
>single-argument constructor to fix the copyable requirement for
>deleters. This also removes the code for deducing the pointer type
>which is duplciated in unique_ptr and unique_ptr<T[], D>, and while in
>the neighbourhood I changed it from old-school SFINAE using overloaded
>functions to the new hotness with __void_t<>.
>
>I intend to commit this to trunk, but on the branches I'll just fix
>the constructor as shown above, as it's a smaller change.
>
>
>	PR libstdc++/77990
>	* include/bits/unique_ptr.h (__uniq_ptr_impl): New type to
>	encapsulate implementation details.
>	(unique_ptr::unique_ptr(_Up)): Don't copy deleter object.
>	(unique_ptr::get, unique_ptr::get_deleter, unique_ptr::release):
>	Call member functions of implementation object.
>	(unique_ptr<T[], D>): Likewise.
>	* python/libstdcxx/v6/printers.py (UniquePointerPrinter): Adjust for
>	new implementation.
>	* python/libstdcxx/v6/xmethods.py (UniquePtrGetWorker): Likewise.
>	* testsuite/20_util/unique_ptr/assign/48635_neg.cc: Adjust dg-error
>	lines.
>	* testsuite/20_util/unique_ptr/assign/cv_qual.cc: Likewise.
>	* testsuite/20_util/unique_ptr/cons/cv_qual.cc: Likewise.
>	* testsuite/20_util/unique_ptr/cons/77990.cc: New test.
>
>Tested powerpc64le-linux.

Committed to trunk. Here's the smaller patch I'm committing to the
branches.


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