[Bug libstdc++/67085] priority queue should not copy comparators when calling push_heap and pop_heap

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67085

--- Comment #14 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Author: redi
Date: Thu Jan 19 23:07:52 2017
New Revision: 244656

URL: https://gcc.gnu.org/viewcvs?rev=244656&root=gcc&view=rev
Log:
PR67085 pass comparison functions by reference in heap algorithms

        PR libstdc++/67085
        * include/bits/predefined_ops.h (_Iter_less_val, _Val_less_iter): Add
        converting constructors from _Iter_less_iter.
        (_Iter_comp_val, _Val_comp_iter): Add converting constructors from
        _Iter_comp_iter.
        (__iter_comp_val(_Iter_comp_iter<C>): Use converting constructor.
        (__val_comp_iter(_Iter_comp_iter<C>): Likewise.
        * include/bits/stl_heap.h (__is_heap_until, __push_heap, __pop_heap)
        (__make_heap, __sort_heap): Change _Compare parameters to references.
        (__is_heap, push_heap, __adjust_heap, __pop_heap, pop_heap)
        (__make_heap, make_heap, sort_heap, is_heap_until): Pass comparison
        functions as lvalues.
        (is_heap): Call __is_heap_until directly to avoid copying __comp.
        * testsuite/23_containers/priority_queue/67085.cc: Adjust test to
        count copies during construction with empty sequence.

Modified:
    trunk/libstdc++-v3/ChangeLog
    trunk/libstdc++-v3/include/bits/predefined_ops.h
    trunk/libstdc++-v3/include/bits/stl_heap.h
    trunk/libstdc++-v3/testsuite/23_containers/priority_queue/67085.cc