https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60519
--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
I was thinking we'd add a new macro to <debug/macros.h>
#define __glibcxx_check_strict_weak_order(_First,_Last,_Pred) \
_GLIBCXX_DEBUG_VERIFY(_First==_Last || !_Pred(*_First, *_First), \
_M_message(__gnu_debug::__msg_strict_weak_order))
(with accompanying __msg_strict_weak_order message)
Then simply add that where appropriate:
--- bits/stl_algo.h.orig 2015-04-11 13:58:05.253760716 +0100
+++ bits/stl_algo.h 2015-04-11 13:58:11.483766861 +0100
@@ -4725,6 +4725,7 @@
typename iterator_traits<_RandomAccessIterator>::value_type,
typename iterator_traits<_RandomAccessIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);
+ __glibcxx_check_strict_weak_order(__first, __last, __comp);
std::__sort(__first, __last,
__gnu_cxx::__ops::__iter_comp_iter(__comp));
}
We could also consider including the function name in the message, either
passed to the macro directly:
#define __glibcxx_check_strict_weak_order(_First,_Last,_Pred,_Where) \
_GLIBCXX_DEBUG_VERIFY(_First==_Last || !_Pred(*_First, *_First), \
_M_message(__gnu_debug::__msg_strict_weak_order)) \
._M_string(_Where)
or using __func__ or __PRETTY_FUNCTION__:
#define __glibcxx_check_strict_weak_order(_First,_Last,_Pred) \
_GLIBCXX_DEBUG_VERIFY(_First==_Last || !_Pred(*_First, *_First), \
_M_message(__gnu_debug::__msg_strict_weak_order)) \
._M_string(__func__)
This would allow something like:
/home/jwakely/gcc/5/include/c++/5.0.0/bits/stl_algo.h:4729:error:
comparison function passed to 'std::sort' is invalid because comp(x, x)
returns true (the function must define a Strict Weak Ordering, so must be
irreflexive).
Aborted (core dumped)
If the checks are added in _Iter_comp_iter we lost the ability to include the
location string in the output.
