https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78830
Piotr Nycz <piotrwn1 at gmail dot com> changed:
What |Removed |Added
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CC| |piotrwn1 at gmail dot com
--- Comment #5 from Piotr Nycz <piotrwn1 at gmail dot com> ---
Still not "enhanced" (gcc9).
CLANG with its std-lib correctly (IMO) does not compile it.
I understand this is UB - but implementation might suggest it is checked that
iterator is biderectional (at least ) but this check has no effect.
```
template<typename _BidirectionalIterator>
inline _BidirectionalIterator
prev(_BidirectionalIterator __x, typename
iterator_traits<_BidirectionalIterator>::difference_type __n = 1)
{
// concept requirements
__glibcxx_function_requires(_BidirectionalIteratorConcept<
_BidirectionalIterator>)
std::advance(__x, -__n);
return __x;
}
```
it is very troublesome to realize that there is something wrong here - when you
have UB="very long time consuming loop (LONG_MAX iteration probably)"
Is there anything that can be done to increase importance of this enhancement?
