Unable to use scn::scan with string_view under MSVC. about scnlib HOT 8 CLOSED

Maybe I forgot to pull updated code. The test passed. Everything works fine for now.

from scnlib.

It seems all the code should run correctly under Release mode.
But under Debug mode, whenever you operate an iterator with another one, such as

auto raw = "123456";
std::string_view s(raw);
std::string_view s(raw+2);
s.begin() - s2.begin();  // _STL_VERIFY fails:
/*
code in xstring:
    _NODISCARD constexpr difference_type operator-(const _String_view_iterator& _Right) const noexcept {
#if _ITERATOR_DEBUG_LEVEL >= 1
        _STL_VERIFY(_Mydata == _Right._Mydata && _Mysize == _Right._Mysize,
            "cannot subtract incompatible string_view iterators");
        return static_cast<difference_type>(_Myoff - _Right._Myoff);
#else // ^^^ _ITERATOR_DEBUG_LEVEL >= 1 ^^^ // vvv _ITERATOR_DEBUG_LEVEL == 0 vvv
        return _Myptr - _Right._Myptr;
#endif // _ITERATOR_DEBUG_LEVEL
    }

*/

MSVC will check if s and s2 points to the same buffer and have the same size. If not, exception is thrown.
Thus, the ranges intenally used by scn is not compatible with MSVC's std::string_view under Debug mode. Because write_return function will construct a new ranges(std::string_view), making all operators for iterator invalid.

from scnlib.

Aw bugger, it's those MSVC debug iterators again. I'll look into this on ~Monday, once I have access to a Windows PC.

from scnlib.

Fixed in 5b2eb91. Thanks for reporting!

from scnlib.

MSVC under Debug mode still not work.
The test string_view.cpp fails.

from scnlib.

It seems that under MSVC debug mode(_ITERATOR_DEBUG_LEVEL >=1), you must change the range recursively after calling write_return.

from scnlib.

How can I re-open this issue?
Or should I create a new issue?

from scnlib.

I can't get that assertion to fire on my Windows PC nor on Appveyor. Can you see if it does for you after 8b3ab27?

from scnlib.