[boost] Result of boost::split against empty string changed in post-1.45 release

Subject: [boost] Result of boost::split against empty string changed in post-1.45 release
From: Mateusz Loskot (mateusz_at_[hidden])
Date: 2012-06-11 10:58:40

Hi,

I have a simple program runs boost::split against empty string.
I'm testing with Boost 1.45 and later versions like 1.46 or 1.49.
As stated in the // comment below, there is difference in behaviour
depending on the Boost version:

// https://gist.github.com/2910461
#include <cassert>
#include <string>
#include <vector>
#include <boost/algorithm/string/split.hpp>
#include <boost/algorithm/string/classification.hpp>

int main(int argc, wchar_t* argv[])
{
    std::wstring s;
    std::vector<std::wstring> a;

    assert(s.empty());
    boost::split(a, s, boost::is_any_of(L", "), boost::token_compress_on);
    // Boost 1.45:  true
    // Boost 1.46+: false
    //   Assertion failed: s.empty() == a.empty(), file
boost_split_empty_string.cpp, line 16
    assert(s.empty() == a.empty());
    return 0;
}

IMHO, the behaviour exposed in newer versions is a bug.
Could anyone shed light on what happened in post-1.46?

Best regards,
-- 
Mateusz Loskot, http://mateusz.loskot.net