Opened 6 years ago

Last modified 4 years ago

#7538 new Bugs

boost::spirit::istream_iterator does not handle incrememt correctly at the end

Reported by: zhuo.qiang@… Owned by: Joel de Guzman
Milestone: To Be Determined Component: spirit
Version: Boost 1.52.0 Severity: Showstopper
Keywords: spirit, istream_iterator, multi_pass Cc:

Description

boost::spirit::istream_iterator (or its super class multi_pass )does not handle incrememt correctly at the end position. One more end char will be yielded which is incorrect:

#include <sstream>
#include <boost/spirit/include/support_istream_iterator.hpp>
#include <boost/test/minimal.hpp>

int test_main(int, char*[])
{
    std::istringstream in("12");
    boost::spirit::istream_iterator it(in), end;

    BOOST_CHECK(*it++ == '1');
    BOOST_CHECK(*it++ == '2');

    // it should be end now, however it failed
    BOOST_CHECK(it == end); // !failed here
    // and yield the last char once more
    BOOST_CHECK(*it != '2'); // !failed here

    // only after another dereference will it really equal to end
    BOOST_CHECK(it == end);

    return 0;
}

The output is:

test.cpp(14): test it == end failed in function: 'int test_main(int, char **)'
test.cpp(16): test *it != '2' failed in function: 'int test_main(int, char **)'

**** 2 errors detected

#6750 may be a duplicated issue.

Reproducable under:

  • Apple clang version 4.1 (tags/Apple/clang-421.11.65) (based on LLVM 3.1svn)
  • Target: x86_64-apple-darwin12.2.0
  • With C++ 11 turn on: "-std=c++11 -stdlib=libc++"
  • Boost 1.52 and Boost Trunk rev.81030

Change History (2)

comment:1 Changed 4 years ago by code@…

I would mark this as rejected (or similar). I tried this with:

Apple LLVM version 6.0 (clang-600.0.51) (based on LLVM 3.5svn)
Target: x86_64-apple-darwin13.4.0
Thread model: posix

and only the BOOST_CHECK(*it != '2'); check failed. However, thats undefined iterator behavior since the iterator currnetly equals the end. So I'm not sure what caused this, but it doesn't show up on newer clang-Apple builds.

comment:2 Changed 4 years ago by code@…

I forgot to mention that I was testing against the develop branch of spirit, everything else in boost was the current master branch. The last commit was for spirit was 850c71a3d78665359911a15911cf263763087eff.

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