Runtime error message when using boost::wave

Question

I get the following runtime error message

terminate called after throwing an instance of 'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::wave::cpplexer::lexing_exception> >'
  what():  boost::wave::lexing_exception

When I am trying to run the following code:

#include <vector>
#include <algorithm>
#include <boost/wave.hpp>
#include <boost/wave/cpplexer/cpp_lex_token.hpp>
#include <boost/wave/cpplexer/cpp_lex_iterator.hpp>

std::string strip_comments(std::string const& input)
{
    std::string output;
    typedef boost::wave::cpplexer::lex_token<> token_type;
    typedef boost::wave::cpplexer::lex_iterator<token_type> lexer_type;
    typedef token_type::position_type position_type;

    position_type pos;

    lexer_type it = lexer_type(input.begin(), input.end(), pos, 
        boost::wave::language_support(
            boost::wave::support_cpp|boost::wave::support_option_long_long));
    lexer_type end = lexer_type();

    for (;it != end; ++it)
    {
        if (*it != boost::wave::T_CCOMMENT
         && *it != boost::wave::T_CPPCOMMENT)
        {
            output += std::string(it->get_value().begin(), it->get_value().end());
        }
    }
    return output;
}

int main()
{
    std::string text="aaa bbb /*cccc*/ ddd // eee";
    std::cout<<strip_comments(text)<<std::endl;
    return 0;
}

I use gcc compiler:

g++ -std=c++11 test.cpp -o test -lboost_wave -lboost_system

This code is supposed to remove C++ comments from a text specified by // and /* ... */.

Here is gdb backtrack:

GNU gdb (Ubuntu 7.7.1-0ubuntu5~14.04.2) 7.7.1
Copyright (C) 2014 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from a.out...done.
[New LWP 10573]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Core was generated by `./a.out'.
Program terminated with signal SIGABRT, Aborted.
#0  0x00007ff38fe96cc9 in __GI_raise (sig=sig@entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:56
56  ../nptl/sysdeps/unix/sysv/linux/raise.c: No such file or directory.
(gdb) bt
#0  0x00007ff38fe96cc9 in __GI_raise (sig=sig@entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:56
#1  0x00007ff38fe9a0d8 in __GI_abort () at abort.c:89
#2  0x00007ff3904cb78d in __gnu_cxx::__verbose_terminate_handler() () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#3  0x00007ff3904c97f6 in ?? () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#4  0x00007ff3904c9841 in std::terminate() () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#5  0x00007ff3904c9a58 in __cxa_throw () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#6  0x00007ff390a9e063 in void boost::throw_exception<boost::wave::cpplexer::lexing_exception>(boost::wave::cpplexer::lexing_exception const&)
    () from /usr/lib/x86_64-linux-gnu/libboost_wave.so.1.54.0
#7  0x00007ff390aa3a5e in boost::wave::cpplexer::re2clex::lexer<__gnu_cxx::__normal_iterator<char const*, std::string>, boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > >, boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >::report_error(boost::wave::cpplexer::re2clex::Scanner const*, int, char const*, ...) ()
   from /usr/lib/x86_64-linux-gnu/libboost_wave.so.1.54.0
#8  0x00007ff390aaf2f0 in boost::wave::cpplexer::re2clex::scan(boost::wave::cpplexer::re2clex::Scanner*) ()
   from /usr/lib/x86_64-linux-gnu/libboost_wave.so.1.54.0
#9  0x00007ff390aa4329 in boost::wave::cpplexer::re2clex::lexer<__gnu_cxx::__normal_iterator<char const*, std::string>, boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > >, boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >::get(boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > >&) () from /usr/lib/x86_64-linux-gnu/libboost_wave.so.1.54.0
#10 0x000000000040a3b8 in boost::wave::cpplexer::impl::lex_iterator_functor_shim<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >::get_next<boost::spirit::multi_pass<std::pair<boost::wave::cpplexer::impl::lex_iterator_functor_shim<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >, boost::wave::cpplexer::lex_input_interface<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >*>, boost::spirit::iterator_policies::default_policy<boost::spirit::iterator_policies::ref_counted, boost::spirit::iterator_policies::no_check, boost::spirit::iterator_policies::split_functor_input, boost::spirit::iterator_policies::split_std_deque> > > (mp=..., result=...)
    at /usr/include/boost/wave/cpplexer/cpp_lex_iterator.hpp:80
#11 0x0000000000409efb in boost::spirit::iterator_policies::split_functor_input::unique<std::pair<boost::wave::cpplexer::impl::lex_iterator_functor_shim<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >, boost::wave::cpplexer::lex_input_interface<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >*>, true>::advance_input<boost::spirit::multi_pass<std::pair<boost::wave::cpplexer::impl::lex_iterator_functor_shim<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util---Type <return> to continue, or q <return> to quit---
::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >, boost::wave::cpplexer::lex_input_interface<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >*>, boost::spirit::iterator_policies::default_policy<boost::spirit::iterator_policies::ref_counted, boost::spirit::iterator_policies::no_check, boost::spirit::iterator_policies::split_functor_input, boost::spirit::iterator_policies::split_std_deque> > > (mp=...)
    at /usr/include/boost/spirit/home/support/iterators/detail/split_functor_input_policy.hpp:91
#12 0x000000000040969f in boost::spirit::iterator_policies::multi_pass_unique<std::pair<boost::wave::cpplexer::impl::lex_iterator_functor_shim<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >, boost::wave::cpplexer::lex_input_interface<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >*>, boost::spirit::iterator_policies::ref_counted::unique, boost::spirit::iterator_policies::no_check::unique, boost::spirit::iterator_policies::split_functor_input::unique<std::pair<boost::wave::cpplexer::impl::lex_iterator_functor_shim<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >, boost::wave::cpplexer::lex_input_interface<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >*>, true>, boost::spirit::iterator_policies::split_std_deque::unique<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >, true, true, true>::advance_input<boost::spirit::multi_pass<std::pair<boost::wave::cpplexer::impl::lex_iterator_functor_shim<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >, boost::wave::cpplexer::lex_input_interface<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >*>, boost::spirit::iterator_policies::default_policy<boost::spirit::iterator_policies::ref_counted, boost::spirit::iterator_policies::no_check, boost::spirit::iterator_policies::split_functor_input, boost::spirit::iterator_policies::split_std_deque> > > (mp=...)
    at /usr/include/boost/spirit/home/support/iterators/detail/combine_policies.hpp:441
#13 0x0000000000408d7c in boost::spirit::iterator_policies::split_std_deque::unique<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >::increment<boost::spirit::multi_pass<std::pair<boost::wave::cpplexer::impl::lex_iterator_functor_shim<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >, boost::wave::cpplexer::lex_input_interface<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >*>, boost::spirit::iterator_policies::default_policy<boost::spirit::iterator_policies::ref_counted, boost::spirit::iterator_policies::no_check, boost::spirit::iterator_policies::split_functor_input, boost::spirit::iterator_policies::split_std_deque> > > (mp=...)
    at /usr/include/boost/spirit/home/support/iterators/detail/split_std_deque_policy.hpp:107
#14 0x0000000000408450 in boost::spirit::multi_pass<std::pair<boost::wave::cpplexer::impl::lex_iterator_functor_shim<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >, boost::wave::cpplexer::lex_input_interface<boost:---Type <return> to continue, or q <return> to quit---
:wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >*>, boost::spirit::iterator_policies::default_policy<boost::spirit::iterator_policies::ref_counted, boost::spirit::iterator_policies::no_check, boost::spirit::iterator_policies::split_functor_input, boost::spirit::iterator_policies::split_std_deque> >::operator++ (this=0x7fff7d8f66e0)
    at /usr/include/boost/spirit/home/support/iterators/multi_pass.hpp:119
#15 0x000000000040680e in strip_comments (input="aaa bbb /*cccc*/ ddd // eee") at test.cpp:23
#16 0x0000000000406927 in main () at test.cpp:37

Update

Thanks to jpo38 for his comment. I initialized the pos by

position_type pos(0);

And the previous runtime error fixed. Now, I got a different runtime error:

#0  0x0000000000406ff8 in std::char_traits<char>::length (__s=0x0) at /usr/include/c++/4.9/bits/char_traits.h:263
#1  0x0000000000408504 in boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> >::flex_string (this=0x7ffee3d536a0, s=0x0, a=...)
    at /usr/include/boost/wave/util/flex_string.hpp:1502
#2  0x000000000040693f in strip_comments (input="aaa bbb /*cccc*/ ddd // eee") at test.cpp:16
#3  0x0000000000406bf0 in main () at test.cpp:37

I catched the general exception and tried to show it by:

std::cout << "Error occurred: " << ex.what() << std::endl;

while it was not successful.

Answer 1

boost love exception-programming. Meaning exceptions are used to raise errors and warnings....I hate that, but you need to accept it if you use those fantastic c++ libraries. Exceptions lead to "crash" if you don't be careful and catch them, like that:

std::string strip_comments(std::string const& input)
{
    std::string output;
    typedef boost::wave::cpplexer::lex_token<> token_type;
    typedef boost::wave::cpplexer::lex_iterator<token_type> lexer_type;
    typedef token_type::position_type position_type;

    boost::wave::util::file_position_type current_position; // for error reporting

    try
    {
        position_type pos;

        lexer_type it = lexer_type(input.begin(), input.end(), pos, 
            boost::wave::language_support(
            boost::wave::support_cpp|boost::wave::support_option_long_long));
    lexer_type end = lexer_type();

        for (;it != end; ++it)
        {
            current_position = (*it).get_position();  // for error reporting

            if (*it != boost::wave::T_CCOMMENT
             && *it != boost::wave::T_CPPCOMMENT)
            {
                output += std::string(it->get_value().begin(), it->get_value().end());
            }
        }            
    }
    catch (boost::wave::cpplexer::lexing_exception const& e) {
        // some lexing error
        std::cerr
            << e.file_name() << "(" << e.line_no() << "): "
            << e.description() << std::endl;
    }
    catch (std::exception const& e) {
        // use last recognized token to retrieve the error position
        std::cerr
            << current_position.get_file()
            << "(" << current_position.get_line() << "): "
            << "exception caught: " << e.what()
            << std::endl;
    }
    catch (...) {
        // use last recognized token to retrieve the error position
        std::cerr
            << current_position.get_file()
            << "(" << current_position.get_line() << "): "
            << "unexpected exception caught." << std::endl;
    }  
    return output;
}

Then, instead of a "crash", you'll get this nice ans safe message:

(1): warning: generic lexer warning: Unterminated 'C++' style comment

You can see that, by not catching exception, a simple boost warning was transformed in a critical crash at your level ;-)

I'm not familiar with wave library, but adding a \n to the end of your string fixes the issue and then no error is reported anymore (by the way, it was actually just a warning):

Change main function text string to: std::string text="aaa bbb /*cccc*/ ddd // eee\n"; and the program will output aaa bbb ddd.

You can add this \n, but you may also rework the code to try/catch within the loop and then report but ignore warnings.

Note: The fact that boost::wave expects a EOL is probably related to this well known C++ warning (but it is really just a warning): "No newline at end of file" compiler warning