How can I debug Boost by viewing the file after precompilation? - c++

Question

I'm getting a very weird bug when defining a test suite with boost like this:
BOOST_AUTO_TEST_SUITE(zerocoin_implementation_tests)
The error looks like this:
terminate called after throwing an instance of 'std::length_error'
what(): basic_string::_M_create
Here's the relevant backtrace:
#5 0x00007ffff5ce6fe8 in __cxa_throw () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#6 0x00007ffff5ce2875 in ?? () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#7 0x00007ffff5d7c949 in std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_create(unsigned long&, unsigned long) ()
from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#8 0x00007ffff70afe15 in boost::unit_test::test_unit::test_unit(boost::unit_test::basic_cstring<char const>, boost::unit_test::basic_cstring<char const>, unsigned long, boost::unit_test::test_unit_type) () from /usr/lib/x86_64-linux-gnu/libboost_unit_test_framework.so.1.65.1
#9 0x00007ffff70b0456 in boost::unit_test::test_suite::test_suite(boost::unit_test::basic_cstring<char const>, boost::unit_test::basic_cstring<char const>, unsigned long) () from /usr/lib/x86_64-linux-gnu/libboost_unit_test_framework.so.1.65.1
#10 0x00007ffff70b0612 in boost::unit_test::ut_detail::auto_test_unit_registrar::auto_test_unit_registrar(boost::unit_test::basic_cstring<char const>, boost::unit_test::basic_cstring<char const>, unsigned long, boost::unit_test::decorator::collector&) ()
from /usr/lib/x86_64-linux-gnu/libboost_unit_test_framework.so.1.65.1
From what I can tell, this has to do with Boost trying to create a max length string. I'd like to see exactly what it is doing. What's the best way of expanding boost macros to see the pre-compiled version?
Side Note
Weirdly, if I change the line very slightly to:
BOOST_AUTO_TEST_SUITE(zerocsoin_implementation_tests)
I get the following error:
terminate called after throwing an instance of 'std::bad_alloc'
what(): std::bad_alloc
And backtrace:
#6 0x00007ffff5ce7594 in operator new(unsigned long) () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#7 0x00007ffff70afe15 in boost::unit_test::test_unit::test_unit(boost::unit_test::basic_cstring<char const>, boost::unit_test::basic_cstring<char const>, unsigned long, boost::unit_test::test_unit_type) () from /usr/lib/x86_64-linux-gnu/libboost_unit_test_framework.so.1.65.1
#8 0x00007ffff70b0456 in boost::unit_test::test_suite::test_suite(boost::unit_test::basic_cstring<char const>, boost::unit_test::basic_cstring<char const>, unsigned long) () from /usr/lib/x86_64-linux-gnu/libboost_unit_test_framework.so.1.65.1
#9 0x00007ffff70b0612 in boost::unit_test::ut_detail::auto_test_unit_registrar::auto_test_unit_registrar(boost::unit_test::basic_cstring<char const>, boost::unit_test::basic_cstring<char const>, unsigned long, boost::unit_test::decorator::collector&) ()
from /usr/lib/x86_64-linux-gnu/libboost_unit_test_framework.so.1.65.1
The source code for the file (and the rest of the project) can be found here: https://github.com/phoreproject/Phore/blob/segwit/src/test/zerocoin_implementation_tests.cpp
Diff that probably caused the bug: https://github.com/phoreproject/phore/compare/master...segwit#diff-bb4f094cc636d668944ed6af9b72c0d9

Answer 1

Two approaches:
Exception Breakpoints
Just start the test in the debugger and catch the exception.
In gdb you could do
(gdb) catch throw
Catchpoint 2 (throw)
which act like a general breakpoint. Visual Studio has a Manage Exeptions dialog.¹
Boost Test Breakpoints
For debugging Boost Test I like to set a break at the test_method member of the specific test case class I want to break at. E.g. with a test_runner that has a few nested suites like:
./test_runner --list_content
import*
utility*
xml*
xml_utilities*
child_text_test*
loggable_xml_path_test*
And we run these 3 tests like:
./test_runner -t import/utility/xml
Running 3 test cases...
*** No errors detected
To debug them with gdb I'd do
gdb ./test_runner
start -t import/utility/xml
Which stops at main, then I type:
break import::utility::xml
Auto completion helps, so to get the exact names, you can just pick from the completions:
xml
xml::as_element(xmlpp::Node const&)
xml::attr_value(xmlpp::Element const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)
xml::attr_value(xmlpp::Node const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)
xml::child_text[abi:cxx11](xmlpp::Element const&, char const*)
xml::child_text_test
xml::child_text_test::test_method()
xml::child_text_test_invoker()
xml::child_text_test_registrar62
xml::end_suite94_registrar94
xml::first_child(xmlpp::Element const&, char const*)
xml::get_content[abi:cxx11](xmlpp::Element const&)
xml::get_content[abi:cxx11](xmlpp::Node const*)
xml::is_attr_value(xmlpp::Node const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)
xml::loggable_xml_path[abi:cxx11](xmlpp::Node const&)
xml::loggable_xml_path_test
xml::loggable_xml_path_test::test_method()
xml::loggable_xml_path_test_invoker()
xml::loggable_xml_path_test_registrar77
xml::trace_xml(xmlpp::Element const&, LogSource::LogTx)
xml::trace_xml_formatted(xmlpp::Element const&, LogSource::LogTx)
xml::xml_registrar20
xml::xml_utilities
xml::xml_utilities::test_method()
xml::xml_utilities_invoker()
xml::xml_utilities_registrar22
Pick the ones named test_method(), e.g.
break import::utility::xml::child_text_test::test_method()
Breakpoint 2 at 0x730762: file /path/src/import/utility/xml_tests.cpp, line 62.
Now you can continue execution and the debugger will automatic pause execution at the start of your unit test.
¹ see also
Make Visual Studio break on User (std::exception) Exceptions?
How do I make VC++'s debugger break on exceptions?