[Boost-bugs] [Boost C++ Libraries] #11906: BOOST_TEST() violates expectations about expression lifetime

Subject: [Boost-bugs] [Boost C++ Libraries] #11906: BOOST_TEST() violates expectations about expression lifetime
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2016-01-12 21:57:06

#11906: BOOST_TEST() violates expectations about expression lifetime
------------------------------+---------------------
 Reporter:  bspencer@…        |      Owner:  rogeeff
     Type:  Bugs              |     Status:  new
Milestone:  To Be Determined  |  Component:  test
  Version:  Boost 1.59.0      |   Severity:  Problem
 Keywords:                    |
------------------------------+---------------------
 The new BOOST_TEST() macro is a step in a great direction.  However,
 because of how the macro expands to multiple expressions, it leads to
 simple checks performing undefined behaviour.

 For example, consider the following complete test program:

 {{{
 #define BOOST_TEST_MAIN
 #include <boost/test/included/unit_test.hpp>

 struct Object
 {
   Object()
     : m_value("A value for this string to have")
   {}

   const std::string &get() const
   { return m_value; }

 private:
   std::string m_value;
 };

 BOOST_AUTO_TEST_CASE(test)
 {
   BOOST_TEST(Object().get() == "check");
 }
 }}}

 This program fails because only a "const std::string &" is captured for
 the left-hand side of the test, and then, in a separate expression (in the
 expanded BOOST_TEST() macro), that reference is used to evaluate the
 expression.  This fails because the temporary Object has already been
 dereferenced.

 Compare to BOOST_CHECK() with the same content (or BOOST_CHECK_EQUAL()
 with a comma instead of "==").

 This kind of subtlety makes it difficult to write safe checks with
 BOOST_TEST().

 Example valgrind output from the above program:
 {{{
 ==24714== Invalid read of size 8
 ==24714==    at 0x4EF3C2E: std::string::compare(char const*) const (in
 /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.20)
 ==24714==    by 0x414160: operator==<char, std::char_traits<char>,
 std::allocator<char> > (basic_string.h:2540)
 ==24714==    by 0x414160: eval (assertion.hpp:162)
 ==24714==    by 0x414160: value (assertion.hpp:348)
 ==24714==    by 0x414160: evaluate (assertion.hpp:357)
 ==24714==    by 0x414160: test::test_method() (foo.cc:19)
 ==24714==    by 0x414529: test_invoker() (foo.cc:17)
 ==24714==    by 0x4294BA: operator() (function_template.hpp:771)
 ==24714==    by 0x4294BA: operator() (execution_monitor.ipp:1304)
 ==24714==    by 0x4294BA:
 boost::detail::function::function_obj_invoker0<boost::detail::forward,
 int>::invoke(boost::detail::function::function_buffer&)
 (function_template.hpp:138)
 ==24714==    by 0x40ABEC: operator() (function_template.hpp:771)
 ==24714==    by 0x40ABEC:
 do_invoke<boost::shared_ptr<boost::detail::translator_holder_base>,
 boost::function<int()> > (execution_monitor.ipp:281)
 ==24714==    by 0x40ABEC:
 boost::execution_monitor::catch_signals(boost::function<int ()> const&)
 (execution_monitor.ipp:870)
 ==24714==    by 0x40AC98:
 boost::execution_monitor::execute(boost::function<int ()> const&)
 (execution_monitor.ipp:1207)
 ==24714==    by 0x40B376:
 boost::execution_monitor::vexecute(boost::function<void ()> const&)
 (execution_monitor.ipp:1313)
 ==24714==    by 0x410F31:
 boost::unit_test::unit_test_monitor_t::execute_and_translate(boost::function<void
 ()> const&, unsigned int) (unit_test_monitor.ipp:46)
 ==24714==    by 0x43A332:
 boost::unit_test::framework::state::execute_test_tree(unsigned long,
 unsigned int) (framework.ipp:685)
 ==24714==    by 0x43A466:
 boost::unit_test::framework::state::execute_test_tree(unsigned long,
 unsigned int) (framework.ipp:636)
 ==24714==    by 0x41C4A1: boost::unit_test::framework::run(unsigned long,
 bool) (framework.ipp:1220)
 ==24714==    by 0x41C8AE:
 boost::unit_test::unit_test_main(boost::unit_test::test_suite* (*)(int,
 char**), int, char**) (unit_test_main.ipp:228)
 ==24714==  Address 0x5a11a50 is 0 bytes inside a block of size 56 free'd
 ==24714==    at 0x4C2A360: operator delete(void*) (in /usr/lib/valgrind
 /vgpreload_memcheck-amd64-linux.so)
 ==24714==    by 0x41433B: _M_dispose (lazy_ostream.hpp:35)
 ==24714==    by 0x41433B: ~basic_string (basic_string.h:547)
 ==24714==    by 0x41433B: ~Object (foo.cc:4)
 ==24714==    by 0x41433B: test::test_method() (foo.cc:19)
 ==24714==    by 0x414529: test_invoker() (foo.cc:17)
 ==24714==    by 0x4294BA: operator() (function_template.hpp:771)
 ==24714==    by 0x4294BA: operator() (execution_monitor.ipp:1304)
 ==24714==    by 0x4294BA:
 boost::detail::function::function_obj_invoker0<boost::detail::forward,
 int>::invoke(boost::detail::function::function_buffer&)
 (function_template.hpp:138)
 ==24714==    by 0x40ABEC: operator() (function_template.hpp:771)
 ==24714==    by 0x40ABEC:
 do_invoke<boost::shared_ptr<boost::detail::translator_holder_base>,
 boost::function<int()> > (execution_monitor.ipp:281)
 ==24714==    by 0x40ABEC:
 boost::execution_monitor::catch_signals(boost::function<int ()> const&)
 (execution_monitor.ipp:870)
 ==24714==    by 0x40AC98:
 boost::execution_monitor::execute(boost::function<int ()> const&)
 (execution_monitor.ipp:1207)
 ==24714==    by 0x40B376:
 boost::execution_monitor::vexecute(boost::function<void ()> const&)
 (execution_monitor.ipp:1313)
 ==24714==    by 0x410F31:
 boost::unit_test::unit_test_monitor_t::execute_and_translate(boost::function<void
 ()> const&, unsigned int) (unit_test_monitor.ipp:46)
 ==24714==    by 0x43A332:
 boost::unit_test::framework::state::execute_test_tree(unsigned long,
 unsigned int) (framework.ipp:685)
 ==24714==    by 0x43A466:
 boost::unit_test::framework::state::execute_test_tree(unsigned long,
 unsigned int) (framework.ipp:636)
 ==24714==    by 0x41C4A1: boost::unit_test::framework::run(unsigned long,
 bool) (framework.ipp:1220)
 ==24714==    by 0x41C8AE:
 boost::unit_test::unit_test_main(boost::unit_test::test_suite* (*)(int,
 char**), int, char**) (unit_test_main.ipp:228)
 }}}

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/11906>
Boost C++ Libraries <http://www.boost.org/>
Boost provides free peer-reviewed portable C++ source libraries.