[Bug c++/55918] New: Stack partially unwound when noexcept causes call to std::terminate

["tobias at ringis dot se" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55918

             Bug #: 55918
           Summary: Stack partially unwound when noexcept causes call to
                    std::terminate
    Classification: Unclassified
           Product: gcc
           Version: 4.7.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: tobias@ringis.se


Created attachment 29123
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=29123
Test program to illustrate the problem

When a noexcept function is "violated", std::terminate is called.  While the
standard allows for the stack to be fully unwound, partially unwound, or not
unwound at all, it is impossible to find the location where the exception was
thrown, unless the stack is left unwound.

GCC currently leaves the stack unwound in most cases, but in a very common
case, which is illustrated by the attached example program, the stack is
partially unwound.

If the noexcept is removed to allow the exception to propagate all the way past
main, std::terminate is called with the stack fully unwound, so it seems that
GCC is able to do what I want. It would be highly desirable for the noexcept
case to work in the same way as the unhandled exception case.

# g++ -std=c++0x -g tmp3.cpp
# gdb a.out
[...]
(gdb) bt
#0  0x000000318f036285 in raise () from /lib64/libc.so.6
#1  0x000000318f037b9b in abort () from /lib64/libc.so.6
#2  0x00000031964bbc5d in __gnu_cxx::__verbose_terminate_handler() ()
   from /usr/lib64/libstdc++.so.6
#3  0x00000031964b9e16 in ?? () from /usr/lib64/libstdc++.so.6
#4  0x00000031964b8e49 in ?? () from /usr/lib64/libstdc++.so.6
#5  0x00000031964b973d in __gxx_personality_v0 ()
   from /usr/lib64/libstdc++.so.6
#6  0x000000319000f6fb in ?? () from /lib64/libgcc_s.so.1
#7  0x000000319000fb58 in _Unwind_Resume () from /lib64/libgcc_s.so.1
#8  0x0000000000400911 in level2 () at tmp3.cpp:16
#9  0x000000000040091a in level1 () at tmp3.cpp:20
#10 0x0000000000400925 in main () at tmp3.cpp:24

As you can see, bad_guy is not in the backtrace.

There are two simple modifications that makes the backtrace complete. The first
is to remove the noexcept from level1, and the second is to remove the Foo
declaration in level2 (or delete Foo's destructor).