I've discovered a problem with backtraces when using noexcept, but I
don't know if it's a bug, required behaviour, or if I'm missing
something. I'd appreciate a little guidance.
The problem is that when an exception is thrown and there's a "noexcept"
function earlier in the call stack, the backtrace is sometimes
incomplete, i.e. it ends before the throw location. Specifically, it
seems to end at the first function above the "noexcept" function that
has an object with a destructor in it.
It's probably easier to understand with an example:
class Foo
{
public:
Foo() { }
~Foo() { }
};
void bad_guy()
{
throw "die die die";
}
void level2()
{
Foo foo;
bad_guy();
}
void level1() noexcept
{
level2();
}
int main()
{
level1();
}
# 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 0x0000000000400722 in level2 () at tmp3.cpp:14
#9 0x000000000040072b in level1 () at tmp3.cpp:18
#10 0x0000000000400736 in main () at tmp3.cpp:22
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). I
really need the noexcept because in my real application, level1 is a
thread main function, which needs the noexcept, or I don't any call
stack below libstdc++'s thread caller, because it has a try/catch all
block to call terminate.
Should I file a bug report? I've tested 4.6.3, 4.7.2 and 4.8-20130106,
with identical results.
/Tobias
