[
https://issues.apache.org/jira/browse/STDCXX-643?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12582529#action_12582529
]
vitek edited comment on STDCXX-643 at 3/27/08 12:34 AM:
---------------------------------------------------------------
I've already suggested that we try to determine, at configuration time, the
size and layout of the exception classes so that we can emulate them. If we
don't go that far, we should at least add something that will check that the
sizes match up and force the library to not compile if they don't. Something
like this...
{noformat}
// looking for runtime library exceptions
#include <exception>
#include <typeinfo>
#include <stdio.h>
template <class T>
void run_test (const char* s)
{
printf ("#define %-18s %u\n", s, sizeof (T));
}
int main ()
{
#define TEST(s,t) run_test<t>(#s)
TEST (_RWSTD_EXCEPTION_SIZE , std::exception);
TEST (_RWSTD_BAD_ALLOC_SIZE , std::bad_alloc);
TEST (_RWSTD_BAD_CAST_SIZE , std::bad_cast);
TEST (_RWSTD_BAD_EXCDEPTION_SIZE, std::bad_exception);
TEST (_RWSTD_BAD_TYPEID_SIZE , std::bad_typeid);
return 0;
}
{noformat}
Then we would put something like this near the top of exception.cpp
{noformat}
_RWSTD_NAMESPACE (__rw) {
static void
__rw_exception_compile_asserts ()
{
#define TEST(s,t) _RWSTD_COMPILE_ASSERT (s == sizeof (t))
TEST (_RWSTD_EXCEPTION_SIZE , std::exception);
TEST (_RWSTD_BAD_ALLOC_SIZE , std::bad_alloc);
TEST (_RWSTD_BAD_CAST_SIZE , std::bad_cast);
TEST (_RWSTD_BAD_EXCDEPTION_SIZE, std::bad_exception);
TEST (_RWSTD_BAD_TYPEID_SIZE , std::bad_typeid);
#undef TEST
}
} // namespace rw
{noformat}
was (Author: vitek):
I suggested trying to determine the size of the runtime library
std::exception object and then mimic that in our implementation, but that was
shot down. If we aren't going to try to determine the size/layout at compile
time, then at the very least we need to do something to prevent this from
happening on other platforms.
One option would be to add a test to verifiy this problem isn't happening. A
normal regression type test would work, but might not be in-your-face enough to
ensure that it is fixed before a release. I'm thinking that a compile assert in
<exception> and a configuration test to collect the size of of the exception
object used by the runtime library is one way.
{noformat}
// looking for runtime library exceptions
#include <exception>
#include <typeinfo>
#include <stdio.h>
template <class T>
void run_test (const char* s)
{
printf ("#define %-18s %u\n", s, sizeof (T));
}
int main ()
{
#define TEST(s,t) run_test<t>(s)
// bad_alloc, bad_cast, bad_exception, and bad_typeid
TEST ("_RWSTD_EXCEPTION_SIZE" , std::exception);
TEST ("_RWSTD_BAD_ALLOC_SIZE" , std::bad_alloc);
TEST ("_RWSTD_BAD_CAST_SIZE" , std::bad_cast);
TEST ("_RWSTD_BAD_EXCDEPTION_SIZE", std::bad_exception);
TEST ("_RWSTD_BAD_TYPEID_SIZE" , std::bad_typeid);
return 0;
}
{noformat}
Then, somewhere near the bottom of our <exception> header...
{noformat}
_RWSTD_COMPILE_ASSERT (_RWSTD_EXCEPTION_SIZE == sizeof (std::exception))
_RWSTD_COMPILE_ASSERT (_RWSTD_EXCEPTION_SIZE == sizeof (std::exception))
> std::exception declaration incompatible with implementation provided by
> runtime library on AIX
> ----------------------------------------------------------------------------------------------
>
> Key: STDCXX-643
> URL: https://issues.apache.org/jira/browse/STDCXX-643
> Project: C++ Standard Library
> Issue Type: Bug
> Components: 19. Diagnostics
> Affects Versions: 4.2.0
> Environment: AIX
> Reporter: Travis Vitek
> Fix For: 5.0
>
>
> A description of the problem is available here.
> http://www.nabble.com/19.exceptions.mt.cpp-fails-on-AIX-tf4738595.html
> Essentially we need to add a const char* member to std::exception for AIX.
> Unfortunately the fix is a binary incompatible with previous versions of
> stdcxx.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
