Re: [PATCH] libstdc++: Fix exceptions being generated when compiling with -fno-exceptions

[Federico Lenarduzzi <federico dot lenarduzzi at tallertechnologies dot com>]

Thanks for comments.

I forgot to mention that this change came of working with the target
fragment file
for the generation of libraries with and without exceptions. After that, the
choice of the multilibs with or without exceptions will depend on the use the
-fno-excepcions flag at the moment of compilation of an application.

As you mentioned in the thread linked to this new flag, have the option
--disable-libstdcxx-verbose is very useful, especially in embedded software
development.

Now, If I have the below case: I'm developing two applications, the first not
want to have exception handling, therefore I would like to have the library
without verbose_terminate_handler () function and the second application handles
exceptions, with which I would like to have the library with the function
mentioned above.

To achieve this, I should have two copies compiled in different ways or
recompile all gcc to enable or disable this function.

The idea of this patch is that using this function not depends from a
configuration
flag but depends of a flag which participates in the selection of the
correct multilib.

I think it could be discuss, I would like read some opinions and
comments about this.



2015-04-14 16:27 GMT-03:00 Jonathan Wakely <jwakely.gcc@gmail.com>:

> On 14 April 2015 at 16:17, Federico Lenarduzzi wrote:
> > When the libstdc++ is compiled, the compiler sets the std::terminate_handler function with __verbose_terminate_handler() or std::abort() depending on _GLIBCXX_HOSTED && _GLIBCXX_VERBOSE being true or false.
> >
> > However, even if we compile with -fno-exceptions, the compiler will use __verbose_terminate_handler(), which uses exceptions. Therefore, the library is not fully exception-free.
>
> I guess this makes sense, but you can just build with
> --disable-libstdcxx-verbose to have the same effect.
>
> > It also makes std::uncaught_exception() throw() return false if __EXCEPTIONS is not defined.
>
> This part seems like a good idea, but we'll also need to do it to the
> new uncaught_exceptions() function about to be added, so let's wait
> until that in committed first (which will be shortly after the 5.1
> release).
>
> The checks should use __cpp_exceptions not __EXCEPTIONS, see the current trunk.




-- 
Federico Lenarduzzi
Software Engineer

Taller Technologies Argentina
San Lorenzo 47, 3rd Floor, Office 5
Cordoba, Argentina
Phone: +54 351 4220701
Mobile: +54 358 4289083
Skype: federico.lenarduzzi1







-- 
Federico Lenarduzzi
Software Engineer

Taller Technologies Argentina
San Lorenzo 47, 3rd Floor, Office 5
Cordoba, Argentina
Phone: +54 351 4220701
Mobile: +54 358 4289083
Skype: federico.lenarduzzi1