Exception handling in Ada -> C++ call?

Exception handling in Ada -> C++ call?

[kevin.a.peterson]

Hi, I'm having problems with an Ada program I've been working on. This Ada program makes a call to a C++ library, and the C++ call has a try/catch block. I think my problem boils down to uncaught exceptions hanging on the c++ side hanging the program. This code demonstrates the issue:

Ex.C:
#include <stdexcept>
#include <iostream>
extern "C"
void tester(){
 try{
  throw 1;
 }
 catch(std::logic_error e){
 }
};

testada.adb:
with Ada.Text_Io;
procedure testada is
 procedure TestCpp;
 pragma import(C,TestCpp,"tester");
begin
 Ada.Text_Io.Put_Line("Calling TestCpp");
 TestCpp;
end testada;

When I build this and run testada, I get "terminate called after throwing an instance of 'int'," which I expect, however the application doesn't actually exit but spins a core to 100% usage until I kill it. Also interesting: If I replace the try block with

int x=5/0;

and ignore the compiler warning, the application correctly crashes with SIGFPE, however if I replace the try block with

std::cout << "WHY" << std::endl;
int x=5/0;

I receive "terminate called without an active exception" and the application hangs again until I kill it. Does anyone know the reason for this behaviour? 

I'm currently using GNAT Pro 6.0.2 with GCC 4.1.2 and running on RHEL6, although I've also tried the same program on RHEL5 with earlier GNAT/GCC versions and get the same results. I've also compiled 32 and 64 bit with no difference.

Thanks for the help

Re: Exception handling in Ada -> C++ call?

[Simon Wright]

kevin.a.peterson@gmail.com writes:

> When I build this and run testada, I get "terminate called after
> throwing an instance of 'int'," which I expect, however the
> application doesn't actually exit but spins a core to 100% usage until
> I kill it. Also interesting: If I replace the try block with

On Mac OS X (ML, Darwin 12.5.0) it doesn't spin: with GCC 4.8.0,

   $ ./testada 
   Calling TestCpp
   terminate called after throwing an instance of 'int'

   raised PROGRAM_ERROR : unhandled signal

and with GNAT GPL 2013,

   $ ./testada 
   Calling TestCpp
   libc++abi.dylib: terminate called throwing an exception

   raised PROGRAM_ERROR : unhandled signal

Re: Exception handling in Ada -> C++ call?

[Egil H H]

On Friday, October 18, 2013 3:53:27 PM UTC+2, kevin.a....@gmail.com wrote:
> Hi, I'm having problems with an Ada program I've been working on. This Ada 
> program makes a call to a C++ library, and the C++ call has a try/catch block.
> I think my problem boils down to uncaught exceptions hanging on the c++ side
> hanging the program. This code demonstrates the issue:

You may want to take a look at this gem:
http://www.adacore.com/adaanswers/gems/gem-114-ada-and-c-exceptions/