Re: try/catch behaviour with SEH (VC++ 8)

From:

Ulrich Eckhardt <eckhardt@satorlaser.com>

Newsgroups:

microsoft.public.vc.language

Date:

Fri, 07 Sep 2007 13:05:07 +0200

Message-ID:

<4sn7r4-0c2.ln1@satorlaser.homedns.org>

Aurelien Regat-Barrel wrote:

     void test()
     {
         try
         {
             int *p = 0;
             *p = 0;
         }
         catch ( ... )
         {
             std::cout << "Catched in C++ handler!\n";
         }
     }

FYI: the past tense of 'catch' is 'caught' - stupid English irregular
verbs...

Now, the code above doesn't throw a C++ exception so the catch(...) handler
should never be invoked. Under VC though, such program faults can be mapped
to C++ exceptions which is why it works in the first place.

     int main()
     {
         __try
         {
             test();
         }
         __except( EXCEPTION_ACCESS_VIOLATION == GetExceptionCode() )
         {
             std::cout << "Catched in SEH handler!\n";
         }
         return 0;
     }

outputs "Catched in C++ handler!" if compiled with VC++ 6 - okay. But
VC++ Express 2005 SP1 warns about unreachable code in the catch(...)
block (warning C4702), and the compiled program outputs "Catched in SEH
handler!".

I guess VC knows that the code will never throw a C++ exception and thus
emits the warning. VC8 has a few flags that control the exception
behaviour. Which compiler flags (/EHsc or /EHa) do you use?

Uli