Re: [boost] [exception] Incompatibility betweenboost::throwexception and throw prototype declarations

6 Sep 2008

      ----- Original Message ----- 
From: "Andrey Semashev" <andrey.semashev@gmail.com>
To: <boost@lists.boost.org>
Sent: Saturday, September 06, 2008 8:59 AM
Subject: Re: [boost] [exception] Incompatibility 
betweenboost::throwexception and throw prototype declarations
...
On Sat, Sep 6, 2008 at 9:16 AM, vicente.botet 
<vicente.botet@wanadoo.fr>wrote:
...
----- Original Message ----- From: "Emil Dotchevski" <
emil@revergestudios.com>
To: <boost@lists.boost.org>
Sent: Saturday, September 06, 2008 6:52 AM
Subject: Re: [boost] [exception] Incompatibility between
boost::throwexception and throw prototype declarations
If G throws the excp using the boost::throw(excep) on 1.15 I was able to
write
void F() thows (excp) {
  // ...
  G();
  // ...
}
With 1.136 this code do not compile any more because 
boost::throw_exception
throws an unspecified exception. So what can I write instead of
--unspecified--
void F() thows (excp, --unspecified--) {
  // ...
  G();
  // ...
}
I hope this answer your question, let me know if it is not the case.
If I'm not mistaken, you are safe to add base classes to the exception
specification list. Since the "unspecified" exception derives from the
"excep" (otherwise you wouldn't be able to catch it), I assume you don't
need to change your code.
I have tried with a simple example that confirm what you said.

#include <boost/throw_exception.hpp>
#include <iostream>

struct excp : std::exception {};

void G() {
    boost::throw_exception(excp());
}

void F() throw (excp) {
    try {
        G();
    } catch (excp& e) {
        std::cout << __LINE__ << std::endl;
        throw;
    } catch (...) {
        std::cout << __LINE__ << std::endl;
        throw;
    }
}

int main() {
    try {
        F();
    } catch (excp& e) {
        std::cout << __LINE__ << std::endl;
    }

    return 0;
}

and compiled it with both versions. Everything is OK.

Sorry for the noice,

Vicente