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POWhat the c++ standard says about loosing throw specifier in default destructor
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  1. POWhat the c++ standard says about loosing throw specifier in default destructor
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    copied!<p>Three different compilers show three different behaviours compiling this code:</p> <pre><code>class MyException : public std::exception { public: MyException(std::string str) : m_str(str) {} virtual const char * what() const throw () {return m_str.c_str(); } protected: std::string m_str; }; </code></pre> <p>Sun C++ 5.8 Patch 121017-22 2010/09/29: <strong>Warning</strong> Function MyException::~MyException() can throw only the exceptions thrown by the function std::exception::~exception() it overrides</p> <p>g++ 3.4.3: <strong>Error</strong> looser throw specifier for `virtual MyException::~MyException()'</p> <p>Visual Studio 2005: <strong>It is very happy</strong> (neither error or warning)</p> <pre><code>class exception { public: exception () throw(); exception (const exception&amp;) throw(); exception&amp; operator= (const exception&amp;) throw(); virtual ~exception() throw(); virtual const char* what() const throw(); } </code></pre> <p>I know what the problem is and how I can fix it:</p> <pre><code>class MyException : public std::exception { public: MyException(std::string str) : m_str(str) {} virtual const char * what() const throw () {return m_str.c_str(); } ~MyException() throw() {} &lt;------------ now it is fine! protected: std::string m_str; }; </code></pre> <p><strong>However I am wondering what the standard says in specific situation.</strong></p> <p>I ran another small test in Visual Studio 2005 and I have found something that really surprise me:</p> <pre><code>struct Base { virtual int foo() const throw() { return 5; } }; struct Derived : public Base { int foo() const { return 6; } }; int main() { Base* b = new Derived; std::cout &lt;&lt; b-&gt;foo() &lt;&lt; std::endl; //&lt;-- this line print 6!!! delete b; } </code></pre> <p>The signature of the two functions are different. How can this work? It seems that visual studio 2005 completely ignore the exception specification.</p> <pre><code>struct Base { virtual int foo() const throw() { return 5; } }; struct Derived : public Base { int foo() { return 6; } // I have removed the const keyword // and the signature has changed }; int main() { Base* b = new Derived; std::cout &lt;&lt; b-&gt;foo() &lt;&lt; std::endl; // &lt;-- this line print 5 delete b; } </code></pre> <p><strong>Is this c++ standard? Is there any magic flag to set?</strong></p> <p><strong>What about VS2008 and VS2010?</strong></p>
 

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