This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 116a. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.

2024-12-19

265. Destructors, exceptions, and deallocation

Does the Standard require that the deallocation function will be called if the destructor throws an exception? For example,

    struct S {
        ~S() { throw 0; }
    };
    void f() {
        try {
            delete new S;
        }
        catch(...) { }
    }

The question is whether the memory for the S object will be freed or not. It doesn't appear that the Standard answers the question, although most people would probably assume that it will be freed.

Notes from 04/01 meeting:

There is a widespread feeling that it is a poor programming practice to allow destructors to terminate with an exception (see issue 219). This question is thus viewed as a tradeoff between efficiency and supporting "bad code." It was observed that there is no way in the current language to protect against a throwing destructor, since the throw might come from a virtual override.

It was suggested that the resolution to the issue might be to make it implementation-defined whether the storage is freed if the destructor throws. Others suggested that the Standard should require that the storage be freed, with the understanding that implementations might have a flag to allow optimizing away the overhead. Still others thought that both this issue and issue 219 should be resolved by forbidding a destructor to exit via an exception. No consensus was reached.

Rationale (October, 2008):

It was noticed that issue 353, an exact duplicate of this one, was independently opened and resolved.