[FIXED] How to deal with "exit-time destructor" warning in clang?

Issue

In my C++11 code I get the clang warning "Declaration requires an exit-time destructor" in the following case:

static const std::map<int, const someStruct> mymap = {
    {1, {
        "A",
        "B",
        "C"
    }},
    {2, {
        "D",
        "E",
        "F"
    }}
};

As far as I understand Google an "exit-time destructor" is required to destroy main() and statics in a deterministic way to prevent crashes on exit due to "already released variables". Is that right? Can someone explain it better?

Plus: What can I do about it (I don't want to disable the warning)? The code above is used within context of one thread only.

Looks like this is the way Chromium deals with these cases; would that be the right way for my case as well?

#define CR_DEFINE_STATIC_LOCAL(type, name, arguments) \
  static type& name = *new type arguments

(Source: https://chromium.googlesource.com/chromium/src/+/32352ad08ee673a4d43e8593ce988b224f6482d3/base/basictypes.h)

Solution

Global and function static objects will get their destructors called when your application is exiting. these destructors are "exit time destructors". and are called in the reverse order that they were constructed in.

As you said, if some of these destructors touch already destroyed objects, your program could crash. Also, destructors running at exit time will make the program exit slower, and most of the time they are not necessary for the correctness of the program (since when the program exits, it'll release all its memory anyway).

The warning is simply pointing out that you have destructors that'll be run at exit time.

The fix you proposed will heap allocate the object, which will not cause it to be automatically destroyed at program exit. For your case, this is probably good enough.

Answered By - yiding

Answer Checked By - Katrina (PHPFixing Volunteer)