g++ can't override exit function

问题

I have a c++ program where I want to compile out std::exit and use my own, i.e. via:

-Dexit=myExit

However, I run into this issue:

In file included from /usr/include/c++/7/ext/string_conversions.h:41:0,
                 from /usr/include/c++/7/bits/basic_string.h:6352,
                 from /usr/include/c++/7/string:52,
                 from /usr/include/c++/7/bits/locale_classes.h:40,
                 from /usr/include/c++/7/bits/ios_base.h:41,
                 from /usr/include/c++/7/ios:42,
                 from /usr/include/c++/7/istream:38,
                 from /usr/include/c++/7/sstream:38,
                 from tests/helpers.h:4,
                 from tests/helpers.cpp:1:
/usr/include/c++/7/cstdlib:146:11: error: ‘::exit’ has not been declared
   using ::exit;

I'm running it on virtualBox: Ubuntu 18.04 / 18.10 / Debian 10

回答1:

Instead of overriding exit on your own, which is non standard and risky, you could register your own functions to be executed at program exit using atexit.

atexit takes a function pointer parameter, (void (*func)(void)), and registers that function to be executed by exit (for reference, see glibc exit.c source code).

With this approach, you could register multiple functions to be executed at exit, plus, atexit behaviour is well defined in the C++ standard.

For examples and documentation, see:

• http://www.cplusplus.com/reference/cstdlib/atexit
• https://www.gnu.org/software/libc/manual/html_node/Cleanups-on-Exit.html

来源：https://stackoverflow.com/questions/53531550/g-cant-override-exit-function