Return code from main ignored

[paulhankin]

The return code from main using libsupcxx is not the same as calling exit, at least in linux-x86_64-libsupcxx . Specifically, sys::exit(1) (which calls the C function exit(1)) causes a shell exit status of 1, whereas "return 1;" from an initial call to main leads to a shell exit status of 0.

Note, the C standard says:
5.1.2.2.3 Program termination

1. If the return type of the main function is a type compatible with int, a return from the
   initial call to the main function is equivalent to calling the exit function with the value
   returned by the main function as its argument.

[paulhankin]

This is strongly related to #25

My quick look suggests:

• return n; from main results in an exit status of 0 for all n
• running off the end of main correctly results in an exit status of 0
• calling std::exit(n) results in a exit status of 1 for all n (including 0)

I quick look at the code, and a simple test case suggests also that functions registered with std::atexit() are only called if std::exit is not called.